Ni-P electroless deposition with different complexing agents under high uniform and gradient magnetic fields

Xiao Lu^1,2 - Donggang Li² - Qiang Wang² - Changsheng Lou¹ - Yongze Cao² - Jicheng He²

¹ School of Materials Science and Engineering, Shenyang Ligong University, No.6 Nanping Central Rd., Shenyang, 110159, PR China
² Key Laboratory of Electromagnetic Processing of Materials (Ministry of Education), Northeastern University, No.3--11 Wenhua Rd., Shenyang, 110819, PR China

Abstract
Effects of a static high magnetic field of 4 T on the electroless Ni-P deposition with sodium citrate and lactic acid as a complexing agent, respectively, are studied in this work. The results show that the magnetic field accelerates nickel deposition using sodium citrate as a complexing agent. On the contrary, the deposition process is retarded in case of applying lactic acid as a complexing agent. The influence of a high uniform magnetic field on nickel deposition originates from two mechanisms: a ∆g mechanism and a Zeeman splitting mechanism, impacting on the complexation during electroless deposition. The composition analysis reveals that the P content in the films decreases from 8.2 to 6.99 wt.% with the increasing magnetic flux density 0 to 4 T. Comparing with the phosphorous content increasing during the process of plating without magnetic field, the depositing rate of phosphorus under a magnetic field of 4 T is relatively uniform. In addition, the mass of deposits under a gradient magnetic field of -79.860 T²/m is reduced if compared with the deposits under a static magnetic field. This effect is related to the magnetization force acting in the electroless bath, i.e., additional convection is suppressed, which decreases the mass transport. Tables 1, Figs 7, Refs 22.