China's Refractories

Abstract: New apparatus for the determination of torsion strength of refractory materials at elevated temperatures has been developed in this work. With the employment of heating wire and induction heating unit, this device can carry out torsion strength test at high temperatures at the heating rate ranging from 10 ℃/min to 200 ℃/min. Torsion strength of high alumina brick, magnesia brick and Si3N4 bonded SiC brick has been tested at different heating rates of 10 ℃/min, 100 ℃/min and 200 ℃/min, separately. Results indicate that, for high alumina brick, the tested torsion strength at the heating rate of 10 ℃/min is very close to that at 100 ℃/min, but very different from that at 200 ℃/min. The tested torsion strength of magnesia brick at different heating rates differs greatly, while that of Si3N4 bonded SiC brick is similar. This suggests that the structure of refractory materials with poor thermal shock resistance might be damaged when the heating rate of 200 ℃/min was applied, but the heating rate of 100 ℃/min is possible for a lot of refractory products. At fast heating rates, it takes only 1 h to finish a test at elevated temperatures, thus saving a lot of time and energy. 

Key words: torsion strength, heating rate, refractory materials, local heating