Sintering and microstructure of Al_2O_3 with a coating

摘要

Because of good wear resistance and superior anticorrosion properties, AI2O3 is a ceramic material that is widely used in various industries. It is well known that Al2Oj powder can be hot pressed and pressureless sintered to full density at temperatures above 1600 °C, and the crystal grains of AI2O3 are large. In order to improve the microstructure and to decrease the sintering temperature of AI2O3, im-purity doping is a very effective method. For example, MgO doping can decrease the size of AI2O3 crystal grains [1—3], because of the formation of a spinel layer around the AI2O3 grains under sintering conditions limiting the growth of AI2O3. Adding some SiO2 and CaO to AI2O3 can cause a glass phase to form and can decrease the sintering temperature [4, 5}. In this work, the sintering tem-perature was decreased greatly and the microstruc-ture was improved by coating the AI2O3 powder with low-melting-point impurities.