Effect of Firing Temperature on Mechanical Properties of AI_2O_3-C Sensor for Continuous Measurement of Molten Steel Temperature

摘要

Al_2O_3-C sensor based on the blackbody cavity theory achieved a continuous measurement of molten steel temperature. Its mechanical properties were affected by the firing temperature. Firing temperature has great influences on the weight changing, decalescence/heat felease reaction and structure evolution of the resin binder used for Al_2O_3-C sensor. Results showed that the porosity increased and the strength declined below 750℃, main exothermic reaction and weight loss of the binder occurred. As the firing temperature increased to 800℃, a great enhancement of endothermic reaction and a drastic increase of crystallite size were observed, relating to the rapid shrinkage of the binder. The porosity decreased from 10.3% to 8.8% and the strength improved remarkably from 6.5 to 8.2 MPa in this temperature range. Strengths and porosities of the sensors fired under 800-950℃ were similar (8.2-8.5 MPa and 8.8%-8.4% respectively). Moreover, the temperature response and lifetime of the sensor fired at 800℃ were almost equal to the sensor fired at 950℃ according to industrial tests, which were about 165 s and 24 h.