NASA Glenn Research Center
Research & Technology
Materials Highlights - CY 2004
U. S. Patent Awarded for Dual Microstructure Heat Treat (DMHT) process
Interaction with Worcester Polytechnic Institute Initiated
Modified Tape Cast Process for Solid Oxide Fuel Cells
Fabrication Process Developed to Increase Creep Resistance of SiC/SiC CMCs
Mach 0.3 Burner rig Incorporates a 12-caliber ballistic impact gun
A thin-walled, air-film-cooled combustor liner
Composite Materials for Fan Engine Containment featured in "Reinforced Plastics" magazine
Visit to the University of Puerto Rico – Mayaguez
NASA-Industry Nanotechology Workshop
Brazing techniques developed to bond metal and ceramic materials for solid oxide fuel cells
GRC-developed Ceramic Repair Material for On-orbit Repair of Space Shuttle RCC Leading Edge Successfully Tested at JSC
Furnace Study Experiments on Reinforced Carbon/Carbon
Studies to Predict Behavior of Reinforced Carbon/Carbon
Wrap Materials and Protective Coatings Identified for Reinforced Carbon/Carbon
GRABER (Glenn Refractory Adhesive for Bonding and Exterior Repair)
Nano-Lubricants
Radiative Heat Flux Through Translucent Thermal Barrier Coatings
Pinholes in Reinforced Carbon/Carbon
Guest Editor
Lightweight Polymer Matrix Composite Combustor Support
Optical, SEM, and microprobe characterization of Space Shuttle Panels
Reinforced Carbon-Carbon Crack Repair
RCC Pinholes, Again
NASA Engineering Safety Center Members
Assessment of Advanced Materials for a High-Temperature Stirling Convertor
On-Orbit Repair of Space Shuttle RCC Leading Edges
Adjunct Faculty Appointment
Ceramic matrix composite cooled panels successfully tested in scramjet rig
GRC developed GRABER (Glenn Refractory Adhesive for Bonding and Exterior Repair) compound scheduled for KC 135 flight test
Successful demonstration of Glenn Adhesive Refractory for Bonding and Exterior Repair (GRABER) at Ames Research Center
Rare Earth Silicate Environmental Barrier Coatings
Novel Molecular Architectures for Low Temperature Solid Polymer Electrolytes
New composite proton exchange membrane materials
International Thermal Spray Conference
Support for OV 105 Nose Cap Refurbishment Incident Investigation
Studies on the Reinforced-Carbon/Carbon (RCC) Recovered from Columbia featured article in The American Ceramic Society Bulletin
Simple Inspection Method for Thermal Barrier Coatings
Dr. Nathan S. Jacobson received the Silver Snoopy Award
A New Ceramic Matrix Composite (CMC) Cooled Panel Concept Successfully Tested
Return-to-Flight RCC Wrap Team Workshop
Advanced Turbine Disk Alloy ME3 receives R&D Magazine 2004 R&D 100 Award
“Development of Silicon Carbide/Silicon Carbide Ceramic Matrix Composites (SiC/SiC CMC’s) for High Temperature Space Transportation Applications,”
Modified Composition of Glenn Refractory Adhesive for Bonding and Exterior Repair (GRABER)
A Study of Volatile Species in the Cr2O3 – H2O – O2 System
Dr. Becky MacKay Providing Materials Consultation to the RCS (Reaction Control System) Thruster team for the Shuttle Orbiter
Dr. Rebecca A MacKay Receives Women in Aerospace, 2004 Outstanding Achievement Award
"Mechanics of Biological Tissue"
August 2004 Aerospace America article on Glenn-developed copper alloy GRCop-84
Best Paper award winner from the American Society of Mechanical Engineers and the International Gas Turbine Institute
American Helicopter Society (AHS) International Best Paper Award in Propulsion
Addition of Exfoliated Graphite to PMR-15 and its Effect on Processing and Performance
Fluorescent Chemical Sensor
Mechanism for environmental embrittlement of advanced titanium aluminide alloy identified
Lanthanum chromite based ceramic interconnect materials
Lower CTE fuel cell component
Advanced low conductivity coatings
A new polymer membrane for Proton Exchange Membrane (PEM) fuel cells
Vibration damping studies performed on a sample of GRC developed polymer cross-linked aerogels (X-aerogels)
January 2004
U. S. Patent Awarded for Dual Microstructure Heat Treat (DMHT) process
A U. S. Patent No. 6,660,110 was awarded for an innovative, low cost heat treat technology to produce superalloy turbine disks with a dual grain structure. The Dual Microstructure Heat Treat (DMHT) process produces disks with fine grain bores for optimal burst and fatigue strength, and coarse grain rims for optimal creep strength and crack growth resistance. The new method’s advantages include significantly lower cost and more reproducibility compared to prior methods, and it is being evaluated by Pratt & Whitney, Rolls Royce, and the Ladish Company for use in future aircraft engines for military and civilian applications. Various aspects of this work were funded by the Aviation Safety, Higher Operating Temperature Propulsion Components, and Ultrasafe Projects. (Point of Contact: 5120/John Gayda 3-3273; 5120/Tim Gabb; and 5920/Pete Kantzos, 3-5202)
Interaction with Worcester Polytechnic Institute Initiated
An innovative (to GRC) interaction with Worcester Polytechnic Institute (WPI) has just been initiated. For many years, WPI has had a graduation requirement for their senior engineering students to conduct a research project at an industrial or government laboratory. They have been interacting with both JSC and GSFC in past years. Their process includes developing a research proposal, a two-month residence at the partner's lab, and then a final report to their WPI faculty advisor. WPI pays for all expenses, including travel, housing and subsistence. This year we are fortunate to have five students on-site from 1/07/04 to 3/5/04. Three of these students will be conducting research projects in the Communications Division, and one each in the Structures and Acoustics Division and the Materials Division. Volunteer mentors in these Divisions have been coordinating project definitions with the students and their faculty advisors for the past several months to define exciting and challenging technical opportunities. The office of University Affairs will coordinate this program in the future. (Points of Contact: 5100/Hugh Gray, 3-3230 and 5010/Dave Kankam, 3-6143,
Modified Tape Cast Process for Solid Oxide Fuel Cells
A modified tape cast processing technique has been developed to fabricate solid oxide fuel cell (SOFC) with functionally graded and engineered pore structure. One of the challenges for high power density SOFC systems is mass transport at high fuel utilization. The modified process, called freeze-tape casting, allows the tailoring of pore structures to achieve optimal gas diffusion and infiltration properties to minimize effects of concentration polarization in electrode supported SOFC systems. Graded pore structures with directionally aligned pores have successfully been fabricated with several ceramic SOFC constituent materials, such as yttria stabilized zirconia, strontium titanate, and lanthanum strontium manganate. This work was supported by the LEAP Project. (Point of Contact: 5130/Stephen Sofie, 3-3869)
Fabrication Process Developed to Increase Creep Resistance of SiC/SiC CMCs
A fabrication process has been developed to increase creep resistance of silicon carbide fiber reinforced silicon carbide ceramic matrix composite (SiC/SiC CMC) by more than an order of magnitude. Silicon carbide based CMC systems are prime candidates for application in cooled CMC structures for space propulsion systems. The creep rupture life of current state-of-the-art SiC/SiC CMC is on the order of 20 hr at 2650oF, the life being limited by the presence of silicon in the matrix. A process consisting of a combination of chemical vapor infiltration and polymer impregnation pyrolysis has been developed to eliminate silicon in the matrix. This has increased the creep rupture life of SiC/SiC CMC at 2650oF to more than 500 hours. This work was supported by the NGLT Program. (Point of Contact: 5130/Ram Bhatt, 3- 5513; 5100/Jim DiCarlo, 3-5514)
Mach 0.3 Burner rig Incorporates a 12-caliber ballistic impact gun
A Mach 0.3 burner rig has been modified through the incorporation of a 12-caliber ballistic impact gun for studies of the foreign object damage to monolithic and composite ceramics at temperatures as high as 2400oF. Environmental barrier coated-silicon nitride materials are being developed for cooled vane applications in turbine engines. Establishing the durability of the material system in a water-vapor containing combustion environment is well underway. However, in application the coating must be resistant to impact damage, cracking and spallation, so that the vane may continue to function as required. Various aspects of this work were funded by the High Operating Temperature Propulsion Components within the Propulsion & Power and the Ultra-Efficient Engine Technology Projects. (Points of Contact: 5160/Dennis Fox 3-3295 and 5160/Michael Cuy, 3-3159)
A thin-walled, air-film-cooled combustor liner
A thin-walled, air-film-cooled combustor liner has been fabricated at NASA Glenn for testing in the Research Combustion Laboratory Cell 21. Structural analysis of the liner has shown stresses due to the pressure pulses, which will be experienced in a pulse detonation cycle, will be relatively benign compared to the thermally-induced stresses. This work has been funded by the Power & Propulsion (Pulsed Detonation Engine) and the Low Emissions Alternate Propulsion (Constant Volume Combustion Cycle Engine) Projects. (Points of Contact: 5160/Dennis Fox, 3-3295, 5920/Louis Ghosn, 3-3822 and 5830/Kevin Breisacher, 977-7475)
February 2004
Composite Materials for Fan Engine Containment featured in “Reinforced Plastics” magazine
