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

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 Delta 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 T-2/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.