钕铁硼永磁体室温熔盐电镀铝前处理工艺初探

钕铁硼粉末冶金材料表面存在大量细微孔洞,易吸附腐蚀性溶液而影响电镀层的防护效果.为此,通过对烘烤除油和化学除油,喷砂除锈和酸洗除锈,不封孔和封孔处理,活化和不活化等不同镀前处理方法的比较探讨,并采用扫描电镜(SEM)分析、锉刀和热震试验评估了铝镀层和基体的结合力,研究了一种适合钕铁硼永磁体室温熔盐电镀的无水前处理工艺:烘烤除油,喷砂除锈、干燥、电化学活化、电镀、溶剂洗、水洗、干燥.结果表明,该工艺能有效地去除钕铁永硼磁体表面及细微孔洞中的氧化膜,提高镀层和基体之间的结合力.

Pretreatment Processes for Al Electroplating of NdFeB Permanent Magnet in Melted Salt at Room Temperature

The effects of various pretreatments on the electroplating process and performance of electroplated Al coating were investigated and compared, attempting to establish a novel water-free pretreatment process for Al electroplating of NdFeB permanent magnet from a melted salt bath at ambient temperature and hence get rid of the damage to the Al coating by a large number of micropores on the surface of the NdFeB powder metallurgy material. Thus comparative investigations were made among various pretreatment proces-ses such as roasting degreasing and chemical decreasing, sand blasting and acid pickling, sealing and without sealing, and activating and without activating, with respect to the effects of the pretreatment on the adhesion of the Al coating to substrate. And the adhesion of the Al coating to the substrate was evaluated based on scanning electron microscopic observation and chisel -knife test and heat-quench test. As the results, it was suggested to apply the pretreatments including roasting degreasing, rust removal by sand blasting, drying, and electrochemical activation; and carry out cleaning in solvent, rinsing in water, and drying at the end of the electroplating, so as to effectively remove the oxidation film in the surface and bulk of the NdFeB material and hence increase the adhesion of the Al coating to the substrate.