1. Scope 1.1 This test method covers the determination of the thermal diffusivity of homogeneous solid materials. Thermal diffusivity values ranging from 0.1 to 1000 mm2/s are readily measurable by this test method and measurements can be made from about 100 to 2500 K normally in a vacuum or inert gas environment. 1.2 This test method is a more detailed form of Test Method C714 but has applicability to much wider ranges of materials, applications, and temperatures with improved accuracy of measurement. 1.3 This test method is applicable to the measurement of a wide variety of homogeneous opaque materials and, with special precautions, can be used on transparent and some porous and composite materials. 1.4 This test method is intended to allow a wide variety of apparatus design and design accuracies to satisfy the requirements of specific measurements problems. It is not practical in a test method of this type to establish details of construction and procedures to cover all contingencies that might offer difficulties to a person without pertinent technical knowledge or to stop or restrict research and development for improvements in the basic technique. 1.5 This test method can be considered an absolute (or primary) method of measurement since no heat flux reference standards are required except for verification purposes and to confirm accuracy statements. 1.6 The values stated in SI units are to be regarded as the standard. 1.7 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.