共查询到20条相似文献,搜索用时 109 毫秒
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对隔热材料的分类、国内外柔性隔热材料的研究现状及存在的问题进行了概括性的论述,说明了多层柔性隔热材料的设计原理及材料筛选对隔热效果的影响,从而指出SiO2气凝胶是目前固体中最好的隔热材料,高真空多层绝热是当前绝热性最好的一种绝热方式,亦称为"超级绝热",其导热系数比空气的导热系数还要低2个数量级.最后指出了理想轻薄柔性隔热材料的结构与组成. 相似文献
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气凝胶是一种以气体代替凝胶中液体组分的合成多孔材料,具有优良的物理和化学特性,如半透明结构、低密度、低导热系数等。因此,被广泛应用于航空航天、汽车、电子设备、服装等领域,同时也被认为是建筑领域最有发展前景的高性能隔热材料。尽管目前气凝胶隔热材料的成本仍高于传统的隔热材料,但科学家们正在努力降低其制造成本,使其在世界范围内得到广泛应用。主要综述了气凝胶隔热材料用于建筑行业的研究进展,包括介绍了气凝胶隔热材料的隔热机理、制备方法、特性和改性以及在建筑行业的应用,并对气凝胶隔热材料进行了展望。 相似文献
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高效隔热材料掺TiO2及玻璃纤维硅石气凝胶的研制 总被引:11,自引:0,他引:11
研究了掺TiO2粉末物玻璃纤维的硅石气凝胶的热导率与气压,温度的关系,结果表明,这种掺杂的硅石气凝胶在高温下具有比普通隔热材料低得多的导热系数,因此用来作为高效高温隔热材料将颇具前景。 相似文献
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耐高温气凝胶隔热材料的研究进展 总被引:3,自引:0,他引:3
气凝胶极高的孔隙率有效降低了材料的固相热传导,孔径主要分布在介孔范围内(2~50nm),有效抑制了气相传热,而遮光剂的引入可起到很好的反射、吸收和再散射作用,进一步降低气凝胶的辐射热传导,从而使得气凝胶材料具备极低的热导率,是一种优质的高效隔热材料。根据组分的不同,气凝胶主要可分为氧化物气凝胶、炭气凝胶和碳化物气凝胶。氧化物气凝胶材料在高温区(1000℃)容易发生晶型转变及颗粒的烧结,其耐温性相对较差,但是其在中高温区(1000℃)具备较低的热导率。炭气凝胶材料在真空或惰性氛围下耐温性最高可达3000℃,2000℃下热导率低至0.601W·m-1·K-1,密度可调,但是该材料在有氧氛围下容易发生烧蚀,这需要通过涂覆某些抗氧化性涂层来加以有效解决。碳化物气凝胶材料目前研究较为匮乏,报道最多的是碳化硅气凝胶,但是也仅限于对该材料的制备与表征,而对于其热学性能方面的研究仍然较少。主要介绍了这三大类耐高温气凝胶隔热材料的研究进展,并对其未来的发展方向进行了展望。 相似文献
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Qianyun Cao Changqiong Xie Jinghui Fan Juying Wu Kai Zhang 《Fullerenes, Nanotubes and Carbon Nanostructures》2019,27(6):492-497
A novel kind of paraffin-based shape-stable phase change materials (SSPCMs) was prepared by introducing paraffin into reduced graphene oxide (rGO)/carbon nanotubes (CNTs) aerogel via vacuum-assisted impregnation method. The effects of ratio of rGO to CNTs in 3D network structure on morphology, structure and property of paraffin-based SSPCMs were investigated. The rGO/CNTs 3D network structure with high thermal conductivity, served as thermally conductive skeleton together. In particular, CNTs was used as a secondary heat conductive filler, which could be well dispered in the SSPCMs to conduct heat synergistically. The SSPCMs exhibited high thermal conductivity and excellent shape-stability. And the thermal conductivity of SSPCMs can be regulated by adjusting the ratio of rGO to CNTs in aerogels. These results indicate that 3D rGO/CNTs aerogels have advantages as thermally conductive skeleton, and can endow phase transition materials with stable shape, so as to realize the application of phase change materials in the field of heat dissipation. 相似文献
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Silica aerogels are highly porous solid materials consisting of three-dimensional networks of silica particles and are typically obtained by removing the liquid in silica gels under supercritical conditions. Several unique attributes such as extremely low thermal conductivity and low density make silica aerogels excellent candidates in the quest for thermal insulation materials used in space missions. However, native silica aerogels are fragile at relatively low stresses. More durable aerogels with higher strength and stiffness are obtained by proper selection of silane precursors and by reinforcement with polymers. This paper first presents a brief review of the literature on methods of silica aerogel reinforcement and then discusses our recent activities in improving not only the strength but also the elastic response of polymer-reinforced silica aerogels. Several alkyl-linked bis-silanes were used in promoting flexibility of the silica networks in conjunction with polymer reinforcement by epoxy. 相似文献
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Shengyang Zhou Varvara Apostolopoulou‑Kalkavoura Marcus Vinicius Tavares da Costa Lennart Bergstrom Maria Stromme Chao Xu 《纳微快报(英文)》2020,(1):102-114
