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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。
In this paper, cordierite-mullite composite ceramics were prepared by in-situ reaction sintering with different contents of B 2 O 3, Nd 2 O 3 and Y 2 O 3 sintering aids using kaolin, talc and industrial alumina as raw materials. Density and sintering characteristics. The crystal phase composition and microstructure of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). The phase composition and liquid holdup of the system were compared and analyzed by FactSage 6.0 software. The results show that: B_2O_3 has the best sintering aid. The sintering temperature of the composite ceramics with 2.0% B 2 O 3 reduced, the density and mechanical strength increased, the water absorption and the flexural strength after sintering at 1 420 ℃ were 0.03% and 116.70 MPa, respectively. XRD analysis and FactSage simulation confirmed that the solid phase diffusion between the two substances changed into the liquid phase diffusion due to the liquid phase sintering of B 2 O 3, which promoted the tetradite cordierite formation in the sample (the phase composition of B 2 O 3 was not hexagonal cordierite). The results of SEM and EDS showed that 2.0% B 2 O 3 promoted the growth and development of the crystal, and the tetragonal or massive cordierite interweaved with the needle-rod mullite to give higher density and strength of the sample.