Effects of Al2O3 Species and Particle Sizes on Properties of Al2O3-Cr2O3 Refractories

摘要

The microstructure of Al2O3-Cr2O3 refractories is an important factor to affect its high temperature performance.The Al2O3-Cr2O3 green bodies were prepared by hot pressing using aluminum oxide and Cr2O3 powder mixture by adding a binder.And then the specimens were sintered at 1650°C for 4h in the electric muffle furnace.Properties of specimens with different species of Al2O3 powders were studied,including α-Al2O3 powder,ρ-Al2O3 powder,and fused corundum powder.Moreover,three sizes of α-Al2O3 powder (D50=0.8 μm,1.4 μm,4.0 μm) were used as additive.Properties of specimens,including apparent porosity,bulk density,cold modulus of rupture,pore size distribution were tested.The morphology of sintered specimens was analyzed by the Scanning Electron Microscope.The results showed that the specimens adding α-Al2O3 powder had the better properties since α-Al2O3 powder has higher sintering activity,and it was more efficient for Al2O3-Cr2O3 solid solution.The specimens with α-Al2O3 had lower porosity,higher bulk density and cold modulus of rupture,and more uniform pore distribution.There were great differences in sintering activity for specimens with different particle size of α-Al2O3 powder.And the microstructure of Al2O3-Cr2O3 was significantly dissimilar.The specimen with the addition of the activated alumina powder of D50 with the size of 1.4 μm and bimodal size distribution showed the perfect performance,including high density and high flexural strength.The experimental results showed that the microstructure of this specimen was uniform and its pore size was homogeneous.This special microstructure is beneficial for improving the slag resistance and thermal shock resistance of Al2O3-Cr2O3 refractories.