Study Of Composite Coating By Arc Spraying Feeding Ceramic Powders From Outside

Arc spraying is a rapid-developing material processing technology, anti-wear, anti-corrosion and parts repairments are widely used. Arc spraying materials include solid wire and cored wire. Solid wire is easy to operate and high efficiency, but the composition is not easy to adjust, it is difficult to obtain high-performance coatings. Cored wire can be adjusted according to actual needs in order to get all kinds of special powder composition of the coating performance, but it has some shortcomings, such as high cost, hard to make, composition more difficult to adjust.In this study, the concept of arc spraying feeding ceramic powders from outside is proposed. Solid wire and ceramic powders from outside combine to get a composite coating. Two kinds of feeding ceramics from outside methods are studied. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDAX), X-ray diffraction (XRD) test methods are used in the study. The results are as follows:When ceramic powders of SiO₂ and TiO₂ are close to the substrate for sending, the coating contains part of the ceramic particles. Al₂O₃ powder is used, almost no ceramic particles come into the coating. When ceramic powder are close to the arc zone by using SiC powders or SiC Fe-Al mill powders, part of the powders embed in the coating at the original shape, the other part of SiC particles have decomposed so that C elements and SiO₂ deposit to the coating. In hardness and wear resistance of the coating has improved to some extent.Process parameters on the hardness of composite coatings from the main to the secondary were: spray current, atomizing air pressure, spray voltage. The optimum process parameters for the spray voltage of 30V, Spraying current of 220A, atomizing air pressure is 0.7MPa. When ceramic powders of SiO₂ are close to the substrate, the abrasive wear and along with adhesive wear are the main wear style in dry friction. When ceramic powder are close to the arc zone by using SiC powders or SiC Fe-Al mill powders, the abrasive wear are the main wear style along with adhesive wear in dry friction.