Arc jet testing and evaluation of Mo–Si–B coated Mo and SiC–ZrB2 ceramics

The transition from blunt leading edges to sharp leading edges on re-entry aircrafts is necessary to increase both maneuverability and safety. However, the oxidation resistance of current materials is inadequate for the extreme conditions experienced by sharp leading edge re-entry vehicles. The Mo–Si–B alloy system has been utilized to design a multilayer coating that has the ability to protect from 800 to 1700 °C. Substrates of Mo and ZrB2–50 vol% SiC with a flat profile were coated with the Mo–Si–B based coating and evaluated using arc jet testing performed at NASA Langley Research Center. Heat fluxes of 2.5 to nearly 3.5 MW/m2 and surface temperatures of 1500–1650 °C were achieved during the 20-min tests. The samples presented in this study showed <3% mass loss and retention of sample shape and integrity, demonstrating the robust environmental protection under a simulated hypersonic environment offered by the Mo–Si–B based coating on refractory metals and ceramics.