纳米-Al2O3/SiO2加入量对MgO-Al2O3-SiO2复相陶瓷烧结机理的影响

Effect of Nano-Al2O3/SiO2 Addition Amount on the Sintering Mechanism of MgO-Al2O3/SiO2 Ceramic Composites

中文关键词: 氧化镁 Al₂O₃/SiO₂ 陶瓷基复合材料 烧结行为

英文关键词: MgO, Al₂O₃/SiO₂, ceramic-matrix composites, sintering behavior

中文摘要:

      为了探究纳米-Al₂O₃/SiO₂加入量对MgO-Al₂O₃-SiO₂复相陶瓷烧结行为的作用机理。以微米级MgO、纳米级Al₂O₃和SiO₂为主要原料制备陶瓷基复合材料。通过XRD和 SEM等检测手段对烧后试样的物相组成和微观结构进行测试与表征,重点研究Al₂O₃/SiO₂的加入对复相陶瓷物相组成、微观结构及烧结性能的影响。结果表明:随着Al₂O₃/SiO₂加入量的增大,试样烧后相对密度和烧后线变化率呈先增大后减小再增大的趋势,加入15%Al₂O₃/SiO₂(质量分数)的试样经1 500 ℃烧结后,其相对密度可以达到94%。引入的Al₂O₃/SiO₂与基体中的MgO生成镁铝尖晶石与镁橄榄石相,原位反应伴随的体积膨胀,抵消部分烧结过程中的体积收缩。Al₂O₃/SiO₂加入量为75%(质量分数)的试样经1 400 ℃烧结后,基体中有大量堇青石相生成,随着煅烧温度提高到1 500 ℃,堇青石分解所产生的高温液相促进了试样的烧结收缩。

英文摘要:

      In order to explore the effect of nano-Al₂O₃/SiO₂ addition amount on the mechanism of sintering behavior of MgO-Al₂O₃-SiO₂ composite ceramics, ceramic-matrix composites were prepared from micron-sized MgO, nano-sized Al₂O₃ and nano-sized SiO₂ as the main raw material. The phase composition and microstructure of sintered samples were characterized by X-ray diffraction and scanning electron microscopy, respectively. Effects of Al₂O₃/SiO₂ addition amount on the phase composition, microstructure and sintering properties of composite ceramics were mainly investigated. The results showed that the relative density and linear dimension change rate of the sintered sample firstly increased, then decreased and then increased with increasing Al₂O₃/SiO₂ addition amount. The relative density of the sample introduced with 15% Al₂O₃/SiO₂ sintered 1 500 ℃ reached 94%. The magnesium aluminate spinel and forsterite formed by solid reaction including Al₂O₃, SiO₂ addition, and the MgO itself. Meanwhile, in-situ reaction coupled with a volumetric expansion, it could offset part of the volumetric shrinkage caused by the sintering process. The cordierite phase was formed in the matrix when the sample introduced with 75wt% Al₂O₃/SiO₂ sintered 1 400 ℃. The high temperature liquid phase decomposed from cordierite calcined at 1 500 ℃ and promoted the sintering shrinkage of the sintered sample.