Electrodeposition of Ni-P-PTFE composite coatings and evaluation of their electrochemical behavior

There are many modern technologies, like medical devices and machines and aerospace need dry coatings with low friction and high wear resistant[1]. Characteristic of Ni–P alloy is that the incorporation of phosphorus, as alloying element, in the nickel lattice affects the structure of the deposit. Thus, depending on the phosphorus content the alloy could be crystalline, amorphous or a mixture of crystalline and amorphous phase. PTFE was added to composite to enhance lubricant characteristics of composite. In this study, the electrochemical performances of electrodeposited nickel-phosphorus (Ni-P) coating containing Polytetrafluoroethylene (PTFE) particles were investigated. Electroplating bath containing six different concentrations of PTFE (0, 5, 10 ,15, 20 and 30 g L-1) was used to prepare Ni-P-PTFE composites. Ni–P/PTFE composite coatings were produced under direct current conditions from a modified Watts type bath at optimum current of 30 mA cm-2. Mild steel and pure nickel plate were used as cathode and anode materials, respectively. Corrosion behavior of the coatings was examined using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results show that there is a significant enhancement in corrosion resistance with the incorporation of PTFE particles into the Ni-P matrix. It was also observed that the addition of PTFE in the Ni-P alloy matrix has resulted in a smoother surface with a low friction coefficient.