Microstructure and Properties of Nanocrystalline Ni-Mo Coatings Prepared by Ultrasound-Assisted Pulse Electrodeposition

Electroplating Nickel-Molybdenum (Ni-Mo) coatings with superior corrosion and wear resistance has remained a challenge in materials sciences and engineering. Cracks caused by excessive Mo content and hydrogen evolution reaction during electroplated process are still abounded, resulting in properties degradation. Here, we develop a facile approach to produce crack-free Ni-Mo coatings with excellent properties by using ultrasound-assisted pulse electrodeposition. Effect of current density on microstructure, chemical composition, microhardness, corrosion and wear resistance of Ni-Mo coatings is systematically investigated. With the increase in current density, Mo content increases, grain size decreases and Ni-Mo coatings change from colony-like to cauliflower type morphology. The higher Mo content and smaller gain size enhance the microhardness and endow Ni-Mo coatings with superior corrosion resistance for electrochemical tests in 0.5 M H 2 SO 4 solution. The higher microhardness improves the wear resistance of Ni-Mo coatings in tribological tests sliding against GCr15 steel ball under dry sliding condition. Graphic Abstract