Microstructure and Tribological Properties of Fe-Based-Al2O3-B4C Composite Coatings Prepared by High-Velocity Arc Spraying

Fe-based-Al2O3-B4C coating was prepared on the low-carbon steel substrates using high-velocity arc spraying. The effects of voltage, current, and distance on the porosity and microhardness of the coating were studied by an orthogonal test, and the optimum spraying parameters were determined. The microstructure and properties of Fe-based-Al2O3-B4C coatings prepared under optimum process parameters were characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), microhardness and friction wear tester. The results showed that the optimum process parameters were a spraying voltage of 41 V, a spraying current of 200 A, and a spraying distance of 150 mm. The porosity was 2.24 ± 0.32%, and the microhardness was 1543 ± 145 Hv0.1, which was 8 times that of the substrate. Under the same load of 4.2 N and varying sliding speeds of 500 t/min, 750 t/min, and 1000 t/min, the coefficient of friction of the coating was less than that of the low-carbon steel, and the wear rate of the coating was 65%, 70%, and 63% lower than that of the low-carbon steel, respectively. The main wear mechanism of the coating was material spalling, accompanied by slight oxidative wear and abrasive wear.