陶瓷材料抗热震性研究进展

阐明了陶瓷材料抗热震性研究的重要意义，系统总结了脆性陶瓷抗震性的评价理论，热震断裂机制和设计制造高抗热震陶瓷材料的新近研究成果，并由此得出制作高抗热震陶瓷材料的工程技术途径。     

含h-BN复相陶瓷制备及性能研究进展

陶瓷材料密度低、抗腐蚀性及耐磨性良好,但是其硬而脆导致加工困难、抗热震性差。h-BN具有弹性模量低、硬度低的特点,其可加工性能和抗热震性能优异。将h-BN引入陶瓷基体制备含h-BN复相陶瓷,能够有效改善陶瓷材料的可加工性能和抗热震性。对含h-BN复相陶瓷的材料体系、制备工艺和性能的研究一直备受关注。本文以h-BN的引入方式为分类依据较全面地总结了含h-BN复相陶瓷的制备方法。本文对引入h-BN后所制备的含h-BN复相陶瓷的常规力学性能、抗热震性、可加工性、透波性、摩擦磨损等性能的影响进行了综述;对含h-BN复相陶瓷的制备及性能研究中存在的问题进行了概括,并对该材料体系的研究方向提出了建议。     

晶须增韧陶瓷复合材料

综述了晶须增韧陶瓷复合材料的制备方法和分类;讨论了影响增韧效果的各种因素及对陶瓷材料力学性能、抗热震性和耐磨性等方面的影响;并将近年来有关晶须增韧陶瓷基复合材料机理方面的研究进展,晶须在陶瓷材料中的应用及今后的发展趋势等作以介绍.     

BN对Sialon复相陶瓷性能的影响

本文分析讨论了不同ＢＮ含量对热压ＢＮ－Ｓｉａｌｏｎ复相陶瓷材料力学性能及热学性能的影响。结果表明，ＢＮ粉末的加入极大地提高了Ｓｉａｌｏｎ陶瓷的抗热震性，并使材料的高温强度有所提高。     

BN对Sialon复相陶瓷性能的影响

本文分析讨论了不同 BN 含量对热压 BN-Sialon 复相陶瓷材料力学性能及热学性能的影响。结果表明,BN 粉末的加入极大地提高了 Sialon 陶瓷的抗热震性,并使材料的高温强度有所提高。     

陶瓷圆球的抗热震参数

在陶瓷材料临界应力断裂理论的基础上，通过求解陶瓷圆球体第三类边界条件的瞬态温度场和瞬态热应力场，研究了陶瓷圆球的热冲击行为，建立了一个引起陶瓷圆球表面临界应力的临界温差表达式，并以此作为陶瓷圆球的抗热震参数。计算结果表明，陶瓷圆球体的临界温差大于相同Biot模数的无限大陶瓷平板的临界温差，但其表面达到临界热应力的无量纲时间远远小于无限大平板的数值。     

多孔ZTM陶瓷的制备与性能

高温性能稳定、抗热震性好的莫来石是一种重要的工程陶瓷材料.但是莫来石的室温强度较低,使其工程应用受到很大的限制.由于多孔莫来石的强度大大低于致密莫来石,因而对其研究较少.通过在氢氧化锆和氢氧化钇混合溶胶中加入莫来石制备了5%(体积分数)3Y-TZP/莫来石粉体,800℃煅烧后再添加5%～25%(质量分数)淀粉作为造孔剂,在1500～1600℃烧成后获得了强度高、抗热震性好的多孔ZTM陶瓷.     

高温气体过滤除尘材料的研究进展

高温介质过滤除尘技术的关键是高温过滤材料,本文主要介绍了金属多孔材料和陶瓷多孔材料以及新型过滤材料各自的特点和最新研究进展,其中金属陶瓷复合膜等新型多孔材料因克服了陶瓷材料密封性、抗热震性差以及金属材料制备困难、稳定性差等缺点,成为高温气体除尘材料研究者关注的焦点。     

基于高抗热震性能的陶瓷刀具材料的微观结构设计

本文以现有的抗热震断裂和抗热震损伤的评价理论为基础，通过对材料中微裂纹的长度进行预测，从而实现了对陶瓷刀具材料的抗热震性能的微观结构设计。根据此理论对现有材料的抗热震性能的进行预测，预测结果与实际的测量结果相符，验证了该理论的正确性。     

