ASTM C664-10 (2020) Standard Test Method for Diffusion Coating thickness standard specifies the test method for measurement of diffusion Coating thickness. Diffusion coatings are commonly used to improve corrosion resistance and abrasion resistance of substrates and are widely used in industries such as aviation, automotive and engineering. The standard details a variety of measurement techniques, including Microscope method, section method, etc., for accurate measurement of coating thickness. The standard emphasizes technical requirements such as sample preparation, Measuring location, operation steps and data processing during the test process to ensure high-precision and Reliability of measurement results. By implementing this standard, the mass of diffusion coatings can be effectively assessed to ensure their functionality and durability in practical applications.