Si-20Fe-20Cr(wt%) fused silicide coatings on Nb and Nb alloys, to protect them against high temperature oxidation, have been characterized. The fused silicide coatings reveal a complex structure with 4-7 reaction layers. The coating structure and their protectiveness are determined by the base alloy composition.
High temperature (600-1200 C) oxidation tests were conducted on Nb-Ti alloys (Ti/Nb=1.0) containing 9Al-13Cr(at%), 10Al-10Cr(at%) or 12Hf-(0, 6, 12, 18)Al (at%) additions. Results indicate that Nb-Ti alloys have significantly higher oxidation resistance and embrittle far less rapidly compared to commercial Nb-base alloys. Oxidation rates, several orders of magnitude below those of Nb alloys, can be produced by a correct balance of alloying additions. Metal loss rate, oxide growth rate and ...
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