ZrB_2基超高温陶瓷材料抗热震性能及热震失效机制研究进展

ZrB_2基超高温陶瓷具有高熔点、较高的强度、高热导率等优点,是一种性能优异的高温结构材料,成为高超声速飞行器关键热部件的首选候选材料。介绍了ZrB_2的基本性能,以及ZrB_2基超高温陶瓷材料的抗热震性能及改进情况,讨论了表面热交换系数梯度对材料热震行为的影响,对超高温陶瓷材料的热震行为和热震失效机制有了新的认识,为材料在实际服役条件下的性能预测提供参考,并为材料抗热震性能的提高提供了新的研究思路。     

泡沫陶瓷成孔性能对热震性的影响

详细研究了泡沫陶瓷成孔性能对热震性的影响规律，并对泡沫陶瓷热震破坏机理作了探讨。     

Al2O3+ZrO2层状复合陶瓷的表面抗裂纹行为及抗热震性能

用压痕一强度法获得了Al2O3 Zr02单层和层状陶瓷的表面抗裂纹曲线,用压痕法测试了2种材料的抗热震性能,分析了材料的表面抗裂纹行为、抗热震性与断裂形貌,强韧化之间的相关性。实验结果毒明：Al2O3 ZrO2层状陶瓷对表面裂纹表现出不敏感性,临界热震温差为400℃,高出单层陶瓷150℃左右。进一步分析表明：2种陶瓷的表面抗裂纹及抗热震性能与材料的强韧化机制密切相关。表面压应力作用强化了相变增韧效果,改善了材料的表面抗裂纹性能和抗热震稳定性等力学性能。     

硅溶胶对刚玉莫来石复相陶瓷的性能影响

采用溶胶-凝胶法在刚玉-莫来石质材料中引入活性硅溶胶(SiO2),分析了硅溶胶对刚玉-莫来石复相陶瓷性能的影响机制。研究结果表明,SiO2在主体材料中形成纳米包裹薄膜,SiO2的分布可控、掺入均匀,从而提高了复相陶瓷的抗热震性、高温强度及蠕变性。加入SiO2溶胶产生的莫来石反应化和微裂纹增韧是刚玉-莫来石质材料热震稳定性提高的主要原因。     

浅谈丝网印刷在陶瓷颜料质量检测过程中的影响因素

丝网印刷在陶瓷颜料质量检测过程中是非常重要的环节,直接影响待检颜料的检测准确性,本文通过在丝网印刷的过程中总结发现印刷环境、陶瓷颜料含水率、丝网与印刷花纸的间距、颜料印刷厚度、陶瓷颜料粒度及分布等因素对待检颜料与标样产品的对比结果有影响,通过多年的陶瓷颜料检验经验积累,总结了如何把握好以上因素,找到合适的参数更能有利于提高陶瓷颜料质量检测的准确性。     

太阳能热发电莫来石-硅酸锆复相陶瓷的原位合成及性能

以红柱石、ZrO2、苏州土和长石为主要原料,采用无压烧结制备了太阳能热发电用莫来石-硅酸锆复相陶瓷.研究了烧结温度对材料吸水率和力学性能的影响,采用空冷法研究了材料的热震性能,利用X射线衍射仪和扫描电子显微镜分析了复相陶瓷热震前后的物相组成和显微结构.结果表明:在1490℃烧结的最优样品A2吸水率为0.41％,气孔率为1.10％,体积密度为3.06 g/cm3,抗折强度达128.78MPa;复合材料有很好的热震性能,1100℃空冷热震损失率上升10.69％,可耐受30次以上热冲击,该复相陶瓷可作为潜在的太阳能热发电管道材料.     

SiC晶须补强ZTM陶瓷复合材料的抗热震性研究

本文研究了SiC晶须〔SiC_((w))〕加入对氧化锆增韧莫来石(ZTM)陶瓷抗热震性影响。实验结果表明:加入SiC_((w))使ZTM材料的抗热震性有明显改善;临界温差△T。从300℃提高到650℃。其主要原因为:材料力学性能提高及晶须对热震裂纹钉扎、架桥作用。     

