The effect of compression pressure on activation energy of spinel formation

The paper presents the influence of compression pressure on the apparent activation energy of crystallization of Al-Si spinel phase. This is achieved on the samples which are made from the elecroporcelain mixture under the pressures from 70 MPa up to 110 MPa. The apparent activation energy is determined from the series of non-isothermal thermodilatometry experiments using the Kissinger method. The results show that the apparent activation energy decreases with compression pressure. The determined values of apparent activation energy of samples made with pressures of 70 MPa, 80 MPa, 90 MPa, 100 MPa, and 110 MPa are (670 ± 24) kJ mol⁻¹, (568 ± 40) kJ mol⁻¹, (543 ± 12) kJ mol^–1, (526 ± 30) kJ mol^–1, and (506 ± 16) kJ mol^–1, respectively. The decrease of apparent activation energy with compression pressure may be caused by the decreasing distance between the grains in the material.