反应烧结制备多孔tib2tic复相陶瓷的研究.docx

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中南大学硕t学位论文摘要
摘 要
、高硬度、高导热、低膨胀系数、高耐磨性与良好导电性等特点,因此这类材料在高温过滤方面具有很好的应用前景,从而开展这类材料的研究,特别是采用原位合成技术来制备该材料具有一定创新性的。
本文在真窄烧结条件下,采用反应烧结原位合成技术,以Ti、 B4C和炭黑为原料,。研究了原料颗粒尺寸、原料配比、、孔隙结构和力学性能的影响。
℃存在TiB和 Ti384中间过渡相,当烧结温度高于1300。C,反应烧结制备的材料产物较为纯净,中间过渡相消失,烧结样品中只含有TiB2和TIC两相。 ,且孔隙分布较为均匀,孔径分布范围较窄。烧结样品的断口表面一部分比较平整,表现为穿晶断裂;另一部分表面高低不平,表现为沿晶断裂。总的来说,多孔TiB2一TiC复相陶瓷材料的断裂方式既存
在沿晶断裂,又具有穿晶断裂的混合断裂模式。 、孔径大小和力学性能有重
要影响。对于同一系统来说,烧结温度高的烧结样品具有高的密度、三点抗弯强度和低的孔径。在同一烧结温度下,,,—C系统的。结果表明,B4C粉末颗粒的大小直接影响到所制备出材料的性能。
℃下的平衡相图和Ti—,对该体系中未知的化合物的热力学数据进行了估算。同时根据热力学稳定相平衡的条件,。据此, 复相陶瓷的反应扩散路径为: TiffiC/TiB/Ti384/TiB2/B4C。
关键词:反应烧结,原位合成,多孔复相陶瓷,
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中南大学硕E学位论文 ABSTRACT
AB STRACT
Boride ceramics have some special properties,such as high melting points,high hardness,high heat conductivity,low-expansion coefficient, excellent corrosion resistance and high electrical the boride materials have great potential tO be used as high temperature filter is innovative to investigate the boride materials,especially, formation boride materials by in—situ synthesis technical
In this paper,porous TB2-posites are fabricated with Ti,B4C and carbon black powder by in situ synthesis under vacuum sintering. Effect of powder size,mol ratio of Ti,B4C and carbon black,sintering temperature and dwell time on the sintering properties,pore—size distribution and mechanical properties are ,pore morphology of porous ZiB2·-posites are investigated by X··ray diffraction(XRD),and scanning electron microscopy(SEM).The results on their properties of densities,three-point bend strength and gas permeability show that porous TiB2-posites have good
performances by in—situ synthesis under vacuum sin