Effects of laser power on friction-wear performances of laser thermal sprayed Cr3C2-NiCr composite coatings at elevated temperatures

Cr3C2-NiCr composite coatings were fabricated on H13 hot work mould steel using a laser thermal spraying (LTS) at the laser power of 1200, 1400 and 1600 W. The surface and cross-section morphologies, chemical compositions, bonding strengths, phases and roughness of obtained coatings were analyzed using a scanning electronic microscopy (SEM), energy dispersive spectroscopy (EDS), scratch, X-ray diffractometer (XRD), and atomic force microscopy (AFM), respectively. The friction-wear properties of Cr3C2-NiCr composite coatings at 600 degrees C were analyzed using a high temperature wear test, and the wear mechanism were also discussed. The results show that the Cr3C2-NiCr composite coatings are primarily composed of Cr7C3 and Cr3C2 hard phases, and NiCr binder phase, the average bonding strengths is 46.25 N, which forms the metallurgical bonding at the coating interface. The average coefficients of friction (COFs) of Cr3C2-NiCr coating fabricated at the power of 1200, 1400 and 1600 W is 0.65, 0.34, and 0.67, respectively; the corresponding wear volumes are 111.3, 101.1, and 143.2 mm(3), respectively, the wear mechanism of Cr3C2-NiCr coatings is primary abrasive wear and oxidation wear.