Effect of boron oxide on mechanical properties of Al2O3-SiC-C castables
To further improve their mechanical properties by utilizing the indirect sintering characteristics of boron oxide,Al2O3-SiC-C castables were prepared with mullite particles FM60,dense corundum,silicon carbide and α-Al2O3 micropowder as main raw materials and boron oxide(≤0.075 mm)as the sintering aid.The effect of the boron oxide fine powder addition(mass fractions of 0,0.2％,0.4％and 0.6％,re-spectively)on the structure and properties of the castables was investigated.The results show that adding boron oxide fine powder significantly increases the water demand of the castables,but it is beneficial for the formation of mullite whiskers,thereby strengthening the bonding between the aggregates and the matrix and significantly improving the mechanical properties of the samples.However,when the addition of boron oxide fine powder increases to 0.6％,the sample presents decreased length to diameter ratio of mullite whiskers and lower strength.Generally,the optimal boron oxide addition is 0.4％.
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