n unconventional energy exploration and development technology, it is urgent to improve the mud bag resistance and wear resistance of PDC bit. CoCr powder cermet coating prepared by supersonic flame spraying technology has excellent wear resistance, corrosion resistance and good bonding strength. It is suitable for strengthening PDC bit steel, but it is necessary to improve its surface hydrophobicity to improve the mud bag problem. In this study, a 200 mm thick film was prepared by supersonic flame spraying μ M CoCr cermet coating was modified by sandpaper grinding to change the surface roughness and laser surface texture. The cross-sectional morphology of the original coating was characterized by scanning electron microscope, and the white light morphology instrument was used to characterize the three-dimensional morphology of the textured coating. The hydrophobicity and tribological properties were tested by contact angle test and friction experiment.

The main research results include:

(1) Increasing the surface roughness can improve the hydrophobicity of the surface. The contact angle CA is proportional to the roughness SA, and the coating surface changes from hydrophilicity to hydrophobicity. The results of slurry lubrication friction experiment show that the increase of surface roughness will increase the friction coefficient and slightly reduce the wear volume, but the overall difference is not obvious. During the friction process, adhesive wear mainly occurs, accompanied by oxidation.

(2) The hydrophobic properties of the surface treated by laser texture were significantly improved, and the spacing was 100 μ The mesh texture contact angle of M is the largest, and it has obvious antifriction effect under dry friction. The texture coverage r increases with the decrease of texture spacing, and the CA value increases with the increase of texture coverage. The increase of Ca value is due to the joint action of surface morphology and chemical composition changes. Under dry friction, the friction coefficient of each texture increases with the increase of spacing, and the friction coefficients of grids, grooves and pits with the same spacing increase in turn. Under the condition of slurry lubrication, the friction coefficients of the three textures are higher than those of the original surface. The wear mechanism under dry friction is mainly adhesive wear and oxidation wear. Under mud lubrication, three body wear mainly occurs on the textured surface.

(3) The surface of CoCr powder cermet coating modified by fluorosilane showed good hydrophobicity and antifriction properties. The contact angle increases with the increase of texture coverage, and all the modified contact angles show hydrophobicity, with a spacing of 40 μ m. Width 100 μ M texture has the largest contact angle with deionized water and drilling fluid, reaching 138.22 ° and 125.5 ° respectively. The contact angle between deionized water and modified textured surface is consistent with the theoretical value of Cassie model θ C very close. The results of slurry lubrication friction experiment show that when the texture width or spacing is the same, the larger the texture coverage is, the smaller the friction coefficient is, and the friction coefficient of textured surface is basically less than that of polished coating surface. However, the wear volume increases with the increase of texture coverage.