Electro-Spark Deposition Coating of AISI 4140 and AISI 1040 Steels by WC, Ni and M42 Electrodes and their Wear Properties

One of the promising methods to produce a hard and wear-resistant coating on metallic surfaces is through electro-spark deposition (ESD). Electro-spark deposition is a micro-welding process based on the principle of depositing the electrode material on the surface by means of the microarc formation created by pulsed electric currents, which enables coatings to be bonded metallurgically to the substrate and exhibiting better adhesion properties compared to some of the traditional methods. In order to improve the wear properties of AISI 1040 and 4140 steels, Ni, WC and M42 steels single coatings and Ni + WC and Ni + M42 steel dual coatings were deposited using ESD. The structural and microstructural properties of the coating layers and the matrix steels were characterized by x-ray diffraction (XRD) and scanning electron microscopy (SEM). W2C, Fe-gamma and Fe-alpha phases were detected in the coatings obtained from XRD analysis. The coating layer thicknesses ranged from 64 to 86 mu m. The surface hardness of all steels in this study increased with the coatings, and the wear resistance improved approximately between 150 and 300%.