Pulsed electrodeposition and characterization of bronze-graphite composite coatings

Composite coatings containing self-lubricant particles like graphite, MoS2, PTFE are extensively used to decrease the coefficient of friction of tribo-surfaces. The aim of this study is to investigate the effect of pulse electrodeposition parameters on particle codeposition process and characteristics of bronze-graphite composite coatings electrodeposited from cyanide-stannate bronze electroplating bath. Results showed a slight increase in tin content and a promising increase in hardness of bronze coating by a decrease in duty cycle at constant average current density. Both tin content of the coating and grain refinement seem to participate in hardness enhancement. By increasing the agitation rate, an increase in graphite content of composite coating is observed followed by a decrease by further increasing of agitation rate. Keeping the average current density constant at 10 mA cm− 2, graphite content of the coating is increased from 4% vol. to 18% vol. by decreasing the duty cycle from 1 to 0.05. The results showed that with an increase in graphite content of the coating, hardness and coefficient of friction of the coating would decrease and the lowest friction coefficient was obtained at 12% vol. graphite.