反应烧结Si／SiC复相陶瓷的的高温性能

研制的Ｓｉ／ＳｉＣ复相陶瓷强度达到３００～５００ＭＰａ，随温度升高，材料高温强度和韧性显著提高，１２００℃强韧性达最大值。高温性能研究表明，这种材料具有良好的抗热震性、抗熔盐腐蚀性能和抗氧化性。通过控制硅含量和合金化处理，能够大范围调探材料高温电导性能。研究结果表明，反应烧结Ｓｉ／ＳｉＣ复相陶瓷制备工艺简单，成本低，在１３５０℃以下性能优良，是一种应用领域广泛、适于大规模工业化生产的工程陶瓷材料。     

Thermal shock resistance of ultra-high temperature ceramics including the effects of thermal environment and external constraints

The thermal shock resistance of ceramics depends on the materials mechanical and thermal properties, also is affected by component geometry and external factors and so on. Therefore, the thermal shock resistance of ceramic materials is the comprehensive performance of their mechanical and thermal properties corresponding to the various heat conditions and external constraints. In the present work, a thermal shock resistance model of the ultra-high temperature ceramics which considered the effects of thermal environment and constraints was established. With this model, the influence of constraints on the thermal shock resistance and critical fracture temperature difference had been studied and an effective idea to improve thermal shock resistance for ceramic material and structure was found. Furthermore, the model was validated by finite element method.     

Thermal shock resistance analysis methodology of ceramic coating/metal substrate systems

The paper establishes a methodology for the study of thermal shock resistance behavior of ceramic coating/metal substrate systems, based on multiple cracking analysis. The stress criterion and the toughness criterion are used to predict the failure behavior of the system. Multi-scale analysis of the thermal shock resistance of the system is made and variations of the thermal shock resistance of the system with crack density are displayed for different values of coating to substrate thickness ratio. Some critical size parameters, which control the applicability of the stress-based criterion and the fracture mechanics-based criterion for the determination of the thermal shock resistance of the coating/substrate systems, are explored.     

Erhöhung der Thermoschockbeständigkeit von Sinterglas und Keramik über das Verbundwerkstoffkonzept

Increasing the Thermal Shock Resistance of Sintered Glass and Ceramics by the Composite Materials Concept The thermal shock resistance of brittle materials such as glass and ceramics is one of their weaknesses. Pores and above all incorporated second phases in these materials alter these properties which are decisive for thermal shock behavior, and may therefore increase this behavior in a precalculable manner. The present paper will first theoretically demonstrate when and why porosity leads to an improvement in thermal shock resistance. The thermal shock resistance for porous borosilicate sintered glass and porous eutectic calcium titanate ceramic are calculated and compared to experimental values. They confirm

• that low porosities lead to an improvement in thermal shock resistance
• that the thermal shock resistance has a maximum at a certain porosity and
• that above certain porosities the presence of pores deteriorates the thermal shock resistance.

If one considers porous materials as a special case of composite materials then relations valid for composite materials can be transferred to porous materials (“composite material concept”) and viceversa. This is investigated using the examples of borosilicate sintered glass with incorporated antimony particles and eutectic calcium titanate ceramic with incorporated paladium particles. In the case of the glass-antimony composite material, improvements in thermal shock resistance of about 15% with 10 vol% antimony incorporation were calculated and confirmed experimentally, while for calcium titanate-paladium composite materials a 15% improvement in thermal shock resistance was already achieved with about 5 vol% of the metallic phase.     

