Effect of firing temperature on the properties of inorganic high temperature phosphate adhesive

High-temperature adhesives are considered for high-temperature applications such as the refractory industry. In this research, inorganic high-temperature phosphate-based adhesive was prepared using alumina and micro silica as the main raw materials and monoaluminum phosphate as a binder. The effect of firing temperature on the properties of the adhesive including phases, microstructure, compressive strength and shear strength was investigated. For this purpose, adhesive samples were fired at three temperatures of 1200, 1300, and 1430 °C for 3 hours. At a firing temperature of 1200 °C, corundum and cristobalite phases were detected and by increasing the firing temperature, the mullite phase was detected in the adhesive. The compressive strength and shear strength of the adhesive improved significantly with increasing firing temperature so that with increasing temperature from 1200 ° C to 1430 °C, the compressive strength increased from 56 to 239 MPa and the shear strength increased from 1.8 to 6.2 MPa. The increase in the mechanical properties of the adhesive at higher firing temperatures is attributed to the presence of the mullite phase.