A new GRC efforts in the development and evaluation of composite materials for fan engine containment systems was featured in the December 2003 issue of “Reinforced Plastics” magazine (vol. 47, no. 11, p28). Previous attempts to use composites to reduce the weight of metal fan cases have not been successful because of inadequate damage tolerance and high cost. The article describes work done by A&P Technology (SBIR Contract NCC3-01260, Gary Roberts COTR) to demonstrate a low cost manufacturing approach for composite fan cases. In this approach, T700 triaxial carbon sleeve is braided in a custom shape that exactly fits the dimensions of the fan case. The composite case is then made by infusion of resin into the carbon fiber preform. Researchers at GRC collaborated with A&P to determine optimum fiber architectures and matrix materials (5150/Gary Roberts, 5930/Cheryl Bowman) and to develop advanced analytical methods for the braided materials (5920/Robert Goldberg, 5930/Kelly Carney). The article also describes results of recent impact tests in the Ballistic Impact Laboratory at NASA GRC that demonstrated the high damage tolerance of composites fabricated using the T700 triaxial braid (5930/Mike Pereira, Duane Revilock, Dale Hopkins). The A&P/GRC team is currently working with GEAE, Honeywell International, and Williams International to transition the technology to commercial engines. Fabrication and testing of several full size composite fan cases is planned for FY04. This work is supported by the Aviation Safety and Security Program (Susan Johnson, Project Manager). (Point of Contact: 5150/Dr. Gary D. Roberts, 3-3244)
Visit to the University of Puerto Rico – Mayaguez
Dr. Marla Perez-Davis (5420) and Dr. Michael A. Meador (5150) visited the University of Puerto Rico – Mayaguez on February 3rd and 4th. They presented a seminar on nanotechnology, including the rationale for NASA’s interest in this area and examples of recent GRC research in nanotechnology derived materials. A meeting was held with UPR faculty in Chemistry and Chemical Engineering to discuss areas of mutual interest in nanotechnology and the possibility for collaborations between NASA and UPR-Mayaguez. Dr. Meador toured laboratories in the Chemistry and Chemical Engineering Departments and had further discussions with faculty. (Point of Contact: 5150/Dr. Michael A. Meador, 3-9518)
NASA-Industry Nanotechology Workshop
Dr. Michael A. Meador(5150) and William Saettel (9400) participated in the NASA-Industry Nanotechology Workshop held at the Crystal City Marriott on January 22nd and 23rd . This workshop, sponsored by the NASA Technology Transfer Center and Code R, was designed to introduce representatives from a select group of industry leaders in nanotechnology to NASA research programs in the development and application of nanotechnology for advanced materials, electronics and sensors. Break-out sessions were held to allow industry participants to comment on NASA research and outline potential opportunities for collaboration. These collaborations were further discussed in one-on-one
Brazing techniques developed to bond metal and ceramic materials for solid oxide fuel cells
Brazing techniques have been developed to bond metal and ceramic materials used in solid oxide fuel cell stack construction. This work is being conducted in collaboration with SOFCo-EFS Holding, LLC, a solid oxide fuel cell manufacturer located in Alliance, Ohio. Active brazing techniques have successfully been developed to bond stainless steel end plate to yttria stabilized zirconia based interconnect used in SOFCo’s stack designs. Several braze materials have been identified for further evaluations leading to stack demonstration at SOFCo-EFS. The initial success of the brazing study has resulted in a Reimbursable Space Act with SOFCo-EFS. This work was supported by the LEAP Project. (Points of Contact: 5130/ Trah Shpargel, 3- 2644; 5130/Jay Singh, 3-8883)
GRC-developed Ceramic Repair Material for On-orbit Repair of Space Shuttle RCC Leading Edge Successfully Tested at JSC
The ceramic repair material developed at GRC for on-orbit repair of space shuttle RCC leading edge has been successfully tested in the arc jet facility at JSC. Three samples of the repair material called GRABER (Glenn Refractory Adhesive Bonding and Exterior Repair) were tested in the JSC arc jet facility at 2960oF for a total time of 12 minutes. One specimen performed exceptionally well for the entire 12 minute test. The other two specimens performed well up to 8 minutes, the shorter time attributed to fabrication defects. Because of the success in the arc jet test, the GRABER material is now being considered for other repair concepts, as a patch in plug repair concept and as a paste to cover small surface cracks. The next generation of GRABER material (GRABER-12) will be tested in JSC arc jet facility within the next month. This work was supported by the RTF project. (Points of contact: 5130/Jay Singh, 3-8883; 5130/Tarah Shpargel, 3-2644)
Furnace Study Experiments on Reinforced Carbon/Carbon
A series of controlled laboratory experiments are underway to explore and understand observed changes between as-processed and post-flight Space Shuttle Reinforced Carbon/Carbon leading edge panel materials. The furnace study experiments include: A.) Exposure of a carbon fabric infiltrated with carbon matrix material and treated with tetra-ethyl-ortho-silane (RCC P-3 + TEOS) to 10 cycles at 3000oF to determine the role of a carbothermal reduction reaction in the RCC aging process. B.) Furnace testing of an RCC with SiC coating was exposed to 10 oxidation cycles (5 torr, air) to 2900 oF, to compare with the oxidation pattern observed following RCC aging C.) Exposure of RCC with SiC coating to 10 cycles in gettered argon to 2900 oF to confirm that no oxidation-like reaction occurs in an inert environment. Exposed specimens are currently being prepared for microstructural analyses. (Point of Contact: 5160/Dr. Nathan S. Jacobson, 3-5498)
Studies to Predict Behavior of Reinforced Carbon/Carbon
Two new studies have been initiated to understand and predict Reinforced Carbon/Carbon (RCC) behavior, in collaboration with Dr. Donald Curry, NASA-JSC Leading Edge Subsystem Group. In previous studies at NASA GRC an oxidation model based on molecular oxygen – containing environment was developed and verified using experimental furnace data. Modeling of oxidation below craze cracks found in RCC materials is now underway to adapt the existing model to the use of atomic oxygen, which is the environment for RCC materials in an arc jet test and during Shuttle flight. In a second study, a sodium silicate glass sealant, which is the outermost coating on RCC materials, will be evaluated in the laboratory at high temperatures. The nose caps of the Orbiter loose glass at a rapid rate--more so than the wing leading edge. This appears to be a vaporization problem through a boundary layer. There are correlations for the wing leading edge, but these will require modification. This work is funded by the Return to Flight through the Space Propulsion Office. (Point of Contact: 5160/Dr. Nathan S. Jacobson, 3-5498)
Wrap Materials and Protective Coatings Identified for Reinforced Carbon/Carbon
Progress and status of the GRC Return to Flight (RTF) Reinforced Carbon/Carbon (RCC) Wrap Team have identified wrap materials and protective coatings. Five refractory sheet alloys and a silicide coating have been obtained through GRC procurement and/or through ATK Thiokol and H.C. Stark. The sheet material will be machined into test strips or disks early in the week of 3/16 and shipped to the coating vendor. Fe, Cr and Si powders were also procured to explore formation of silicide coatings on Re which, to our knowledge, has not been previously performed. In addition a test fixture has been designed and fabricated to hold a 2"x2" piece of RCC analog for calibration testing in the QARE rig. Calibration runs to heat this material to 2960oF are underway. The Agency wrap team leadership has also become interested in a Cr-MgO material tested in the 1960's and recently developed further by Dr. Michael Brady at Oak Ridge National Laboratory. A 1/8" thick piece of this material survived torch test screening at ATK Thiokol. Dr. Brady provided funds for ORNL to fabricate this alloy for arc jet testing in late February. The torched sample has been sent to GRC for analysis. Scanning electron microscopy of surface oxides and morphology has been performed. Further analysis at GRC, ORNL and NASA LaRC will be conducted once sectioned pieces are available for metallurgical mounting. The GRC wrap team lead (F. Ritzert) attended an RTF materials meeting at JSC on 2/11/04 to discuss materials issues for RTF repairs and observe arc jet testing. (Points of Contact: 5160/Dr. James Nesbitt, 3-3275 and 5120/Frank Ritzert, 3-8199)
GRABER (Glenn Refractory Adhesive for Bonding and Exterior Repair)
GRC-developed GRABER (Glenn Refractory Adhesive for Bonding and Exterior Repair) is one of the three concepts downselected for fast track development so that the concept can be evaluated as part of DTO (Define Test Objectives) for STS 114 flight. The GRABER based solution will be an integral part of the inflatable fabric balloon repair concept. The efforts from now on will be focused on design and development activities to gain maximum confidence in repair capability prior to flight. The GRABER development activities at GRC will support PDR at the end of April 2004 and CDR at the end of July 2004. The GRABER concept is also being considered for repair of small cracks. This work was supported by the Return to Flight Program. (Point of Contact: 5130/Jay Singh, 3-8883; Tarah Shpargel, 3-2644).
