Al-12.5%Si合金表面ZrO2溶胶改性PEO陶瓷层的形成机制  

Formation mechanism of PEO ceramic coating modified by ZrO2 sol on Al-12.5%Si alloy surface

作　　者：王萍[1] 张春青[2] 马群[3] WANG Ping;ZHANG Chun-qing;MA Qun(School of Materials and Chemical Engineering,Xi’an Technological University,Xi’an 710021,China;Mechanical Department,Chengde Petroleum College,Chengde 067000,China;Military Academy,Xi’an Technological University,Xi’an 710021,China)

机构地区：[1]西安工业大学材料与化工学院,陕西西安710021 [2]承德石油高等专科学校机械系,河北承德067000 [3]西安工业大学兵研院,陕西西安710021

出　　处：《材料热处理学报》2020年第5期160-167,共8页Transactions of Materials and Heat Treatment

基　　金：陕西高校“金属腐蚀防护与表面工程技术”青年创新团队;陕西省重点研发计划(2018GY-111);陕西省教育厅产业化培育项目(17JF009);榆林科技计划项目(2018-2-30)。

摘　　要：采用ZrO2溶胶改性的等离子体电解氧化(PEO)技术在Al-12.5%Si合金表面制备Al2O3-ZrO2陶瓷层,研究ZrO2溶胶对PEO陶瓷层形成机制的影响。采用扫描电镜(SEM)、能谱仪(EDS)、X射线衍射仪(XRD)、红外光谱仪(FTIR)和激光粒度仪等研究了ZrO2溶胶的微观组织结构、粒径及荷电性以及陶瓷层的微观形貌、成分及物相。结果表明:荷负电的ZrO2溶胶粒径为50~60 nm,烧结后以四方相t-ZrO2存在,含有少量m-ZrO2。ZrO2溶胶改性的PEO涂层较未改性的涂层均匀、致密,并且生长速率提高。由于ZrO2溶胶吸附在基体表面形成凝胶层,凝胶层的高电阻使PEO初期更易产生火花放电,促进了Al2O3膜的形成。ZrO2溶胶改性的PEO涂层由Al2O3、c-ZrO2、t-ZrO2和少量的SiO2组成,而溶胶改性前SiO2的含量较高。ZrO2凝胶颗粒在等离子体放电产生的高温下进入放电通道,与电化学反应形成的Al2O3烧结形成Al2O3-ZrO2复合陶瓷层。The Al2O3-ZrO2 ceramic coating was prepared on the surface of Al-12.5%Si alloy by plasma electrolytic oxidation(PEO)in a silicate electrolyte with zirconia sol addition,and the influence of ZrO2 sol on the formation mechanism of the PEO ceramic coating was studied.The microstructure,particle size and charge properties of ZrO2 sol,as well as the micro-morphology,composition and phase of the ceramic coating were characterized by means of scanning electron microscopy(SEM),energy dispersive spectrometer(EDS)analysis,Xray diffraction(XRD),Fourier transform infrared spectrometer(FTIR)and laser particle size analyzer.The results show that the particle size of the zirconia sol with negative charges is 50-60 nm,after sintering,it changes into tetragonal t-ZrO2 and has a small amount of m-ZrO2.The ceramic coating formed in the electrolyte with zirconia sol addition has more uniform morphology,less micro-pores and faster growth rate than that of without zirconia sol addition.Since ZrO2 sol adsorbs on the substrate surface to form a gel layer,the high resistance of the gel layer makes it easier to generate spark discharge at the initial stage of the PEO,which promotes the formation of the Al2O3 coating.The ZrO2 sol modified PEO coating consists of Al2O3,c-ZrO2,t-ZrO2 and a small amount of SiO2,and the content of SiO2 is lower than that of the PEO coating without ZrO2 sol modification.The ZrO2 gel particles enter the discharge channel at high temperature generated by plasma discharge and sintered with Al2O3 to form Al2O3-ZrO2 composite ceramic coating.

关 键 词：Al-12.5%Si合金 等离子体电解氧化 ZrO2溶胶 生长机制模型 

分 类 号：TG174.4[金属学及工艺—金属表面处理]