耐火材料力学—热物理性能的评述

本文简述了对耐火材料机械性能及热震稳定性的已有知识及有关研究的进展。讨论了耐火材料化学成份，相组成，微观及宏观组织对其弹性常数、力学强度、断裂及热震参数等物理化学性能的影响；探讨了耐火材料现有测试评价技术中的问题和未来研究的方向。     

用超声波探伤仪测定耐火材料的热震结构损伤

探讨了利用超声波探伤仪测定耐火材料热震结构损伤的可行性。结果表明：对于在试验温度范围内不发生物理化学变化的耐火材料，如镁尖晶石砖，用超声波探伤仪测定其热震结构损伤具有可行性；而对那些在试验温度范围内发生物理化学变化的耐火材料，如含钛酸铝制品，是不可行的。对于含碳的制品，应选择适宜的超声波频率，才能获得较好的试验效果。     

提高刚玉质耐火材料热震稳定性的研究

利用微气孔和弥散的ＺｒＯ２能改善耐火材料热震稳定性的特点，在含有一定数量微气孔的刚玉质耐火材料中，加入弥散的ＺｒＯ２，将ＺｒＯ２的增韧作用应用于刚玉质耐火材料热震稳定性的设计中。实验结果表明，当气孔的数量控制在１４％左右，ＺｒＯ２的外加量达６～９ｗｔ％时，能有效地改善刚玉质耐火材料的热震稳定性。在１１００℃，水冷的条件下，经１０次热震试验后，耐压强度保持不变，残余抗折强度为４５％。     

莫来石-堇青石耐火材料的热震性能

研究了作为快速烧成卫生陶瓷基质使用的堇青石一莫来石耐火材料板中热震损坏的特性。研究了由不同钙硅比为特点的两种不同耐火材料组成（称为REFO和CONC）。试样于1250℃进行水冷试验来诱导热震损坏。采用标准技术在室温时测定热与机械性能，然后计算抗热震参数R。在采用V形切口技术进行热震的前后测定了选择试样的断裂韧性。研究了在指定次数热震后评价小的热震差值这项技术的可靠性。在本项研究中证实了采用V形切口技术的测定值KIC的可靠性来说明热震损坏形成的特点。     

连铸用铝碳耐火材料的抗热震性

本文说明的是维苏威研究中心和库克森技术中心最近所做的工作。这些工作着重于进一步提高连铸用耐火材料的抗热震性。这里我们把它们分成三部分。重点是：１．进一步提高对铝／碳耐火材料热震断裂特性的认识；２．研究显微结构如何影响材料的性能；３．用有限元模型法预测材料在使用中应力产生的位置和有关数值。接着本文讨论了改进材料和提高构伯性能的意义。     

利用铝型材厂工业废渣制备莫来石质耐火材料

以铝厂污泥和苏州土合成的不同粒径级配的莫来石作为原料,添加少量堇青石作为结合剂,甲基纤维素、水作为添加剂研制优质莫来石耐火材料。通过测定耐火材料的抗折强度、热稳定性、气孔率等性能指标确定出最佳配方。结果表明：No.1配方的0次抗折强度为126.76 kgf/cm^2,1次热震抗折强度为81.07 kgf/cm^2,10次热震抗折强度为45.07 kgf/cm^2。1次热震强度保持率为49.24%,10次热震强度保持率为36.52%,10次热震后气孔率为40.37%,0次热震吸水率为24.76%,0次热震体积密度为1.61g/cm3。     

纤维增强铝硅质耐火材料的抗热震机理

在不同热震温差下,研究了高铝纤维对铝硅质耐火材料的强度和裂纹形成及扩展的影响。利用海氏理论和（Ｇｒｉｆｆｉｔｈ断裂力学理论,推导出临界热震温差与裂纹扩展之间的解析式．研究认为：引入数量和长径比适宜的纤维,可在基体内形成大量微裂纹,而微裂纹增韧则是纤维增强耐火材料抗热震的主要机理之一     

含碳耐火材料的抗热震性

由于抗热震性评估的综合过程所涉及的费用和时间，通常选用有良好导热性的含碳耐火材料。文中探讨了USIMINAS为确定浇注钢包用含碳耐火材料抗热震性所用的方法。所采用的检测方法涉及到根据裂纹开口位移和热震参数(R″″和Rst)测定断裂功。现已证实这种方法对选择和研究合适的显微结构借以延长耐火材料内衬寿命是有用的。     

钛酸铝对刚玉质耐火材料性能的影响

探讨了在刚玉质耐火材料的基质中引入TiO2 原位形成钛酸铝对其性能的影响。结果表明 :钛酸铝的形成可显著提高刚玉质耐火材料的热震稳定性及热态强度 ,从而有望生产出性能更加优良的刚玉质耐火材料。     

对普通,低水泥和超低水泥浇注料断裂和热震性能的评估

由于耐火材料浇注料广泛地应用于钢铁工业中,因此耐火材料系统的设计和材料的选择越来越需要技术数据的支持。对材料的机械断裂的热震性能的广泛研究,为材料在具体操作条件下的适用性提供了某些有价值的信息。在本篇中,通过损伤和无损伤试验,从其断裂和热震性能方面,对普通、低水泥和超低水泥浇注料作出了评价。     

Parameters of corundum spheres for packing high-temperature air heaters

Conclusions Parameters have been defined that need to be considered in choosing compositions and manufacturing techniques for spheres for packing high-temperature heaters. Tests have been made on the failure load, temperature for the start of deformation under load, creep strain under load, and strength reduction on thermal shock for these corundum spheres.The parameters have been determined for spheres with various compositions and made in various ways; they can be related to the porosity and crystal size.The creep varies from 0.6 to 5.2% at loads of 30 and 50 N in 10 h between 1300 and 1600°C. Shrinkage occurs on heating above the firing temperature, which attains 2.8% at 1950°C. The strength reduction after thermal shock is about 0.1%/°C.Defects also affect the deformability and strength.Translated from Ogneupory, No. 3, pp. 11–15, March, 1989.     

