Protective Coatings for Niobium Alloys and Their Properties

摘要

Niobium alloys cannot be used at high temperatures without protective coatings.Superficial alloying of niobium alloys with only one element (aluminum, silicon or chromium) does not make it possible to obtain a coating which reliably protects the alloy for a prolonged period of time. The development of complex coatings is still proceeding only by empirical means, since the chemistry of their formation reactions is unknown. This work studied chromium-aluminum-silicon and chromium-titanium-silicon coatings which were applied to alloys VN-2A and VN-4 in two stages. first the alloys were subjected to saturation with chromium, aluminum, or chromium and titanium, and then siliconing was performed. The chemical and phasal composition of the coating were determined by the method of by-layer phasal analysis and the method of microprobe. A metallographic analysis was also performed, heat-resistance curves were plotted, and certain mechanical properties were determined.