彩涂胶辊用聚氨酯弹性体的研制

合成了一种彩涂胶辊用聚氨酯弹性体材料,考察了聚酯多元醇、异氰酸酯、扩链剂、催化剂、操作工艺等因素对材料性能的影响。所制聚氨酯弹性体具有较高的力学性能、良好的耐溶剂性能、较好的切削加工性和较长的使用寿命。     

推进剂药粒干燥过程的安全性分析

分析了推进剂药粒在干燥过程中发生热分解、燃烧或热爆炸的起因。通过比较几种典型干燥方法,了解其干燥过程的优缺点。根据推进剂干燥过程中所发生的物理化学变化,讨论了干燥过程中硝化甘油蒸发及推进剂热分解、燃烧或热爆炸的机理。通过烘箱法模拟热分解,找到了发生热分解、燃烧或热爆炸的时间和温度点。最后分析了推进剂药粒在干燥过程中的危险性。     

绝缘导热高分子复合材料研究

介绍了导热绝缘高分子复合材料的导热性能、导热机理,综述了各类导热绝缘高分子如复合型导热塑料、橡胶、胶粘剂、涂层等的研究,并展望了其应用前景及未来发展方向.     

聚醚的热降解研究进展

介绍了无氧条件下和有氧条件下聚醚的热降解产物,综述了无氧条件下和有氧条件下聚醚结构中聚氧乙烯链节和聚氧丙烯链节的热降解机理和热降解反应路径、影响聚醚热稳定性能的主要因素及聚醚的热降解反应动力学。     

烃类水合物导热特性的分子动力学模拟

采用分子动力学模拟方法Green-Kubo理论计算了263.15 K、3 MPa,sⅠ乙烷水合物、乙烯水合物的导热,给出密度和热导率值。从主客体分子和晶体结构（致密性、规整程度）对导热的影响等角度研究了烃类水合物（甲烷水合物、乙烷水合物、乙烯水合物）导热的特性。结果显示化学性质相似、分子量相差不大的烃类形成的水合物,其导热具有相似的温度压力依赖关系和晶体结构相关关系。对于sⅠ型水合物,水分子对水合物导热的影响远远超过客体分子对导热的影响。水合物的分子量越大,水合物密度越大,热导率越大。水合物晶体越致密、晶格越规整,热导率越大。     

Research advances in residual thermal stress of ceramic/metal brazes

Brazing, as a common method of bonding ceramic and metal, has been applied in microelectronics, aerospace, machinery and other domains extensively. The residual thermal stress in the brazed joint has direct effects on the mechanical properties of the joint, so how to control the generation of residual thermal stress has become the vital point. In this paper, the methods of reducing residual thermal stress in the brazing process in recent years are reviewed. The generation and effects of residual thermal stress in the brazed joint are introduced. Besides, the methods of detecting residual thermal stress are discussed, and different methods of reducing residual thermal stress in brazed joints are also analyzed. Finally, the future development directions of reducing residual thermal stress in the brazed joint are proposed.     

Analysis of Thermal Stress Resistance of Partially Absorbing Ceramic Plate Subjected to Asymmetric Radiation, I: Convective Cooling at Rear Surface

An analysis is presented of the thermal stresses in a partially absorbing brittle ceramic flat plate asymmetrically heated by radiation on the front surface and cooled by convection on the rear surface with a heat transfer coefficient, h , being finite or zero. For finite A, the transient thermal stresses are a function of h , whereas the steady-state thermal stresses are independent of h . The maximum value of tensile thermal stresses occurs at an optical thickness μ a = 2 and equals zero for μ a = 0 or ∞. For an optical thickness μ a <10.7, the steady-state thermal stresses exceed the transient stresses, with the converse being true for μ10.7. The maximum tensile thermal stresses occur in the front surface where the temperatures are highest. For h =0, the tensile thermal stresses increase with increasing value of optical thickness. The role of the material properties which control the thermal stress resistance under conditions of combined radiation heating and convection cooling are discussed. Appropriate thermal stress resistance parameters are proposed.     

Thermal and rheological properties of poly(phenylene sulfide) and poly(ether etherketone) resins and composites

Poly(phenylene sulfide) (PPS) and poly(ether etherketone) (PEEK) are high performance engineering thermoplastics with a unique combination of excellent environmental, mechanical, and thermal properties. Research on the thermal and rheological properties of PPS and PEEK resins and carbon fiber reinforced prepregs are described. Experimental studies of the dynamic viscoelasticity and thermal properties of these materials are summarized. The effects of processing cycles and environment on the thermal and rheological properties are discussed. The effects of the processing environment and the addition of carbon fiber on the thermal stability are reported. Crosslinking of poly(phenylene sulfide) in air, enhancing thermal stability, is also investigated.     

聚丙烯管材专用料热稳定性研究

采用热重分析仪(TG)分析了国内外几种典型的聚丙烯管材专用料的热降解稳定性,并对这几种聚丙烯管材专用料的热降解动力学进行了研究,发现这些专用料的热稳定性存在显著差异.通过对6种专用料的热降解动力学机理验证发现,聚合法生产的聚丙烯专用料的热降解机理比较相似,改性PPHB的热降解机理则较为复杂.     

