共查询到20条相似文献,搜索用时 78 毫秒
1.
2.
以SiO2粉体为主要原料,加入石英纤维和硬硅钙石晶须作为增强材料,通过湿法工艺制备了纳米孔SiO2.制备的纳米孔SiO2密度为0.3g/cm3,孔隙率为85%左右.孔隙直径主要分布在20到80nm之间.由于大量纳米孔的存在,纳米孔SiO2中固相导热和对流传热大大降低.为了降低纳米孔SiO2的高温辐射传热,采用辐射屏蔽层与纳米孔SiO2叠层复合来制备纳米孔SiO2多层隔热材料.采用有限元方法,通过传热计算得到纳米孔SiO2多层隔热材料等效导热系数随辐射屏蔽层的发射率、层密度及工作温度的变化规律.提出了纳米孔 SiO2多层隔热材料的结构优化设计方案. 相似文献
3.
用静电纺丝技术成功制备出复合中空 TiO 2/ SiO 2纳米纤维。用动态热分析仪、 红外光谱仪、X射线衍射仪、 扫描电镜、 透射电镜和 X射线能谱仪等分析技术对样品进行了表征。分析结果表明 , 得到的产物为复合中空TiO 2/ SiO 2纳米纤维 , 以非晶 SiO 2为外壳 , 内壁由粒径为 50 nm的晶态 TiO 2粒子组成 , 复合中空纳米纤维平均直径 2μm , 长度 > 100μm。讨论了复合中空纳米纤维的形成机制 , 复合纤维在烧结过程中 , 芯层 TiO 2纳米粒子向外表面扩散 , 与壳层 SiO 2粒子形成新化学键 , 得到复合中空纳米纤维。 相似文献
4.
首先,利用上浆法,将改性纳米SiO2与玄武岩纤维复合;然后利用手工铺料法,制备了纳米SiO2/玄武岩纤维增强环氧树脂层状复合材料(S-BF/EP).利用SEM对改性玄武岩纤维和玄武岩纤维/环氧树脂层状复合材料的表面形貌和界面形貌进行了研究;利用FT-IR、TGA和万能力学试验机对复合材料的分子结构、热解性能和耐久性能进... 相似文献
5.
采用溶胶-凝胶法、分子模板法及旋转涂覆法在硅衬底上制备掺杂TiO2的SiO2薄膜,并采用差热分析(DSC-TGA)、红外吸收光谱(FTIR)、X射线衍射、小角衍射(SAXS)、原子力显微镜(AFM)、台阶仪(Atomic-Profiler)以及纸擦拭法(paper-wiping method)和胶带剥离法(adhesive tpe-stripping method)对薄膜的性能进行了分析与表征,结果表明,薄膜的最佳热处理温度为400℃,所制备的掺杂TiO2的SiO2薄膜为多孔结构的无定形态,具有较好的机械性能,平均孔径随着膜层的增加而减小,一层膜和两层膜的平均孔径分别为87.4nm和62.8nm,厚度分别为538.7nm和1032.3nm。 相似文献
6.
采用干法成型工艺制备了纤维增强纳米SiO2复合隔热材料,考察了成型压力和纤维长度对复合材料力学性能的影响。结果表明,成型压力越大,复合材料承受压力载荷的能力越强,纤维表面致密的纳米级颗粒覆层对纤维起到的保护和应力缓冲作用越强,抗折强度越高。增强纤维长度对抗压强度影响不大,纤维越长,抗折强度越高,但当纤维过长时会因分散困难而导致抗折强度下降,故适宜的纤维长度为5mm。此外,采用等效包容体理论建立了纤维增强复合材料细观力学分析模型,并对纤维增强机理进行了深入分析和探讨。 相似文献
7.
以无机纤维毡为增强材料,正硅酸乙酯为硅源,采用溶胶一凝胶技术制备了无机纤维毡/Si02气凝胶隔热材料。研究了无机纤维毡的类型、密度等因素对复合材料的影响。结果表明:无机纤维毡/siO2气凝胶复合材料的隔热性能优,导热系数仅略高于纯Si02气凝胶,强度则有显著提高。 相似文献
8.
