The Design and Testing of a High-Temperature Graphite Dilatometer

A dilatometer for investigating the high-temperature behavior of carbonaceous materials has been constructed within a graphite tube furnace in the Composites Section of the Mechanics and Materials Technology Center of The Aerospace Corporation. The dilatometer is a single-pushrod type with a linear variable differential transformer LVDT dilation measurement system and employs computer data acquisition and analysis. It can measure thermally induced strain of a sample from room temperature to over 3000 deg C, a temperature that has been difficult to reach with currently available laboratory apparatus. The estimated uncertainty of the dilation measurement system is about or - 5 micrometers over the entire temperature range. All components in the hot zone, including the sample holder and pushrod, are made of polycrystalline graphite. A three-point-bend fixture can be placed in the apparatus to measure the rheological properties of a pyrolyzing carbon precursor or the high-temperature creep properties of a carbon under conditions of constant flexural stress. Carbon, Dilatometry, Graphite, Thermal strain, Pyrolysis, Glassy carbon, Composites carbon-carbon, Thermal expansion.