Microstructures and properties of Cu–Cr–W composite coatings fabricated by surface mechanical alloying technique

Abstract

Cu–Cr–W composite coatings were prepared by mechanical alloying (MA) method using different powder ratios, rotational speeds and milling time. The microstructures and chemical compositions of as-synthesized coatings were analyzed by scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). Phases of ball-milled powders were identified by X-ray diffraction (XRD). The results indicate that the coating fabricated with powder ratio of 40 wt% Cu–Cr–W has better surface and cross-sectional microstructures and higher microhardness. The comparisons of cross-sectional microstructures of the coatings fabricated at different rotational speeds suggest that rotational speed of 300 r·min−1 is the optimal for fabrication the coating, and the optimal milling time for the formation of coating is 7 h. The results of microhardness test show that the hardness of the substrate is largely improved because of the as-fabricated coatings. The results of the friction and wear tests indicate that the wear resistance of the copper substrate is improved after the deposition of Cu–Cr–W coating on it. The coating fabricated for 7 h exhibits the lowest friction coefficient, indicating its favorable friction and wear resistance. The formation mechanism of the coating was elucidated. According to the investigations in this work, the Cu–Cr–W coating fabricated by MA method is considered to be effective to reinforce the copper substrate.