Effect of abrasive particle size on the tribological behavior of thermal sprayed WC-Cr3C2-Ni coatings

Abstract

In order to improve the wear performance of ball mill liners, two types of WC-Cr3C2-12Ni coatings with different Cr3C2 contents were prepared based on high- velocity oxygen fuel (HVOF) spraying technology. The three-body abrasive wear behavior of the WC-10Cr3C2-12Ni (W10N) and WC-30Cr3C2-12Ni (W30N) protective coatings under different particle sizes was systematically evaluated. Results show that the phase composition, microstructure, and mechanical properties of WC-Cr3C2-12Ni coatings were influenced by Cr3C2 content. A large amount of WC phase with good dispersion and fine morphology must be maintained to improve the wear resistance of the coatings. The friction coefficient of both coatings was the lowest when the abrasive particle size was 12.0 µm, but it was still lower than under the no-particle condition. In addition, the friction coefficient of the W30N coatings fluctuated when the particle size were 1.5 and 4.0 µm. The primary wear mechanisms of the two coatings without particles were oxidation wear and fatigue wear, respectively, and the microstructure unevenness and low WC volume fraction led to serious wear of the W30N coatings by preferential removal of the binder phase and pull-out of the WC. The wear mechanisms of the coatings after adding small to large particles were as follows: abrasive particles protected the coatings; rounded the WC grains; and planed the coating to exfoliate in layers. By contrast, the wear resistance of the W10N coatings was obviously superior to that of the W30N coatings. Importantly, the particle size influenced the counter-balls more than the coatings. This study provides potential applications for the surface protection and life extension of ball mill liners.