In-depth investigation of pore structure and fracture behavior of CAC bonded alumina-spinel castables treated at 110 ∼ 1600 °C

Abstract

An in-depth investigation of pore structure evolution and corresponding fracture behavior of calcium aluminate cement (CAC) bonded alumina-spinel castables treated at 110–1600 °C has been carried out by taking the respective advantages of mercury intrusion and micro-CT scanning, wedge splitting test and acoustic emission, respectively. The results showed that the complexity of nano-sized and submicron-sized pores increased from 110 to 800 °C, and then decreased gradually from 800 to 1600 °C due to the dehydration of hydrates and formation of C12A7, CA, CA2, and CA6 phases. In comparison, the complexity of the pores above 1 μm increased with the ascent of treating temperatures. Consequently, the heat treatment resulted in deterioration of “toughness” owing to the vanish of majority of nano-sized and submicron-sized pores and the subsequent formation of strong ceramic bonding. The fractal dimension of pore structure presented positive correlation with “toughness” of castables, where higher fractal dimension standed for higher frature energy consumption within matrix caused by tortuous crack propagation paths.