The sealing surface is the most critical working surface of the valve. The quality of the sealing surface directly affects the service life of the valve. The material of the sealing surface is also an important factor in ensuring the quality of the sealing surface. Therefore, when choosing the material for the valve sealing surface, the following factors should be considered: 

① Corrosion resistance. "Corrosion" refers to the process where the sealing surface is damaged due to the action of the medium. If the surface is damaged in this way, the sealing performance cannot be guaranteed. Therefore, the sealing surface material must be corrosion-resistant. The corrosion resistance of the material mainly depends on its composition and chemical stability.

② Anti-abrasion. "Abrasion" refers to the damage caused to the sealing surface due to friction during relative movement. This damage will inevitably lead to the destruction of the sealing surface. Therefore, the sealing surface material must have good anti-abrasion performance, especially for gate valves. The anti-abrasion property of the material is often determined by the internal properties of the material.

③ Corrosion resistance. "Corrosion" refers to the process where the sealing surface is damaged when the medium flows at high speed. This kind of damage is more obvious in throttling valves and safety valves used in high-temperature and high-pressure steam media, and has a significant impact on the sealing performance. Therefore, corrosion resistance is also one of the important requirements for the sealing surface material.

④ It should have a certain hardness and a significant decrease in hardness at the specified working temperature.

⑤ The linear expansion coefficients of the sealing surface and the body material should be similar. This is more important for the structure of the sealing ring to avoid the generation of additional stress and loosening at high temperatures.

⑥ Under high-temperature conditions, it should have sufficient oxidation resistance, anti-thermal fatigue properties, and thermal cycling resistance, etc.

At present, it is very difficult to find a sealing surface material that fully meets the above requirements. Only by focusing on meeting the requirements of certain aspects for different valve types and purposes can it be achieved. For example, valves used in high-speed media should pay special attention to the corrosion resistance requirements of the sealing surface; while when the medium contains solid impurities, a sealing surface material with higher hardness should be selected.