二元混合熔盐的制备及热物性研究

采用静态混合熔融法制备了多组LiNO_3-KNO_3不同比例的二元混合熔盐,通过X射线衍射仪(XRD)、TG/DSC同步热分析仪分别对其组成和热物性进行表征.实验结果表明,5∶5组混合熔盐的熔点最低,为129.6℃;4∶6组混合熔盐的相变潜热值最高,为170.2 J/g;6∶4组仍有部分过剩的LiNO_3不能参与共熔.     

用于外墙保温涂层的相变复合微骨料的制备及性能表征研究

将相变材料应用于轻质建筑围护结构外表面,可起到增大建筑热惰性的作用.以低温石蜡作为相变蓄热材料,采用真空吸附法与膨胀珍珠岩相结合,制备出石蜡-膨胀珍珠岩复合相变微骨料,再与环保涂料按照一定比例混合制成潜热蓄热型保温涂层.通过最佳配比量测试、SEM微观形态特征扫描、DSC相变热物性测试及红外波谱测试,对相变微骨料的相变过程、热物性及稳定性进行对比与分析.实验结果显示:1)相变复合微骨料的石蜡与膨胀珍珠岩最佳吸附比为1.9∶1;2)相变复合微骨料具有较高潜热蓄热性能;3)石蜡完全被膨胀珍珠岩吸附且没有空隙余留;4)相变复合微骨料具有很好的热物性和化学稳定性.因此,相变复合微骨料可作为一种热熔型保温基材与涂料混合构成新型外墙保温涂层.     

LiNO3KNO3二元混合硝酸盐热稳定性分析

热稳定性是衡量材料能否长期作为相变材料应用的一个十分重要的指标.由于相变材料在使用时会有长期周而复始的升温熔化和降温凝固的过程,因此对所制备的二元混合硝酸盐(LiNO_3∶KNO_3为4∶6)分别进行了循环热稳定性和高温热稳定性测试.试验结果表明,所制备的40%LiNO_3-60%KNO_3二元混合熔盐具有较好的热稳定性能,适合作为140℃左右的太阳能储热材料.     

膨胀石墨/石蜡复合相变蓄热材料的制备及性能研究

以石蜡作为相变蓄热材料的基本材料,利用膨胀石墨的高吸附性和高导热性提高相变材料的传热性能,制备出不同配比的中低温相变蓄热材料,利用DSC测试出各组复合相变蓄热材料的热物性参数.研究结果表明:膨胀石墨含量不宜过多,应该小于5％;添加的膨胀石墨对石蜡相变点和焓变的影响很小.     

膨胀石墨/石蜡复合相变蓄热材料的制备及性能研究

以石蜡作为相变蓄热材料的基本材料,利用膨胀石墨的高吸附性和高导热性提高相变材料的传热性能,制备出不同配比的中低温相变蓄热材料,利用DSC测试出各组复合相变蓄热材料的热物性参数.研究结果表明:膨胀石墨含量不宜过多,应该小于5%;添加的膨胀石墨对石蜡相变点和焓变的影响很小.     

石蜡@SnO_2-Al_2O_3微胶囊复合相变材料的合成及其热物性

通过原位化学沉积的方法制备了石蜡@SnO_2-Al_2O_3微胶囊复合相变材料,采用场发射扫描电子显微镜(SEM)、傅里叶红外光谱仪(FT-IR)以及X射线衍射仪(XRD)等方法测定分析了该复合相变材料的微观表面形貌、化学构成和晶体结构;采用差示扫描量热计(DSC)、热导率仪和热重分析仪(TGA)法测试分析了该复合材料的相变特性、热导率以及热稳定性等热物性。结果表明:原位化学沉积方法可成功制备石蜡@SnO_2-Al_2O_3微胶囊复合相变材料,且石蜡@SnO_2-Al_2O_3复合材料具有明显的核壳结构;石蜡@SnO_2-Al_2O_3微胶囊复合相变材料的相变潜热为85.14 J/g,该复合材料的热导率有明显提高,并在190℃以下表现出优异的热稳定性能。     

相变储能材料溶胶-凝胶复合法研究

提出一种采用溶胶-凝胶法对相变储能材料进行复合的制备方法.在模拟环境中,重点研究了制备工艺各因素如陈化时间、陈化温度、相变材料用量、分散剂用量和超声波分散时间等对复合相变材料的影响.研究表明:当相变材料加入量为14 g、陈化温度为80℃、陈化时间为4 min、分散剂用量为1.5 g和超声波分散时间为10 min时,制备出的储能复合相变材料具有极好的热性能,达到了储能效果.     

