氢对Nd-Dy-Fe-B合金粗粉氧化的影响  

Effects of hydrogen on the oxidation of coarse Nd-Dy-Fe-B powder

作　　者：谭春林[1] 白书欣[2] 张虹[2] 张家春[1] 蔡珣[1] 

机构地区：[1]上海交通大学材料科学与工程学院,上海200030 [2]国防科技大学材料工程与应用化学系,湖南长沙410073

出　　处：《功能材料》2003年第5期522-524,共3页Journal of Functional Materials

基　　金：湖南省自然科学基金资助项目(00JJY2042)

摘　　要：　烧结钕铁硼工业中,用于粗破碎钕铁硼合金铸锭的氢脆工艺的应用越来越广泛。本文研究了氢脆后经不同温度脱氢处理的Nd Dy Fe B磁粉的氧化过程。磁粉的氧化在室温下大气环境(相对湿度为60%～75%)和干燥器中(相对湿度为10%～15%)进行。采用重量法研究了磁粉的氧化速率和吸湿率。研究发现,未脱氢磁粉的氧化快,吸湿率大,特别是在氧化的初期阶段。脱氢粉抗氧化能力的提高来源于低的氢浓度和少的氢化物的存在。对比钕氢化物(NdHx)的氧化结果,可以得出,氢促进氧化的机理可能是磁粉中氢化物和大气中水蒸气之间的氢键促进磁粉吸湿,加速磁粉的电化学腐蚀。而且氢在磁粉中产生的缺陷可以诱导加快氧的扩散。Hydrogen Decrepitation (HD) process has been widely used to crash Nd-Fe-B ingots in sintered Nd-Fe-B magnet industry. This article studied the oxidation of Nd-Dy-Fe-B coarse powder heat treated at different temperature after HD process. The oxidation of powder in ambient air (with 60%-75% relative humidity) and in dryer (with less than l5% relative humidity) was investigated by weight gain method, as well as water absorptance. It was found that powder A (not dehydrogenated) is oxidized more quickly, and absorbs much more water, especially at the first stage. Powder B and C (dehydrogenated) have higher oxidation resistance because of lower hydrogen concentration and hydride amount. Comparing with the oxidation of neodymium hydrides (NdHx), it was shown that the mechanism of hydrogen accelerating oxidation probably focus on that hydrogen bonds between hydrides in powder and water molecules in air, which accelerate the absorption of water from ambient air and promote the electrochemical reaction in powder. Defects caused by hydrogen in powder induce oxygen diffusion more quickly.

关 键 词：钕铁硼 Nd-Dy-Fe-B合金 氧化 氢脆 脱氢处理 氢键 

分 类 号：TM273[一般工业技术—材料科学与工程]