钕铁硼永磁材料在不同体系化学镀液工艺中的腐蚀

Corrosion of Nd-Fe-B Permanent Magnet Material in Various Electroless Plating Baths

NdFeB材料中钕的含量极高,极易被氧化而产生严重的腐蚀。为提高钕铁硼材料的耐蚀性,采用性能优良的化学镀方法寻找NdFeB永磁材料在不同化学镀液中的腐蚀规律。研究了NdFeB永磁材料在化学镀铜液、酸性化学镀镍磷液、中性化学镀镍磷液、碱性化学镀镍磷液、碱性除油液中的浸泡腐蚀试验,并测试了这些溶液的E-t曲线。结果表明,在NdFeB的化学镀中为减少对NdFeB基体的腐蚀应采用碱性化学镀铜液打底,碱性除油液对NdFeB材料基本无腐蚀。

Nd-Fe-B permanent magnet material of an extremely high content of Nd is liable to severe corrosion,due to the oxidizing of Nd.Fortunately,it could be feasible to significantly increase the corrosion resistance of the Nd-Fe-B permanent magnet material making use of electroless plating of various metal and/or alloy systems.Thus the corrosion behavior of the Nd-Fe-B permanent magnet material in electroless copper plating bath,acidic electroless Ni-P plating bath,neutral electroless Ni-P plating bath,alkaline eletroless Ni-P plating bath,and alkaline degreasing solution was investigated.Moreover,its corrosion behavior in nitric acid solutions of pH values 1,3,and 5,respectively,and sodium hydroxide solutions of pH values 8,10,and 12,respectively,was also examined at various temperatures.The E-t curves for the Nd-Fe-B in different mediums were measured.It was found that the corrosion rate of the Nd-Fe-B material decreased with increasing pH value of the mediums.Almost no weight loss attributed to corrosion was observed as the pH value of the mediums was above 10.Moreover,the static state experimental results were validated by the corresponding E-t curves.In general,it was suggested to clean the Nd-Fe-B substrate using alkaline degreasing solution and to introduce a bottom deposit using alkaline electroless copper plating prior to the final electroless plating,so as to minimize the possible corrosion of the Nd-Fe-B substrate in different bath systems.