Fused Quartzose Multiphase Composite Refractory Performance Study

Our country is the world's largest consumer of refractory.Great efforts are made by researchers to optimize the performance of refractory,to which our country attaches significant importance.Our research subject innovatively synthesize multi-phase composite refractory material using fused silica,clay,cordierite and sillimanite as main raw materials.Performance testing on thermal expansion coefficient,firing shrinkage,water absorption,apparent porosity and flexural strength are conducted in this paper.the XRD diffraction and SEM electron microscope scanning test are taken to observe the internal structure of the sample.This work discusses the impact of different grain size distribution,sintering temperature,bonding agent,the amount of clay,cordierite and sillimanite on various properties of the samples.On the analysis of the thermal expansion coefficient of samples,the flexural strength and other various performance test,the results show that at the fixed total percentage of fused silica,thermal expansion coefficient and flexural strength of samples gradually increases with greater percentage of fused silica in small particles.Based on thermal expansion coefficient in our earlier tentative experiments,the optimized particle distribution for fused quartz are represented by 20?30 mesh:30?60 mesh:60?160 mesh=13:9:7,12:9:8 and 21:16:21.When sintering temperature are fixed at 1300?>1340?and 1380?,thermal expansion coefficients and flexural strength are calculated to be 0.96?1.08×10-6?-1 and 8.01?9.96 MPa,respectively.In the experiments for different binders,it is concluded that clay are the best binder and tthe optimized particle distribution for fused quartz are represented by 20?30 mesh:30?60 mesh:60?160 mesh=12:9:8.In the experiments for different additions of clay,the optimized clay to fused silica mass ratio are found to be 29:21 and sintering temperature is fixed around 1340?,where the thermal expansion coefficient and flexural strength for samples is 1.01×10-6?-1 and 8.86 MPa,respectively.In the experiments for cordierite additives,it can be observed that appropriate cordierite additives can promote the growth of mullite and significantly improve the flexural strength of samples.Analysis reveals that the optimal mass percentage of cordierite was fixed at 30%,where the thermal expansion coefficient and flexural strength are calculated to be 1.17×10-6 ?-1 and 15.6MPa and increase by 15%and 75%in comparison with those samples with no cordierite,respectively.In the experiments for sillimanite additives,with no apparent change in low thermal expansion coefficient and flexural strength,the optimized mass percentage of sillimanite was fixed to be 10%,where firing shrinkage is reduced by 18.3%.These results indicate that the addition of sillimanite significantly helps reduce shrinkage of the sample.Our research subject conducts the thermal shock resistance test on the selected samples with the optimized mass percentage of clay and cordierite,respectively.For samples with optimized percentage of clay,their strength retention ratio and thermal expansion coefficient change rate remains 90.4%and 3.96%respectively after three thermal shock test.And for samples with optimized percentage of cordierite,their strength retention ratio and thermal expansion coefficient change rate remains 95.3%and 2.44%respectively after three thermal shock test.Comparative analysis on experimental data reveals that cordierite additives help improve thermal shock resistance of the samples.