Effect of relative moving speed on microstructure of flexible friction assisted electrodeposited Ni coating

Ni coatings were prepared by a novel flexible friction assisted electroplating technology from an additive-free Watts bath at different relative moving speed. The morphology, microstructure, residual stress and microhardness of deposits were characterized by SEM, AFM, XRD, TEM, X-ray stress tester and microhardness tester, respectively. The results show that relative moving speed has important effect on the microstructure of Ni coating. At a relative moving speed range of 4.8-14.4 m/min, electrodeposited Ni coatings have face center cubic crystallography structure with a strong preferred orientation of (311). With the increase of the relative moving speed, the needle-like Ni crystallites gradually becomes uniformity, fine and compact on the surface of coatings; Tensile stress of the coatings firstly decrease then increase, but the microhardness gradually increase from 406 HV to 471 HV. When the relative moving speed achieves 12 m/min, the electrodeposited Ni coating shows much higher microhardness of 460 HV, a lowest tensile stress of about 100 MPa, and the average grain size of about 100 nm. © Copyright.