Measurement of Thermal Expansion over a Wide Range of Temperatures by a Pushrod Dilatometer

The coefficient of thermal expansion (CTE) is an intrinsic property of a material and is a very important value in various science and engineering fields. Among various methods for measuring the CTE, the dilatometer is the most commonly used equipment, but it has not been frequently used for measurement due to its performance at very low temperature. In this study, we used a pushrod dilatometer to measure the CTE of candidate metallic alloys for liquefied hydrogen storage containers in the temperature range from −170 °C to 70 °C. In order to secure the reliability of the measured cryogenic CTE values of the metallic alloys, we introduced a method for calibrating the pushrod dilatometer system by using a standard specimen, and we assessed the uncertainty of measurement associated with the process according to the ISO Guide to the Expression of Uncertainty in Measurement. As a result, reliable CTEs for the metallic alloys for liquefied hydrogen storage containers with an uncertainty of measurement of 2.2% ∼ 4.7% according to the measurement temperature were obtained; the results showed good agreement, within the level of the uncertainty of measurement, with other data found in the literature.