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借鉴“过渡塑性相工艺”思想,在刚玉-氮化硅复合材料中引入12.5%(质量分数)的铝粉,研究了铝粉对刚玉-氮化硅复合材料成型性能以及1 600℃空气中烧成后样品的体积密度、显气孔率和耐压强度的影响;利用X射线衍射仪和扫描电镜对材料的物相和微观结构进行了分析。结果表明:在刚玉-氮化硅复合材料中引入铝粉,有利于成型过程中孔隙的填充,坯体显气孔率由21.57%下降为20.42%,坯体致密度提高。样品在空气气氛中烧成后,未加铝粉样品表面形成的致密氧化膜厚度约为3 mm,而加入铝粉样品表面氧化膜的厚度约为0.2 mm;铝粉先于氮化硅粉发生原位氧化,降低了样品内部的氧分压,残留的铝粉发生氧化或氮化反应生成活性中间产物,促进了样品的烧结。
With reference to the idea of “transitional plastic phase technology”, 12.5% (mass fraction) aluminum powder was introduced into the corundum-silicon nitride composite to study the effect of aluminum powder on the forming properties of corundum-silicon nitride composite and air at 1 600 ℃ After sintering, the bulk density, apparent porosity and compressive strength of the samples were investigated. The phase and microstructure of the samples were analyzed by X-ray diffraction and scanning electron microscopy. The results show that the introduction of aluminum powder into the corundum-silicon nitride composite is beneficial to the filling of pores in the forming process. The apparent porosity decreases from 21.57% to 20.42% and the density of the green body increases. After the sample is fired in the air, the thickness of the dense oxide film formed on the surface of the sample without aluminum powder is about 3 mm, while the thickness of the oxide film on the surface of the sample is about 0.2 mm. The aluminum powder is generated before the silicon nitride powder In-situ oxidation reduces the oxygen partial pressure inside the sample, and the residual aluminum powder oxidizes or nitrates to form an active intermediate product, which promotes the sintering of the sample.