热分析在煤燃烧和热解及气化动力学研究中的应用

论述了煤的燃烧、热解、气化反应动力学的常用的单一升温速率法、多重扫描速率法、动力学补偿效应以及分布活化能动力学模型等热分析研究方法，分析了现用热分析动力学方法的局限性；并对反应控制热分析、微热分析技术、微波热分析以及热分析技术与其他分析技术的联用，热分析技术间的联用等热分析新技术在煤的燃烧、热解、气化反应动力学研究上的应用进行了展望．     

Thermal properties of silicate esters

Fourteen dimethyldialkoxysilanes are prepared by reacting dimethyldichlorosilane with corresponding alcohols in the liquid phase. Their physicochemical properties are determined by standard methods and their tentative empirical formulae are elucidated. The thermal conductivity values of dimethyldialkoxysilanes are determined using a two slab guarded hot plate apparatus over a temperature range of 30–190°C. The thermal conductivity values of dimethyldialkoxysilanes calculated from empirical equations are found to vary from -14% to +19%. Because thermal conductivity is an important parameter in heat transfer calculations, and to minimise the deviation of the values, new equations involving easily measurable ultrasonic parameters have been formulated. The proposed equations have been tested for the series of dimethyldialkoxysilanes, tetraalkoxysilanes and polydimethylsiloxanes. The thermal conductivity values computed from the proposed equations are comparable with experimental thermal conductivity values. Further, an equation involving the calculation of thermal conductivity values at varying temperatures is also proposed.     

Factors Affecting Thermal Stress Resistance of Ceramic Materials

The sources and calculation of thermal stresses are considered, together with the factors involved in thermal stress resistance factors. Properties affecting thermal stress resistance of ceramics are reviewed, and testing methods are considered.     

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.     

Thermal shock resistance of porous ceramic foams with temperature-dependent material properties

The impact of temperature dependence of material properties on thermal shock resistance of porous ceramic foams is studied in this paper. Two cases of thermal shock are carried out: sudden heating and sudden cooling. Finite difference method and weight function method are employed to get the thermal stress field at crack tip. The effects of time dependence and temperature dependence of material properties on thermal shock behavior are analyzed. The thermal shock resistance is acquired based on two different criteria: fracture mechanics criterion and stress criterion. By comparison analysis, results show that taking temperature dependence of the material properties into account is crucial in the assessment of thermal shock resistance of ceramic foams. Cold shock fracture experiments of Al₂O₃ foams with different relative densities are also made, and the obtained results are in coincidence with theoretical results very well.     

平板状SOFC结构热应力特性分析

本文对平板状固体氧化物燃料电池的热应力进行了分析,并对其结构建立了三维有限元计算模型,探讨了工作温度、电极厚度和电解质厚度、以及各层间的热膨胀系数差异对热应力的影响。仿真结果表明,热应力的最大值出现在电极与电解质界面处;降低电池工作温度有利于电极和电解质热应力的降低:热应力的大小和分布与电极材料的热膨胀系数、电极厚度和电解质厚度密切相关。     

Development of Advanced Low Conductivity Thermal Barrier Coatings

Advanced multi-component, low-conductivity oxide thermal barrier coatings have been developed using an approach that emphasizes real-time monitoring of thermal conductivity under conditions that are engine-like in terms of temperatures and heat fluxes. This is in contrast to the traditional approach where coatings are initially optimized in terms of furnace and burner rig durability with subsequent measurement in the as-processed or furnace-sintered condition. The present work establishes a laser high-heat-flux test as the basis for evaluating advanced plasma-sprayed and electron beam-physical vapor deposited (EBPVD) thermal barrier coatings under the NASA Ultra-Efficient Engine Technology (UEET) Program. The candidate coating materials for this program are novel thermal barrier coatings that are found to have significantly reduced thermal conductivities and improved thermal stability due to an oxide defect-cluster design. Critical issues for designing advanced low-conductivity coatings with improved coating durability are also discussed.     

双热流计法测定聚氨酯保温材料的导热系数

简要介绍了几种测定固体材料导热系数的方法,重点讨论了稳态双热流计法测定聚氨酯保温材料导热系数的方法原理、导热仪的结构、影响测试结果的因素,并对提高检测结果的准确性、减少误差提出了建议。     

Chances of Thermal Properties of Fruits and Vegetables During Drying

An increase in moisture content in fresh fruit and vegetables results in an increase of heat capacity, thermal conductivity and thermal diffusivity. Variations of thermal properties with moisture content are linear provided the changes in moisture content are small. The way water is bounded in dried fruits and vegetables influences their thermal properties.     

Modeling of Thermal Stresses in Joining Two Layers with Multi- and Graded Interlayers

The technique of introducing interlayers has been used extensively to mitigate residual thermal stresses in joining dissimilar materials. Finite-element analyses have often been used to quantify thermal stresses in these layered structures in case-by-case studies. Recently, simple analytical models containing only three unknowns have been developed to derive closed-form solutions for elastic thermal stresses in both multilayer systems and two layers joined by a graded junction. The analytical solutions are exact for locations away from the free edges of the system. Application of these solutions is shown here to provide a systematic study of thermal stresses in Si₃N₄ and Al₂O₃ layers joined by various sialon polytypoid-based multi- and graded interlayers. The effects of the thickness, stiffness, and coefficient of thermal expansion of the interlayer on thermal stresses in the system are examined. The differences in thermal stresses resulting from multi- and graded interlayers are shown.     

红外热反射涂层的研究进展

综述了红外热反射涂料的研究进展,分别介绍了喷涂红外热反射涂层及溶胶凝胶红外热反射涂层的特点及应用。重点阐述了纳米TiO2–SiO2复合红外热反射涂层对纤维隔热材料的改进。