Microstructure and High-Temperature Friction–Wear Properties of Laser-Cladded Cr–Ni–Al2O3–TiO2 Composite Coating

A Cr–Ni–Al2O3–TiO2 composite coating was fabricated on H13 hot work mold steel using a laser cladding. The surface and cross-sectional morphologies, chemical elements and phases of obtained coating were analyzed using an electron scanning microscope, energy-dispersive spectroscope and X-ray diffractometer, respectively. The friction–wear behaviors of Cr–Ni–Al2O3–TiO2 composite coating at 400, 500 and 600 °C were investigated using a high-temperature wear tester, and the worn morphologies and wear mechanism were also analyzed. The results show that the laser-cladded Cr–Ni–Al2O3–TiO2 composite coating is composed of Ni, Cr and intermetallic compounds of NiCr, Al0.34Cr0.21 and Al0.5Ni3Ti0.5, which effectively increase the oxidation resistance of H13 hot work mold steel. The average coefficients of friction (COFs) of Cr–Ni–Al2O3–TiO2 coating at 400, 500 and 600 °C are 0.205, 0.375 and 0.293, respectively, and the corresponding wear rates are 5.337 × 10−6, 5.919 × 10−6 and 6.162 × 10−6 mm3 N−1 s−1, respectively, which increase with the increase in temperatures. The wear mechanism at 400 and 500 °C is abrasive wear, while that at 600 °C is adhesive wear with the knot-like wear scar.