The guide method to select Thermal spray material

Selecting coating materials properly is the key work to ensure the coating performance needed. When selecting the coating material, we should firstly consider the working conditions of the work piece and the performance of the coating, and also the material, batch, economy and the proposed thermal spraying method of the work piece. According to the function of the coating, it can be basically classified as corrosion-resistant coating, abrasion-resistant coating, anti-friction and sealing coating, high-temperature thermal barrier coating, insulating or conductive coating, dimensional repair coating etc.

The failure of the surface-coated work piece in use is often not caused by a single factor, so there is not always a simple relationship between the requirements of the working conditions and coating performance. The working conditions should be analyzed in detail, and the properties of the coating structure, physics, chemistry and mechanics should be considered synthetically according to the reference or experimental data, so as to determine one or several coating materials.

Wear-resistant coating is one of the main application areas of surface coating technology. Although there is a rough relationship between the hardness and wear resistance of the coating, hardness does not fully represent the wear resistance of the surface coating. Because different types of wear have different material performance requirements, and are often accompanied by impact, corrosion, fatigue and temperature.

The surface coating materials can not be blindly pursued with high-performance or high-priced coating materials that will result in unnecessary waste. The price of materials can not be used as the standard for the selection of coating materials, and use inexpensive coating materials instead under the premise of meeting requirements of working conditions, which is especially important in batch production. For example, favor nickel-based alloy coating materials over cobalt-based alloy coating materials. 

When selecting the coating material, we should generally follow these steps:

(1)Analyze working condition and part performance, and figure out the cause of failure and the requirements for coating performance;

(2)List the coating materials available for selection;

(3)Analyze the compatibility of the selected material and matrix material and the thermal spray method adoptable;

(4)Conduct laboratory or field tests if necessary;

(5)Consider the service life, cost and factory conditions together to decide coating material;

(6)Determine the surface coating method and develop a coating process.