Permanent Linear Change in Heating

Operating Procedures for the Test of Permanent Linear Change in Heating

Objective: To measure the size change rate of refractories after being reheated to the specified temperature and kept for a certain time and cooled. To reflect the volume stability of refractory products at high temperature.

The operating steps are as follows:

1. Sample preparation: there are three bricks for test. To prepare one sample from each brick. Each group of samples prepared shall be consistent with each other. The cuboid sample shall be *50mm*65（±2）mm, and the cylinder sample shall be 50mm in diameter and 50±2mm in height.

2. To put the sample into the electric drying oven and dry it to a constant amount at 110℃±5°C, and to measure its length before burning. To put the sample into the test furnace. The sample spacing shall not be less than 15mm.

3. To determine the heating temperature according to the product technical conditions or to make negotiation on it among relevant parties. Heating rate: 5~10℃/min for shaped refractory products; 4~6℃/min for amorphous refractories; Finally, at 50°C, the heating rate of shaped refractory products and amorphous refractories shall be 1-5°C/min and 1-2°C/min respectively. To control the temperature difference of the test furnace in the heat preservation stage within ±10℃.

4. To measure the change of heating line according to the length measuring instrument method. To measure the original measuring position of the sample as required and calculate its rate of change, or to do this with the volumetric method.

Note: 1) The direction of the sample height shall be consistent with the pressurizing direction of brick molding. 2) It is improper to take rather fast heating rate.

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Compressive Strength Test

Porosity and Bulk Density Test

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