烧结钕铁硼永磁合金在不同酸溶液中的腐蚀行为  

Corrosion behavior of the sintered Nd-Fe-B permanent magnets in different acid solutions

作　　者：丁霞[1] 薛龙飞[1] 丁开鸿 崔胜利 孙永聪 李木森[1] 

机构地区：[1]山东大学材料液固结构演变与加工教育部重点实验室,山东济南250061 [2]烟台首钢磁性材料股份有限公司,山东烟台265500

出　　处：《中南大学学报（自然科学版）》2016年第4期1105-1110,共6页Journal of Central South University:Science and Technology

基　　金：国家稀土与稀有金属材料重大专项课题资助(发改办高技(2012)1743号)~~

摘　　要：对烧结钕铁硼永磁合金在盐酸、硝酸和磷酸3种不同酸溶液中的腐蚀行为进行研究。采用扫描电镜和能谱仪观察和测试样品腐蚀前后的微观形貌和元素质量分数,用磁性测量仪测试样品侵蚀前后的磁性能。研究结果表明:烧结钕铁硼永磁合金在盐酸和磷酸溶液中呈现均匀腐蚀特征,而在硝酸溶液中其边缘腐蚀严重;在盐酸溶液中的腐蚀速率最大,在磷酸溶液中腐蚀速率最小。盐酸溶液明显腐蚀晶界富钕相,并且会在侵蚀过程中渗入基体孔隙中,造成磁体近表面的进一步腐蚀;硝酸溶液主要腐蚀主晶相,对晶界相影响不大;磷酸溶液会在烧结钕铁硼表面形成一层块状磷酸盐产物。盐酸溶液腐蚀会造成磁体剩磁和最大磁能积的明显降低,而磷酸溶液腐蚀会在一定程度上影响磁体的内禀矫顽力,硝酸溶液腐蚀对磁体磁性能的综合影响最小。The corrosion behavior of sintered Nd-Fe-B permanent magnets in hydrochloric acid, nitric acid and phosphoric acid was investigated, respectively. The morphologies and element contents before and after corrosion were characterized by scanning electron microscopy and energy disperse spectroscopy. A NIM-2000 model of magnetism tester was employed to test the magnetic properties of the samples. The results show that Nd-Fe-B magnets present uniform corrosion in both hydrochloric acid and phosphoric acid solution, but it has more severe edge corrosion in nitric acid solution. The corrosion rate of the magnets is maximum under hydrochloric acid solution condition while it is minimum in phosphoric acid. The corrosive attack of hydrochloric acid mainly corrodes the intergranular Nd-rich phase. And the acid solution penetrates to Nd Fe B matrix through the pores in the erosion process, resulting in further corrosion of the sub surface. Conversely, the erosion of nitric acid primarily occurs in the Nd2Fe14 B phase. And it has little effect on the Nd-rich phase. A layer of phosphate products on the surface of the magnet can be formed in the phosphoric acid solution. The remanence and maximum energy product of the magnets are significantly decreased by the corrosion of hydrochloric acid solution, and the intrinsic coercive force decreases to a certain extent by corrosion of phosphoric acid solution. The corrosion of nitric acid has the smallest effect on the integrated magnetic properties of the magnets.

关 键 词：烧结钕铁硼 酸溶液 腐蚀 组织结构 磁性能 

分 类 号：TG171[金属学及工艺—金属表面处理]