电流密度和施镀温度对铝合金表面Ni-SiC-MoS2复合镀层显微组织的影响

目的研究电镀工艺参数中的电流密度和施镀温度对铝合金表面Ni-Si C-MoS_2复合镀层组织形貌及成分的影响。方法利用复合电镀的方法在铝合金上制备Ni-Si C-MoS_2复合镀层。通过扫描电子显微镜、能谱仪以及显微硬度仪,分析不同电流密度和施镀温度下复合镀层的组织结构、成分、界面之间的结合情况以及显微硬度。结果电流密度为4 A/dm2时,镀层与基体的结合差,镀层表面粗糙不平;当电流密度增加到5 A/dm2时,镀层与基体结合紧密,并且镀层表面平整;当电流密度增大到6 A/dm2时,镀层表面平整度变差。施镀温度为40℃时,镀层厚度较薄;施镀温度为50℃时,镀层与基体结合良好,镀层表面平整;当施镀温度上升到60℃时,镀层与基体结合处出现裂纹,镀层质量下降。随电流密度和施镀温度的升高,镀层中Si C和MoS_2摩尔分数先增加后减小,显微硬度先增大后减小。结论采用复合电镀的方法在铝合金表面可以制备出Ni-Si C-MoS_2复合镀层,当电流密度为5 A/dm2、施镀温度为50℃时,制备出的Ni-Si C-MoS_2复合镀层表面平整,厚度均匀,Si C与MoS_2摩尔分数可分别达到10.40%和0.77%。复合镀层的显微硬度与其Si C含量成正比,最高可达357.7HV0.01,是基体合金硬度的3.7倍。

Effects of Current Density and Plating Temperature on Microstructure of Ni-SiC-MoS2 Composite Coatings on Aluminum Alloy

The work aims to study effects of current density and plating temperature on microstructure and composition of Ni-SiC-MoS2 composite coatings on aluminum alloy.Ni-SiC-MoS2 composite coatings were prepared on aluminum alloy by composite plating.Microstructure,composition,interface bonding and microhardness of the composite coatings at different current density and plating temperature were analyzed with scanning electron microscopy,energy dispersive spectrometer and microhardness tester.When the current density was 4 A/dm2,the coatings and substrate were poorly bonded,and the surface of the coatings was rough;when the current density increased to 5 A/dm2,the coatings and the substrate were closely bonded,and the surface of the coatings was smooth;when the current density increased to 6 A/dm2,surface roughness of the coatings became worse.At the plating temperature of 40 ℃,the coatings were thin;at 50 ℃,the coatings and the substrate were well bonded,and the surface of the coatings was smooth;when the plating temperature increased to 60 ℃,cracks appeared at the joint of the coatings and substrate,and the quality of the coatings degraded.Mole fraction of SiC and MoS2 and the microhardness of the coatings first increased and then decreased with the increase of current density and plating temperature.Ni-SiC-MoS2 composite coatings can be prepared on aluminum alloy in the method of composite plating.When the current density is 5 A/dm2 and plating temperature is 50 ℃,the as-prepared composite coatings are smooth and uniform,and mole fraction of SiC and MoS2 reaches 10.40％ and 0.77％,respectively.Microhardness of the composite coatings is proportional to SiC content,and can be up to 357.7HV0.01,which is 3.7 times as much as that of the matrix alloy.