船舶蒸汽蓄热器放汽管路热冲击特性预测

船舶放汽管路具有放汽周期短、热冲击能量高、负荷波动大的特点,其运行特性直接影响蒸汽蓄热器的安全稳定工作。以典型船舶蒸汽蓄热器放汽管路为原型,采用标准k-ε模型计算湍流脉动过程,通过数值模拟的方法计算了船舶蒸汽蓄热器放汽管路的水动力特性,获得流速、压力、湍动能及壁面剪切应力等参数的分布规律,基于流致振动而诱发流体热冲击的机理,揭示了与流致振动密切相关的热冲击能量图谱。计算结果显示,在高温高压饱和蒸汽掺混流动过程中,三通管区域呈现蒸汽冲击流速高,湍流脉动剧烈,壁面剪切应力大的特点;基于蒸汽热冲击能量分布图谱,放汽管路上弯管和三通管件局部区域蒸汽热冲击能量较大,其中三通管热冲击能量最大,可以预测三通管件承受的热冲击破损最严重,实物检测破损数据验证了数值预测结果。     

The Thermal Shock Resistance Analysis of Ceramic Foams

This article studies the thermal shock resistance behavior of ceramic foams under sudden thermal load induced by a sudden temperature variation. Two types of thermal shock loading conditions are considered: cold shock and hot shock. Variations of the stress and stress intensity factor with thermal shock time, location, crack size, medium thickness, and relative density of the ceramic foam are given. Crack growth behavior is studied and crack growth velocity is explained from energy equilibrium consideration. The thermal shock resistances of ceramic foams are established from the view points of energy criterion and fracture mechanics concept.     

Design of Composite Ladle Shroud for Improving Thermal Shock Resistance

A ladle shroud is one of the functional refractories for continuous casting,which undergoes severe thermal shock by molten steel when used without pre-heating.The composite ladle shroud with an insulating liner presents excellent thermal shock resistance.Finite element simulation is an effective method to explore the maximum thermal stress for predicting the thermal shock resistance of ladle shrouds.In this paper,the influence of the lining materials and the structure of ladle shrouds on the thermal stress distribution is systematically researched.The working mechanism of the lining material on the body material is also presented.Lining materials with low thermal expansion,elastic modulus and thermal conductivity are helpful to improve the thermal shock resistance and an optimum lining thickness is suggested.The lining material can both serve as thermal resistance for the body material to buffer the thermal stress,and apply a strain load to the body material by the thermal strain to increase the stress.     

等离子喷涂工艺参数对B4C涂层性能的影响

本文研究了喷涂距离对大气等离子喷涂Ｂ４Ｃ涂层的沉积效率、气孔率、显微硬度和抗热震性能的影响,发现喷涂距离会严重影响Ｂ４Ｃ粉末在等离子体射流中的熔融状态,从而对这些性能产生显著影响。实验结果表明,通过优化工艺参数,尤其是选择适当的喷涂距离,可以在大气呀涂条件下制得同高压等离子喷涂相近所孔率和显微硬度的Ｂ４Ｃ涂层。     

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。     

The thermal shock behaviour of ductile particle toughened alumina composites

Over recent years, it has been established that the incorporation of metallic particles into a ceramic matrix can lead to enhanced fracture properties. Relatively few attempts, however, have been made to establish whether or not the improved fracture toughness typically observed in such composite systems can offer improved performance in demanding environments. The current study is concerned with the thermal shock behaviour of a ceramic matrix composite consisting of an alumina matrix containing 20 vol% of discrete iron particles. The composite material has been produced by both hot pressing and conventional sintering techniques. The hot pressed composite shows a greater resistance to thermal shock than the monolithic matrix, both in terms of the critical temperature differential and retained strength, whereas the sintered material has been found to behave as a typical low strength refractory ceramic. The calculation of thermal shock resistance parameters for the composites and the monolith has indicated possible explanations for the differences in thermal shock behaviour.     

Thermal shock behavior of nano-sized ZrN particulate reinforced AlON composites

Aluminum oxynitride (AlON) has been considered as a potential ceramic material for high-performance structural and advanced refractory applications owing to its excellent stability and mechanical properties such as high rigidity and good chemical stability. Thermal shock resistance is a major concern and an important performance index of refractories and high-temperature ceramics. While zirconium nitride (ZrN) particles have been proven to improve mechanical properties of AlON ceramic, the thermal shock behavior has not been evaluated yet. The aim of this investigation was to identify the thermal shock resistance and underlying mechanisms of hot-pressed 2.7% ZrN–AlON composites by a water-quenching technique over a temperature range between 225 °C and 275 °C. The residual strength and Young's modulus after thermal shock decreased with increasing temperature range and thermal shock times due to large temperature gradients and thermal stresses caused by abrupt water-quenching. The presence of nano-sized ZrN particles exhibited a positive effect on the improvement of both residual strength and critical temperature difference of AlON ceramic due to the toughening effects, the higher thermal conductivity of ZrN, the refined grain size and the reduction of porosity. Different toughening mechanisms including crack deflection, crack bridging and crack branching were observed during thermal shock experiments, thus effectively enhancing the crack initiation and propagation resistance and leading to a considerable improvement in thermal shock resistance in the ZrN–AlON composites.     

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.