导热硅橡胶的老化性能研究

热老化是影响导热硅橡胶使用寿命的主要因素之一。该文分别采用氧化铝、氮化硼和石墨烯作为导热填料制备导热硅橡胶,研究其热老化性能。通过研究不同导热系数的导热硅橡胶复合材料热氧老化过程中交联密度和导热系数的变化,提出了不同导热系数的样品在热氧老化过程中导热系数变化的机理。     

组成对尾矿多孔玻璃陶瓷物理性能的影响研究

本文以铁尾矿为主要原料,石灰石、白云石、纯碱、砂岩以及分析纯Al2O3为校正原料,CaF2为助熔剂,NaHCO3为发泡剂,采用粉末烧结法制备了多孔玻璃陶瓷,通过L9(34)正交实验设计,研究了基础玻璃中主要氧化物SiO2、CaO、MgO、Al2O3的含量变化对多孔玻璃陶瓷表观密度、孔隙率、导热系数等物理性能及主晶相组成的影响.研究结果表明:随着SiO2含量的增加,Al2O3含量的减少,多孔玻璃陶瓷的表观密度降低,闭口孔隙率增大,导热系数减小;CaO与MgO含量的变化对表观密度无明显影响;随着CaO与MgO含量的增加,孔隙率先增大后减小;多孔玻璃陶瓷主晶相均为透辉石,在研究的成分范围内,四种主要氧化物含量的变化对主晶相无影响,但随着CaO/MgO的增加,多孔玻璃陶瓷衍射峰逐渐增强,晶相随之增多.     

煤矸石制备多孔复相陶瓷材料及导热系数研究

利用煤矸石作为主要原料,以有机物交联丙烯酸树脂(AMR)作为造孔剂,合成多孔复相陶瓷,用作保温材料.通过对材料性能测试表明,随着造孔剂含量的增加,材料的体积密度下降、气孔率增加、导热系数和抗压强度也降低.添加10％～ 40％ AMR造孔剂后合成的多孔陶瓷性能符合高效能外墙外保温材料标准.通过对合成样品导热系数和气孔率关系的研究,表明两相材料导热系数模型中的有效介质理论公式可以应用于多孔复相陶瓷中.     

热处理对AlN陶瓷的热导率及介电性能的影响

采用放电等离子烧结技术制备Al N陶瓷,并利用真空无压烧结方法进行热处理。研究了不同烧结助剂在高温热处理过程中对Al N陶瓷的物相组成、显微结构、导热性能及介电性能的影响。结果表明,Al N陶瓷经过热处理后,Al N晶粒进一步发育长大,尽可能实现面接触,材料中的晶间相分布更加合理。与只引入单一稀土氧化物为烧结助剂的Al N陶瓷相比,引入复合烧结助剂稀土氧化物及氟化钙(Ca F2)的Al N陶瓷经过热处理后,在有效除氧及生成具有挥发性晶间相双重效果作用下,材料热导率及介电损耗改善效果明显。     

五种保温材料的耐久性性能试验研究

为研究外墙外保温材料的耐久性能,对聚氨酯泡沫,硅酸铝陶瓷,铝箔玻璃棉,橡塑保温板和挤塑聚苯板进行抗冻性、耐老化、抗压强度和抗拉强度测试.根据测试结果得出:20次冻融循环后,聚氨酯泡沫的导热系数增长81.25％,硅酸铝陶瓷的导热系数增长57.78％,铝箔玻璃棉的导热系数增长28.95％,橡塑保温板的导热系数增长34.48...     

改善石蜡相变材料导热性能的研究进展

近年来石蜡作为一种相变储能材料受到越来越多的关注,由于石蜡PCM本身的导热系数偏低,导致储能系统在吸热或放热过程中的有效热率极低,热量无法快速有效地进行存储和释放。因此,提高石蜡PCM的导热系数成为了近年来的研究重点。主要从翅片结构、组合相变材料、复合相变材料、相变材料微胶囊化这几个方面总结了在改善石蜡PCM导热性能方面的国内外研究状况。     

以二水石膏为发泡剂制备多孔陶瓷及其性能研究

以二氧化硅、氧化铝分析纯为主要原料,二水石膏为发泡剂制备多孔陶瓷,研究发泡剂的用量和烧成温度对多孔陶瓷导热系数、质量吸水率、抗压强度的影响。研究结果表明：随着发泡剂用量和烧成温度的提高,多孔陶瓷的吸水率增大,抗压强度下降。当烧成温度1260℃,二水石膏用量6%时,制备的多孔陶瓷晶相主要为石英和镁橄榄石,吸水率6.83%、导热系数0.315 W/(m·K)、抗压强度13.68 MPa,具有良好的综合性能。     

