热处理对Cr/Al复合镀层组织转变的影响  

Effects of heat treatment on structure transformation of Cr/Al composite coatings

作　　者：李文川[1] 徐霸津[1] 凌国平[1] 

机构地区：[1]浙江大学材料科学与工程学系,浙江杭州310027

出　　处：《材料热处理学报》2011年第5期147-152,共6页Transactions of Materials and Heat Treatment

摘　　要：通过先在水溶液中电镀Cr之后再在摩尔比为2∶1的AlCl3-EMIC(氯化1-甲基3-乙基咪唑)离子液体电镀Al的方法,在1Cr17钢表面制备出Cr/Al复合镀层。研究了在740℃条件下不同时间热处理对涂层组织和结构的影响。光学显微镜、二次电子和特征X射线能谱及X射线衍射研究结果表明:Cr/Al复合镀层通过740℃热处理可以得到Al-Cr涂层,随着时间的延长,外表面合金层成分依次按Al4Cr→Al11Cr4→Al9Cr4→Al8Cr5变化,最后形成单相的Al8Cr5,且涂层与基体之间不发生明显的互扩散;在5～20 min内Al9Cr4成分层的厚度及反应掉的Cr镀层厚度与时间平方根符合线性关系;氮气气氛中热处理可以减少涂层表面的空洞。显微硬度测试结果表明:Al8Cr5的脆性小,且硬度高于其他3种合金层。The Cr/Al composite coatings were prepared on 1Cr17 stainless steel by electrodepositing Cr from aqueous solution followed by electrodepositing Al from AlCl3-EMIC（molar ratio 2：1） ionic liquid.Effects of heat treatment at 740 ℃ for various time on phase composition and structure of the alloy layers were studied.The samples were analysed by means of optical microscopy（OM）,scanning electron microscopy（SEM）,with energy dispersive spectroscopy（EDS） and X-ray diffraction（XRD）.The results show that the composition of outer Al-Cr layers in the coatings changed to Al4Cr,Al11Cr4,Al9Cr4 and Al8Cr5 in turn as the heat treatment process prolonged.The single phase Al8Cr5 layer was obtained without obvious interdiffusion with the substrate.There are linear relationships between the thickness of Al9Cr layer,reacted Cr layer and the square root of the time from 5 min to 20 min.The voids formed in coating surface during heat treatment under nitrogen are less than that formed under air atmosphere.The Knoop hardness tests indicate that the Al8Cr5 layer exhibits lower brittleness and higher hardness than other Al-Cr alloy layers.

关 键 词：Cr/Al复合镀层 离子液体 热处理 Al8Cr5 

分 类 号：TG174.44[金属学及工艺—金属表面处理]