March 2004
Nano-Lubricants
Nano-lubricants, such as single-wall carbon nanotubes (SWNTs), multi-wall carbon nanotubes (MWNTs), graphitized MWNTs, carbon nano-onions, and fluorinated SWNTs, with superior friction properties and endurance lives in air or ultrahigh vacuum, a space-like environment, have been developed. Aerospace applications include the development of microelectromechanical systems (MEMS) and micromachines. The nano-lubricants can be applied to physical, chemical, and mechanical contacting surfaces in relative motion. Friction contributes to decreased performance, increased energy consumption, wear damage, added maintenance, shortened lives or catastrophic failure, and reliability issues for contacting interfaces of all mechanical systems. All nano-carbons dramatically improve stiction (or adhesion) and friction between contacting surfaces under dry conditions, a major issue for MEMS and micro-machines. In particular, the coefficient of friction for reduced SWNTs and nascent SWNTs is one fiftieth and one tenth, respectively, of that for conventional graphite lubricants in air. The coefficient of friction for graphitized MWNTs is one fifth that of MoS2 lubricants in ultrahigh vacuum. This work was sponsored by the Alternate Fuel Foundation Technologies Subproject of the Low Emissions Alternative Power Project at the NASA Glenn Research Center. (Points of Contact: RMD (5160)/Dr. Kazuhisa Miyoshi, 3-6078; RU (6711)/Dr. Randy Vander Wal, RU (6700)/Aaron J. Tomasek; RS (5960)/Dr. Kenneth W. Street, Jr., Rice University/Professor Valery N. Khabashesku, and Akima/Richard J. Mondry)
Radiative Heat Flux Through Translucent Thermal Barrier Coatings
Predicting the radiative heat flux through translucent thermal barrier coatings (TBCs) and its effect on the degree of thermal protection provided by the TBC depends on knowing the coating’s radiative properties. Absorption and scattering coefficients over a wavelength range from 0.8 to 7 microns for a plasma sprayed yttria-stabilized zirconia TBCs were determined by fitting a four-flux radiation model to measurements of hemispherical reflectance and transmittance for eight different thicknesses of TBCs. This has enabled prediction of radiative heat flux through any combination of TBC thickness and choice of substrate. An immediate benefit of the model using the determined radiative properties was gained by calculating the reflectance expected at the operating wavelength of a 4 micron wavelength probe from a 120 micron thick TBC that was attached to its substrate versus the reflectance for a TBC that had delaminated – These calculated values showed excellent agreement with actual measurements and provide a firm basis for using reflectance to monitor TBC delamination. Funding for this work was provided by the UEET Project. (Point of Contact: RMD (5160)/Dr. Jeffrey Eldridge, 3-6074 and RMC (5130)/Charles Spuckler, 3-2167)
Pinholes in Reinforced Carbon/Carbon
In the mid-1990’s, pinholes were first observed in the reinforced carbon/carbon (RCC) wing leading edge and nose cone materials on a returning Space Shuttle which had been flown over ten missions. Dr. Nathan Jacobson was contacted by the RCC Leading Edge Project Manager (Donald Curry) to examine/characterize the pinholes and to identify possible chemical reaction mechanisms which could lead to their formation. Through careful study of the flown RCC, using a new field emission scanning electron microscope, zinc was found within the pinholes. Technical discussions with Donald Curry’s team resulted in identifying the likely source as zinc primer paint on the launch pad (for corrosion protection). An experimental study was initiated at Glenn to reproduce the pinhole formation in the laboratory. The chemical mechanism of pinhole formation, which did indeed require the presence of zinc, was identified. In-depth follow-on contamination studies were conducted by NASA Johnson, Kennedy and contractor engineers by installing witness panels to launch pad structures for data on the extent of the contamination. Following the loss of the Shuttle, the Columbia Accident Investigation Board was aware of this work and requested an additional study to determine if zinc was continuing to leach off the launch structures. KSC completed their evaluation and reported finding significant levels of zinc contamination from the launch pad. A presentation of the study results and recommendations for implementing new sampling/analysis, wing protection and post-launch pad cleaning procedures, including a dedicated maintenance crew for the launch towers, was given to the Shuttle management in early March 2004. NASA Glenn was an important contributor to the initiation of this comprehensive study, providing evidence of the presence of zinc and the mechanism of RCC degradation. This work was funded by the Shuttle Office at Johnson Space Center. (Point of Contact: RMD (5160)/Dr. Nathan S. Jacobson, 3-5498 and RMM (5120)/Terry R. McCue, 3-3349)
Guest Editor
Dr. Dongming Zhu was a Guest Editor for a special publication issue of the Journal of Thermal Spray Technology, Volume 13 (1), March 2004. Three journal articles written by Glenn researchers were incorporated in this issue. The research topics were all related to our work in thermal barrier coatings and included: Depth-Penetrating Temperature Measurement of Thermal Barrier Coatings Incorporating Thermographic Phosphors by J. I. Eldridge (RMD(5160)), T. J. Bencic (RI (5520), S.W. Allison (ORNL) and D. L. Beshears (ORNL) pp 44-50 Improved Oxidation Life of Segmented Plasma Sprayed 8YSZ Thermal Barrier Coatings by J. L. Smialek (RM (5100) pp 66-75 Furnace Cyclic Oxidation Behavior of Multicomponent Low Conductivity Thermal Barrier Coatings by D. Zhu (RMD/Army (5160)), J.A. Nesbitt (RMD (5160)), C.A. Barrett (RMD (5160), T. R. McCue RMM (5120) and R. A. Miller (RMD (5160)) pp 84-92
Lightweight Polymer Matrix Composite Combustor Support
A lightweight high temperature polymer matrix composite (HTPMC) combustor support chamber for a Rocket Based Combined Cycle engine successfully survived hot-fire testing at ATK-GASL. This testing concludes a three year collaboration between GRC and Boeing to design, fabricate and test the support structure and fulfills a GPRA milestone for the UEET Program. The support structure was prepared from a GRC developed high temperature composite material, PMR-II-50. In addition to satisfying an important technical milestone, this activity is noteworthy because it constitutes a number of “firsts.” This is the first application for Rocketdyne of a high temperature polymer matrix composite in a space propulsion component. Successful completion of this test will enable Rocketdyne to explore other applications for HTPMCs in their engines. It is also the first time that a full-scale PMC structure has been tested at GASL. Experience gained from this testing will enable GASL to more easily test similar structures. In addition to Rocketdyne, this effort involved the participation of twenty-four companies (component designers, fabricators, resin/materials suppliers, etc.), universities (U of Dayton, U of Denver), and the Air Force Materials Lab. This effort utilized GRC expertise and facilities in the Life Prediction (5920), Structural Mechanics and Dynamics (5930) Branches, and Engineering and Technical Services Directorate. This project was supported by the former HOTPC program and is currently funded by UEET-Highly Loaded Light Weight Compressors and Turbines. (Points of Contact: RMP (5150)/Dr. James K. Sutter, 3-3226; RMP(5150)/Dr. E. Eugene Shin, 3-2544; RSL (5920)/Dr. John Thesken, 3-3012)
Optical, SEM, and microprobe characterization of Space Shuttle Panels
A “micro” strip 0.25 inches wide x 15 inches long from panels 10L (19 flights) and 12R (15 flights has been sectioned into one inch lengths. 6 samples from each panel have been polished for optical, SEM and microprobe characterization. Preliminary results show microstructural differences between these panels and OV 103 Panel 8L, characterized previously. Some iron contamination is observed beneath the sealant glass in 12R, and is being investigated further. This work will continue over the next 4-5 weeks and is supported by the Return to Flight project. (Point of Contact: RMC (5130)/Dr. Frances Hurwitz, 3-5503)