高导热陶瓷材料的研究现状与前景分析

高导热率陶瓷材料因其具备陶瓷的优异性能与高导热率特性而具有重要的研究意义。笔者主要介绍了导热系数概念、陶瓷材料高导热率规律、高导热陶瓷材料分类、高导热陶瓷应用以及热导率的测试方法、机理、影响因素及提高方法,并对高导热陶瓷材料研究现状与专利情况进行了评述,同时分析了高导热陶瓷材料的发展前景。     

高性能陶瓷隔热材料的研制

通过溶胶一凝胶法制备了中空石英纤维增强石英基体的多孔陶瓷隔热材料,进行了力学和热物理性能测试,结果表明：材料密度0．95g／cm^3,常温下的导热系数0．135W／m·K,材料具有质量轻、强度高、隔热性能好及耐高温（1200℃）的特点。     

微/纳米锂锌铁氧体-锌铁氧体空心复相陶瓷微珠的低温自反应淬熄法制备及其电磁损耗性

以Li(NO3)-Zn(NO3)2-Fe(NO3)3-CO(NH2)2-酚醛树脂-KH550为反应配系,采用低温自反应淬熄法,制备了微/纳米锂锌铁氧体-锌铁氧体空心复相陶瓷微珠。通过扫描电子显微镜、X射线衍射、透射电子显微镜、综合热分析、高速摄影技术与矢量网络分析仪分别测定了空心复相陶瓷微珠的本征参数与电磁参数,并研究了其形成机理。结果表明:制备的空心复相陶瓷微珠粒径处于几十纳米至5μm之间,成分由尖晶石型的ZnFe2O4和Fe3O4、四方或立方晶系的Fe2O3、菱面体LiFeO2与立方晶系的Li0.5ZnFe2O45种物相组成,表面形貌呈现出纳米等轴晶、多种形貌的纳米析出晶与非晶形态,其中多种形貌的纳米析出晶与非晶组成共晶结构。制备的空心复相陶瓷微珠在低频段具有良好的磁损耗性。"自身细化"、"自身爆裂"、"碰撞"与"边缘效应"是微/纳米锂锌铁氧体-锌铁氧体空心复相陶瓷微珠形成的主要机理。宽的尺寸分布、表面组织结构多样化以及多种成分构成的复相结构是具有良好的电磁损耗性的原因。     

陶瓷纤维技术前沿探秘

陶瓷纤维是一种集传统绝热材料、耐火材料优良性能于一体的纤维状轻质耐火材料,陶瓷纤维具有重量轻、耐高温、热稳定性好、导热率低、比热小及耐机械震动等优点,因而其产品涉及各领域,发展前景十分看好。本文分别介绍了陶瓷纤维的种类及性能特点,陶瓷纤维的结构性质和制造方法;陶瓷纤维的主要用途和应用范围;以及陶瓷纤维在热工窑炉中的应用技术;同时指出了陶瓷纤维的发展趋势。     

粉煤灰基轻质多孔陶瓷的制备及性能研究

采用XRF、XRD、SEM等测试手段,研究了山西朔州粉煤灰的物理性能、化学成份、显微结构与组成.以粉煤灰为原料,采用正交实验,研究了粉煤灰、陶瓷抛光废渣、废熔块、烧滑石等含量对轻质多孔陶瓷性能的影响.研究表明:SiC含量对粉煤灰基轻质多孔陶瓷性能影响最大,熔剂废熔块含量次之.确定了最优配方,制得密度0.51 g/cm3,导热系数0.082 W/(m·K)的轻质发泡陶瓷.     

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.     

Transparent YAG:Ce ceramic with designed low light scattering for high-power blue LED and LD applications

Yellow-emitting YAG:Ce transparent ceramic is recognized as an ideal color converter in high-power blue LEDs and LDs, but the absence of scattering centers in its microstructure leads to a low light extraction efficiency and poor light uniformity. Here, taking advantage of the scattering effect and the transparency of YAG:Ce ceramics, Ce-free YAG phase was used as a second component to form a composite with YAG:Ce phosphor. The sintered YAG:Ce-YAG ceramic possessed a high transparency of ～63 % and a thermal conductivity of 8.9 Wm^?1 K^?1. Due to its beneficial thermal properties and high external quantum efficiency of 70.2 %, the YAG:Ce-YAG ceramic could be excited under a high blue-laser flux density of up to 9.60 W/mm² and showed a luminous emittance of 1220 lm/mm². Due to light scattering arising from the slightly different refractive indices of the two phases, the designed YAG:Ce-YAG ceramic showed better lighting effects than a single-phase transparent YAG:Ce ceramic.     

