Effect of spraying power on the microstructure and wear behavior of the plasma-sprayed FeCoCrNiMo0.2 coating

In this work, FeCoCrNiMo0.2 high-entropy alloy coatings were fabricated using the atmospheric plasma spraying technique. The dependence of the microstructure and wear property of the coatings on spraying power was explored. The results showed that with increasing spraying power, the streamlined structure of the coating was gradually disturbed, the content of the oxides in the coating was enhanced, and the distribution of oxides became relatively uniform. Meanwhile, the porosity in the coating was reduced due to the increased melting degree of feeding particles. As the spraying power increased from 25.5 to 45 kW, the micro-hardness of the coating was improved from 438 ± 15.27 to 558.73 ± 7.23 HV0.2 and the wear loss of the coating decreased from 2.05 × 10−4 to 1.18 × 10−4 mm3/nm. The synergistic effect of the dispersive oxides and the reduced porosity could account for the enhanced micro-hardness by the second phase strengthening mechanisms. Subsequently, the wear resistance of the coating prepared at a high spraying power was improved due to the increased micro-hardness and the reduced crack behaviors. In addition, the broken oxides of metal elements, especially Cr oxides, during wearing led to the abrasive wear behavior, and the broken oxides could work as a lubricant to decrease the wear coefficient of the coating. Finally, the FeCoCrNiMo0.2 coating prepared at a power of 45 kW had the best wear resistance.