Synthesis Of Aluminium Titanate With Waste Activated Alumina

Aluminium titanate (Al2TiO5) ceramics is one of the best materials with a series ofgood characteristics such as high melting point, low thermal expansion coefficient, lowthermal conduction coefficient, endured corrosion, thermal shock-resistance and so on.The application foreground of aluminium titanate is quite abroad. But it can decomposeinto Al2O3and TiO2easily within the temperature range of750-1300℃, so it is difficultto synthesize high-purity aluminium titanate materials. The waste activated alumina wasused as raw materials. The water cooling method and the addition of the additives wereadopted to suppress the decomposition of Al2TiO5to obtain the high purify product,which results in the improvement on the thermal stability and high performance of suchmaterial.The effect of mass ratio of Al2O3to TiO2, calcinations temperature and holdingtime on the formation and content of aluminium titanate, crystalline structure andmicrostructure were investigated to determine the optimal prescription, calcinationstemperature and holding time. The influences of talc, potassium feldspar, and siliconpowder mineralizers on the microstructure and properties of aluminium titanate wereinvestigated to determine the optimal amount of additives. X-ray diffraction (XRD) andscanning electron microscopy (SEM) were used to characterize the crystalline phasesand microstructures of sintered samples. Rietveld quantification analysis was performedto calculate the content of crystal phases. Moreover, the properties including bulkdensity, apparent porosity, water absorption, bending strength, strength maintenance,etc. were also detected.The research results show that there three crystalline phases in all sinteredsamples,and aluminium titanate is the main crystalline phase. The optimal prescriptionconsists of59.85wt%waste activated alumina,40.15wt%manufactured titanium oxideand the mass ration of Al2O3to TiO2is1.27. The sintering temperature of aluminiumtitanate can be lowered by waste activated alumina due to its large surface area, highactivity and powerful impetus on diffusion. A calcinations temperature of1400℃and aholding time of4hours are determined to be the optimal one, samples prepared by such firing process obtain a peak aluminium titanate content of90.12wt%. The aluminiumtitanate is in square columnar and random columnar shape, Al2O3is in hexagonaltabular shape and TiO2is in anamorphosis tetragonal crystal. Adding mineralizers suchas talc, potassium feldspar, and silicon powder into Al2TiO5can form solid solution,which can restrain the decomposing of aluminium titanate effectively.All of themineralizers not only apparently increase the bending strength and the thermal shockbending strength conservation rate, but also apparently reduce the apparent porosity andthe water absorption of samples. The optimal amount of talc, potassium feldspar, andsilicon powder is determined to be5wt%,6wt%and7wt%respectively.