MICROSTRUCTURE AND OXIDATION BEHAVIOR OF ZrSi2-NbSi2 MULTILAYER COATINGS ON AN Nb-Ti-Si-Cr BASE ULTRAHIGH TEMPERATURE ALLOY

Abstract

The rather poor oxidation resistance of Nb-Si base ultrahigh temperature alloys has seriously limited their practical applications at high temperatures. Niobium disilicide coatings, especially those modified by reactive elements (RE) such as Zr and Y, have been shown to possess good anti-oxidation properties at high temperatures due to the formation of a protective RE-containing SiO2 scale. Halide activated pack cementation (HAPC) is one of the most widely used techniques for preparing protective coatings on Nb-Si base ultrahigh temperature alloys, because compact coatings and metallurgical substrate/coating bonds can be obtained with using this technique. However, only a very limited amount of Zr and Y can be diffused into the coatings by a single co-deposition pack cementation process as a result of their large atomic radii and high melting points. To solve this problem, a method such as magnetron sputtering, which can be used for producing overlay coatings with different composition ratios of coating elements, seems to be feasible. In the present study, ZrSi2-NbSi2 multilayer coatings were prepared on an Nb-Ti-Si-Cr base ultrahigh temperature alloy by first magnetron sputtering 2 μm thick Zr-film, and then Si-Y *国家自然科学基金项目51371145, 51431003和U1453201,高等学校学科创新引智计划项目B080401和凝固技术国家重点实验室 自主研究课题项目116-QP-2014资助 收到初稿日期: 2014-09-09,收到修改稿日期: 2015-04-07 作者简介:李 轩,男, 1982年生,博士生 DOI: 10.11900/0412.1961.2014.00498 第693-700页 pp.693-700