Heat transfer conditions and ultrasonic measurements of alumina based refractories

Abstract

In this paper temperature difference and resistance parameters were used for prediction of thermal shock behavior of alumina based commercial refractories with content of Al2O3 from 28 % to 78 %. Thermal and mechanical properties of the materials were measured. Thermal shock stability was measured using water quench test (JUS. B. D.8. 319.) as experimental method. Values of temperature difference were calculated using heat transfer conditions and material properties. Equation given by J.H.Ainsworth and R.H.Herron for temperature difference was used. The heat transfer coefficient under conditions of free convection for a circular cylinder held in stationary position was calculated for water bath from equation given by Holman. Quenching heat transfer coefficient was also calculated, using expressions given by Sparrow and Cess. Calculated values of temperature difference were compared to measured number of quench experiments. Linear regression analysis was used to determine the correlation between calculated values for critical temperature difference with the results of water quench test. Resistance parameter was used for describing the thermal stability of the samples. Resistance parameter was calculated using usual equation based on material properties. Ultrasonic measurements for ultrasonic velocity, strength degradation were used for describing the resistance parameter degradation. Resistance parameters degradation was related to the number of quench experiments.