Figure 1 is the SEM picture of the cross-section of the coating.

Figure 1 SEM photo of WC-10Co-4Cr coating It can be seen from the figure that there are no oxide inclusions and no obvious voids between the coating and the substrate. At the same time, the substrate has good roughness and forms an ideal zigzag occlusion with the coating, which ensures Good bonding strength between coating and substrate. 　　2.2、Coating hardness 　　 After grinding and polishing the coating, the finish of the coating reaches the level of Ra≤1, and then the Vickers hardness test is carried out directly on the coating working surface of the valve plate, and the test pressure is 300g force. The test method is: randomly hit five points in the same field of view, and then take the average of the five values obtained, which is the degree value of the sample. Table 5 shows the Vickers hardness values tested on two samples. According to the data in the table, the average hardness of the two samples is above 0.31200. It can be seen from Figure 2 that the indentation state of the coating is good, and there is no collapse at the indentation, indicating that the coating is denser and uniform in hardness. At the same time, no cracks appear along the indentation, indicating that the coating has good toughness. The good density, toughness, and relatively uniform micro-hardness of the WC-10Co-4Cr coating ensure that the coating has excellent wear resistance and good impact resistance. Table 5 Vickers hardness of WC-10Co-4Cr coating (HV0.3)