Alumina Ceramics

Also known as porous mullite porcelain. Strong and heat-resistant. Al2O3, also termed alumina, is produced by heating hydrates of alumina. Because of strong chemical bond strength between the Al and O ion , alumina has outstanding physical stability, such as high melting point (2050 °C), the highest hardness among oxides and high mechanical strength at room temperature. Mechanical strength is lowered largely above 1100 °C. Alumina is a typical electrically insulating material. Alumina is also chemically very stable and has a high corrosion resistance. It is insoluble in water and very slightly soluble in strong acid and alkaline solution. The mechanical properties are strongly dependent on their surfaces and the presence of defects resulting from their finishing and handling. Production of ceramic articles start with fine powder which is given shape by various casting and pressing methods prior to sintering at approximately 0.7 of the melting temperature.