ASTM D7635/7635M test method determines the thickness of various coatings. This is done by measuring their magnification, calibration, and resolution with the help of a microscope. The results help specify the application, quality, reliability, performance, and durability of the coatings. Moreover, research can be conducted, and developmental standards can be devised to improve the performance of various coatings.
In ASTM D7635/7635M test, the specimen is prepared by cutting it from the plane of the available sheet. The specimen is weighed, placed in the sample cup, and observed closely by placing it under a microscope. A micrometer is used to measure the thickness of the sample up to 10µm. The digital images of the sample are taken by placing the calibrated scale marker on the microscope. These pictures are further used to study the resolution, calibration, and magnification.
Video 01: Method to measure the thickness of a duplex coating
The specimen used in ASTM D7635/7635M testing is taken as per the requirements.
The overall thickness of the sample is reported to the nearest 10µm, and reproducibility limits are devised (denoted by R).
ASTM D7635/7635M test method determines the thickness of various coatings.