How to Evaluate Thermal Stability of Gas Explosive Spray Coatings

       The ability of a coating to withstand severe temperature fluctuations without breaking is called thermal stability. Due to the great difficulty in determining the thermal stress distribution of the coating under thermal load, it is quite difficult to quantify the thermal stability of the coating. Usually, qualitative methods are used to evaluate the thermal stability of the coating.



     Use plasma jet or oxygen-acetylene flame to heat the sample to a specified temperature, and for an easily oxidized sample, heat it in a protective oxygen atmosphere or in a vacuum; then let the sample cool according to a given procedure (according to the different test conditions, use Free cooling, air cooling, water cooling). This cycle is repeated until a given critical index of performance degradation is reached.

     The critical index can be the crack initiation or total fracture of the coating, the mass loss of the coating, the loss of the strength of the sample, etc. Therefore, the thermal stability of the coating can be characterized by the corresponding number of cycles.