Preparation of Ni-W alloy disc for dynamic friction polishing of diamond

Abstract

To investigate the impact of bath composition and process conditions on Ni-W alloy coating, Ni-W alloy discs with low internal stress and high hardness were prepared for dynamic friction polishing of diamonds. The effects of complexing agent concentration, solution pH, and saccharin sodium concentration on the internal stress, tungsten content, hardness, and deposition rate of the coating were investigated by single experiments. Additionally, the effects of different additives on the surface leveling of the coating were also investigated. Finally, salicylaldehyde was selected as the leveling agent, and the reverse pulse current was applied to reduce the surface roughness of the coating. A Ni-W alloy disc with a hardness of HV 713 and a coating thickness of about 0.66 mm was prepared. Diamond dynamic friction polishing was carried out using these alloy discs to explore appropriate polishing process parameters. The best polishing effects were achieved at a disc speed of 8000 r/min and a pressure of 40 N, yielding a removal rate of 5.56 μm/min, a grinding ratio of 0.394, and a surface roughness (Ra) of 3.7 nm. Comparing wear parameters revealed that Ni-W alloy discs can achieve better polishing effects using traditional cast iron discs in friction chemical polishing of diamonds.

Keywords

• diamond
• ni-w alloy
• internal stress of coating
• tribochemical polishing