热处理对高温固体自润滑涂层组织结构及结合强度的影响  

INFLUENCE OF HEAT TREATMENT ON MICROSTRUCTURES AND ADHESIVE STRENGTH OF HIGH TEMPERATURE SOLID SELF-LUBRICANT COATING

作　　者：徐娜[1,2] 张甲[2] 侯万良[2] 全明秀[2] 李荣德[1] 常新春[2] 

机构地区：[1]沈阳工业大学,沈阳110178 [2]中国科学院金属研究所,沈阳110016

出　　处：《金属学报》2009年第8期943-948,共6页Acta Metallurgica Sinica

摘　　要：采用等离子喷涂技术在GH4169基体上制备了NiCr Cr_2O_3 Ag-BaF_2/CaF_2高温固体自润滑涂层,并对涂层进行了热处理.通过SEM观察,XRD分析及拉伸实验,对热处理前、后涂层的微观组织结构及结合强度进行了对比研究.结果表明:喷涂态涂层由Ni(Cr)相、Cr_2O_3相、Ag相和(Ba,Ca)F相组成.组织形貌为粗大的层状结构,结合强度为30.4 MPa:经500和650℃热处理后.(Ba,Ca)F相转变为BaF_2和CaF_2相,涂层内氟化物相与喷涂态相比更致密:大量Cr_2O_3和NiO析出相的形成、长大使涂层内Ni(Cr)相细化;在650℃下进行12或24h热处理后,涂层结合强度增至46.5 MPa;热处理温度为800℃时,BaF_2发生严重氧化,致使涂层内组织疏松,局部形成大面积孔洞.涂层结合强度显著降低.Foil air bearings are self-acting hydrodynamic bearings relying on solid lubricants to reduce friction and wear during sliding at start up and shut down when speeds are too low to allow the formation of a hydrodynamic air film. The service temperature of traditional solid lubricants such as graphite, PTFE and MoS2 is limited to only about 300℃. The NiCr Cr203-Ag-BaF2/CaF2 solid lubricants can make foil air bearings run from room temperature to 650℃. In this paper, the NiCr-Cr2O3-Ag BaF2/CaF2 high temperature solid self-lubricant coatings were fabricated on GH4169 matrix using plasma spray technology. Microstruetures and adhesive strengths of the coatings as sprayed and treated at 500, 650 and 800℃ were analyzed by SEM, XRD and tensile test. The results show that the as-sprayed coating consists of Ni（Cr） phase, Cr2O3 phase, Ag phase and （Ba,Ca）F phase and has coarse lamellar-like structures, the adhesive strength reaches 30.4 MPa. After heat treatments at 500 and 650℃, （Ba, Ca）F phase transforms into BaF2/CaF2 phase, meanwhile the BaF2/CaF2 becames compacted. The formation and growth of lots of black Cr203 and NiO precipitations make Ni（Cr） phase refine. After heat treatment at 650℃ for 12 or 24 h, the adhesive strength increases to 46.5 MPa. But after heat treatment at 800℃ BaF2 was oxidized, which makes the mierostructures loose and the porosities are formed in a large area. The adhesive strength is decreased evidently.

关 键 词：高温固体润滑涂层 热处理 组织结构 结合强度 等离子喷涂 

分 类 号：TG174.442[金属学及工艺—金属表面处理]