The effects of
methylacetic,
glycocoll,and succinic acids as accelerators on the
properties of electroless
Ni-Sn-P coating were investigated in the presence of complex stabilizing agents used for electroless Ni-P plating,which was aiming at increasing the plating velocity and bath stability for the electroless Ni-Sn-P plating.Thus the dosages of the accelerators in the plating bath were determined making use of three-factor orthogonal tests,while the plating velocities at different conditions were measured,and the
porosity and
microhardness of the relevant Ni-Sn-P coatings were determined.Results indicated that the porosity and hardness of the Ni-Sn-P coatings were closely dependent on the accelerating effects of the accelerators.Namely,the accelerators of stronger accelerating effects contributed to generate the Ni-Sn-P coatings with lower porosity and higher microhardness.In particular,methylacetic and glycocoll acids were more effective in speeding the plating process,while glycocoll and succinic acids contributed to increase the microhardness of the Ni-Sn-P coatings to some extent.Moreover,all the three kinds of acids acted to reduce the porosity of the Ni-Sn-P coatings to varied degrees,and glycocoll and methylacetic acids were more effective in decreasing the porosity.The optimum contents of the accelerators glycocoll,methylacetic,and succinic acids in the plating bath were suggested as 25 mg/L ,4 mL/L,and 2.5 g/L,respectively.The corresponding Ni-Sn-P coatings deposited at the optimized conditions had a depositing rate about 14~15 m/h,microhardness from 480 HV to 550 HV,and were free of porosity.