Study On Composition, Structure And Properties Of β-Sialon Bonded Corundum Composites For Torpedo Car

β-Sialon bonded corundum materials have been prepared by using tabular alumina, fused corundum, Si powder, Al powder and ultra fine α-Al2O3as starting materials. The effects of Z value, Sialon content, SiC powder and different aggregates (tabular alumina, brown corundum, fused corundum, super-grade bauxite) on the physical properties, hot modulus rupture (HMOR), thermal shock resistance (TSR), oxidation resistance and corrosion resistance have been studied. The results were as follows:(1) XRD results showed that the main crystal phase was corundum and the other phase was β-Sialon in the specimens after fired at1500℃under flowing nitrogen atmosphere. With the increase of Z value, the common modulus rupture (CMOR), TSR, oxidation resistance and slag resistance became worse.(2) With the increase of β-Sialon content (10%-30%), the physical properties had a little change, but HMOR, TSR, oxidation resistance, slag resistance and desulfurizer resistance improved obviously, reflecting in that HMOR increased from8.6MPa to18.2MPa at1400℃; The residual strength ratio of the specimens increased from43.6%to63.0%after three thermal shocks at1100℃(water cooling); The thickness of oxidation layer decreased from2.7mm to1.6mm.(3) After added5%and10%SiC powder instead of fused alumina, the bulk density failed slightly, CMOR slightly increased, HMOR and TSR increased signi-ficantly. HMOR at1400℃increased from13.5MPa to18.8MPa; The residual strength ratio of the specimens increased from64.9%to92.6%after one thermal shocks at1100℃(water cooling).(4) When fused alumina particles and brown corundum particles replaced tabular alumina particles, the physical properties of the specimens at room temperature, HMOR, TSR, oxidation resistance, slag resistance and desulfurizer resistance had a little change; The use of super-grade bauxite particles alternative to tabular alumina particles, making HMOR, TSR, slag resistance and desulfurizer resistance became worse. HMOR of the the specimens with tabular alumina, brown corundum, fused corundum, super-grade bauxite as aggregates at1400℃were15.9MPa,15.5MPa.10.7MPa and8.2MPa respectively; The residual strength and residual strength ratio were9.8MPa,9.2MPa,8.1MPa,7.1MPa and72.6%,73.5%,62.3%,44.0%respectively after three thermal shock at1100℃(water cooling). The specimens with super-grade bauxite as aggregate had poor high temperature performance which could be attributed to:On one hand, SiO2in bauxite participated in gas phase reactions to form O’-Sialon which resulted in elevated porosity; On the other hand, more impurities in super-grade bauxite had an adverse effect on HMOR, TSR and erosion resistance of the specimens.