摘要：
为了研究Al2O3-SiC-C材料与其他材料复合后的性能,在复合加入6%(w)的Al粉+Si粉的基础上,再分别加入质量分数为0、0.5%、1%、2%、4%和6%的电熔镁砂粉,以研究引入MgO对该复合材料热膨胀性和抗氧化性的影响,并探讨高温下MgO在Al2O3-SiC-C-Si-Al体系中可能发生的反应.结果表明:1)向Al、Si复合Al2O3-SiC-C材料中加入少量的镁砂粉后,MgO与C、Si、Al、SiC等发生反应生成Mg、CO等气体而导致材料结构疏松,降低了材料的抗氧化性;2)高温下,MgO与Al2O3以及由Si氧化生成的SiO2等形成复杂的多元体系,有大量的低熔点相生成,收缩效应明显,减弱了生成尖晶石所产生的膨胀效应.因此,必须严格控制镁砂粉加入量在2%(w)以下,才能使Al2O3-SiC-C材料保持优良的高温性能.%In order to research the properties of the composite of Al2O3-SiC-C and other materials,based on 6 mass% addition of Al powder and Si powder,fused magnesia powder(0,0.5%,1%,2%,4%,or 6%, by mass)was added to study the effect of MgO on the thermal expansion and oxidation resistance of the composite,and to discuss possible reactions of MgO in Al2O3-SiC-C-Si-Al system at high temperatures. The results show that:(1)when a small amount of magnesia powder is added into Al and Si incorporated Al2O3-SiC-C composite,MgO reacts with C,Si,Al and SiC forming Mg vapor,CO and other gases,cau-sing a loose structure,and decreasing the oxidation resistance of the material;(2)MgO,Al2O3,and SiO2 formed by the oxidation of Si generate a complex multi-component system at high temperatures,a large amount of low-melting phases form,and there is an obvious shrinkage,which weakens the expansion effect caused by spinel formation.Therefore,the addition of magnesia powder must be strictly controlled under 2 mass%,so that the material can maintain good performance.
