基于双向脉冲电沉积下的Ni-纳米TiC复合镀层结构及耐磨性能

Structure and Wear Resistance of Ni-nano TiC Composite Coatings Based onDouble-pulse Electrodeposition

为探究第二相TiC颗粒对Ni基复合镀层组织结构及耐磨性能的影响,利用双向脉冲电沉积技术在Q235钢表面分别制备了纯Ni镀层、Ni-微米TiC复合镀层及Ni-纳米TiC复合镀层。通过FESEM、XRD、EDS对镀层的表面形貌、物相及成分进行了表征,并对比研究了镀层的表面粗糙度、显微硬度和耐磨性能。结果表明:加入TiC颗粒后,镀层表面由胞状结构转变为菜花状结构,同时基质金属镍的沉积取向行为发生了变化。Ni-纳米TiC复合镀层的平均晶粒尺寸为24.9 nm,约为Ni-微米TiC复合镀层的1/3。与Ni-微米TiC复合镀层相比,Ni-纳米TiC复合镀层具有更小的表面粗糙度(R a=3.500μm)和更高的表面硬度(820.5HV 0.1)。磨损试验结果表明,复合镀层的磨损机制是轻微的磨粒磨损和粘着磨损混合,TiC颗粒延缓了基质镍镀层的磨损速率。其中,Ni-纳米TiC复合镀层的平均磨损速率为5.6 mg/(cm 2·min),约为Ni-微米TiC复合镀层的1/2,表现出对基体更为优异的耐磨性能。

In order to investigate the influence of the second-phase(TiC particles)on the microstructure and wear resistance of Ni-based composite coatings,pure Ni coating,Ni-micro TiC composite coating and Ni-nano TiC composite coating were prepared on the Q235 steel by double-pulse electrodeposition,respcetively.The surface morphology,phase structure and composition of the coatings were characterized by FESEM,XRD and EDS,and the surface roughness,microhardness and wear resistance of the coatings were compared,respectively.The results show that after adding TiC particles,the surface morpholgogy of the coating changes from a cellular structure to a cauliflower structure,and the deposition orientation behavior of the nickel matrix also changes.The average grain size of Ni-nano TiC composite coating is 24.9 nm,approximately 1/3 of Ni-micro TiC composite coating.Compared with the Ni-micro TiC composite coating,Ni-nano TiC composite coating has a smaller surface roughness(R a=3.500μm)and a higher surface hardness(820.5HV 0.1).The results of the abrasion test indicate that the wear mechanism of the composite coating is a mixture of slight abrasive wear and adhesive wear,and the wear rate of the nickel-based coating decreases due to the presence of TiC particles.Among them,the average wear rate of the Ni-nano TiC composite coating is 5.6 mg/(cm^2·min),which is about 1/2 of the Ni-micro TiC composite coating,showing better wear resistance to the substrate.