EVA/SiO2纳米复合材料的制备与性能研究 总被引:2,自引:0,他引:2
采用一步法制备出 EVA/SiO2 纳米复合材料,利用 FESEM、FTIR、SEM 等测试手段表征纳米SiO2 微粒在 EVA 基体中的分散性,并研究其力学性能及流变性能。结果表明 SiO2 微粒以 30~40nm 左右的粒径分散于EVA基体之中,并与 EVA形成化学键合结构,断裂时呈现脆韧双重断裂特征。当纳米SiO2 填充量为1%时,拉伸强度与断裂伸长率分别提高16.1%与11.7%,并以该含量处为转折点先提高后降低。纳米SiO2 微粒填充量在1%~3%范围内,复合熔体的表观粘度低于纯 EVA,熔点变化较少,加工流动性得到改善。 相似文献
9.
10.
11.
12.
13.
《功能材料》2015,(21)
无定形结构TiO2纳米管阵列(titania nanotube arrays,TNA)在浸泡AgNO3溶液后,再经适当的热处理,不仅可使TNA的晶体结构转变为锐钛矿型或金红石型,还可以制得海绵状TiO2-Ag复合涂层。深入研究了AgNO3溶液浓度、热处理温度等对TiO2-Ag复合涂层结构和光催化制氢性能影响的影响。研究结果表明,AgNO3溶液浓度对TiO2-Ag复合涂层形貌结构和晶体结构具有重要影响。当AgNO3溶液浓度为0.1~0.5 mol/L、热处理温度为500℃时,可制得海绵状TiO2-Ag复合涂层,该涂层在紫外-可见光光照条件下,光催化制氢速率为2.14μmol/cm2·h。 相似文献
14.
The sorption behaviour of water molecules in epoxy-based thermosetting networks is discussed and related to the modifications of the polymer properties. The hypothesized sorption modes and the corresponding mechanisms of plasticization are discussed on the basis of experimental liquid-sorption tests, differential scanning calorimetry (DSC), and electrical analyses. Two modes of moisture sorption are assumed: a sorption leading to an increase in the free volume of the system, and adsorption of the water molecules due to hydrogen bonding to hydrophilic groups present in the network and to the surfaces of holes which make up the excess free volume of the glassy polymer. Electrical investigation improved the understanding of the hygrothermal ageing phenomena. Water conditioning of the composites modified the surface and bulk resistivities as a consequence of microstructural damage and plasticization. 相似文献
15.
16.
This paper investigates the compression properties of square and triangular honeycomb core materials based on co-mingled flax fibre reinforced polypropylene (PP) and polylactide (PLA) polymers. Initial testing focused on investigating the sensitivity of the tensile properties of the composites to variations in processing conditions. Following this, a range of triangular and square honeycomb structures were manufactured using a simple slotting technique. These structures were tested in compression at quasi-static rates of strain and their strength and specific energy absorption characteristics were determined. Finally, a finite element analysis was undertaken to accurately predict the strength, energy-absorbing characteristics, buckling behaviour and failure modes of these natural fibre based core materials. 相似文献
17.
18.
19.
Jiayong Gan Teng Zhai Xihong Lu Shilei Xie Yanchao Mao Yexiang Tong 《Materials Research Bulletin》2012,47(3):580-585
In the present work we report the design and synthesis of CdSe/TiO2 nanotube arrays (NTAs) and their implementation as a photoanode for photoelectrochemical (PEC) application. CdSe nanoparticles with well dispersion were decorated on the inner and outer surfaces of 2.5 μm-long TiO2 nanotubes via electrodeposition. These CdSe/TiO2 NTAs exhibit a significant photocurrent responds under visible light illumination (λ ≥ 420 nm). The results presented in this study display a promising method that the photoelectrochemical performance could be improved via composition, size and crystalline control of CdSe/TiO2 NTAs. And the tubular morphology is also able to facilitate charge transport in nanostructure-based PEC cells. This research demonstrates a new approach, which have great potential applications in fabricating novel heterostructure-photoelectrochemical devices. 相似文献
20.