添加剂对二氧化硅包裹碳化硅材料性能的影响

本文利用碳化硅颗粒表面氧化生成的二氧化硅将碳化硅颗粒包裹起来的方法,制备了二氧化硅包裹碳化硅材料;借助XRD、SEM分析了加入不同添加剂对材料抗折强度及抗热震性等性能的影响。结果表明添加硅粉能提高二氧化硅包裹碳化硅材料的抗弯强度和抗热震性,而Cu粉和V2O5对材料的性能影响不大。     

反应烧结碳化硅高温性能的研究进展

反应烧结碳化硅具有优良的力学性能、抗侵蚀性能和抗氧化性能等优点,是一种高致密度、低成本和净尺寸成型的材料.但由于反应烧结法的特殊工艺,反应烧结碳化硅中常含有较多游离硅,严重损害了材料的高温性能.主要阐述了反应烧结碳化硅高温力学性能、抗氧化性能、导热性能和抗热震性能的研究现状,并总结了近年来降低游离硅含量、提高反应烧结碳...     

渗硅碳化硅材料结构与性能关系的研究

采用低廉石油焦碳分为原料制造全碳粉生坯，通过有机添加剂来调配生坯中碳的比例，以控制烧结体中游离硅（fsi）、游离碳（fC）含量（其中fs,fc为烧结中未反应的硅和碳），研究了全碳粉反应硅碳化硅（PCRSC）材料的结构与力学性能的关系，分析了渗硅碳化硅材料中游离硅、游了碳含量对抗弯强度的影响。结果表明：渗硅碳化硅材料中随游离硅含量的增加，其抗弯速度下降，并且二者呈直线关系，符合线性复合规则，另一方面，游离碳含量较高的渗硅碳化硅材料，尽管游离硅含量低，但其抗弯强度低于等量或较多游了硅含量的渗硅碳化硅材料的抗弯强度。     

碳化硅材料中游离硅及游离碳对性能的影响

研究了全碳粉反应渗硅碳化硅（PCRBSC）材料的结构与力学性能的关系。分析了渗硅碳化硅材料中游离硅（fsi),游离碳（fc)含量对抗折强度的影响。结果表明：参硅碳化硅材料中随游离硅（fsi)含量的增加,其抗折强度下降,并且二者呈直线关系,符合线性复合规划,另一方面,游离碳（fc)含量较高的渗硅碳化硅材料,尽管游离硅（fsi)含量低,但其抗折强度低于等量或较多游离硅（fsi)含量的渗硅碳化硅材料的抗折强度。     

不烧改性树脂结合碳化硅材料的性能研究

为了开发具有更高抗热震性的陶瓷窑具,以优质碳化硅为原料,含Si、O、C、H元素的改性树脂为结合剂,研制了不烧改性树脂结合碳化硅材料,并重点对该材料的抗热震性、高温荷重变形性、高温抗折强度进行了试验研究。结果表明:该碳化硅材料具有非常好的抗热震性、高温强度和很好的抵抗高温载荷的能力,在陶瓷窑具等温度波动大的环境下应该有很好的应用前景。     

工艺参数对反应烧结碳化硅结构的影响

文中列出了利用岩相Ｘ射线结构分析、化学分析及光谱分析方法，对采用碳化硅颗粒及其与石油焦混合物压制成型的坯体。在硅硅烷融物及硅蒸气中通过反应烧结制成的碳化硅材料的结构及石油焦的配比，碳化硅颗粒及碳素颗粒的粒度、压制成型坯体的密度及反应烧结温度等，便可调节反应烧结碳化硅材料的结构和组成，实验证明，在石油焦与硅发生反应烧结事成致密的碳化硅骨架，而残余的气孔被未化合的硅所充填。单相材料采用此种方法可以制成     

氮化硅结合碳化硅复合材料性能优化的研究进展

氮化硅结合碳化硅具有优异的力学性能、抗蠕变性能、抗热冲击性能、热学性能和抗化学侵蚀性能,被广泛应用于冶金、化工、机械和国防军工等领域.氮化硅结合碳化硅的服役环境恶劣,材料的力学性能、抗热震性能、抗侵蚀性能和抗氧化性能是影响其服役寿命的关键.本文针对如何提升氮化硅结合碳化硅材料的服役性能,对氮化硅结合碳化硅力学性能、抗热...     

