Study On Properties Of Arc Sprayed Coating With Carbide Ceramic

Cermet composite coatings have high hardness, wear resistance, high temperature oxidation, corrosion resistance and high chemical stability, also have high toughness and plasticity. Therefore, it's a perfect coating material. At present, many thermal spraying methods for cermet composite coating have been commonly used, such as powder flame spraying, plasma spraying, HVOF spraying and arc spraying. Compared with several spraying methods, arc spraying has the advantages of easy-adjusting chemical compositions, low cost and operating on site applicable.In this study, iron-based composite coatings were deposited on mild steel substrate by arc spraying cored wire with TiC, WC, Cr₃C₂ ceramic powders. The microstructure, phase compositions and worn surface morphologies of the coatings were examined by means of optical, scanning electron microscopy and X-ray diffraction. The abrasion wear resistance properties were evaluated by MLS-225 wet sand/rubber wheel tester. The effect of carbide ceramic content in cored wire and post heat-treatments on the properties of the coatings was studied. Research results are as follows:1. It is feasible that iron-based composite coatings were deposited on mild steel substrate by arc spraying cored wire with TiC, WC, Cr₃C₂ ceramic powders. The results showed that all coatings exhibited better abrasive wear resistance and about 6～18 times higher than that of the Q235 mild steel.2. The experiment studied the matching of ceramic and alloys system, the influence of ceramic content on the abrasion wear resistance of composite coatings. The results showed that the hardness and the abrasive wear resistance of the coatings increased with increasing the ceramic powders (TiC, WC, Cr₃C₂) in the cored wire. When the content of ceramic reached to certain level, the abrasive resistance of coatings began to decrease. 3 The effect of post heat-treatments on the abrasive wear resistance of the composite coatings was studied. The results showed that the micro-hardness of coatings was improved with the temperature's increase of post heat-treatment. However, the abrasive resistance of three coatings is different. TiC coatings increase gradually, WC coatings first decline and then increase, and Cr₃C₂ coatings gradually decrease.4. Micro-ploughing and brittle fracture were the major abrasive wear mechanisms of the coatings. The coatings have better abrasive wear resistance because the metallic matrix of the coatings have higher hardness and plasticity. The coatings are obviously reinforced by the carbide ceramic hard particles distributed in the iron-based coating. With the increase of the wear time, the abrasive wear resistance of the three coatings has been enhanced.