Experimental Investigation of Insulating Refractory-Metal Heat-Shield Panels

The results of an experimental study to determine the capabilities and limitations of a thermal protection system utilizing thin-gage, refractory-metal shields are presented. Cyclic radiant-heating tests to 2,4OO F (l,589 K) were performed on a heat-shield panel with molybdenum-alloy shields coated with a silicide-base coating, and a radiographic technique was used to detect oxidation damage and brittle cracking of the coated shields. A heat-shield panel with columbium-alloy shields was subjected to supersonic flow conditions at a Mach number of 3 and dynamic pressure of l,5OO lb/ft2 (71.8 kN/m2). The results of preliminary tests on a prototype panel with nickel-alloy shields subjected to radiant-heating and wind-tunnel conditions are also reported. Evaluation tests on the molybdenum-alloy shield material were made at temperatures ranging from room temperature to 2,9000 F (1,8660 K). Oxidation results and metallurgical studies covering diffusion phenomena for coated molybdenum-alloy coupons and small riveted configurations under continuous and cyclic conditions at temperatures to 2,9000 F are also given.