氮化硅陶瓷材料高温抗热震性能及其衰减规律研究

氮化硅陶瓷作为先进陶瓷材料具有耐高温、抗腐蚀等优异性能,因此被广泛应用于航空航天领域的强热冲击环境。热压烧结制备的Si3N4复合材料的抗弯强度较高,但抗热震性能随温度升高显著降低,热压烧结工艺在提升抗热震性能方面尚有不足。本文提出了使用二次热处理烧结方式来提高Si3N4陶瓷的抗热震性能,通过热压烧结-气压烧结二次热处理的烧结方式获得更致密、抗热震性能更好的Si3N4陶瓷材料。测试结果显示,常规热压方式制备的氮化硅陶瓷,随着热震温度的升高、次数的增加,材料内部产生微裂纹的概率增大,热震后试样抗弯强度逐渐降低,1200℃时平均强度下降率达23.48%。而经过二次热处理后氮化硅陶瓷抗弯强度略有降低,但抗热震性能得到明显改善,随着热处理时间增加,二次热处理后氮化硅陶瓷显微结构更加致密,抗热震性能将明显提高,热震后强度下降率明显减小,1200℃热震10次后强度下降率为12.25%。本文提出了提高Si3N4陶瓷的抗热震性的方法,探讨了氮化硅陶瓷在1200℃高温下的抗热震性能及其衰减规律,为改善氮化硅陶瓷器件高温性能提供了参考。     

耐火材料损伤蚀变研究的进展

简述了高温、化学腐蚀、热震和多种机械载荷对耐火材料损伤依变的影响；综述了陶瓷耐火材料冲击、磨损、热震、疲劳和慢速裂纹扩展方面研究的进展；讨论了综合破坏作用下材料的行为及模拟性试验。     

Mg2+、La3+和Ce4+对红柱石增强莫来石质陶瓷性能的影响

以天然红柱石和活性氧化铝为原料,利用细磨、等静压等工艺,通过固相反应烧结制备出红柱石增强莫来石质陶瓷。借助于X射线衍射、扫描电子显微镜等对样品的相组成、晶胞参数和显微结构进行计算和分析,研究了成型方式和Mg2+、La3+和Ce4+掺杂对反应烧结制备红柱石增强莫来石质陶瓷烧结性能和热震稳定性的影响。结果表明:通过掺杂一定量Mg2+、La3+和Ce4+,利用等静压成型,经1 500℃保温2h烧成,可制备出具有高致密度和良好热震稳定性的莫来石质陶瓷。加入大于4%的氧化镁可以显著提高红柱石增强莫来石陶瓷的致密性和热震前后常温耐压强度保持率。掺杂La3+可以起到促烧结作用;引入少量Ce4+,不仅有利于提高莫来石陶瓷烧结性,而且有利于提高材料的热震稳定性。     

莫来石-钛酸铝陶瓷材料性能的研究

用预合成的钛酸铝制备了莫来石-钛酸铝(MT)陶瓷材料,研究了材料组成与其烧结性能、抗弯强度、热膨胀性能及抗热震性的关系。结果表明,随着钛酸铝含量的减少,MT陶瓷材料的抗弯强度提高,热膨胀系数增大,抗热震性降低,但在钛酸铝含量大于43％时,陶瓷材料的强度有所增加,仍保持较低的热膨胀系数,具有良好的抗热震性。     

膨胀珍珠岩对镁钙质陶瓷热震稳定性的影响

以煅烧白云石、工业氧化镁为主要原料,通过添加膨胀珍珠岩制备镁钙质陶瓷试样;探讨膨胀珍珠岩含量对试样显气孔率、体积密度、抗热冲击性能及热冲击对试样抗折强度的影响。试验结果表明：添加适量的膨胀珍珠岩能有效地提高镁钙质陶瓷的抗热冲击性能。     

The fabrication of SiBCN ceramic components from preceramic polymers by digital light processing (DLP) 3D printing technology

We present a novel method to fabricate SiBCN ceramic components with complex shapes from preceramic polymers by using digital light processing (DLP) 3D printing technology in this research work. The photocurable precursor for 3D printing was prepared by blending high ceramic yield polyborosilazane with photosensitive acrylate monomers. The material formulation and printing parameters were optimized to fabricate complicated SiBCN ceramic components with high precision. The printed SiBCN ceramic materials were pyrolyzed at different temperatures, and retained their fine features after pyrolysis. Their microstructures were characterized by FTIR, XRD and TEM respectively. Furthermore, the thermal stability and mechanical properties of the SiBCN ceramic samples were investigated and discussed in detail. The 3D printed SiBCN ceramic material exhibited excellent thermal stability and resistance to high temperature oxidation up to 1500?°C.     

