Effect of Microsilica on Chemical Bond of Calcium Aluminate Cement Bonded Corundum Castable at Low and Intermediate Temperatures

摘要

Calcium aluminate cement bonded corundum castable specimens were prepared using brown fused corundum( 8- 5,5- 3,3- 1 mm),white fused corundum( ≤ 1,≤ 0. 045 mm),micro-sized α-Al_2O_3 and microsilica as starting materials. This work focused on investigating the relationship between the bond change in the castable matrix and the strength of the castable with 5 mass% microsilica or without microsilica after heat treatment at 110,800 and 1 000 ℃, respectively.Chemical bond changes between the microsilica and hydrates of calcium aluminate cement after drying at110 ℃ or firing at 800 ℃ were investigated by XPS and FTIR. The results show that Si—O—Al bonds form between the microsilica and hydrates of calcium aluminate cement after drying at 110 ℃ or firing at 800 ℃.Therefore,the increased strength of castable specimens is attributed to the formation of Si—O—Al bonds from110 ℃ to 800 ℃.