Effects of Cr 2 O 3 Content on Microstructure and Mechanical Properties of Al 2 O 3 Matrix Composites

: Al 2 O 3 -Cr 2 O 3 refractories are completely substitution solid solutions and can effectively resist slag erosion when used as an industrial furnace lining. In order to provide suitable chromium corundum refractory with excellent slag resistance and mechanical properties for smelting reduction ironmaking, Al 2 O 3 -Cr 2 O 3 samples with different mass percentages (0, 10, 20, 30, 40 wt.%) of Cr 2 O 3 were prepared by a normal pressure sintering process to study its sintering properties, mechanical properties, thermal shock resistance, and microstructure. The results of densification behavior showed that the introduction of Cr 2 O 3 deteriorates the compactness, the relative density and volume shrinkage rate of the composite material decrease with the increase of the Cr 2 O 3 content, and the apparent porosity increases accordingly. In terms of mechanical properties, the hardness, compressive strength, and flexural strength of Al 2 O 3 -Cr 2 O 3 material decrease gradually with the increase of Cr 2 O 3 . After 10 and 20 thermal shock cycles, the flexural strengths of the samples all decreased. With the increase of Cr 2 O 3 in these samples, the loss rate of flexural strength gradually increased. Considering the slag resistance and mechanical properties of the composite material, the Al 2 O 3 -Cr 2 O 3 composite refractory with Cr 2 O 3 content of 20–30% can meet the requirements of smelting reduction iron making kiln lining.