Purpose

The microstructure and properties of Zn-Sn coating on sintered Nd-Fe-B magnets were investigated by the grain boundary diffusion process, to improve the corrosion resistance of magnet surface and explore the feasibility of realizing the lower-temperature grain boundary diffusion.

Design/methodology/approach

The Zn-Sn coating was deposited on sintered Nd-Fe-B magnets by magnetron sputtering, and then the Zn-Sn coated magnets were put into the vacuum tube furnace for grain boundary diffusion process. The morphology and structure of Zn-Sn coating as well as its mechanical properties and corrosion resistance were investigated.

Findings

Results showed that the particle size of vacuum diffusion-treated Zn-Sn coating increased and the particle agglomeration was weakened with increasing diffusion temperature, and the non-vacuum diffusion-treated Zn-Sn coating was oxidized to generate SnO₂ and ZnO compounds. The binding force of coating first increased and then decreased with increasing diffusion temperature, and the maximum binding force was obtained at 540 °C. The binding force and corrosion resistance of non-vacuum diffusion-treated Zn-Sn coating were higher than the vacuum diffusion-treated Zn-Sn coating at the same diffusion temperature.

Originality/value

The Zn-Sn coating after diffusion treatment can provide complete protection, and the coating elements diffusion can be carried out at the same temperature as the secondary aging of sintered Nd-Fe-B magnets. Simultaneously, further diffusion process optimization needs to be completed because the diffusion depth is very low and only about 10 µm, which does not meet the requirements of traditional grain boundary diffusion method.

中文翻译：

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烧结钕铁硼磁体表面Zn-Sn镀层组织和性能的晶界扩散研究

目的

通过晶界扩散工艺研究了烧结Nd-Fe-B磁体表面Zn-Sn涂层的组织和性能，以提高磁体表面的耐腐蚀性能，探索实现低温晶界扩散的可行性。

设计/方法/方法

通过磁控溅射在烧结的Nd-Fe-B磁体上沉积Zn-Sn涂层，然后将Zn-Sn涂层磁体放入真空管式炉中进行晶界扩散处理。研究了Zn-Sn涂层的形貌、结构、力学性能和耐腐蚀性能。

发现

结果表明，随着扩散温度的升高，真空扩散处理的Zn-Sn涂层粒径增大，颗粒团聚减弱，非真空扩散处理的Zn-Sn涂层被氧化生成SnO ₂和ZnO化合物。涂层的结合力随着扩散温度的升高先增大后减小，在540℃时获得最大结合力。在相同扩散温度下，非真空扩散处理的Zn-Sn涂层的结合力和耐腐蚀性能高于真空扩散处理的Zn-Sn涂层。

原创性/价值

扩散处理后的Zn-Sn镀层可以提供完全的保护，镀层元素的扩散可以在与烧结钕铁硼磁体二次时效相同的温度下进行。同时，由于扩散深度很低，只有10μm左右，无法满足传统晶界扩散方法的要求，需要进一步优化扩散工艺。