ASTM B748-90(2021)

4.1?This test method is useful for the direct measurement of the thicknesses of metallic coatings and of individual layers of composite coatings, particularly for layers thinner than normally measured with the light microscope.

4.2?This test method is suitable for acceptance testing.

4.3?This test method is for the measurement of the thickness of the coating over a very small area and not of the average or minimum thickness per se.

4.4?Accurate measurements by this test method generally require very careful sample preparation, especially at the greater magnifications.

4.5?The coating thickness is an important factor in the performance of a coating in service.

1.1?This test method covers the measurement of metallic coating thicknesses by examination of a cross section with a scanning electron microsope (SEM).

1.2?The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.3?This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.4?This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.