Corrosion Behavior of Sintered NdFeB Magnets in Differ- ent Acidic Solutions

摘要:

通过酸洗、浸泡法和电化学腐蚀测试分析了烧结 NdFeB永磁体在不同浓度的 H2SO4 溶液、HCl溶液和 HNO3 溶液中的腐蚀行为。结果表明，烧结 NdFeB磁体在 HNO3 溶液中的腐蚀机制为均匀腐蚀，而在H2SO4溶液和HCl溶液中的腐蚀机制为选择性的晶间腐蚀。烧结NdFeB磁体在酸溶液中的腐蚀速率随着酸溶液浓度的增加而增加。在浸泡试验和电化学腐蚀试验中，烧结NdFeB磁体在HNO3溶液中的腐蚀速率均最小。因此，HNO3溶液更适合作为烧结NdFeB磁体的酸洗液

Abstract:

Corrosion behaviors of sintered NdFeB magnets in H2SO4 solution, HCl solution and HNO3 solution of different concentrations were investigated by pickling, immersion test and electrochemical test. The results show that the corrosion mechanism of sintered NdFeB magnets in HNO3 solution is uniform corrosion, while the one in H2SO4 solution and HCl solution is selectively intergranular corrosion. The corrosion rate of NdFeB magnets increases with increasing of the concentrations of the three acid solutions, and the corrosion rate of NdFeB magnets in the HNO3 solution is the smallest among the three acid solutions both in immersion test and electrochemical test. Therefore, the HNO3 solution is more suitable to be used as the pickling solution for the surface pretreatment of sintered NdFeB magnets.