| This paper is based on the current production technology of SiC-mullite brick,through adding kyanite based mullite into SiC-mullite brick formulation,to investigate the properties of SiC-mullite brick.80 bauxite clinker,95 SiC,50 and 60 kyanite based mullite are applied in this study.First,the effects of different kinds and amount of kyanite based mullite on the properties of the specimens are investigated.Secondly,the experiment keeps the kyanite based mullite with a certain amount,researching the properties of the specimens with different addition and particle size of SiC.Finally,on the basis of laboratory work,verifying the feasibility of laboratory results for industrial production.Because of the low density and high glass phase content of kyanite based mullite,when KBM50 and KBM60 are added into the formulation,the bulk density,the room temperature mechanical strength and the refractoriness under load of the specimens appear to be reduced.However,KBM50 and KBM60 increase the content of mullite and promote mullitization of the specimens,and due to the unique high temperature mechanical property of mullite,the hot modulus of rupture of the specimens with kyanite based mullite increase to a certain extent.In addition,kyanite based mullite is composed of mullite with compact structure and high viscosity glass phase,therefore,the thermal shock resistance of the materials with the kyanite based mullite are significantly improved.When the addition of KBM50 and KBM60 are 20wt%,the residual strength ratio of the specimens are 53.0% and 50.4% respectively,and comparing with the residual strength ratio(44.0%)of the blank specimens,these specimens achive better thermal shock resistance.Because of the high content of Al2O3,the room and high temperature mechanical properties of KBM60 series specimens are slightly better than those of KBM50 series specimens,While,the thermal shock resistance of KBM60 series specimens are not as good as that of KBM50 series specimens.In subsequent laboratory experiments,the addition of KBM50 we select is 20wt%.When the amount and particle size of SiC increase,the sinterability of the specimens become to worse.But the increase of SiC powder can partly fill the framework of corundum-mullite in the specimen,and improve the mechanical strength of the specimen to a certain extent.Due to the superior thermal conductivity of SiC,the thermal shock resistance of the specimens improve gradually when the content of SiC increases.When the addition of SiC is 19wt%,the thermal shock resisrance of specimens are the best,and the residual strength ratio is up to 59.0%.When largen the particle size of SiC,the SiC become discontinuous and isolated in the material,and its thermal conductivity is greatly weakened,and the thermal shock resistance deteriorates gradually.The experiment results under the factory condition show that,when the addition of KBM50 in the brick is 20wt%,the thermal shock resistance of SiC-mullite brick is far better than others.The thermal shock cycle of the SiC-mullite brick achives 30 times while the area loss rate is only 27.4%.While,When the addition of KBM50 is all powder,the thermal shock resistance of the experiment brick is the best,and the thermal shock cycle of the experiment brick achives 30 times while the area loss rate of it is only 5.7%.However,because of the concentrated distribution of the KBM50,the time and temperature of mullitization are too concentrated,which results in lower refractoriness under load and cold crushing strength of the bricks.When the addition of SiC increases from 3% to 19%,the thermal shock resistance of the SiC-mullite bricks are improved,and the thickness of the oxide layer on the brick surface decreases.When the addition of SiC are 15wt% and 19wt%,the thicknesses of oxide layer are 3mm and 1mm respectively.Due to the protective oxidation of SiC,the presence of a certain thickness of oxide layer can improve the oxidation resistance of the SiC-mullite bricks,so that the function of silicon carbide can be maintained... |
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