烧结助剂对堇青石-莫来石复相陶瓷的致密化和烧结特性的影响（英文）

Effect of Sintering Aids on Densification and Sintering Behavior of Cordierite-mullite Composite Ceramics

以高岭土、滑石、工业氧化铝为原料,加入不同含量的B_2O_3、Nd_2O_3、Y_2O_3烧结助剂,通过原位反应烧结法合成了堇青石-莫来石复相陶瓷,研究了烧结助剂对其致密度和烧结特性的影响。采用X射线衍射(XRD)、扫描电子显微镜(SEM)和能谱仪(EDS)表征试样的晶相组成和微观结构。利用FactSage 6.0软件对系统的相组成和液含率进行了模拟对比分析。结果表明:B_2O_3具有最好的助烧结性。添加2.0%B_2O_3的复相陶瓷样品的烧结温度降低,致密度和机械强度提高,其经1 420℃烧成后吸水率和抗折强度分别为0.03%和116.70 MPa。经XRD分析和FactSage模拟证实,由于B_2O_3的液相烧结作用,物质间的固相扩散转变为液相扩散,促进了样品中四方堇青石的生成(未添加B_2O_3样品相组成为六方堇青石)。SEM和EDS结果表明,2.0%B_2O_3促进了晶体的生长与发育,四方柱状或块状堇青石与针棒状莫来石相互交织穿插排列,赋予样品较高的致密度和强度。

Cordierite-mullite composites as potential supporting materials used at high temperatures were prepared by an in situ reaction sintering method with Kaolin clay, Talc and alumina as raw materials. To obtain dense composite ceramics, four batches of the blank sample, the B2O3-added, Nd2O3-added, and Y2O3-added samples were taken into consideration. The effect of sintering aid additives on the densification and sintering behavior and the morphology of the composite samples were investigated by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and energy dispersive spectrometry （EDS）. A software named FactSage was used to calculate the phase composition and liquid content. The experimental results show that the samples with 2.0% B2O3 （sintered at 1 420℃） exhibit the dentist microstructure （with an water absorption of 0.03%） and the maximum mechanical strength （with a bending strength （σ） of 116.70 MPa）, compared to the other three samples. The XRD analysis proves that the addition of B2O3 promotes the crystallization and growth of orthorhombic-cordierite instead of hexagonal-cordierite, which is a time-temperature-transformation （TTT） behavior. These results are consistent with the results calculated by FactSage. Based on the SEM and EDS analysis, the tetragonal-prismatic or lumpy cordierite grains and needle-shaped mullite grains were formed in irregular rows, resulting in the improved densification and mechanical strength of the sample with 2.0% B2O3.