膨润土/月桂酸/鳞片石墨定型储热材料的制备及性能

采用天然膨润土和月桂酸分别作为支撑基体和相变材料,通过真空浸渍法合成复合相变储热材料。结果表明,添加鳞片石墨不仅提高复合相变储热材料的导热特性,而且阻止相变材料从复合相变材料中泄露。制备的复合相变储热材料经历200次热循环实验后,仍具有较好的可靠性,具备在热能存储系统中应用的较大潜力。     

PEG/PAM复合定形相变材料的制备与热性能

为了设计制备具有较高相变焓的复合定形相变材料,采用化学交联法制备半互穿网络型聚乙二醇/聚丙烯酰胺(PEG/PAM)复合定形相变材料,并通过分子动力学模拟计算其导热系数;采用DSC、TG、泄漏率测试和导热系数测试对复合材料的热性能、热稳定性、固-固定形效果和导热性能进行研究.结果表明:随着PAM含量升高,PEG/PAM复合材料的热焓值和泄漏率降低,热稳定性和导热率增加.其中,PEG质量分数为70%时,复合相变材料具有高的相变焓107 J/g、良好的热稳定性和优异的定形效果.通过模拟计算得出的导热系数值和实验值相一致,误差值都小于5%.本结论能对更复杂复合定形相变材料的导热系数进行预测和理论指导.     

碳纳米管填料对相变储能式热沉性能的影响

为了评估纳米复合相变材料在相变储能式热管理技术中的应用潜力,采用实验方法研究碳纳米管填料对相变储能式电子器件热沉瞬态性能的影响.选用十六醇为基底相变材料,以多壁碳纳米管为填料制备了不同质量分数（0.3%、1%和3%）的纳米复合相变材料,对复合相变材料的关键热物性进行表征.在短时较高热流密度（高达7.0 W/cm2）加热条件下,比较热沉（分为有翅片和无翅片2种结构）的瞬态性能随纳米复合相变材料中碳纳米管质量分数的变化规律.实验结果表明,在添加了碳纳米管填料之后热沉的性能较采用纯十六醇的工况有所削弱.虽然加入碳纳米管后纳米复合相变材料的导热系数有所提升,但黏度的急剧增加极大地削弱了熔化过程中的自然对流效应,从而抵消了导热强化所带来的性能提升.     

Preparation and characterization of CA-MA eutectic/silicon dioxide nanoscale composite phase change material from water glass via sol-gel method

This work mainly involved the preparation of a nano-scale form-stable phase change material(PCM) consisting of capric and myristic acid(CA-MA) binary eutectic acting as thermal absorbing material and nano silicon dioxide(nano-SiO_2) serving as the supporting material. Industrial water glass for preparation of the nano silicon dioxide matrix and CA-MA eutectic mixture were compounded by single-step sol-gel method with the silane coupling agent. The morphology, chemical characterization and form stability property of the composite PCM were investigated by transmission electron microscopy(TEM), scanning electron microscopy(SEM), Fourier-transform infrared(FT-IR) spectroscopy and polarizing microscopy(POM). It was indicated that the average diameter of the composite PCM particle ranged from 30-100 nm. The CA-MA eutectic was immobilized in the network pores constructed by the Si-O bonds so that the composite PCM was allowed no liquid leakage above the melting temperature of the CA-MA eutectic. Differential scanning calorimetry(DSC) and thermogravimetric analysis(TGA) measurement were conducted to investigate the thermal properties and stability of the composite PCM. From the measurement results, the mass fraction of the CA-MA eutectic in the composite PCM was about 40%. The phase change temperature and latent heat of the composite were determined to be 21.15 ℃ and 55.67 J/g, respectively. Meanwhile, thermal conductivity of the composite was measured to be 0.208 W·m~(-1)·K~(-1) by using the transient hot-wire method. The composite PCM was able to maintain the surrounding temperature close to its phase change temperature and behaved well in thermalregulated performance which was verified by the heat storage-release experiment. This kind of form-stable PCM was supposed to complete thermal insulation even temperature regulation by the dual effect of relatively low thermal conductivity and phase change thermal storage-release properties. So it can be formulated that the nanoscale CA-MA/SiO_2 composite PCM with the form-stable property, good thermal storage capacity and relatively low thermal conductivity can be applied for energy conservation as a kind of thermal functional material.     

