Effect of mechanical attrition on microstructure and properties of electro-deposition coatings on NdFeB

Surface mechanical attrition treatment (SMAT) was developed to synthesize nanostructure coatings on alloy surface. The SMAT action was applied in the process of Ni and Cu electroplating coatings on NdFeB substrates in this paper. The role of mechanical attrition during barrel plating on the microstructure, mechanical and corrosion resistant properties of the coatings was examined. The scanning electron microscopy (SEM) observation showed that the mechanical attrition could refine grain size, markedly smooth the coating surface and obviously decrease the number of pore in the coatings. The continuous collisions of glass balls onto the NdFeB samples could induce more beneficial nucleation defects on the coating, which was helpful for increasing nucleation sites and the nucleation rate. The mechanical attrition could also restrain the heterogeneous growth of the coating grain tips due to the abrasive action of stainless steel balls. The Tafel polarization curve experimental results indicated that SMAT process could enhance the corrosion resistance of coatings on NdFeB. The scratching test revealed that the binding force between coating and NdFeB substrate could be improved dramatically with SMAT process.

Graphical AbstractSchematic diagrams of mechanical attrition electroplating devices (a) Stirred grinding for Cu coating; (b) Barrel grinding for outmost Ni coatingFigure optionsDownload as PowerPoint slide