WC-12Co self-lubricating wear-resistant coating

       

WC-12Co self-lubricating wear-resistant coating

Thermal sprayed WC-12Co coating is widely used on the surface of mechanical parts to play a good role in wear resistance and life extension. WC-12Co spray powder is mainly composed of hard wear-resistant WC ceramic phase and cohesive Co metal Phase composition, the temperature of the sprayed particles will affect the phase stability of WC and the adhesion of Co in the powder, and then affect the wear resistance and cohesive bonding strength of the coating. Compared with other thermal spraying technologies (plasma spraying, supersonic flame spraying), explosive spraying technology has the advantages of large adjustable range of spraying energy and high particle flying speed, which can reduce the high temperature decomposition and decarburization rate of WC, and prepare coating oxidation It has low material content, excellent hardness and excellent bonding strength. As an alternative to traditional chrome plating, it has been widely used in the aerospace and aerospace fields to protect the surface of key frictional parts. However, during the service process, it was found that the ceramic wear-resistant phase with higher hardness in the WC-12Co coating increased the friction coefficient between the friction pairs, causing more serious wear on the wear parts, and affecting the wear-resistant protection service life of the coating. Therefore, it is necessary to add lubricant to the coating to improve its friction performance. In order to reduce the friction coefficient of the WC-12Co wear-resistant coating, 4 kinds of powdering processes (wet ball milling, wet stirring, sintering and crushing, spray granulation) are used to compound graphene into WC-12Co powder, and explosive spraying technology is adopted. The graphene self-lubricating wear-resistant coating was prepared. SEM, EDS, Raman, etc. were used to analyze the microstructure and phase composition of graphene in powders and coatings obtained by different powdering processes. The mechanical properties of the coating were studied using a microhardness tester and a universal stretching machine. UMT-3 friction and wear tester was used to study the friction and wear properties of the coating. The results show that the graphene in the composite powder prepared by the spray granulation process is uniformly and tightly adhered to the surface of the WC-12Co particles, and the graphene content in the coating is relatively high, and it is still embedded in the tissue in a transparent and thin layer state. The bonding strength is about 68 MPa and the hardness HV 0.3 is about 9400 MPa. Compared with the original WC-12Co coating, the friction coefficient of the graphene modified coating is reduced by about 25%. The graphene is constantly exposed on the surface of the wear scar during the friction process. A lubricating film is formed in the micro zone, which has a better self-lubricating and anti-wear effect.