Preparation Of High Alumina Ceramic From Aluminous Rocks

In this paper,Taking aluminous rocks in Guizhou Xiuwen area as the main raw materials to prepare high alumina ceramic material.First,the XRD analysis,chemical analysis,trace element analysis,microscope analysis,scanning electron microscope and energy spectrum analysis were used to find out the mineral composition and chemical composition of the aluminite.The main minerals in the aluminite are kaolinite,diaspore and a small amount of anatase.The main chemical composition is Al₂O₃ and SiO₂,which provides a reliable basis for the preparation of high alumina ceramic materials.According to the formula of domestic ceramics to adjust and design the high alumina ceramic formula.the chemical composition of raw material and formula was converted into a considerable amount of Al₂O₃,SiO₂,CaO,and calculating directly blank formula based on the chemical composition of the blank formula.Four sets of high alumina ceramics were prepared.The alumina content was 30%,40%,45%and50%respectively.The experimental results show that the higher the alumina content is,the better the performance of ceramic material is.The alumina content is 50%,the compressive strength of ceramic material is 91.11 MPa,and the flexural strength is14.50 MPa.Different additives（yttrium oxide,titanium dioxide,reduced iron powder）were used to strengthen the ceramic material of 30%of alumina,and the effects of different additives on the properties of ceramic materials were investigated.The experimental results show that yttrium oxide will increase the firing temperature and improve the strength of ceramic materials in a certain range.The sintering temperature decreased from 1250℃to 1175℃with the increase of yttrium oxide content.The maximum compressive strength and flexural strength of yttrium oxide added to 4%were 67.91MPa and 11.69 MPa,respectively.The effect of titanium dioxide and reduced iron powder on the mechanical properties of ceramic materials showed consistency.With the increase of addition,the compressive strength and resistance of the ceramics were increased.The bending strength is increased.The mass fraction of titanium dioxide is10%,and its compressive strength and flexural strength are 70.28 MPa and 17.16MPa respectively.The mass fraction of the reduced iron powder is 10%,the compressive strength is 67.83 MPa and the flexural strength is 12.43 MPa.Magnesia alumina spinel ceramic materials were prepared with aluminous rocks.The proportioning of raw materials and sintered products were investigated,and their compressive,flexural properties and water absorbency were measured.The test results show that the sintering temperature is 1200℃,the best formula is low grade aluminite 60.86%,kaolin 28.68%,quartz 2.46%,dolomite powder 8%,the water absorption rate is 0.4%,the compressive strength is 49.1 MPa,and the flexural strength is 8.2 MPa.The ceramic materials are tested and analyzed by XRD,SEM and microscope.The results show that there are mainly mullite and corundum（Al2O3）in high alumina ceramics.Corundum and mullite are closely connected to be the supporting structure of ceramic materials;Yttrium oxide dispersed in ceramic matrix as the main form of particlesis;Titanium dioxide is coated into mullite to form a supporting structure of ceramics to improve the mechanical properties and frost resistance of ceramics;A part of the reduced iron powder is fused into a sphere filled into the matrix mineral space of mullite at high temperature,and a part of the melting is wrapped in the matrix mineral mullite,which has a toughening effect on the mechanical strength of the ceramic material.The high content alumina ceramics can be used in the development and utilization of other related ceramic products,such as building ceramic materials,building decoration materials,and so on.The research results have important reference and guiding significance for the comprehensive utilization of aluminum rock resources,and have potential economic benefits and environmental protection price.