When does tungsten carbide spraying need to be repaired?

When does tungsten carbide spraying need to be repaired?

Tungsten carbide spraying is an effective method to improve the surface hardness, wear resistance, and corrosion resistance of workpieces. However, during use, the coating may be damaged by various factors and needs to be repaired in a timely manner. The following are some situations that require repair:

The coating shows wear and tear

Slight wear: When slight wear marks are found on the surface of tungsten carbide coating through daily inspection, such as increased surface roughness and decreased glossiness, although it has not yet affected the normal use of the workpiece, if the wear continues to develop, it may lead to a decrease in coating performance. At this point, the wear situation can be evaluated. If the wear is within a controllable range and it is expected that the wear rate will not accelerate during subsequent use, observation can be made and appropriate protective measures can be taken; If there is a trend of further wear and tear, timely repair should be carried out.

Severe wear: If the wear depth of the coating is large, approaching or reaching the thickness jx of the coating, it will cause a significant decrease in the surface properties of the workpiece, such as reduced hardness and decreased wear resistance. In this case, the workpiece may experience issues such as reduced efficiency and shortened service life during use, and may even affect the normal operation of the entire equipment. In this case, immediate repair is necessary.

Coating peeling occurs

Local peeling: When there is local peeling of the coating, even if the peeling area is small, it needs to be taken seriously. Because the peeling area exposes the substrate directly to the external environment, it is susceptible to corrosion and wear, which in turn affects the stability of the surrounding coating and may lead to further expansion of the peeling area. So once local peeling is found, the peeling area should be cleaned and repaired in a timely manner to prevent the problem from worsening.

Large scale peeling: If the coating has a large area of peeling, it will seriously affect the performance and service life of the workpiece. Large scale peeling not only causes the workpiece to lose its original protective function, but may also lead to malfunctions during use, resulting in safety hazards. At this point, it is necessary to stop using the workpiece as soon as possible and conduct a comprehensive repair or re spraying of the entire coating.

Cracks appear in the coating

Surface cracks: When cracks appear on the surface of the coating, the cracks become channels for corrosive media and wear particles to enter the interior of the coating, accelerating the damage of the coating. Even small surface cracks may gradually propagate during subsequent use, leading to coating failure. Therefore, when cracks are found on the surface of the coating, it is necessary to evaluate the length, depth, and density of the cracks, and determine whether timely repair is needed based on the evaluation results.

Penetrating cracks: Cracks that penetrate the coating are a relatively serious situation, as they can directly expose the substrate to the external environment, greatly reducing the protective performance of the coating. Meanwhile, through cracks may also cause the coating to fracture under stress, further damaging the integrity of the coating. Once a through crack is found, it must be repaired immediately.

Decreased coating performance

Hardness reduction: Through regular performance testing, it was found that the hardness of the tungsten carbide coating has significantly decreased, below the design requirements or normal usage range. A decrease in hardness will reduce the wear resistance of the coating, making it susceptible to wear and scratches, and affecting the service life and work efficiency of the workpiece. At this point, it is necessary to analyze the reasons for the decrease in hardness and promptly repair or treat the coating.

Deterioration of corrosion resistance: If the workpiece is used in an environment with corrosive media, the corrosion resistance of its tungsten carbide coating will significantly decrease, such as rusting and corrosion spots on the coating surface. This will cause corrosion of the substrate, affecting the structural strength and performance of the workpiece. When the corrosion resistance of the coating is found to have deteriorated, it should be repaired and protected in a timely manner to improve its corrosion resistance.