Electroless Ni-P-PTFE Composite Plating with Rapid Deposition and High PTFE Concentration through a Two-Step Process

Electroless composite plating enables uniform and thin surface treatment along with composite deposition using nanoparticles. Among such particles, polytetrafluoroethylene (PTFE) is capable of dry lubrication because of its self-lubricating properties. Specifically, the PTFE content in a plating layer increases with the concentration of PTFE in the plating bath. However, a high concentration of PTFE interferes with the co-deposition of Ni and P, thereby reducing the plating speed. Additionally, PTFE is unevenly deposited on the surface of the plating layer. Consequently, a method for increasing the PTFE content at low PTFE concentrations is required. Therefore, in this study, a stirring process in a low-PTFE-concentration plating bath and a process wherein PTFE precipitates on a specimen without stirring were combined. The PTFE content of the plated layer deposited on high carbon steel, plated layer deposition rate, average friction co-efficient, static contact angle, and surface energy were evaluated as 25.96%, 3.44 µm/40 min, 0.195, 141.9°, and 2.74 mN/m, respectively. This technique prevented the decrease in the deposition rate of the plating layer and led to high PTFE content in the plating layer. Notably, even a thin plating layer (5 μm or less in thickness) showed excellent surface characteristics.