Development of new silicide coatings to protect niobium silicide in situ composites alloys against high temperature oxidation

摘要

The future advanced high temperature applications require new materials able to work at temperatures above the nickel based superalloys capabilities. In this paper a study of the oxidation behaviour of Nb_4Fe_4Si_7, envisioned as protective coating for niobium and their alloy is presented. Then, the paper focuses on the way for depositing this phase on both pure niobium and niobium alloys by using the pack cementation process. The oxidation resistance of this phase is then investigated. The weight gain exhibited by this phase for high exposure remains low (<2 mg.cm~(-2) after 50h at 1300 °C) and this coating can offer an effici ent protection up to 550 one hour cycle at 1100 °C.