SiAION Bonded Corundum or SiC Composites Synthesized in Different Atmospheres

摘要

Using corundum powder,SiC powder,Si3N4 powder,α-Al2O3 micropowder and metal Al powder as starting materials,PVA as binder,after ball milling,mixing,aging,moulding and drying,SiAlON bonded corundum or SiC composites were synthesized at 1 600 ℃ for 6 h in air,graphite embedded condition and(graphite+SiC)embedded condition,respectively.Effects of corundum or SiC powder additions(the mass percent was 7.5%-90%)and sintering atmosphere on forming amount and appearance of SiAlON phase,phase composition,microstructure and properties of the composites were studied.The results show that:(1)with corundum powder addition increasing,density and sintering property of SiAlON bonded corundum composites fired in three different conditions all improve,but the sintering property of the specimens fired in oxidation atmosphere is better than that in reduction atmosphere;(2)the main phases of SiAlON bonded corundum composites fired in two reduction atmospheres are corundum,SiAlON and SiC.The specimens fired in oxidation atmosphere have lamination phenomenon,the main phases of non-oxidation layer are SiAlON,corundum and a little mullite;(3)column-like or fiber-like SiAlON forms in SiAlON bonded corundum composites fired in two different atmospheres.Column-like SiAlON forms in oxidation atmosphere grows better than in reduction atmosphere;(4)with SiC powder addition increasing,density and sintering property of SiAlON bonded SiC composites fired in two reduction atmospheres both reduce.The specimens fired in oxidation atmosphere are oxidized and thicker glaze layer forms.