Fabrication of Al<Subscript>2</Subscript>O<Subscript>3</Subscript>-NaCl composite heat storage materials by one-step synthesis method

Thermal energy storage is an attractive option for effectiveness since it gives flexibility and reduces energy consumption and costs. New composite materials for storage and transformation of heat of NaCl-Al₂O₃ composite materials were synthesized by one-step synthesis method. The chemical composition, morphology, structure, and thermal properties were investigated by XRD, EDS, SEM, and DSC. The results show that NaCl can be absorbed by Al₂O₃ particle from 800 to 900 °C for Al₂O₃ particle surface is rich active structure. The results also indicate that the leakage of NaCl when the phase change can be prevented by Al₂O₃ particles and the enthalpy of phase change of NaCl-Al₂O₃ material is 362 J/g. The composites have an excellent heat storage capacity. Therefore, this study contributes to one new thought and method to prepare high temperature heat storage material and this material can be applied in future thermal engineering.     

MXene/二氧化硅/六水氯化钙复合相变储热材料的制备及性能

六水氯化钙作为一类低温体储热材料, 在蓄热节能方面有着巨大的应用前景。单一的六水氯化钙相变储热材料存在导热系数低和熔化时易泄漏的缺点, 具有较大的内芯和互穿介孔孔道结构的介孔二氧化硅可以解决上述 问题。介孔二氧化硅具有低密度, 热膨胀系数小, 折射率低, 比表面积大等优点, 但其导热系数低, 需要与热性能良好的材料复合来增强导热能力。选用MXene 作为导热增强材料, 在其表面上生长介孔二氧化硅, 再把相变材料六水氯 化钙负载其中。通过综合热分析仪和红外热成像仪测定, 证明复合相变材料的储热性能、热稳定性和传热速率都有显著提升; 在烘箱中观察六水氯化钙的泄漏情况也明显被载体材料所抑制, 成功制备一种热性能和稳定性俱佳的复 合相变储热材料。     

相变微胶囊制备及其性能表征研究进展

相变微胶囊是将相变材料微胶囊化,以改善易泄漏、相分离问题,有效提高相变材料的热性能,是近年来储热领域的研究热点。首先,介绍了相变微胶囊芯材与壳材的选择;其次,从物理法、物理化学法和化学法3个方面分别介绍了相变微胶囊的常用制备方法,如喷雾干燥法、溶胶-凝胶法、复凝聚法、界面聚合法和微乳液聚合法;再次,分析了相变微胶囊的性能表征,包括物理性能(包埋率、粒径分布)、化学性能(傅里叶变换红外光谱分析、X射线衍射图谱分析)以及热性能(相变储热性能、相变性能、热稳定性);最后,对相变微胶囊的研究进行了总结并提出了展望。     

In-Situ Preparation and thermal shock resistance of mullite-cordierite heat tube material for solar thermal power

In order to improve the thermal shock resistance of solar thermal heat transfer tube material, the mullite-cordierite composite ceramic as solar thermal heat transfer tube material were fabricated by pressureless sintering using α-Al2O3 , Suzhou kaolin, talc, and feldspar as starting materials. The important parameter for solar thermal transfer tube such as water absorption (Wa ), bulk density (Db ), and the mechanical properties were investigated. The phase composition and microstructure of the composite ceramics were analyzed by XRD and SEM. The experimental results show that the B3 sintered at 1 300 ℃ and holding for 3 h has an optimum thermal shock resistance. The bending strength loss rate of B3 is only 2% at 1 100℃ by air quenching-strength test and the sample can endure 30 times thermal shock cycling, and the water absorption, the bulk density and the bending strength are 0.32%, 2.58 g·cm-3 , and 125.59 MPa respectively. The XRD analysis indicated that the phase compositions of the sample were mullite, cordierite, corundum, and spinel. The SEM images illustrate that the cordierite is prismatic grain and the mullite is nano rod, showing a good thermal shock resistance for composite ceramics as potential solar thermal power material.     

