The main purpose of the chromium carbide coating in the process of its use is to require almost certain appearance quality in addition to the protective substrate and to reach certain functional indicators. It is not allowed to have obvious defects, and it can be inferred through visual inspection. Defects in the process of chromium carbide coating. Therefore, the appearance inspection of the chromium carbide coating is the most basic and most commonly used inspection content. If the appearance is unqualified, no other items are required to be tested.
The surface of the chromium carbide coating should be uniform in color, the chromium carbide coating and the corners of the workpiece are not oxidized, the thickness is uniform, the appearance is smooth and flat, and the polycondensation and chromium carbide coating peeling are not allowed. There should be no pores, slag inclusions, cracks, pinholes. And other defects.
Polycondensation: Polycondensation is a defect often occurring in the spray-melting layer. When the alloy powder is melted during remelting, it cannot uniformly wet the surface of the substrate but shrinks into a ball.
The chromium carbide coating is mainly due to the oxidation of the surface of the substrate or the alloy powder, which exceeds the oxidizing ability of the solvent. The oxide layer separates the alloy from the surface of the substrate, and the liquid alloy is caused by the surface tension. The polycondensed carbonized chromium coating is a waste product and must be removed for re-spraying.