Nb-Ti-Si-Cr基超高温合金表面ZrSi_2-NbSi_2复合渗层的组织及其抗高温氧化性能  

MICROSTRUCTURE AND OXIDATION BEHAVIOR OF ZrSi_2-NbSi_2 MULTILAYER COATINGS ON AN Nb-Ti-SiCr BASE ULTRAHIGH TEMPERATURE ALLOY

作　　者：李轩[1] 郭喜平[1] 乔彦强[1] 

机构地区：[1]西北工业大学凝固技术国家重点实验室,西安710072

出　　处：《金属学报》2015年第6期693-700,共8页Acta Metallurgica Sinica

基　　金：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;凝固技术国家重点实验室自主研究课题项目116-QP-2014资助~~

摘　　要：采用先磁控溅射Zr膜,再Si-Y扩散共渗的方法,在新型Nb-Ti-Si-Cr基超高温合金表面制备了Zr Si2-Nb Si2复合渗层,分析了渗层的显微组织及形成机制,并研究了其在1250℃的恒温氧化行为.结果表明,1150,1250和1350℃下Si-Y共渗4 h所制备的渗层具有相似的显微组织,均主要由Zr Si2外层,(Nb,X)Si2(X=Ti,Cr,Zr和Hf)中间层和(Ti,Nb)5Si4内层组成.恒温氧化实验结果表明,所制备的渗层具有优异的抗高温氧化性能.氧化时渗层表面形成了由Si O2,Ti O2,Zr Si O4和Cr2O3混合组成的致密氧化膜,能够在1250℃空气中保护基体合金至少100 h不被氧化.The rather poor oxidation resistance of Nb-Si base ultrahigh temperature alloys has seriously limit- ed their practical applications at high temperatures. Niobium disilicide coatings, especially those modified by reac- tive elements （RE） such as Zr and Y, have been shown to possess good anti-oxidation properties at high tempera- tures 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 al- loys, because compact coatings and metallurgical substrate/coating bonds can be obtained with using this tech- nique. 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, ZrSi：-NbSi： multilayer coatings were prepared on an Nb-Ti-Si-Cr base ultrahigh temperature alloy by first magnetron sputtering 2 gm thick Zr-film, and then Si-Y co-deposition at respectively 1150, 1250 and 1350℃ by HAPC process. The structures and formation processes, as well as the static oxidation behavior of the coatings were investigated. The results show that the coating pre-pared at respectively 1150, 1250 and 1350℃ had similar structures, consisting of a ZrSi2 outer layer, a （Nb, X）Si2 （X=Ti, Cr, Zr and Hf） middle layer and a （Ti, Nb）sSi4 inner layer. However, the higher co-deposition temperature （1350 ℃ ） could cause cracks at the interfaces between the constituent layers of the coatings. The formation of the coating was dominated by inward diffusion of Si, accompanied with a certain degree of outward diffusion of Nb, Ti and Cr from the base alloy during the second Si-Y co-deposition process. The oxidation tes

关 键 词：Nb-Ti-Si-Cr基超高温合金 Zr Si2-Nb Si2复合渗层 组织形成 抗氧化性能 

分 类 号：TG174.44[金属学及工艺—金属表面处理]