The effect of heat treatment on the microstructure and mechanical properties of electrodeposited nanocrystalline Ni–W/diamond composite coatings

• Ni–W/diamond coatings were prepared by the electrodeposition method with different current densities.
• The Ni–W/diamond coatings contain a maximum diamond volume fraction at 10 A/dm2.
• The grain size of Ni–W/diamond coatings grew up with an increase in the heat treatment temperature.
• Microhardness of the Ni–W/diamond coating was raised to 1205 HV at annealing temperature of 600 °C.
• Heat-treated Ni–W/diamond composite coatings show a better wear resistance than the as-plated ones.

Ni–W/diamond composite coatings were electrodeposited from the Ni–W plating bath containing diamond particles. The influences of current density on composition of the nanocomposite coatings were investigated. The dependence of physicochemical properties, including microstructure, microhardness, and wear resistance on the annealing temperatures was also systematically compared. The results show that the content of the codeposited diamond particles increases initially with the current density and reaches a maximum at 10 A/dm2. When current density is higher than 10 A/dm2, the volume percentage of the codeposited diamond particles decreases. The incorporation of diamond particles into Ni–W matrix leads to an increase in microhardness and wear resistance of the nanocomposite coatings and reduces the wear weight loss. In addition, the heat-treated Ni–W/diamond composite coating shows a better wear resistance than that of the as-plated one. The microhardness reached a maximum (1205 HV) after annealing at 600 °C due to the precipitation of the Ni4W phase.