Preparation Of Lightweight Thermal Insulating Bricks Of High Alumina

In the article ,the preparation of lightweight brick of high alumina using ignition loss of pore-making agents is investigated .Withα-Al2O3 powder,mullite,kaolin,clay,kyanite as raw materials and wood sawdust and polystyrene bubble as pore-making agent , the effect of firing system (firing temperature and socking time ),the amount of pore-making agent and another micro powder on the properties of samples is carried out.Furthermore ,optimum firing temperature and socking time,amounts of pore-making agent and different micro powder was confirmed by means of SEM and XRD .The effect of firing system on the properties of samples was studied .When the sample is sintered at 1450℃for 5h, the results showed that samples are of good physical performance ,which form a amount of crossing cylindrical mullite.In the aspect of selecting pore-making agent , the results show that mixed additive will be advantageous to produce porosity of uniform distribution.When the amount of wood sawdust and polystyrene bubble is 14 percents and 2 percents respectively, bulk density of sample is 1.1g/cm3 .The coefficient of heat conductivity is 0.33 W/(m.k).The influence of additive of different micro powder on properties of the samples was studied .The results showed thatα-Al2O3 powder of 325 eyes is benefit to increase the ability of sintering and improve the physical properties of samples .BD,PLC and the residue ratio of compressive strength of samples is optimum when the ratio ofα-Al2O3 versus clay reach 1.1,which is 1.04g/cm3,-1.19% and 75% respectively.Bauxite promotes the ability of sintering ,but excessive amount of bauxite will decrease thermal shocking resistance . Kyanite is a kind of good expanding agent for lightweight bricks of high alumina, which will produce mullite after sintering which will offset the shrinkage of samples because of the ignition loss of pore-making agent and the sintering of clay .Finally ,with the optimization of production technology and mix-proportion ,the sample with 14 percent wood sawdust and 2 percent polystyrene bubble after sintered 1450℃for 5h,which will produce the sample with 1.1g/cm3 ,and its coefficient of heat conductivity 0.33 W/(m.k),optimum compressive strength 4.73MPa, permanent liner change less 2 percent .