Reinforced Carbon-Carbon Crack Repair
Reinforced Carbon-Carbon (RCC) Composite disks (2.8” diameter) with machined cracks were successfully repaired with Glenn Adhesive Refractory for Bonding and Exterior Repair (GRABER-12 A) material. These specimens were tested in ArcJet facility at Johnson Space Center. The crack repaired composite disks survived the test duration simulating the reentry conditions. Preliminary examination shows the formation of a thin layer of glassy phase on the heated surface. Detailed micro-structural characterization of the tested specimen is underway. This work was supported by the Return to Flight project. (Points of Contact: RMC (5130)/ Jay Singh, 3-8883; and RMC (QSS)/Tarah Shpargel, 3-2644)
RCC Pinholes, Again
In the mid-1990’s, pinholes were first observed in the reinforced carbon/carbon (RCC) wing leading edge and nose cone materials on returning Space Shuttle orbiters which had been flown over ten missions. Dr. Nathan Jacobson examined/characterized the pinholes. Using Glenn's advanced field emission scanning electron microscopy, zinc was found within the pinholes. RCC engineers, from Johnson and Kennedy Space Centers indicated the likely source was the corrosion-resistant zinc primer on the launch pad. A study was initiated at Glenn to reproduce the pinhole formation in the laboratory. The chemical mechanism of pinhole formation was identified and did indeed require the presence of zinc. In-depth follow-on studies were initiated by NASA Johnson and Kennedy engineers and involved attachment of witness panels to launch pad structures to quantify the amount of zinc contamination. In addition, the Columbia Accident Investigation Board, being aware of this issue, requested follow-on studies to determine if zinc was continuing to leach off the launch structures. Significant levels of zinc contamination continued to be problematic. Results of the contamination studies and recommended procedures, which if implemented would minimize zinc contamination, were given to Shuttle management in early March 2004. The recommendations included continuing sampling/analyses for zinc on the pad, wing protection structures on the launch structure and a post-launch pad cleaning procedure, to be performed by dedicated maintenance crew for the launch towers. NASA Glenn was an important contributor to the initiation of this comprehensive study, providing the evidence of the presence of zinc associated with each pinhole and the identification of the chemical mechanism of RCC degradation. This work was funded by the Shuttle Office at Johnson Space Center. (Contact: RMD (5160)/Dr. Nathan S. Jacobson, 3-5498 and RMM (QSS)/Terry R. McCue, 3-3349)
NASA Engineering Safety Center Members
The NESC (NASA Engineering Safety Center) has approved three members from GRC's Materials Division for the Materials Super Problem Resolution Team. Dr. Andy Eckel will be the team lead for ceramics, ceramic matrix composites and appropriate protective coatings; Dr. Jim Sutter will be the team lead for polymers, polymer matrix composites and appropriate protective coatings; while Dr. Becky MacKay will be the lead for two teams - high temperature metals/alloys and their failure mechanisms, as well as micro-structural characterization of all classes of materials. Additional materials experts from LaRC, JSC, and MSFC round out this team. (Point of Contact: RM (5100)/Hugh Gray, 3-3230)
April 2004
Assessment of Advanced Materials for a High-Temperature Stirling Convertor
An assessment of advanced materials for a high-temperature Stirling Convertor was recently completed and presented at the Space Technology and Applications International Forum (STAIF) Conference. The current Stirling design operates with a heater head temperature of 650°C and is fabricated from the nickel base superalloy 718. This temperature is at the limit of Alloy 718’s capability, and any planned increase in temperature will be contingent upon identifying a more capable material from which to fabricate the heater head. Materials and fabrication schemes were presented that would allow the operating temperature to be increased within the range of 850-2000°C. This work under the Advanced Stirling Technology Development for Radioisotope Power is funded by the Office of Space Science (Code S) and was previously funded by the Office of Aerospace Technology (Code R) at NASA Headquarters. (Point of Contact: RMM (5120)/Randy Bowman, 3-3205)
On-Orbit Repair of Space Shuttle RCC Leading Edges
As part of the Space Shuttle Return-to-Flight Activities, research is underway in the Materials Division to develop and demonstrate advanced materials that can meet the requirements of an on-orbit repair of damage to the Reinforced Carbon- Carbon (RCC) wing leading edges. Since prescreening of candidate materials is required prior to arc jet testing, an oxygen-propane torch test has been developed to simulate the high heat fluxes and temperatures encountered by the RCC material during re-entry. Test conditions were established to duplicate the hottest RCC re-entry temperature of 2960º F for 15 minutes. The heat flux necessary to achieve this temperature on RCC analog is approximately 220 BTU/ft2-sec. To date, numerous refractory-based alloys (Ta, Mo, Nb, Re) with silicide coatings have been tested as well as two uncoated Cr-Re-MgO alloys. Only the uncoated Cr-Re-MgO alloys and the coated Re material have passed this severe prescreening test and are undergoing additional testing. This work was funded by the Return to Flight Project via the Space Transportation Project Office. (Point of Contact: RMD(5160)/Jim Nesbitt, 3-3275; RMD(QSS)/Craig Robinson (3-5547); RMM(5120)/Frank Ritzert, 3-8199; and RMM(QSS)/Mark Jaster, 8906)
Adjunct Faculty Appointment
The Cleveland State University Provost for Academic Affairs has appointed Dr. James Smialek, Materials Division, as an adjunct faculty member of the Department of Chemistry. He is serving as co-advisor for the doctoral research of Ms. QuynhGiao Nguyen, a researcher in the Durability and Protective Coatings Branch. He recently gave a talk at the CSU Chemistry Department graduate seminar series entitled, "Chemistry Issues in the High Temperature Corrosion of Aerospace Materials." (Point of Contact: RMD(5160)/Jim Smialek, 3-5500)
Ceramic matrix composite cooled panels successfully tested in scramjet rig
Ceramic matrix composite cooled panels have successfully been tested in a scramjet rig in a joint NASA GRC/United Technologies Research Center (UTRC) program. This is a major technological milestone toward the future use of ceramic composites in the Next Generation Launch Technology program. The 6” x 30” cooled panel, which is the largest cooled CMC panel tested to date, survived the maximum possible run duration of thirty seconds under scramjet conditions in the UTRC test rig. Material temperatures measured just below the surface of the panel recorded sustained temperatures of 2533oF, while estimated surface temperatures of approximately 3000oF were calculated. The CMC heat exchanger design using hydrocarbon fuel cooling was optimized based on earlier tests in the Cell 22 Research Combustion Lab at NASA GRC. This work was supported by the NGLT Program. (Point of Contact: RMC (5130)/Martha Jasjowiak, 3-5515)
GRC developed GRABER (Glenn Refractory Adhesive for Bonding and Exterior Repair) compound scheduled for KC 135 flight test
GRC developed GRABER (Glenn Refractory Adhesive for Bonding and Exterior Repair) compound is scheduled for KC 135 flight test during the second week of April. The goal of the flight test is to compare the material behavior under zero G and 1 G conditions. In preparation for the KC 135 flight test, more than three pounds of the GRABER were produced at GRC and sent to Johnson Space Center. The flight test will also simulate crack repair and plug repair. This work was supported by the Return to Flight project. (Points of Contact: RMC(5130)/Jay Singh, 3-8883; RMC(QSS)/Tarah Shpargel, 3-2644; and RMC(QSS)/Ron Phillips, 3- 6216)
May 2004
Successful demonstration of Glenn Adhesive Refractory for Bonding and Exterior Repair (GRABER) at Ames Research Center
