ASTM E831-24

SIGNIFICANCE AND USE 5.1 Coefficients of linear thermal expansion are used, for example, for design purposes and to determine if failure by thermal stress may occur when a solid body composed of two different materials is subjected to temperature variations. 5.2 This test method is comparable to Test Method D3386 for testing electrical insulation materials, but it covers a more general group of solid materials and it defines test conditions more specifically. This test method uses a smaller specimen and substantially different apparatus than Test Methods E228 and D696. 5.3 This test method may be used in research, specification acceptance, regulatory compliance, and quality assurance. SCOPE 1.1 This test method determines the technical coefficient of linear thermal expansion of solid materials using thermomechanical analysis techniques. 1.2 This test method is applicable to solid materials that exhibit sufficient rigidity over the test temperature range such that the sensing probe does not produce indentation of the specimen. 1.3 The recommended lower limit of coefficient of linear thermal expansion measured with this test method is 5 μm/(m·°C). The test method may be used at lower (or negative) expansion levels with decreased accuracy and precision (see Section 12). 1.4 This test method is applicable to the temperature range from −120 °C to 900 °C. The temperature range may be extended depending upon the instrumentation and calibration materials used. 1.5 SI units are the standard. No other units of measurement are included in this standard. 1.6 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. 1.7 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.