Influence Of Additives On The Properties Of Aluminium Titanate Ceramics

Aluminium titanate is a kind of excellent ceramic material with low thermal expansion and high resistance to elevated temperature. In the present paper, the AT (aluminium titanate) powders were gained by solid state reaction method and the AT ceramics were obtained by the powder metallurgy method of prilling, pressing and sintering. Additives such as MgO、SiO2、Fe2O3、MgO+SiO2、MgO+Fe2O3、SiO2+Fe2O3were added into powders during the process of ceramics preparation. The bulk density and apparent porosity were measured by the method of drainage. X-ray diffraction was used to determine the phases and then the lattice constants of AT were calculated. Heat shock experiment was used to measure the resistance to elevated temperature. The strength of AT ceramics was investigated by three-point bending experiment. Through analysis of bulk density, strength and observation of fracture surface, the effect of additives on the properties of AT ceramics was discussed.The main discoveries in the experiment ware as follows:(1) Under the temperature of1480℃, solid state reaction containing Al2O3and TiO2with the mole ratio of1:1produced AT powders and the rate of conversion was fine;(2) Under the temperature of1500℃, Additives of MgO or SiO2increased the bulk density and strength of AT ceramics sintered for3hours, in addition, the same samples sintered for6hours reached a higher bulk density prepared to the samples sintered for3hours, samples with additive of Fe2O3had a lower strength;(3) Under the temperature of1500℃, samples with compound additives of MgO+SiO2、MgO+Fe2O3and SiO2+Fe2O3achieved a high bulk density and strength sintered for3hours, while the sintering time was6hours,the bulk density were nearly the same with samples sintered for3hours and the strength were lower;(4) Undergone the temperature of1500℃-room temperature for10times, each sample showed no crack and the strength after heat shock text elevated;(5) The samples with higher bulk density held a smaller crystal grain and fewer gas porosities;(6) Additives increased the lattice constant c of AT.