Development of Protective Coatings for High-Temperature Metallic Materials

摘要

Metallic material systems that have potential for high temperature operations are key components for many land-based and space-based systems. Advanced alloys with improved elevated temperature properties and/or reduced densities compared to more conventional alloys show promise for improved structural efficiency and longer service life. However, in extreme operating environments, the metals may require coatings for environmental protection and thermal control. This paper discusses some results from a program to develop ultra-thin, lightweight, protective coatings, applied via sol-gel techniques, for some emerging high-temperature alloys. The coatings were designed to reduce oxidation, increase emittance, and reduce the catalytic efficiency for recombination of dissociated hot-gas species for the candidate materials. The alloys considered in this study include PM1000 (an oxide dispersion strengthened Ni-based alloy), 602CA Ni-based alloy, and a gamma titanium aluminide alloy. Inconel 617, a commercial Ni-based alloy, was included as a reference. Coating processes, oxidation performance, emittance, catalytic efficiency, and the effects of oxidation on the mechanical properties of the materials are discussed.