A new device for expansivity measurements of liquids at high temperature and pressure and expansivity data for liquid tin to 1450 °C

Abstract

We have developed a new technique for measuring thermal expansion of liquids at high temperature. Our device, the volumeter, is a volumetric dilatometer which uses liquid tin to transmit volume changes to a series of electrical contacts. Measurements can be carried out from 250 °C to at least 1450 °C irrespective of the viscosity of the sample. In addition, our technique allows for the direct determination of volume changes due to melting and crystallization, as well as the volumetric properties of heterogeneous mixtures of materials. Furthermore, the device is designed to operate inside an internally heated gas-pressured vessel, allowing for the determination of compressibility. We have measured the thermal expansivity of tin from 435 to 1445 °C. Our data match previous measurements using the Archimedean technique to within 4% and shows the volumetric expansivity of tin to have a temperature dependence of −4×10−9 °C−2. Preliminary measurements of the thermal expansivity of a high-viscosity silicate liquid show a wide degree of scatter but fall within previous estimates based on density data. Improved performance of the device may require its operation under pressure.