Microstructures and nanostructures,elastic properties,and heat resistance of ceramics with a protective coating based on niobium pentoxide exposed to a concentrated light flux

The effect of exposure to a concentrated light flux on the structure, elastic properties, and thermal expansion of ceramic niobium pentoxide has been investigated. The heat resistance of the products obtained from layered ceramics with coatings based on niobium pentoxide has been estimated.     

车用陶瓷新材料成为节能减排新亮点

随着科学技术的不断发展,汽车的研发及生产阶段越来越多地采用新材料及新工艺,这也使得人们对汽车轻质化、低成本、智能化、经济性和可靠性的要求成为可能。特种陶瓷具有各种优异、独特的性能,应用在汽车上,对减轻车辆自身质量、提高发动机热效率、降低油耗、减少排气污染、提高易损件寿命、完善汽车智能性功能都具有积极意义。车用陶瓷已引起工程领域材料科学的关注,根据碳化硅等特种陶瓷的结构性能及种类,分别介绍了陶瓷发动机、热敏陶瓷传感器、车用催化净化器的陶瓷载体、尾气净化蜂窝陶瓷材料载体、柴油车排气净化陶瓷蜂窝过滤器和陶瓷汽车制动器刹车片,以及车用陶瓷轴承等实例,充分反映了车用陶瓷新材料的研究和开发其应用前景广阔。     

Dy3+-doped Y3Al5O12 transparent ceramic for high efficiency ultraviolet excited single-phase white-emitting phosphor

A kind of Dy-doped yttrium aluminum garnet (YAG) transparent ceramic for ultraviolet excited single-phase white light-emitting phosphor was investigated, which has high-quantum efficiency (45%). The temperature field of Dy:YAG transparent ceramic was calculated by steady-state thermal simulation. Moreover, by combining with 365 nm light-emitting diodes (LED) chip directly, the Commission Internationale de l’Éclairage coordinate (x = 0.33, y = 0.35) is close to the standard equal energy white light illumination. The Dy:YAG transparent ceramic, possessing of good optical and thermal properties, is promising for applications in high-power LEDs devices.     

新型陶瓷基片材料的研制

本文用煅烧云南高岭土与碳酸钙,在加入合适的添加剂在合理的烧成制度条件下,用一步法制备出优异的新型钙长石质陶瓷基片;在满足使用强度的条件下与常用的氧化铝质陶瓷基片相比,钙长石质陶瓷基片的介电常数小,电绝缘性能好;热膨胀系数与集成电器 的硅元件的热膨胀系数相差小,体积密度轻,对减轻电器设备的质量有利;烧成温度比较低,原料价格低,有很好的经济效益。     

Low-Thermal-Expansion Polycrystalline Zirconyl Phosphate Ceramic: Solid-Solution and Microcracking-Related Properties

The effects of the addition of Ta205 or Nb205 on the sintering and refractory properties of 2ZrO₂·P₂O₅-based ceramics have been investigated. The solid solution with Nb₂O₅ has a lower average thermal expansion coefficient than the pure phase. The strength of the polycrystalline ceramic is reduced when the grain size exceeds the transition grain size for microcracking. The thermal expansion of the ceramic is abruptly lowered when the grain size exceeds a value which should be termed the "second transition grain size" for additional wider microcracking. SiO₂ was found most effective for inhibiting grain growth to prevent microcracking and for obtaining a strong ceramic.     

SOME FACTORS INFLUENCING THE THERMAL PROPERTIES OF MINERALS AND PRODUCTS OF THE CERAMIC INDUSTRY1

A survey is given of a number of factors which exert an influence upon the following thermal properties of several minerals and ceramic bodies: specific heat, thermal reaction, thermal conductivity, thermal expansion, thermal radiation, etc. The influences in the Case of fired and unfired substances are differentiated. A bibliography is presented, which summarizes the work of recent years bearing on the thermal properties of minerals and ceramic bodies.