The crack repair capability of Glenn Adhesive Refractory for Bonding and Exterior Repair (GRABER) material for Reinforced Carbon-Carbon (RCC) composites was recently demonstrated through successful arc jet tests at Ames Research Center (ARC). Cracks were introduced in RCC specimens by machining slots, and the slots were filled with GRABER repair compound. Six RCC specimens with 0.035” and 1/16” machined slots were repaired with GRABER, and the repaired specimens were tested in arc jet facility at ARC for approximately 15 minutes. All six samples survived the tests without any burn through. This work was supported by the Return to Flight project. (Points of Contact: RMC(QSS)/Jay Singh, 3-8883; RMC(QSS)/Tarah Shpargel, 3-2644)
Rare Earth Silicate Environmental Barrier Coatings
Rare earth silicate environmental barrier coatings (EBCs) developed for silicon carbide-reinforced silicon carbide (SiC/SiC) composites have been applied to silicon nitride ceramics. Volatility tests, conducted up to 2800oF in a simulated combustion environment, indicate that rare earth monosilicates are considerably more stable in water vapor than the current barium-strontium-alumina-silicate (BSAS) EBC. Rare earth monosilicates also exhibit superior chemical compatibility compared to BSAS. The chemical compatibility is especially critical for silicon nitride ceramics because of the high chemical reactivity of the oxide additives in silicon nitride ceramics. Rare earth monosilicates also possess coefficients of thermal expansion which match quite well with silicon nitride ceramics, minimizing the thermal strain that can develop during thermal cycling. Rare earth monosilicate EBC-coated silicon nitride ceramics have exhibited up to 400 hours durability (longer exposures are in progress) in a simulated combustion environment at 2600oF, while the current EBC has suffered from massive glass formation. A U.S. patent is pending. Funding is provided from the Ultra-Efficient Engine Technology Project. (Point of Contact: RMD(CSU)/Dr. Kang N. Lee, 3-5634)
Novel Molecular Architectures for Low Temperature Solid Polymer Electrolytes
Novel molecular architectures for potential use as solid polymer electrolytes suitable for low temperature ionic conductivities are being studied. Under a Space Act Agreement, Eveready Battery Company has finished an initial evaluation of the rod-coil polymer electrolytes developed at NASA Glenn. The stability of the polymers in cells with various electrode materials was measured over a four month timeframe by monitoring impedance. Overall the materials were stable enough to take the next step and prepare cells for cycling. Funding is being provided from the Polymer Energy Rechargeable Systems Program (PERS). (Point of Contact: RMD(5160)/Dr. Mary Ann Meador, 3-3221)
New composite proton exchange membrane materials
New composite proton exchange membrane materials have been made from polystyrene cross-linked aerogels and ionic liquids. These new membrane materials show proton conductivities of 0.01 Scm-1 at 140°C without the need for humidification. Increasing the operating temperature of Proton Exchange Membrane (PEM) Fuel Cells from 80°C to 150°C will significantly enhance the power density of the fuel cell. Conventional PEM fuel cells are limited to operating temperatures no higher than 80°C, because the membrane material, typically Nafion, loses moisture and cannot effectively conduct protons at higher temperatures. Use of Nafion based PEM fuel cells requires the use of rehydration systems, which are heavy, bulky and add complexity to the fuel cell system. The new membrane materials enable the operation of fuel cells at high temperatures and also eliminate the need for rehydration systems. Further development of these materials is underway to increase their operating temperature capability and to evaluate their performance in fuel cells. This work is being supported by the Aircraft Fuel Cell Propulsion Systems subproject in the LEAP project. (Point of Contact: Dr. James D. Kinder, 5150, 3-3149)
June 2004
International Thermal Spray Conference
Professor Joachim Heberlein, from the University of Minnesota, received an award at the May 2004 International Thermal Spray Conference in Osaka, Japan for his presentation “Nanophase Partially Stabilized Zirconia Intermediate Layer for Strain Accommodation in a Multi-Layer Thermal Barrier Coating,” based on research performed in conjunction with the State University of New York at Stoney Brook and NASA Glenn. The research was conducted in the 3000o F advanced coatings effort funded by the Ultra-Efficient Engine Technology Project and technical oversight was performed by Dr. Jeffrey Eldridge. (Point of Contact: RMD (5160)/Dr. Jeffrey Eldridge, 3-6074)
Support for OV 105 Nose Cap Refurbishment Incident Investigation
The Durability and Protective Coatings Branch is providing support for OV 105 Nose Cap Refurbishment Incident Investigation. Free standing Type A coating has been fabricated and is undergoing thermogravimetric measurements and coefficient of thermal expansion (CTE) measurements. Scenarios where pressure could be generated of sufficient force to remove the SiC coating on the reinforced-carbon/carbon (RCC) are being evaluated. Dr. Donald Curry (Leading Edge System Manager, NASA JSC) visited the group for discussions on this topic. (Point of Contact: RMD (5160)/Dr. Nathan Jacobson, 3-5498)
Studies on the Reinforced-Carbon/Carbon (RCC) Recovered from Columbia
The Durability and Protective Coatings Branch in conjunction with Sandia National Laboratory is conducting further studies on the reinforced-carbon/carbon (RCC) recovered from Columbia. Both Raman spectroscopy (Sandia) and electron microscopy (Glenn) are used to examine pieces of the RCC near the breach. Raman spectra are compared to those of carbon chars formed at known temperatures and the results are used to estimate exposure temperatures. Preliminary results indicate temperatures near the breach are in excess of 2700oC. Microstructures indicate heavy oxidation and erosion of these regions. (Point of Contact: RMD (5160)/Dr. Nathan Jacobson, 3-5498)
Featured Article in The American Ceramic Society Bulletin
A NASA Glenn research paper “Thermal Barrier Coating Integrity,” has been selected as a featured article in The American Ceramic Society Bulletin, Volume 83, Number 6 (electronically posted). The paper describes how a four-flux pure-scattering model was used to demonstrate that mid-infrared reflectance could reproducibly track the progression of a yttria-stabilized zirconia thermal barrier coating (TBC) delamination, which was produced by repeated thermal cycling of plasma-spray processed TBCs coatings on superalloy substrates. The authors included Dr. Jeffrey Eldridge, Mr. Charles Spuckler and Dr. James Nesbitt, and Dr. Kenneth Street. (Point of Contact: RMD (5160)/Dr. Jeffrey Eldridge, 3-6074)
Commercialization of the GRC-developed X-Aerogels
On June 2 Nick Leventis visited Keller Companies in Manchester, NH to explore possibilities for collaboration / commercialization of the GRC-developed X-Aerogels. While GRC is working on these novel materials for use as lightweight, durable cryotank insulation materials for hydrogen powered aircraft, they also have numerous non-aerospace applications. Keller is the world leader in manufacturing and sale of translucent insulated building panels for use in walls, as curtain walls and integral wall components, and in roof applications. The selling features are day lighting, providing controlled light, combined with thermal efficiency and architectural appeal. Keller products are installed in many buildings and structures in nearly every city in the USA. The Keller Companies employs about 650 people, and has sales of more than $80M per year. To improve transparency with lower thermal conductivity Keller is interested in commercialization of day-lighting panels filled with aerogel granules. Friability of these granules is something that Keller thinks can be improved if they could be made available in a more elastic form. Keller believes that GRC’s cross-linked translucent and flexible aerogel foam will be critical to eliminate "settling" of the aerogel granules which they currently experience with the commercial product used in their production. This research is funded by Internal Research and Development. (Point of Contact: RMP (5150)/Dr. Nicholas Leventis, 3-3202).
