Hardening of FeCrMoWCBSi amorphous electrospark coatings with tungsten carbide

A new direction in the development of metal-matrix coatings are composites based on an amorphous matrix with reinforcing ceramic additives. In this work, composite coatings were prepared by electrospark treatment of AISI 1045 in a mixture of iron granules with a multicomponent composition CrMoWCBSi and the addition of tungsten carbide powder. According to X-ray analysis, with an increase in the concentration of WC in the mixture of granules up to 1.2 vol.%, the content of the WC phase in the coating composition increased. In addition, the X-ray analysis showed metallic tungsten, which is a product of the partial dissolution of WC particles in the iron melt. In the microstructure of the coatings, inclusions of tungsten carbide with a diameter of 1.8 ± 0.9 μm were observed. The oxidation resistance of the coatings at a temperature of 700°C decreased monotonically with an increase of WC additive in the mixture of granules. The microhardness of the coatings with tungsten carbide was in the range from 814 to 1118 HV, which is higher compared to a completely amorphous sample (743 HV). The average values of the coating friction coefficient with WC ranged from 0.60 to 0.67, which is 30 % lower than that of an amorphous coating. The wear rate of coatings with tungsten carbide was in the range of 0.5 –1.1×10−5 mm3 / Nm, which is lower than that of the sample without WC (1.8 ×10−5 mm3 / Nm). The optimal value of the addition of WC powder in the mixture of granules during the deposition of the coatings for tribotechnical applications is 1.2 vol.%. Thus, the use of amorphous coatings reinforced with tungsten carbide makes it possible to reduce the wear of steel 45 by up to 8 times.