Hydrophobicity And Wear Resistance Of Textured Surface Of PTFE Based Composite Coating

In the process of unconventional oil and gas resources exploitation,the mud package and life of PDC bit are common problems to be solved.PTFE coating is suitable for PDC bit steel,but we need to use surface technology to further improve the hydrophobic and Tribological Properties of PTFE coating.In this study,carbon fiber(CF)and graphene(GE)modified polytetrafluoroethylene(PTFE)composite coatings were prepared on35 CrMo steel by one-step spray method,and then pit texture with different size and density was prepared on the surface of the composite coating by laser surface texturing(LST)technology.The static contact angles of different composite coating surfaces were measured.The friction and wear experiments were carried out on the coating surface.The effects of the type,proportion and texture size density of fillers on the hydrophobicity and Tribological Properties of the modified polytetrafluoroethylene composite coating were studied.The main research results include:(1)The textured CF/PTFE composite coating has good tribological properties and hydrophobicity.When the texture diameter is 200?m,the distance is 100?m,and the mass fraction of carbon fiber is 20%,the friction coefficient of textured CF/PTFE composite coating reaches the lowest value of 0.12±0.02,and the wear rate reaches the lowest value,which is 27.5% lower than that of pure PTFE coating.The main wear mechanism is adhesive wear and abrasive wear.The contact angle of the textured CF/PTFE composite coating increased to 141.0°±2.0°,showing excellent hydrophobicity.The transfer of fluorine from the inner layer to the outer layer may be another reason for its excellent hydrophobicity.The texture can effectively store the wear debris,so as to reduce the adhesive wear.The carbon fiber inside the PTFE coating can prevent the large area damage of the composite coating.(2)The textured Ge/PTFE composite coating has excellent tribological properties and hydrophobicity.When the texture diameter is 100?m,the distance is 100 ?m and the content of graphene is 3%,the friction coefficient of the composite coating is reduced to0.09±0.01,which is the lowest,and the wear rate is 68.7% lower than that of the pure PTFE coating.Texture stores wear debris and protects the cross-linking structure to reduce adhesive wear.In addition,it can be seen that the uniform and continuous transferfilm adhered to the grinding ball helps to reduce the wear rate and improve the wear resistance of the textured Ge/PTFE composite coating.The contact angle of the textured Ge/PTFE composite coating increases to 146.1°±1.8°,showing excellent hydrophobicity,very close to superhydrophobic.It is believed that the reason is that graphene is uniformly dispersed in the pit texture and the surface of PTFE to form the cross-linking structure.The texture and the cross-linking structure increase the surface roughness of the composite coating,and the wear surface of the composite coating after the friction and wear test also shows good hydrophobicity,which proves that the hydrophobicity of the composite coating has excellent maintenance ability,which is beneficial to The service durability and service life of the composite coating are of positive significance.