Molten salts/ceramic-foam matrix composites by melt infiltration method as energy storage material

A new type of high temperature energy storage material was obtained through the melt infiltration method, using compounding SiC ceramic foam as matrix and Na₂SO₄ as phase change material. The resulting composite material was measured by XRD, SEM, TG-DSC methods. The experimental results indicate that the composite is composed of silicon carbide, sodium sulfate and square quartz, and no chemical reactions occurs between Na₂SO₄ and SiC matrix. Na₂SO₄ has a good bonding with the SiC ceramic foam matrix. As the composite material is characterized by high thermal energy storage density and high thermal conductivity, it is suit for energy storage under high temperature. Funded by the “863” Hi-Tech Research and Development Program of China (2008AA05Z418)     

复合相变调湿材料的制备与热湿性能

制备一种兼具调热调湿功能的新型复合相变调湿材料（CMPCM）,该材料由相变微胶囊（MPCM）与多孔调湿材料合成。作为被动式节能材料,能够有效平抑室内温湿度波动和降低建筑能耗。其中,相变微胶囊由癸酸和十八烷酸的混合物为芯材、二氧化硅为壁材通过溶胶凝胶法合成,多孔调湿材料为硅藻土。通过扫描电子显微镜（SEM）、差示扫描量热法（DSC）、热重分析法（TGA）,正杯蒸发法和等温吸放湿法分析表征了复合相变调湿材料的组成结构、热性能、热稳定性以及传湿系数和湿缓冲值。DSC和TGA结果显示,复合相变调湿材料比普通相变材料有更小的过冷度和更好的热稳定性。传湿特性实验显示,该新材料比单纯的多孔调湿材料有更大的传湿系数和湿缓冲值。     

FHA bioceramic composite materials enhanced by ZrO2

Experiments for investigating the problem to improve the mechanical properties of FHA [Ca₁₀(PO₄)₆F(OH)] biomaterial have been presented in this paper. ZrO₂ micro-particle, as strengthening phase, is added into FHA matrix material to make a composite biomaterial. Various mechanical properties were tested. Distribution behaviour of ZrO₂ particle in sintered material and phase structure changes of material at elevated temperature were investigated by means of X-ray and SEM. Some biologic experiments were also carried out on animals to estimate the biological function of the composite material. Project supported by the National Natural Science Foundation of China Synopsis of the first author Ruan Jianmin, associate professor, born in 1957, specializing in powder metallurgy as well as bioceramic materials     

制备工艺对SA/ATTP复合储热材料结构和性能的影响

以硬脂酸为相变材料,以甘肃临泽工业级凹凸棒石为载体,采用热熔法和溶液浸渍法制备了2种硬脂酸/凹凸棒石复合相变储热材料,采用FTIR、XRD、DSC和SEM等手段进行了结构表征和性能测试。结构分析结果表明制备方法对材料的结构和形貌不会产生影响,2种材料具有相似的形貌和结构,SA分别以38.64%和29.13%的比例以物理作用吸附于ATTP表面。性能分析结果表明热熔法和浸渍法制备的复合储热材料其相变温度峰值分别为57.3℃和55.2℃,相变潜热分别为68.71J/g和51.79J/g,均具有较好的储热能力和化学稳定性,且储热能力和SA在ATTP表面的吸附率成正比,但热循环实验表明浸渍法制备的复合材料的热稳定性较差。结合储热性能、储热稳定性和化学稳定性的研究,证明熔融法更适合于制备建筑智能调温和建筑节能相变复合材料。     

PEG/活性炭相变材料改性沥青

利用PEG/活性炭复合固-固相变材料对沥青进行改性,制备出相变材料改性沥青。对不同配比的相变材料改性沥青进行老化、高低温交变等处理,观察其外观,并利用电子拉力试验机和热机械分析仪(TMA)测试改性沥青的延展性、软化点等性能。研究表明,当PEG/活性炭相变材料含量为20%时相变材料改性沥青的延展性最好,相变材料含量为15%~25%时,改性沥青的软化点明显提高。