AS 1774.11:2015 Refractories and refractory materials—Physical test methods
5.2.1.2 Component of thermal expansion test apparatus
The thermal expansion test apparatus shall be comprised of the following.
a) Supporting tube and detecting rod: The supporting tube and detecting rod shall be all made of the same material of high purity alumina sintered object, quartz glass, or high purity graphite sintered object, and shall be the type in which the difference of coefficient of linear thermal expansion between the test piece and supporting tube, i. e. the difference of elongation due to the temperature rise between test piece and reference sample, is measured. New supporting tube and detecting rod, in order to stabilize the thermal expansion characteristic, shall be pre-sintered and cooled gradually prior to use. Moreover, the high purity alumina and high purity graphite shall be pre-sintered at the highest temperature to be used for approximately 7 h and then cooled gradually at the rate of 1 °C /min as a standard. The quartz glass shall be pre-sintered at 1 100 °C, for approximately 7 h and then cooled gradually down to 900 °C at the rate of 0,2 °C/min.
b) Thermal expansion measurement system: The thermal expansion measurement system, of which the measurement error is corrected to+5x 10-4 % of the length of test piece (Lo] (for example,±0,1 um to 20 mm in length of test piece) by using the block gauge (for example, when the length of test piece is 20 mm, 20,0 mm or 20,5 mm in approximate nominal dimension), shall be used. For the measurement of length, a differential transformer shall be used.
c) Electric furnace (thermostatic bath): The electric furnace shall be constructed so as to be capable of controlling heat at a definite rate and maintaining the temperature distribution of the whole heated test piece at±0,5 °C. For the heating unit, any one of silicon carbide heating unit, molybdenum disilicide heating unit, metal heating unit, or graphite heating unit shall be used.