Short-Term High-Temperature Properties of Reinforced Metal Matrix Composites

Abstract

While the Department of Defense initiated Metal Matrix Composite Information Analysis Center (MMCIAC) has been charged with providing centralized information dealing with metal matrix composites (MMCs), test procedures for obtaining primary MMC properties have evolved from ASTM standards. These standards in turn have evolved from polymeric matrix composite (PMC) test procedures and have not yet been established as appropriate for MMC applications. Methods for obtaining short-term high-temperature tensile, flexural, and pin bearing data for reinforced MMC are presented. In addition, coupon design and fabrication, instrumentation, measurement techniques, and some lessons learned are discussed. Rapid heating, typical of tactical missile aerodynamic heating, can be suitably simulated using infrared quartz lamps. In fact, this type of furnace facilitates longer term baseline testing since temperatures can be reached more quickly, and test fixtures and equipment can be easily cooled. For short-term high-temperature strain measurements, extensometers were utilized. A computerized, digital data acquisition and control system is necessary to maximize data retrieval and minimize test errors during rapidly changing test conditions. Results show that while tensile strength of MMCs subjected to rapid heating greatly exceed those strengths obtained for long-term heating, flexure and pin bearing strength exhibit only moderate increases. Furthermore, differences are observed for specimens fabricated from thin versus thick panels.