Views: 0 Author: Site Editor Publish Time: 2024-08-11 Origin: Site
Judging the densification and bonding strength of thermal spray coatings is a key step in evaluating the quality of coatings, which is critical to ensuring the performance and lifetime of coatings in practical applications. The following are several commonly used methods to determine the density and bonding strength of thermal spray coatings:
1, microstructure observation: Use optical microscope or scanning electron microscope (SEM) to observe the microstructure of the coating, check the pores, cracks, oxides and other defects, and evaluate the density of the coating.
2, porosity measurement: Using optical or X-ray tomography (CT scan) technology to measure the porosity of the coating. The lower the porosity, the better the density of the coating.
3, penetration test: Use penetration detection agent (such as red dye) to check the permeability of the coating, the lower the permeability, the better the density of the coating.
4, air tightness test: For applications that require air tightness, the sealing performance of the coating can be evaluated through inflation and pressure testing.
1. Tensile test: Tensile test is performed to measure the tensile strength between the coating and the substrate. Specialized tensile testing machines are usually used to test according to standards such as ASTM C633.
2, shear strength test: Through the shear strength test to evaluate the binding force between the coating and the matrix. This is usually done on a specific shear strength test machine.
3, scratch test: Use Mohs hardness tester or scratch tester, by gradually increasing the load on the surface of the coating to create scratches, until the coating and the substrate separation, in order to assess the bond strength.
4, impact test: Through the impact test to evaluate the impact resistance of the coating, indirectly reflect the coating and matrix bonding strength.
5, micro hardness test: Use Vickers or Rockwell hardness tester to measure the micro hardness of the coating and indirectly evaluate the bond strength. Higher hardness usually means better bond strength.
6, thermal cycle test: by simulating the temperature change in the working environment, evaluate the thermal cycle stability of the coating and the matrix, and indirectly test the bond strength.
7, chemical immersion test: the coating sample is placed in a chemical solution that simulates the application environment to evaluate the stability of the coating in a corrosive environment and indirectly reflect its bond strength.
The densification and bonding strength of thermal spraying coatings can be evaluated comprehensively by the above methods. In practical applications, it may be necessary to combine multiple test methods to understand the properties of the coating.