Great Lakes Photonics Symposium
Dan Tyson gave a presentation entitled “A New Chemosensory Material and Evaluation of Luminescent Behavior” at the Great Lakes Photonics Symposium. This presentation discussed recent work at GRC on the development of fluorescent “on-off” sensors for the detection of chemical species, including chemical warfare agents. The subject sensor molecule, which is not fluorescent by itself, fluoresces a bright green-yellow when exposed to acid or “safe” chemical surrogates for Sarin nerve gas and mustard gas. This molecule is capable of detecting less than parts per million concentrations of these chemicals. This research is funded by Alternative Energy Foundations Technology. (Points of Contact: RMP (OAI)/Dr. Daniel Tyson, 3-3188 and RMP (5150)/Dr. Michael Meador, 3-9518)
Hydrogen Aircraft Technologies Workshop
A Hydrogen Aircraft Technologies Workshop sponsored by the Aeropropulsion Project Office was held at the Hilton Garden Inn in Cleveland, OH on June 10 to develop technology requirements for hydrogen-based and electric drive propulsion systems. The Workshop included participants from across NASA, the Department of Energy, industry and academia. Participants from GRC included representatives from the Power and Electric Propulsion Division, Turbomachinery and Propulsion System Division, Materials Division, Structures and Acoustics Division and the Aircraft Systems Analysis Office. The expected product of the workshop is to identify technology needs that will assist in planning the Alternative Propulsion Systems (APS) sub-project which is part of the Low Emissions Alternative Power (LEAP) project. The APS sub-project will focus on the use of hydrogen as a primary fuel for future aircraft systems and development of aircraft propulsion systems which use electric drive for main propulsion. Discussion breakout groups were led by members of the R&T staff, including Dr. Mike Meador and Mike Meyer in the area of “Storage, Feed, Handling and Production”, Dr. Chi-Ming Lee and Dr. Gerald Brown in the area of “Propulsion Systems”, and Chris Snyder (2400) and Mark Guynn (LaRC) in the area of “Vehicle Configuration and Systems Assessment”,. This work is supported by Code R/Vehicle Systems/LEAP. (Points of Contact: RMP(5150)/Michael Meador, 3-9518 and RTP(5870)/Michael Meyer, 3-7492)
Review of the Durability and Safety of Composite Over-Wrap Pressure Vessels
At the request of the NESC, Dr. Jim Sutter (GRC) and Dr. Brian Jensen (LaRC) are co-leading a materials discipline team to review the durability and safety of composite over-wrap pressure vessels (COPV) for Shuttle (Kevlar/Epoxy wrapped over Titanium liners) and Station (Graphite/Epoxy over-wrap on Ti liners). The Kevlar tanks currently used on the Shuttle were developed in the early '70's at Brunswick Composites in Lincoln, NE and provide a >50% wt reduction versus all metal tanks. The graphite/epoxy tanks used on ISS save even more weight. While no COPV failures have occurred on either Shuttle or ISS, it is predicted that tank failure would lead to the loss of an Orbiter. Because of this the COPVs have a designation of Crit 1 or 1R system component. The COPVs were initially certified for a 10 year service life, however, their service life was later extended to 20 years. While several Agency programs have been in place to assess the long-term durability of COPVs, there is concern about their reliability and safety. The COPV team, comprised of NASA, industry and university experts in materials, life prediction and manufacturing, is currently engaged in compiling details for all vessels in service: Kevlar, graphite and possibly some glass, identifying deficiencies in testing, providing ideas for further tests and developing a flight assessment plan. Point of Contact: RMP (5150)/Dr. James K. Sutter, 3-3226, James.K.Sutter@nasa.gov
“Metallic Over-Wrap” Concept for On-Orbit Repair of Space Shuttle Orbiter Leading Edges
Research and development efforts supporting the “metallic over-wrap” concept for on-orbit repair of leading edges of the Space Shuttle Orbiter are receiving renewed interest as a result of the recent cancellation of the “rigid wrap” repair effort. The over-wrap concept provides the ability to repair areas of larger damage, up to 16 inches diameter. The three metallic candidates (Chromium-Magnesium Oxide, Chromium-Rhenium-Magnesium Oxide, and silicide coated Rhenium) continue to show promise for repair application for re-entry due to their performance in a GRC torch test that simulates the temperature profile during a 15 minute re-entry profile. Verification of the GRC torch results were recently performed at ATK Thiokol. Development work is continuing with the development of an iridium underlayer that will mitigate oxidation attack of the Rhenium in case cracks form in the silicide coating. Metallic candidates are also under consideration for “plug” concepts. Samples are currently awaiting the next evaluation step of arcjet testing at NASA-JSC. This work was funded by the Return to Flight Project via the Space Transportation Project Office. (Point of Contact: RMM (5120)/Frank Ritzert, 3-8199; RMD (5160)/Jim Nesbitt, 3-3275; QSS/Mark Jaster, 3-8906; QSS/Craig Robinson, 3-5547).
July 2004
Simple Inspection Method for Thermal Barrier Coatings
A simple inspection method to evaluate the extent of loss of thermal barrier coatings (TBCs) subjected to erosive environments in gas turbine engines has been developed. It can reveal when any local section of the TBC has eroded more than an acceptable depth and therefore should be replaced. Recently, the potential for TBC erosion indication by doping TBC sublayers with low levels of luminescent rare earth ions was successfully demonstrated. In collaboration with Penn State University, 150 micron thick layer-doped yttria-stabilized zirconia TBCs were deposited with the top third being undoped and the middle and bottom third being doped with 0.5 at % europium and terbium, respectively. The coated disk specimens were then subjected to alumina particle jet erosion and followed by inspection under ultraviolet illumination, which excites only the luminescence in exposed layers. Intense red luminescence was apparent where the middle, europium-doped layer was exposed, while intense green luminescence was visible where the bottom, terbium-doped layer was exposed, thereby providing an immediate indication of location and depth of the erosion. These highly encouraging results suggest that low-level layered doping of TBCs is a practical solution for TBC erosion monitoring by integrating the erosion-indicating function into the TBC itself. Funding for this work was provided by the Intelligent Propulsion Systems Foundation Technology. (Point of Contact: RMD(5160)/ Jeff Eldridge, 3-6074)
Dr. Nathan S. Jacobson received the Silver Snoopy Award
Dr. Nathan S. Jacobson received the Silver Snoopy Award presented by NASA Astronaut Joan Higginbotham recognizing the many contributions, made over the last 10 years, in understanding the high temperature chemistry, behavior and performance of pre- and post-Shuttle flight reinforced carbon-carbon (RCC) leading edge materials. (Point of Contact: RMD(5160)/Leslie A. Greenbauer-Seng)
A New Ceramic Matrix Composite (CMC) Cooled Panel Concept Successfully Tested
A new ceramic matrix composite (CMC) cooled panel concept incorporating metal heat exchanger tubes has been successfully tested in GRC’s Research Combustion Laboratory (Cell 22) under conditions representative of scramjet operating conditions. The new concept is based on an innovative manufacturing process in which the refractory metal tube is inserted in a woven CMC structure, and the hybrid metal-CMC structure is densified by conventional CMC processing techniques. This approach eliminates bonding of refractory metal tubes to the CMC panel that is exposed to the hot gases. The co-processed cooled panels, manufactured by GE Power Systems Composites and Refractory Composites, Inc., were successfully tested in Cell 22 for 2 – 4 minutes at maximum surface temperatures in the range of 2400 – 2900oF. This test is the first successful test for co-processed CMC panels in scramjet combustion environments. This work was supported by the NGLT program. (Points of Contact: RMC(5130)/Martha Jaskowiak, 3-5515 and RTC(QSS)/Kevin Dickens, 3-6491)
Return-to-Flight RCC Wrap Team Workshop
