Condensate Layer Ndfeb Alloy Ni-p Coating And Laser Melting Process And Corrosion Resistance,

NdFeB alloy, the third era permanent magnet, is widely used in electromotor industry and apparatus industry, etc. It has the advantage of distinguished magnetic properties, being machined easily and comparatively low price. But it is prone to be oxidated in common atmosphere, especially be heavily electrochemical eroded at humidity environment. Corrosion becomes the obstruction to broaden applications of NdFeB.In this thesis, anti-corrosion technology of NdFeB was investigated. Based on the thorough comprehension of the character of sintered NdFeB alloy, surface treatment technology was adopted to protect it against corrosion, including elecroless nickel plating and laser precipitated solidification.By ceaseless aimed experiments, the parameters of elecroless nickel plating were optimized, which led to non-crystal Ni-P coating on NdFeB being obtained. Furthermore, the effect of heat treatment of non-crystal Ni-P coating was studied. With the increase of heat temperature, the non-crystal Ni-P coating began to crystal, and it will entirely transform into micro crystal coating at a proper temperature. Finally, high quality anti-corrosion Ni-P coating was obtained on NdFeB's surface, whose average grain size was at 10" m as well.What's more, particular laser precipitated solidification processing was applied to quick melt NdFeB at high heat rate. According to rapid one-dimension conduct of heat by matrix, the melted surface of NdFeB quench to a directional solidification cystiform structure. So an anti-corrosion coating correlated with matrix tightly was made on NdFeB in such a way. The relationship between parameters of laser and the microstructure of laser precipitated solidification coating was discussed either.Compared between Ni-P coating and coating of laser precipitated solidification by corrosion tests, the results show Ni-P coating has excellent corrosion resistances than the latter in various aspects. The key reason causing the difference between those two coating is some micro crevices occurred on NdFeB when utilizing laser surface treatment. In short, elecroless nickel plating is the better choice to prevent NdFeB from corrosion.