1. Insufficient coating hardness
The customer hits the coating with a hammer, and then dents the coating. The customer said: "The hardness of the coating is not good. I cannot deform the hardened steel. The coating is knocked into the groove, which means you are basically not hard enough."
An important feature of thermal spraying is that they are very brittle. When I communicate with customers, I will remind them that "the coating is not impact resistant." The coating is most suitable for resistance to friction and wear, but if friction and wear are accompanied by impact, corrosion, etc., you need to carefully consider whether to use the spraying process. Because the impact will damage the coating, then corrosion will erode the entire coating and product substrate from the damaged location.
Beating with a hammer and deforming the coating cannot prove any problems. I have explained in detail how to judge the hardness of the coating.
Here I give a very simple example:
We can break one chopstick by hand, but due to the different strength, we cannot break 10 chopsticks at the same time. Most of the paint we spray is only about 0.2 mm, what if the spray thickness is 10 mm? The author once sprayed the thickest paint to 32mm, which is very hard, but even with such a thick paint, its brittleness has not changed, and it will still break when subjected to a strong impact.
2. The coating is not wear-resistant
A customer used an angle grinder to grind our thermal sprayed coating, and then told me: "The coating you made is not wear-resistant. I can use an angle grinder to grind it away."
Later, I gave this client an "example of water dripping on a stone". I believe everyone can understand this simple fact. In this world, there is nothing that will not wear out because it is not enough to get the job done. There is another problem. The oxide layer on the surface of the coating is polished off, revealing the metallic color, which does not mean that the coating is gone. The tungsten carbide coating will become brighter after polishing. When many customers use it, the coating is smooth and it is said that the coating has disappeared. This analysis is very arbitrary. The main method is to use a spectrometer to analyze whether the coating is still present. To
We must judge the hardness, wear resistance, corrosion resistance, etc. of the coating in a scientific way to make it reasonable and well-founded, instead of using certain methods that violate the regulations. I have briefly explained some coating inspection methods before. In order to make it easier for customers to choose coatings and test coatings, I will explain the hardness, porosity, bond strength, toughness, wear resistance, and corrosion resistance of the coating. Oxidation resistance, thermal shock resistance, etc.
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