Dr. James Nesbitt a Glenn member of the Return-to-Flight RCC Wrap Team, attended a workshop, held at NASA Langley on June 15-17, 2004. The Team’s charter is to define catastrophic damage to a RCC leading edge and nose cone components on the orbiter and to develop an on-board damage repair capability for the RCC. At the workshop, viable and cost-effective candidates for on-orbit RCC repair with the potential to be certified in wide-ranging repair requirements, especially large area damage, were identified. Reinforced Carbon/Carbon (RCC) Repair Project meeting was hosted by the R&D Team Lead Steve Scotti from NASA Langley and astronaut Charlie Camarda from NASA Johnson. (Point of Contact: RMD(5160)/Dr. James Nesbitt, 3-3275)
Advanced Turbine Disk Alloy ME3 receives R&D Magazine 2004 R&D 100 Award
R&D Magazine has awarded a 2004 R&D 100 Award to the advanced turbine disk alloy ME3 as one of the 100 most technologically significant products of this past year. The alloy was developed by a team of NASA GRC, General Electric, and Pratt & Whitney during the High Speed Research/Enabling Propulsion Materials project, and was refined by further work in the Ultra Efficient Engine Technology program as well as by several DoD projects. Turbine disks are critical to engine performance, efficiency, and safety, so engine companies introduce new disk alloys only if the performance, efficiency, and safety gains justify the implementation costs of greater than $10M. Its first entry into service will be in 2006 on GE-P&W Engine Alliance GP7200 engines, which will power Airbus’ new, four-engine A380 aircraft. ME3 is also slated for the Joint Strike Fighter and several other advanced engine programs. NASA Team members include Robert Draper, David Ellis, Anita Garg, John Gayda, Pete Kantzos, Bill Karpinski, Brian Shannon, and Jack Telesman. (Point of Contact: RMM(5120)/Tim Gabb, 3-3272)
“Development of Silicon Carbide/Silicon Carbide Ceramic Matrix Composites (SiC/SiC CMC’s) for High Temperature Space Transportation Applications”
Mr. Doug Kiser presented a poster paper titled, “Development of Silicon Carbide/Silicon Carbide Ceramic Matrix Composites (SiC/SiC CMC’s) for High Temperature Space Transportation Applications,” at the 2004 National Space and Missile Material Symposium in Seattle, WA. This symposium offers participants from government, industry, and academia an opportunity to discuss state-of-the-art materials and processing technology development for future generations of space and missile systems. The poster advocated SiC/SiC CMC’s for inserted CMC blade, cooled CMC components, and space vehicle airframe applications. SiC/SiC CMCs offer improved durability at temperatures >1400°C through the combination of a refractory, uncracked matrix material and an oxidation and creep-resistant fiber reinforcement. Funding has been provided by the NASA Next Generation Launch Technology (NGLT) Program’s Propulsion Research and Technology Project and the IR&D Program. (Points of Contact: RMC (5130)/Doug Kiser, 3-3247; and (OAI)/Greg Morscher, 3-5512)
Modified Composition of Glenn Refractory Adhesive for Bonding and Exterior Repair (GRABER)
A modified composition of Glenn Refractory Adhesive for Bonding and Exterior Repair (GRABER) was developed to increase working life and to extend the operational temperature range over which it can be applied. The working life of the new composition, GRABER 5AX, which is an advanced version of GRABER 5A, was extended over the following range: -10°C to 120°C. In addition to extended working life, GRABER-5AX exhibits lower viscosity, which is critical for penetration and filling of small cracks and damaged areas. In addition, the effect of storage time and temperature on the working life and viscosity was also evaluated. No apparent change in viscosity and workability of materials was observed after storage up to four months. This data is very useful for the design of EVA (extravehicular activity) tools and for proper storage and handling of materials. Points of Contact: RMC (QSS)/M. Singh, 3-8883 and RMC (QSS)/Tarah Shpargel 3-2644)
August 2004
Summer Faculty Research on Solid Oxide Fuel Cells
Professor Dwight Myers of East Central University, Ada, Oklahoma, completed a successful summer of research as part of the NASA Faculty Fellowship Program. Professor Myers was able to adapt a transpiration setup to study volatile species in the Cr2O3 – H2O – O2 system. This work is of extreme importance for improving the operation of solid oxide fuel cells where volatile Cr-O-H species formed from metallic interconnects can condense and poison the cell cathode. To date there is a large discrepancy in available thermodynamic data for these volatile Cr-O-H species, preventing accurate prediction of Cr2O3 volatility. This summer, Professor Myers was able to establish critical experimental techniques to allow accurate and repeatable collection and analysis of the volatile species. In addition, preliminary flow rate, temperature, and water pressure dependencies of volatile Cr-O-H formation were obtained. This work continues as part of a Space Act Agreement with Sandia National Laboratories. (Points of contact: RMD(5160)/Elizabeth Opila, 3-8904 and RMD(5160)/Nathan Jacobson; 3-5498)
Dr. Becky MacKay providing materials consultation to RCS Thruster team for Shuttle Orbiter
At the request of the NESC (NASA Engineering and Safety Center), Dr. Becky MacKay is providing materials consultation to the RCS (Reaction Control System) Thruster team for the Shuttle Orbiter. A failure analysis is being conducted at Boeing to investigate the cracking that was observed in a primary thruster injector. The primary RCS thrusters guide the orbiter in space. Dr. MacKay has reviewed all previous failure analyses and has provided specific input into the current Boeing Failure Analysis. Dr. MacKay is currently leading a team of researchers from LaRC and MSFC that is recommending further characterization and testing of the injector material to identify the root cause of the cracking and to determine if the cracking would continue to grow under normal orbiter environments. (Point of Contact: RM (5100)/ Dr. Becky MacKay, 3-3269)
Dr. Rebecca A MacKay receives Women in Aerospace, 2004 Outstanding Achievement Award
Dr. Rebecca A MacKay has received the prestigious Women in Aerospace, 2004 Outstanding Achievement Award. Dr. MacKay is being recognized for her world class, career technical achievements in developing high temperature materials for advanced propulsion systems. Dr. MacKay will be presented her award at the Women in Aerospace Annual Awards Ceremony on September 21, 2004, at the Rayburn House Office Building in Washington, D.C. Dr. MacKay is the only recipient of NASA Honor Medals for both Exceptional Scientific Achievement and Exceptional Engineering Achievement in the entire history of LeRC and GRC.
"Mechanics of Biological Tissue"
Alan Freed presented the paper "Invariant Theory for Dispersed Transverse Isotropy: an efficient means for modeling fiber splay", co-authored by Daniel Einstein and Ivan Vesely from the Children's Hospital Los Angeles, at the IUTAM (International Union of Theoretical and Applied Mechanics) Symposium "Mechanics of Biological Tissue" held in Graz, Austria, June 27 - July 2, 2004. This invited presentation discussed analytical models of collagen fibers in a biomatrix. Theories presented in this paper can also be applied to engineered composites and nanotube reinforced materials where fiber alignment is not perfect, but rather, oriented about some mean fiber direction according to a Gaussian probability distribution density. This approach is currently being adopted by leading international biomechanics researchers. Funding from Army and DoD has supported this activity. IUTAM symposia are held once every four years in an emerging field of international interest in the discipline of theoretical and applied mechanics. All talks are by invitation only. There were 44 this year. (Point of Contact: RMP(5150)/Dr. Alan D. Freed, 3-8747)
August 2004 Aerospace America article on Glenn-developed copper alloy GRCop-84
The August 2004 issue of Aerospace America featured a nice article on the Glenn-developed copper alloy GRCop-84. It described the benefits of the alloy for rocket engine applications plus the added benefits provided by environmental barrier coatings. It highlighted the efforts of both NASA GRC and MSFC in successful hot fire testing of coated GRCop-84 subscale combustion chambers. This work is being supported by the Propulsion Technology and Integration program. (Point of Contact: RMM(5120)/Dave Ellis, 3-8736)
Best Paper award winner from the American Society of Mechanical Engineers and the International Gas Turbine Institute.
