Beijing Time, April 10, 2025 — Good news has arrived from the International Organization for Standardization (ISO): the international standard ISO/TS 5770:2025 “Fine ceramics (advanced ceramics, advanced technical ceramics) — Relative method for determining thermal conductivity of ceramic coatings,” led by CTC, has been officially published.

Ceramic coatings are generally very thin, making it difficult to peel them from the substrate to test thermal conductivity as a bulk monolithic material. Therefore, accurate and efficient measurement of the thermal conductivity of ceramic coatings has become a difficult problem. Establishing an effective test method for evaluating the thermal conductivity of ceramic coatings is therefore of great significance for ensuring the safety and reliability of components in service.

To address the above problems, the team led by Wan Detian at CTC, based on the relative method approach, derived the theoretical analytical relationship among the thermal conductivities of the substrate, coating, and composite body, and proposed a simple and indirect test method for coating thermal conductivity, and verified the accuracy and reliability of the method. ISO/TS 5770 specifies a test method for measuring the thermal conductivity of ceramic coatings by the relative method, and specifies specimen preparation methods, test modes, data collection, and report formats. This standard is applicable to ceramic coatings on metal substrates or ceramic substrates, and can be used in directions such as material performance research, quality control, characterization, and data collection.

The international standard ISO 5770 was successfully approved as a project in ISO/TC 206, the ISO technical committee for fine ceramics, through voting in April 2022. After three years, it was finally published after passing through the stages of NP, WD, CD, DIS, and FDIS. The test method in this standard provides technical support for optimizing the thermal conductivity of new coating materials (such as thermal barrier coatings and superalloy protective layers), and promotes their application validation in extreme environments. This is the first ISO standard for coating thermal conductivity testing led by China. The publication of this international standard marks that China's technical strength in the coating field has gained international recognition, and the advanced testing methods in the standard also contribute a Chinese solution to the global standards system.