pH值对Ni-Fe-P化学镀层结构与磁性质的影响

以硼酸为缓冲剂,柠檬酸钠为络合剂,在弱碱性体系中化学沉积Ni-Fe-P合金.采用电子能谱仪、X射线衍射仪、透射电镜和振动样品磁强计,研究镀液pH值和NiSO4/FeSO4物质量的比等对镀层组成、结构和磁性能的影响.结果表明,在化学沉积Ni-Fe-P合金中,Fe随着Ni被还原而共沉积,但镀层中Fe原子数分数不高,属诱导共沉积机理.镀液pH值的提高有利于Fe的还原沉积,但会使镀层中P原子数分数稍微降低,约为17.81%~22.0%,属于中高磷镀层.沉积条件对Ni-Fe-P镀层的结构影响不大,合金镀态均为非晶态或微晶结构.Ni-Fe-P合金的磁性能与沉积条件密切相关,随着镀层中铁原子数分数的增加,镍原子数分数降低,镀层的饱和磁化强度和剩余磁化强度均增加.

The Effect of pH Value on the Composition and the Magnetic Performance of Electroless Ni-Fe-P Alloy

Ni-Fe-P alloy has been electrolessly deposited from a alkaline bath containing boric acid as a buffer agent and sodium citrate as a complexing agent.The effect of deposition parameters,such as pH value and molar ratio of NiSO_4/FeSO_4 on the composition,the structure and the magnetic performance of the deposits was studied by EDX,XRD,TEM and VSM.In the electroless deposition of Ni-Fe-P alloy,iron can be reduced and co-deposited with nickel,but iron content in deposits does not reach high value.The mechanism of co-deposition of Ni-Fe-P alloy is the inductive co-deposition.The increase of pH value of bath favors the reducementof iron,but can decrease phosphorus content in deposits.The phosphorus content of the Ni-Fe-P deposits is high which ranges from 17.81 at% to 22.0 at%.The Ni-Fe-P alloy plated at all conditions is amorphous or microcrystallite structure.The magnetic performance of Ni-Fe-P alloy dependson the plating conditions,and the saturation magnetization and the residual magnetization of the deposit increase with the increase of the iron content in deposits.