The paper, "Case Studies of Fatigue Life Improvement Using Low Plasticity Burnishing in Gas Turbine Engine Applications," by Paul S. Prevéy, Ravi A. Ravindranath, Michael Shepard and Timothy Gabb has been selected by the Manufacturing Materials & Metallurgy Committee as a Best Paper award winner from the American Society of Mechanical Engineers and the International Gas Turbine Institute. This work is being supported by the Aviation Safety program. (Point of Contact: RMM(5120)/Tim Gabb, 3-3272)
Electrically Conductive Ceramics
Ceramics are typically good electrical insulators, but even under extreme conditions such as very high temperatures, some ceramics like cubic Zirconia can conduct relatively weak ionic currents. But certain ceramics, particularly from the pyrochlore family, actually conduct electricity almost as well as metals. We are currently investigating these materials for a host of applications where strong electrical conduction and variable density are needed. Variable density, electrically conducting, ceramics have been produced by wet chemical methods followed by high temperature heat treatments. Applications for this material include situations where high density and high electrical conductivity along with a gas tight seal is crucial as in ceramic interconnects for stack solid oxide fuel cells. In its low density state this ceramic may function as a fuel cell cathode where low electrical losses and high gas permeability are needed. This material, with its comparable thermal coefficient may also be suitable as electrodes for high temperature piezoelectric actuators. This work is supported by the Low Emissions Alternative Power program. (Point of Contact: RMC (5130)/ Dr. Jon Goldsby, 3-8250)
Septembr 2004
American Helicopter Society (AHS) International Best Paper Award in Propulsion
The Propulsion Committee of the American Helicopter Society (AHS) International has recognized Drs. Dongming Zhu and Robert A. Miller’s paper “Thermal and Environmental Barrier Coatings for Advanced Propulsion Engine Systems” for the Best Paper Award in Propulsion. Dr. Zhu presented this work at the AHS International 60th Annual Forum and Technology Display, held on June 7-10, 2004 in Baltimore, Maryland. The research presented in the talk was funded by the Ultra Efficient Engine Technology Project. (Point of Contact: RMD(5160)/Dr. Dongming Zhu, 3-5422 and RMD(5160)/Dr. Robert Miller, 3-3298)
Addition of Exfoliated Graphite to PMR-15 and its Effect on Processing and Performance
Sandi Campbell of the Polymers Branch presented a poster entitled, “Addition of Exfoliated Graphite to PMR-15 and its Effect on Processing and Performance” at Nanocomposites 2004 held in San Francisco from August 31st to September 3rd. In this poster, recent results from GRC efforts to disperse exfoliated graphite nanoparticles into a high temperature polymer, PMR-15 were presented. Inclusion of a small amount (less than 10 weight percent) of exfoliated graphite into PMR-15 resulted in a 15% reduction in oxidative weight loss at 550°F. Use of a exfoliated graphite “paper” on the exterior of the PMR-15 sample led to a 25% reduction in oxidative weight loss. Nanocomposites 2004 was attended by over 150 researchers from industry, academia and Government. The focus of this year’s conference was polymer nanocomposites and included presentations on layered silicate clays, carbon nanotubes, exfoliated graphite, and POSS. This work has been supported by the Alternative Energy Foundations Technology Subproject in the Low Emissions Alternative Propulsion Project. (Point of Contact: RMP (5150)/Sandi Campbell, 3-8489)
Fluorescent Chemical Sensor
A recent paper by Daniel S. Tyson, U. Faysal Ilhan, and Michael A. Meador entitled, “Synthesis and Chemosensory Behavior of Anthracene Bisimide Derivatives” published in Chemistry of Materials was featured in this week’s Heart Cuts, a news weekly published electronically by the American Chemical Society. The subject paper discusses the synthesis and performance of a new fluorescent “on-off” sensor capable of detecting certain chemical compounds, in particular, safe chemical surrogates for Sarin nerve gas. By themselves, these dyes do not fluoresce. However, upon exposure to chemicals, such as Sarin nerve gas derivatives, these compounds fluoresce a bright yellow-green. Experimental studies presented in this paper demonstrate that this compound is capable of sensing these molecules both in solution and in the gas phase. This work has been supported by the Alternative Energy Foundations Technology Subproject in the Low Emissions Alternative Propulsion Subproject and the Internal Research and Development Project. (Point of Contact: RMP (5150)/Michael A. Meador, 3-9518)
Mechanism for environmental embrittlement of advanced titanium aluminide alloy identified
The mechanism for environmental embrittlement of an advanced titanium aluminide alloy has been identified. The advanced alloy known as Gamma MET PX, has exceptional strength combined with low density, making it of high interest for a large number of airframe and engine applications, including commercial and military jets and reusable launch vehicles. During our evaluation, it was discovered that a simulated service exposure of 800 ºC for 200 hours in air caused a reduction in room temperature ductility. This effect was surprising since it was much more pronounced than the effects seen in other alloys. The embrittlement has been shown to be a result of oxygen diffusion and microstructural changes in the near surface region, which is enhanced by the high niobium content of the alloy. This work was funded by the NGLT Propulsion Research and Technology Project. (Point of Contact: RMM(5120)/Susan Draper, 3-3257)
October 2004
Lanthanum chromite based ceramic interconnect materials
Lanthanum chromite based ceramic interconnect materials have been produced by a wet chemical process. By simultaneously adding small amounts of calcium, cobalt and aluminum the process temperature is reduced by 700 degrees while maintaining excellent electrical conductivity. The reduced processing temperature has several benefits such as better compatibility with other fuel cell components both structurally and chemically and an over reduction in manufacturing costs. This work is supported by the Low Emissions Alternative Power program. (Point of Contact: QSS/RMC(5130)/Zhimin Zhong, 3-6494; RMC(5130)/Jon Goldsby, 3-8250)
Lower CTE fuel cell component
Currently, the thermal expansion mismatch between the various fuel cell components can exceed 20% which is large enough to cause cracking and microstructural degradation during repeated thermal cycling. A modified, metal based component with significant reductions (on the order of 8 %) in the coefficient of thermal expansion (CTE) has been developed. The objective of this research is two-fold, the first being the aforementioned CTE reduction and the second involves the issue of sulfur tolerance. Sulfur attacks the material interfaces effectively destroying the fuel cell performance. The sulfur tolerant anodes however have an even greater CTE mismatch. The present study addresses this problem through material and microstructural modifications with support from the Low Emissions Alternative Power program. (Point of contact: QSS/RMC(5130)/Stephen Sofie, 3-3869)
Advanced low conductivity coatings
Advanced low conductivity coatings have been designed by NASA and optimized for improved erosion and impact performance. These UEET low conductivity coating systems -- which consist of zirconia, yttria, plus certain rare earth oxide dopants -- possess essentially the same partially stabilized non-transformable tetragonal t' structure as the current baseline zirconia-yttria specimens. Tests at GEAE show that the erosion resistance is somewhat better than baseline. Other erosion tests will follow at NASA and Pratt & Whitney. In early testing, the thermal conductivity of these coatings was intermediate between that of the lowest conductivity UEET TBC (which have the cubic structure) and the baseline, and the high temperature stability of this coating appears to be significantly better than the baseline zirconia-yttria. Additional improvements may be possible with the incorporation of other dopants. An important feature of the new t'-low conductivity compositions is that they achieve improved performance while maintaining a similar phase structure as the baseline. This may facilitate its acceptance as a reduced-conductivity, enhanced-stability alternative to the current baseline TBC. This research was funded by the Ultra Efficient Engine Technology Project. (Points of Contact: RMD(5160)/Dr. Dongming Zhu, 3-5422 and RMD(5160)/Dr. Robert Miller, 3-3298)
A new polymer membrane for Proton Exchange Membrane (PEM) fuel cells
A new polymer membrane has been developed for Proton Exchange Membrane (PEM) fuel cells with good proton conductivity at 200°C without the need for external humidification. Operation of PEM fuel cells at temperatures above 120°C increases the power output of fuel cell and reduces the risk of electrode catalyst poisoning by carbon monoxide. Recent studies at GRC suggest that operating temperatures as high as 200-220°C may be desirable for fuel cells to power Uninhabited Air Vehicles (UAVs) and other aircraft. Conventional PEM fuel cells are limited to use at temperatures no higher than 80°C, because the polymer membrane uses moisture and cannot effectively conduct protons. Use of conventional PEM fuel cells at higher temperatures requires that special measures be used to rehydrate the membrane. This adds weight and complexity to the fuel cell system. In addition to the performance benefits described above, use of this new membrane could lead to weight reductions in the overall fuel cell balance of plant by eliminating the need for humidifiers and heat exchangers. (Point of Contact: RMP(5150/Dr. James D. Kinder, 3-3149)
Vibration damping studies performed on GRC developed polymer cross-linked aerogels (X-aerogels)
Vibration damping studies performed on a sample of GRC developed polymer cross-linked aerogels (X-aerogels) demonstrate that these materials are effective at damping out acoustic signals over a wide frequency range 0.5 to 2.5KHz). Use of these lightweight materials in aircraft engine structures could provide for a new method of passive noise reduction. The Polymers Branch is currently working with the Acoustics Branch to further explore the potential of this novel material. (Points of Contact: RMP(5150)/Dr. Nicholas Leventis, (216) 433-3202 and RMM(5120)/Santo Padula, 3-9375)