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

摘要

Cu-Cr-W composite coatings were prepared by mechanical alloying(MA)method using different powder ratios,rotational speeds and milling time.The micro structures 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 micro structures of the coatings fabricated at different rotational speeds suggest that rotational speed of 300 r·min-1is 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.