Low-Cost Resin Transfer Molding Process Developed for High-Temperature Polyimide Matrix Composites

Current production methods used to manufacture components from high-temperature PMC's are fairly labor intensive. Although less labor intensive, more efficient processing techniques such as resin transfer molding (RTM) have been developed to process PMC's; these methods are not suitable for use with high-temperature PMC's. RTM involves infiltrating a fiber preform with molten resin. To process good quality parts via RTM, one must use a resin with a low enough viscosity and sufficiently long pot-life to completely infiltrate the preform. Although high-temperature polymers such as PMR-15 melt, the viscosity of the molten resin is too high to be successfully processed by RTM.

One of the goals of the Advanced Subsonic Technology program is to develop new processing methods that enable the low-cost production of high-temperature PMC engine hardware. A recent development of this program is a modification of the RTM process to allow complete infiltration of the fiber preform by monomers prior to processing. A demonstration of this technique, developed jointly by GE Aircraft Engines, Fiber Innovations, Inc., and Lewis, was successfully completed, leading to the production of a center vent tube for the GE-90 engine using a Lewis-developed high-temperature polyimide, AMB-21. It is estimated that this process could reduce manufacturing costs by 30 to 50 percent in comparison to costs for a comparable part produced by hand layup and autoclave processing. Furthermore, this technique should be applicable to a variety of high-temperature PMC's as well as to a number of engine components. Engine testing of this RTM-processed center vent tube is currently underway.