高炉出铁沟用高抗渣性浇注料的开发

碳化硅质浇注料通常被用于高炉出铁沟的渣蚀区,因为碳化硅提供了更高的抗渣侵蚀性。相反,当碳化硅含量增加时,加水混合后的浇注料流动性则降低。为此专门添加超微硅粉,以使材料保持一个适当的流动性。添加的超微硅粉提升了材料的流动性,但是浇注料的耐热性和抗渣性都降低了。而且,超微硅粉过度烧结,会导致抗热震性降低。为了解决这些问题,通过用高岭土基粘土来替换超微硅粉并保持其流动性,为高炉开发了具有高的耐热性、抗渣性和抗热震性的浇注料。     

反应烧结碳化硅的显微组织及其导电性的研究

研究了液态硅参与下的反应烧结碳化硅的工艺参数、显微组织对其电阻率的影响.随着烧结气氛压力和成型压力增加,反应烧结碳化硅中游离硅量减少,电阻率增加.其烧结机理以碳的溶解及碳化硅的淀析过程为主.     

RS-Si_3N_4/BN复合材料的组织与性能

利用硅粉氮化结合BN的反应烧结工艺制备出Si3N4／BN复合材料,并研究了BN含量对复合材料密度、抗折强度、抗热震性以及显微组织的影响规律。结果表明,随BN含量的增加,复合材料的密度和抗折强度均随之降低,而热震性则随之升高。     

Thermal shock resistance of tri‐layer Yb2SiO5/Yb2Si2O7/Si coating for SiC and SiC‐matrix composites

A new tri‐layer Yb₂SiO₅/Yb₂Si₂O₇/Si coating was fabricated on SiC, C/SiC, and SiC/SiC substrates, respectively, using atmospheric plasma spray (APS) technique. All coated samples were subjected to thermal shock test at 1350°C. The evolution of phase composition and microstructure and thermo‐mechanical properties of those samples before and after thermal shock test were characterized. Results showed that adhesion between all the 3 layers and substrates appeared good. After thermal shock tests, through microcracks which penetrated the Yb₂SiO₅ top layer were mostly halted at the Yb₂SiO₅‐Yb₂Si₂O₇ interface and no thermal growth oxide (TGO) was formed after 40‐50 quenching cycles, implying the excellent crack propagation resistance of the environmental barrier coating (EBC) system. Transmission electron microscopy analysis confirmed that twinnings and dislocations were the main mechanisms of plastic deformation of the Yb₂Si₂O₇ coating, which might have positive effects on crack propagation resistance. The thermal shock behaviors were clarified based on thermal stresses combined with thermal expansion behaviors and elastic modulus analysis. This study provides a strategy for designing EBC systems with excellent crack propagation resistance.     

SiC复相陶瓷内加热器套管的制备及性能

用SiC粉作内加热器套管基本原料,采用反应烧结及常压烧结工艺制备具有复层结构的SiC复相陶瓷套管。套管内层为高致密SiC/Si复合材料,外层为SiC/C/SiC复相陶瓷。通过实验模拟内加热器服役环境,将套管内置热源在750℃熔融铝液中加热360 h测试其使用性能,研究外部复杂熔液腐蚀环境及内部强氧化气氛对SiC复相陶瓷套管的密度、抗弯强度、物相组成及显微形貌的影响。结果表明：复层结构SiC套管在模拟实验中展现出良好的抗热震及抗熔液浸蚀能力;内层材料由于高致密性具有良好的抗氧化性能;外层材料浸入熔体部分强度损伤小于10%,液面以上部分残余强度达到48MPa。SiC复相陶瓷套管在有色金属熔炼行业展现出良好的应用前景。     

Towards structural design and thermal management of advanced 2D CMCs

Advanced 2D carbon fiber reinforced silicon carbide (C/SiC) composites are highly advantageous, owing to the excellent temperature tolerance of carbon and the good oxidation resistance of SiC. Therefore, they have been regarded as the most promising thermal structural materials that operate in thermal shock environments. However, studies pertaining to their thermomechanical properties at elevated temperatures are sparse. The understanding of the structural design and thermal management of ceramic matrix composites remains rooted in the idea of traditional bulk materials. In this study, for the first time, the thermal-mechanical-oxidation coupled behaviors of a 2D plain-weave C/SiC material are investigated on an in-house built testing machine that is heated via induction from room temperature to 1400 °C in air. The high-temperature thermal properties are evaluated based on the proposed models and available experimental data. The thermal shock resistance in the simulated environments is subsequently studied. Safe and hazardous thermal shock conditions are identified. Improved methods for structural design and thermal management are proposed.     

