The Thermophysical Properties User Center (TPUC) is equipped with a differential push rod dilatometer which measures linear thermal expansion from 20oC up to 1600oC. The thermal expansion of a test specimen is determined relative to that of a standard reference specimen. The two specimens are placed side by side in a furnace and two alumina push rods that extend from the furnace to a thermally isolated linearly variable displacement transducer (LVDT) bear on the specimens.

The thermal expansion of low thermal expansion ceramics were studied by LoTEC, Inc. of Salt Lake City, Utah

A difference in expansion between the two specimens results in a differential movement of the push rods, thus allowing the linear thermal expansion of the unknown sample to be determined. The temperature of the specimen is measured with a Pt vs. Pt-10Rh thermocouple to a resolution of 0.1^o C.

Features:

• Measurements from 20 to 1600^oC
• Differential length changes measured to +/- 1.5%
• Measurements in air, inert gas, and vacuum environments
• Molten metal specimen holders [Link to molten metal poster materials]
• Dedicated computer control of time-temperature programs for the samples
• Length-change data automatically acquired, analyzed, and plotted

Applications:

In addition to measuring the coefficient of thermal expansion (CTE) as a function of temperature, the dilatometer can serve as a probe to detect various physical or chemical changes in a specimen. For example, the occurrence of a phase change or the approach to the Curie point of a material is almost always accompanied by a change in thermal expansion. The dilatometer can also be used to follow the course of a sintering process.