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

Abstract:

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 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.

• Periodical: Materials Science Forum (Volumes 745-746)
• Pages: 610-615
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.745-746.610
• Online since: February 2013
• Authors: Hong Gang Sun, Peng Tao Li, Shuang Zhi Yan, Gang Wang, Jian Qiang Li, Han Wang
• Keywords: Al₂O₃-Cr₂O₃ Refractories, Microstructure, Particle Size, Pore Size Distribution

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