占空比对TiAl合金表面阴极微弧沉积Al_2O_3涂层的影响研究  

Effect of Duty Ratio on Al_2O_3 Ceramics Coating Fabricated on TiAl Alloy Via Cathodic Plasma Electrolytic Deposition

作　　者：王少青 吴向清[1] 谢发勤[1] WANG Shao-qing;WU Xiang-qing;XIE Fa-qin(School of Aeronautics,Northwestern Polytechnical University,Xi’an 710072,China)

机构地区：[1]西北工业大学航空学院,西安710072

出　　处：《表面技术》2019年第2期232-238,共7页Surface Technology

基　　金：陕西省科技计划发展项目(2018JZ5004)~~

摘　　要：目的通过调整实验工艺,研究占空比对Ti Al合金表面阴极微弧沉积过程的影响规律和作用机制。方法对Ti Al合金进行预处理后,在不同占空比条件下,于Al(NO3)3电解液中制备阴极微弧沉积Al_2O_3陶瓷涂层。采用电子扫描电镜(SEM)、元素能谱分析(EDS)、透射电子电镜(TEM)以及X射线衍射(XRD)等分析测试技术,对不同陶瓷涂层的微观组织结构和成分进行了分析,并使用涡流测厚仪、表面轮廓仪、维氏硬度计和划痕仪等材料性能测试设备,对涂层厚度、粗糙度、硬度、结合强度等力学性能进行了表征。结果在沉积过程中,占空比主要影响试样表面非晶态Al(OH)3的沉积吸附和脱水烧结以及晶体Al_2O_3的形成。随占空比增加,陶瓷涂层内部晶体结晶度提升,表面缺陷和微裂纹减少,均匀性、致密性和表面硬度均有所提高,厚度和结合强度先增加后降低,而表面粗糙度则呈现先降低后增加的趋势。结论占空比为30%时,涂层表面缺陷较少,与基体结合良好,涂层晶格条纹整齐,由α-Al_2O_3、γ-Al_2O_3和少量金红石相rutile-TiO2以及非晶相的Al(OH)3组成,α-Al_2O_3质量分数为89.0%,涂层厚度为47μm,表面粗糙度为1.0μm,结合强度为72 N,硬度为1010 MPa(HV200)。The work aims to study the effect rules and action mechanism of the duty ratio on cathodic plasma electrolytic deposition(CPED)process by adjusting the experimental process.Al2O3 ceramics coating was fabricated via CPED technique on prepared TiAl alloy in Al(NO3)3 electrolyte under different duty ratios.Microstructure and compositions of different ceramic coatings were analyzed by analysis and test techniques including scanning electron microscopy(SEM),energy-dispersive spectroscopy(EDS),transmission electron microscopy(TEM)and X-ray diffraction(XRD),and the material property test equipment such as eddy current thickness meter,surface profiler,Vicker’s hardness tester,scratch tester,etc.The thickness,roughness,hardness and binding strength of coating were also characterized.During the deposition,the duty ratio mainly affected the deposition adsorption and dehydration sintering of amorphous Al(OH)3 and the formation of crystalloid Al2O3.As the duty ratio increased,the relative crystallinity of ceramic coatings increased,the surface defects and cracks decreased,the uniformity,density and hardness improved,the thickness and binding strength increased firstly and then decreased and the surface toughness decreased firstly and then increased.When the duty ratio is 30%,the surface defects are less and the coating is bond with the substrate well.The lattice fringe of coating is neat and composed ofα-Al2O3,γ-Al2O3,small amount of rutile-TiO2 and amorphous phase Al(OH)3.α-Al2O3 is 89.0%,the thickness is 47μm,the surface roughness is 1.0μm,the binding strength is 72 N and the hardness is 1010 MPa(HV200).

关 键 词：阴极微弧沉积 TIAL合金 AL2O3陶瓷涂层 占空比 微观结构 结晶度 

分 类 号：TG174.4[金属学及工艺—金属表面处理]