This part of ISO 10545 defines a test method for determining the coefficient oflinear thermal expansion of ceramic tiles.
Determination of the linear thermal expansion coefficient for the temperature range from ambient temperature to 100 °C.
3.1 Suitable thermal expansion apparatus, capable of a rate ofheating of (5 ± 1) °C/min with uniform distribution of heat. Certain types of apparatus require a soaking time at 100 °C.
3.2 Vernier calipers, or other suitable device.
3.3 Drying oven, capable ofbeing operated at (110 ± 5) °C. Microwave, infrared or other drying systems may be used provided that it has been determined that equal results are obtained.
4 Test specimens
Cut two test specimens at right angles from the central portion of one tile so that their lengths are suitable for the apparatus. The ends of the test specimens shall be ground flat and parallel.
If necessary, grind the test specimens so that the length of any side in cross-section is less than 6 mm and the area of cross-section is greater than 10 mm2. The minimum length of the test specimens should be 25 mm. In the case of glazed tiles, the glaze shall not be ground off the test specimens.
It is necessary to make a previous calibration of the apparatus with a standard test specimen. The dimensions of the standard test specimen shall be the same as the dimensions of the test specimen.
Dry the test specimens at (110 ± 5) °C until they reach constant mass, i.e. when the difference between two successive weightings at intervals of 24 h is less than 0,1 %. Allow them to cool in the desiccator (3.4) at ambient temperature.
Using vernier calipers (3.2). determine the lengths to an accuracy of 0,002 times the length.
Place a test specimen in the apparatus (3.1) and record the ambient temperature.
Initially, and throughout the heating procedure, measure the length to an accuracy of 0,01 mm. Take temperature and length measurements at temperature intervals of no more than 15 °C.
The rate of heating shall be (5 ± 1) °C/min.
6 Expression of results
The linear thermal expansion coefficient, aj, is expressed in 10-6 per degree Celsius (10_6/°C)/ to the first decimal place, in accordance with the expression:
Lo is the length of the test specimen at the ambient temperature;
AL is the increase in length of the test specimen between ambient temperature and 100 °C;
AT is the rise in temperature.
7 Test report
The test report shall specify the following:
a) reference to this part of ISO 10545, i.e. ISO 10545-8—;
b) a description of the tiles, including sample preparation;
c) the linear thermal expansion coefficient for both test specimens.
We recommend our HY8120 Linear Thermal Expansion Tester to run this ISO 10545-8. It is used to determine the coefficient of linear thermal expansion of solid inorganic materials and metal materials, such as corundum, refractories, ceramic products, ceramic raw materials, glass, graphite, etc. The sample in this machine can be protected by atmosphere as required by the user, also the machine can be vacuumed and the vacuum degree is 0.1MPa. (Anytester (Hefei) Co., Ltd.)