Ti3SiC2陶瓷粉末的制备

新型层状陶瓷材料Ti3SiC2集金属和陶瓷的优良性能于一身,如低密度、高熔点、良好的导电导热性、高弹性模量、高断裂韧性、耐氧化、耐热震、易加工且有良好的自润滑性。在高温结构陶瓷、电刷和电极材料、可加工陶瓷材料、自润滑材料等领域有着广泛的应用前景。本文综合介绍了Ti3SiC2粉求制备的研究进展。最近,作者以Ti／Si／C／Al元素粉为原料,采用无压烧结的方法制备出纯度较高的Ti3SiC2陶瓷粉末。为Ti3SiC2基复合材料的发展开辟了一条新途径。     

显微结构对Si_3N_4(Si_2ON_2)结合SiC质棚板性能的影响

通过X射线衍射、扫描电镜、压汞议、立体显微镜等检测手段,对Si3N4(Si2ON2)结合SiC质棚板的显微结构进行了剖析,揭示了显微结构对SiC质棚板宏观性能的影响。认为结合相的抗氧化性及氧化“釉层”的稳定性是决定棚权使用寿命的关键;气孔结构及分布是影响Si3N4(Si2ON2)结合棚极热震稳定性的重要因素。     

层状陶瓷Ti3SiC2的研究现状

新型层状陶瓷Ti3SiC2兼有金属和陶瓷的许多优良性能,具有高的热导率和电导率,易加工,同时具有良好的抗热震性、抗氧化性和高温稳定性.在高温结构陶瓷、电极材料、可加工陶瓷材料、自润滑材料等领域的应用有着很好的前景.本文综合评述了Ti3SiC2的性能、制备技术及应用等.     

Characterization of the Mechanical Behavior of Magnesia Spinel Refractories Using Image Correlation

The improvement in thermal shock resistance of refractory materials is among the crucial properties that interest researchers and industrials. The “flexibility” in terms of large strain‐to‐rupture is, up to now, an important parameter to develop such characteristic. This can be obtained by generating a network of microcracks within the microstructure of the material under mechanical solicitations. As an outcome, the mechanical behavior can vary from fragile to a large nonlinear one depending on the degree of microcracking present inside the material. In fact, this nonlinear behavior of ceramics related to their microstructure is behind the possibility to enhance the level of strain‐to‐rupture for a better accommodation to the high level of strain induced by thermal shock solicitations. This study is devoted to apply digital imaging correlation method to support mechanical behavior analysis for the evaluation of the thermal shock ability of refractory materials. In this paper, mechanical characterization of magnesia spinel materials has been carried out using different experimental tests. These nonlinear materials are characterized by a mechanical behavior strongly dependent on their microstructure.     

Ti3SiC2陶瓷粉末的制备

新型层状陶瓷材料Ti3SiC2集金属和陶瓷的优良性能于一身,如良好的导电导热性、耐氧化、耐热震、高弹性模量、高断裂韧性等,在高温结构陶瓷、电刷和电极材料、可加工陶瓷材料、自润滑材料等领域有着广泛的应用前景。本文综合介绍了Ti3SiC2粉末制备的研究进展。此外,作者以Ti／Si／C／Al元素粉为原料,采用无压烧结的方法制备出纯度较高的Ti3SiC2陶瓷粉末,为Ti3SiC2基复合材料的发展开辟了一条新途径。     

3D microstructure model and thermal shock failure mechanism of a Si3N4-bonded SiC ceramic refractory with SiC high volume ratio particles

In this study, an efficient method was proposed to establish 3D microstructure model of a Si₃N₄-bonded SiC ceramic refractory with SiC high volume ratio particles and its failure mechanism under thermal shock was studied based on the established microstructure model. The proposed modeling method based on modified 3D Voronoi tessellation method and “precise shrinkage ratio method” was able to establish 3D geometric model of a SiC ceramic refractory with SiC high volume fraction particles more quickly than usual methods. The modified 3D Voronoi tessellation method generated Voronoi polyhedrons (VPs) limited in finite space perfectly. The proposed “precise shrinkage ratio method” achieved a precise volume fraction of SiC particles in the established microstructure model. The crack initiation and propagation under thermal shock were calculated by employing the extended finite element method (XFEM) on the established microstructure model. The results showed the failure mode on micro-scale clearly and efforts of interface strength on the failure mode were also explored. The proposed modeling method was especially suitable for establishing 3D microstructure models of ceramic composites or isotropic metal-ceramic particle composites with high volume fraction particles and extended the use of VPs.     

Thermal shock of ground and polished alumina and Al2O3/SiC nanocomposites

The thermal shock behaviour of sintered alumina and alumina/SiC nanocomposites with 1, 2.5 and 5 vol.% SiC was studied. The thermal shock testing was carried out by means of quenching into water from high temperatures (ΔT in the range 0–750 °C). Both single shocks and repeated shocks were used. The damage introduced by thermal shock was characterised by degradation of strength in four-point bending and by changes in Young's modulus. The effects of the surface finish of the test specimens (either ground or highly polished surfaces) on the thermal shock resistance were also studied. In both alumina and nanocomposite materials, specimens with ground surfaces showed a better resistance to thermal shocks than specimens with polished surfaces. However, the resistance of the nanocomposite material to single and repeated thermal shocks was no better than that of the pure alumina.