Microstructural aspects of Thermal Stress Resistance of high-strength engineering ceramics. Part I: Data of thermal stress resistance of high-strength engineering ceramics

Based on the criteria for the improvement of thermal shock resistance mainly two microstructural aspects of thermal stress resistance are discussed: First, the influence of microstructure on thermal shock resistance to fracture initiation, and second, the improvement of thermal shock resistance on the basis of microstructural considerations. In this connection, data of thermal stress resistance (thermal shock and thermal cycling) of various engineering ceramic materials are presented. Using laboratory grades with well-defined microstructures the interdependence between various microstructural variables and the mechanical and thermal properties, which control the thermal shock resistance, is discussed and the relation to thermal shock resistance is outlined by the example of the two materials, dense and porous reaction-bonded Si₃N₄. Moreover, the improvement of thermal shock resistance by microstructural optimization is demonstrated. Some examples of the improvement of thermal stress resistance by developing advanced composite materials are given. The paper is divided into three parts: Part I: Data of Thermal Stress Resistance of High-Strength Engineering Ceramics Part II: Influence of Microstructure on Thermal Shock Resistance of High-Strength Engineering Ceramics Part III: Improvement of Thermal Stress Resistance of High-Strength Engineering Ceramics.     

Theoretical and experimental considerations on the thermal shock resistance of sintered glasses and ceramics using modelled microstructure-property correlations

The thermal shock resistance of brittle materials such as glass and ceramics is one of their weaknesses. Pores and other incorporated second phases in these materials alter these properties which are decisive for thermal shock behaviour, and may therefore increase this behaviour in a precalculable manner. It has been theoretically demonstrated when and why porosity leads to an improvement in thermal shock resistance. The thermal shock resistance for porous borosilicate sintered glass and porous eutectic calcium titanate ceramic have been calculated and compared to experimental values. The results confirm that low porosities lead to an improvement in thermal shock resistance, that the thermal shock resistance has a maximum at a certain porosity, and that above certain porosities, the presence of pores deteriorates the thermal shock resistance. If porous materials are considered as a special case of composite materials, then relations valid for porous materials can be transferred to composite materials and vice versa (composite concept). This has been investigated using the examples of borosilicate sintered glass with incorporated antimony particles and eutectic calcium titanate ceramic with incorporated paladium particles. In the case of the glass-antimony composite material, improvements in thermal shock resistance of about 15% with 10 vol % antimony incorporation, were calculated and confirmed experimentally, while for calcium titanate-palladium composite materials, a 15% improvement in thermal shock resistance was already achieved with about 5 vol % metallic phase.Deceased.     

基于第一抗热震因子的BN纳米管/Si_3N_4复合材料抗热震性能评价

利用Kingery抗热震断裂理论构建了BN纳米管(BNNTs)强韧化陶瓷复合材料的第一抗热震因子模型,通过真空热压烧结法制备了四组BNNTs含量分别为0.5wt%、1.0wt%、1.5wt%和2.0wt%的BNNTs/Si_3N_4复合材料,并采用水浴淬冷法和三点弯曲法测试了复合材料的抗热震性能(震后弯曲强度和临界热震断裂温差)。测试结果验证了在急剧加热和急剧冷却条件下第一抗热震因子模型的正确性。结果表明:添加BNNTs使BNNTs/Si_3N_4复合材料第一抗热震因子增大,抗热震性能提升。分布在晶界上的BNNTs起到裂纹钉扎、桥联和裂纹偏转作用,增加了裂纹扩展的阻力;纳米管孔隙的存在改变了裂纹扩展路径,提高了BNNTs/Si_3N_4的断裂韧度,从而有效提高了其抗热震断裂能力。     

Investigation of the Thermal Shock Behavior of Ceramic Using a Combination of Experimental Testing and FE‐Simulation Methods

Thermal shock behavior of ceramics plays a decisive role in their broad industrial applications. For enhanced understanding of damage and failure mechanism under thermal shock loading, in the present work, a combination of experimental testing and numerical simulation methods has been used. The thermal shock behavior of the alumina (99.7%) disk samples has been investigated by using a plasma test stand: the bottom of the ceramic disks were locally heated in the center by plasma beam; during the heat treatment the temperature distribution at the top of the sample was recorded with a thermographic system. To characterize the thermal shock resistance, a thermomechanical simulation was subsequently carried out. It calculates the temperature and stress distribution within the ceramic disks. The calculated critical thermal tension stresses are reported, which led to the failure of the ceramic disks under thermal shock loading. The effect of the sample thickness on the temperature and stress distribution is presented. Compared with the experimental results the simulated results show excellent agreement. As conclusion, it is possible to determine the thermal shock behavior of ceramic materials by the combination of experimental testing and numerical simulation.