When we prepare metallographic samples, we need to use polishing agents. Polishing agents have several parameters: particle size, material type, and solid-liquid type (physical state).

I have already explained how to choose the particle size in other articles, so I won't go into detail here.

How to choose the type of material? I suggest users choose the corresponding polishing agent according to the industry. The polishing agents used in different industries vary greatly, and their reference value to each other is limited. For example, ceramics and plastics have very large spans.

So this article mainly focuses on the selection of polishing agents for solid-liquid types (physical states). According to the physical state, polishing agents can be divided into: polishing spray, metallographic polishing liquid, metallographic polishing paste, and metallographic polishing powder. They have little difference in performance in normal usage environments and can be chosen arbitrarily. However, in some extreme situations, it is necessary to pay attention to selecting suitable polishing agents.

Polishing spray is very common, easy to use and evenly sprayed, but there is splash when using, and the amount of spray is sometimes insufficient. The proportion of polishing material and lubricant is generally low, which is not suitable for some occasions. After all, the thick and high-density polishing agent can be diluted, but it is difficult to concentrate, which limits the use environment of polishing spray. It is not suitable for occasions with rough materials and harsh environment.

The advantages of metallographic polishing solution are very obvious. It has already been prepared upon purchase, with a moderate fixed proportion, simple and convenient use, and a relatively uniform application. Basically, it can cover almost all the grinding and polishing occasions of common materials, and has its own cooling effect, so it is not necessary to add additional cooling and lubricating fluid. It can be said that metallographic polishing fluid is more general and recommended among the four.

The problem with metallographic polishing paste is that the user needs to apply it evenly, which is not a problem for skilled users. Sometimes it is necessary to add a little coolant. After all, it is relatively thick. If this thick polishing paste is used for on-site metallography (Angle grinder polishing, micro grinder polishing), it has a good effect and can adapt to the harsh environment of the operation site.

There is an additional mixing process for metallographic polishing powder, and the higher the concentration of the mixed polishing powder, the faster the polishing speed. When using small particle polishing powder, the slurry concentration should be appropriately lowered, and the mixing concentration of polishing powder can be adjusted according to needs and usage conditions. There are many types of polishing powders and their applications are also quite flexible.

Alright, that's all for today. If you have any other metallographic related questions, please log in to the official website www.qmaxis.cn to have technical exchanges with QMAXIS engineers, or visit the QMAXIS testing laboratory in Nanjing for on-site testing.