Metal–organic frameworks(MOFs)with high microporosity and relatively high thermal stability are potential thermal insulation and flame-retardant materials.However,the difficulties in processing and shaping MOFs have largely hampered their applications in these areas.This study outlines the fabrication of hybrid CNF@MOF aerogels by a stepwise assembly approach involving the coating and cross-linking of cellulose nanofibers(CNFs)with continuous nanolayers of MOFs.The cross-linking gives the aerogels high mechanical strength but superelasticity(80%maximum recoverable strain,high specific compression modulus of^200 MPa cm3 g−1,and specific stress of^100 MPa cm3 g−1).The resultant lightweight aerogels have a cellular network structure and hierarchical porosity,which render the aerogels with relatively low thermal conductivity of^40 mW m−1 K−1.The hydrophobic,thermally stable MOF nanolayers wrapped around the CNFs result in good moisture resistance and fire retardancy.This study demonstrates that MOFs can be used as efficient thermal insulation and flame-retardant materials.It presents a pathway for the design of thermally insulating,superelastic fire-retardant nanocomposites based on MOFs and nanocellulose. 相似文献
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Benqiang Tian Fangfang He Changqiong Xie Kai Zhang Jinghui Fan 《Fullerenes, Nanotubes and Carbon Nanostructures》2017,25(9):512-518
Two kinds of carbon aerogels, graphene aerogels (GA) and carbon nanotubes-graphene aerogels (CGA), were prepared by modified hydrothermal method. The form-stable phase change materials (PCMs) were fabricated by adsorbing paraffin into carbon aerogels. Morphology, structure, form stability and thermal property were characterized by scanning electron microscope (SEM), in situ X-ray diffraction (in situ XRD) and differential scanning calorimeter (DSC). The results showed that GA presented wrinkled surface textures with curling edges, and carbon nanotubes (CNTs) were interspersed or attached to GA sheets. The phase transition temperature and the phase change enthalpy of the GA/paraffin PCM composite were 48.7 °C and 223.2 J/g, respectively. Thermal and mechanical properties of PCM composites achieved a qualitative leap with the adding of carbon aerogels. The PCM composites had a thermal conductivity of about 2.182 W/m K at the carbon aerogels loading fraction of 2 wt%. The form-stable PCM composites with high thermal conductivity and high enthalpy could be promising for thermal energy storage applications in construction field. 相似文献
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轻质高效保温材料掺杂硅气凝胶 总被引:3,自引:0,他引:3
利用正硅酸甲脂(TMOS)为原料的溶胶-凝胶过程,摸索了不同反应条件下形成凝胶的规律,并选用TiO2粉末及玻璃纤维作为掺杂剂,采用超临界干燥处理制备出掺TiO2的硅气凝胶,通过对红外光谱以及不同温度和气压条件下热导率的测量,讨论了不同成份配比以及相应的热传输过程对材料热导率的影响。结果表明,密度为260kg/m^3的掺杂硅气凝胶在800K时的热导率为0.038w/m.k,是一种新型的轻质高效保温材 相似文献
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Three-dimensional(3D)graphene-based aerogels have significant potential for adsorption,sensors,and thermal management applications.However,their practical applications are limited by their disorganized structure and ultra-low resilience after compression.Some methods can realize a well-aligned structure,however,they involve high costs and complex technology.Herein,a 3D graphene hybrid aerogel with an anisotropic open-cell and well-oriented structure is realized by unidirectional freeze casting,which com-bines the'soft'(e.g.graphene oxide,Tween-80)and'hard'(e.g.graphene assembly)components to realize full recovery after flattening.A graphene aerogel annealed at a moderate temperature(~200℃)can pos-sess superhydrophilicity and outstanding wet-resilience properties,including after being pressed under 40 MPa.Furthermore,the graphene aerogel annealed at a high temperature of~1500℃exhibits excellent thermal conductivity enhancement efficiency in polydimethylsiloxane(PDMS).The resultant nanocom-posites clearly demonstrate anisotropic thermal conductivity and promising applications as thermal interface materials.This strategy offers new insights into the design and fabrication of 3D multifunctional graphene aerogels. 相似文献
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