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

Materials properties characterization in the most extreme environments

“…204 Oxidation testing at these extreme temperatures is usually done in (laboratory) air, either discontinuously in box/muffle furnaces with intermittent weight change measurements, or continuously by thermogravimetric analysis (TGA). Figure 3c 209 (e) Optical image of sample loading into the GEER (Venus chamber) 219 and (f) EDS analysis of the resulting corrosion in Inconel 625. 219 (g) Experimental setup for deuterium charging of atom probe tomography (APT) specimens and cryogenic preservation 132 and (h) corresponding APT atom map of deuterium segregation to transgranular carbides on dislocations.…”

“…205 To simulate reentry conditions, including thermal shock resistance, less expensive oxyacetylene torch tests [206][207][208] and more expensive arc jet tests in a temperature range between 1373 K (simulating hypersonic flights at Mach 6) and beyond 2273 K are carried out; [201][202][203] see Figure 3d representing a test of a ZrB 2 /SiC-based composite, coated with Mo-Si-B, tested at NASA's HyMETS test facility. 209 However, as many of these materials are considered to form a protective silica scale, investigations under water vapor have additionally been carried out, 210,211 which clearly demonstrate (detrimental) accelerated scale growth under wet conditions. An interesting novel method for mechanical testing superimposed with wet air and sodium chloride (i.e., SCC) was exemplified recently for Ti alloys at elevated temperatures (723 K).…”

Surface Engineering of Mo-Base Alloys for Elevated-Temperature Environmental Resistance

“…Following multiple 15-20-min arc jet exposures at temperatures reaching 1,600 • C, the samples maintained their integrity, with no major change in the coating structure (130). In an additional evaluation, the Mo-Si-B coating was applied to a ZrB 2 -SiC composite and other substrates by a two-step process that is illustrated in Figure 12 (130)(131)(132)(133)(134)(135). Again, after arc jet exposure the sample exhibited good coating adherence and an unaltered substrate (130).…”

“…In an additional evaluation, the Mo-Si-B coating was applied to a ZrB 2 -SiC composite and other substrates by a two-step process that is illustrated in Figure 12 (130)(131)(132)(133)(134)(135). Again, after arc jet exposure the sample exhibited good coating adherence and an unaltered substrate (130). Although a further evaluation is necessary, the protection provided by the aluminoborosilica surface again appears to be related to the retention of glass additives that maintain both a noncrystalline surface and reduced oxygen activity at the Mo-Si-B/glass interface.…”

Arc-jet wind tunnel characterization of ultra-high-temperature ceramic matrix composites

“…However, as also suggested in [16], to test the materials survivability in an environment representative of hypersonic flight conditions, a realistic combination of heat fluxes, pressures, flow velocity and chemical composition around the test articles needs to be reproduced. Therefore, the most recommended facilities for the characterization of aerospace ceramic materials in a relevant, simulated flight environment are hypersonic arc-jet wind tunnels [17,18,19].…”