Quantitative Studies of Thermal Shock in Ceramics Based on a Novel Test Technique

A thermal shock test was designed which permits the thermal fracture resistance and the mechanical strength of brittle materials to be quantitatively correlated. Thermal shock results for two materials, A1₂O₃ and SiC, were accurately predicted from biaxial strength measurements and a transient thermal stress analysis (performed using a finite element method). General implications for the prediction of thermal shock resistance, with special reference to ceramic components, are discussed.     

Thermal shock resistance of additively manufactured gas-permeable SiO2 ceramic structures for HIP-quench applications

The increasing demand for hot isostatic pressing (HIP) means that a reliable and efficient operation of modern HIP units with fast cool capability is indispensable. A key factor for efficient operation is the ceramic crucible used as the load basket. Its task is to keep as much of the HIPed parts as possible effectively within the hot zone and to prevent them touching the furnace wall. This work focuses on designing a gas-permeable ceramic structure with a high thermal shock resistance that can be scaled up to a load basket for future HIP applications. Stereolithography (SL) 3D printing of a ceramic resin is employed to build various scalable framework structures inspired by nature and by existing engineering applications. Thermal shock tests with water quenching reveal that framework structures with evenly distributed triangular bracings offer the highest flexural strength, whereas auxetic structures are best at retaining their flexural strength after thermal shock.     

换热器用针状莫来石增强堇青石陶瓷材料

以耐火粘土、高铝矾土及滑石为原料研制了堇青石基陶瓷材料，并对其组织和性能尤其是抗热震性进行了研究。结果表明，堇青石基体上分布着外状莫来石的材料具有更高的抗热震性。对换热器用陶瓷材料抗热震性参数进行了讨论，指出抗热震损伤多数R''更适合于作为优选陶瓷换热器用材料的指标。     

Study on Properties of ZrO_2 Ceramic Material for Porous Media Burner

A kind of ZrO2 ceramic material for porous media burner was prepared by polymeric sponge process with starting materials of zircon, zirconia powder, microsilica, and ball clay, and binder of silica sol through reaction-sintering. The effects of microsilica addition on cold crushing strength and zirconia/zircon adding ratio on thermal shock resistance were studied. The results show that the porous media material has proper porosity, high strength, and excellent thermal shock resistance when zirconia addition...     

连铸用烧成铝碳质滑板研究现状

烧成铝碳质滑板是连铸控流系统的关键功能材料之一,在使用过程中需要承受钢水和渣液的冲刷、快速和反复的热冲击,以及潜在的氧化风险,因此对材料的力学性能、热震稳定性和抗氧化性提出了严苛的要求。近年来,为了持续提高烧成铝碳质材料的上述性能,延长其使用寿命,针对材料结构和组成的优化进行了不断研究,主要包括从金属铝、单质硅等主要添加剂原位形成陶瓷相增强,发展到纳米碳源协同原位陶瓷相增强增韧,以及近期的层状化合物协同纳米碳及原位陶瓷相强韧化和抗氧化。     

Measurement of ceramics cracking during water quenching by digital image correlation

Measuring the thermal shock crack growth process is crucial for revealing ceramic materials and structures’ thermal shock failure mechanisms and evaluating their reliability. We used a self-made water quenching system to conduct thermal shock tests on alumina and zirconia ceramics. The thermal shock process was recorded by high-speed digital image correlation (DIC) during the test. The process of thermal shock crack initiation and propagation in two kinds of ceramics was determined by analyzing the speckle image change on the sample’s surface. It is found that the crack growth rate of alumina is faster than that of zirconia, which is caused by different material parameters. This paper presents an in-situ measurement method for the initiation and propagation of thermal shock cracking in ceramic materials. It can provide a measurement method to identify and predict the thermal shock damage of ceramic components.     

The Role of Thermal Shock on Tool Life of Selected Ceramic Cutting Tool Materials

The introduction of Si₃N₄- and Al₂O₃-based tools has greatly increased the speed of metal removal and the productivity of metal-cutting operations. High-speed machining elevates the temperature at the tool/workpiece interface and subjects the tool to considerably higher stress, resulting from increased mechanical forces and thermal gradients. Under these circumstances, the thermal shock resistance of tool materials would be expected to play a more important role in determining the tool life and should be more prominently considered in both material design and applications. It was of interest to devise a series of controlled thermal shock machining tests and to assess the modes of ceramic cutting-tool wear. The resistance of ceramic cutting-tool materials to wear or fracture under these conditions is discussed in terms of thermal shock parameters.