Strengthening Mullite Ceramic Materials by Gas Infiltration

In order to improve the high-temperature performance of mullite ceramic materials,mullite ceramic bodies were placed in closed containers with AlF3·3H2O powder and kept at 1 600 ℃ for 6 h.AlF3·3H2O reacts with O2 to produce gaseous compounds AlOF and F,which penetrate into the bodies,promote Al2O3 and SiO2 to form mullite whiskers,and strengthen the mullite ceramic materials.The results show that the mullite ceramics have enhanced hot strength,increased bulk density and declined apparent porosity by adding a certain amount of AlF3·3H2O in a closed container.When the addition of AlF3·3H2O is 6％,the bulk density of the ceramic material reaches the maximum and the apparent porosity is the lowest;and when the addition of AlF3·3H2O is 8％,the hot strength of the material is the highest.