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TiO2-SiO2复合半导体气凝胶制备及光催化活性研究 总被引:6,自引:0,他引:6
TiO2-SiO2复合半导体气交是一种新型纳米光催化氧化剂。本文以正硅酸乙酯、钛酸丁酯为原料,用溶胶-凝胶法经超临界干燥制备出了TiO2-SiO2复合半导体气凝胶。研究了TiO2:SiO2不同配比对溶胶-凝胶过程的影响;用BET、XRD、SEM、TEM等测试方法对其结构进行了表征;以苯酚为探针考察了TiO2-SiO2复合半导体气凝胶的光催化氧化活性,并与普通锐钛矿型钛白粉光催化剂进行了对比结果表明 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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溶胶—凝胶法制备纳米TiO2的胶凝过程机理研究 总被引:83,自引:10,他引:73
利用冰醋酸为螯合剂,钛下酯为前驱物,用溶胶-凝胶法制得了TiO2凝胶,对其溶胶-凝胶过程在不同条件进行了分析研究,并对其胶凝过程机理作了初步搪塞,得出了最佳工艺条件。 相似文献
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研究了Al2O3、Al2o3/TiB2和Al2O3/TiB2/SiCW三处陶瓷材料在不同条件下的擦靡损特性。结果表明:三种陶瓷材料与硬质合金摩擦副的摩擦系数随温度温度的增加有不同的变化规律,摩擦表面的X射线衍射分析表明,摩擦系数的变化与陶瓷物膜的和结构有关,在高温下Al2O3/TiB2陶瓷材料摩擦表面形成了具有优良的高温润性的TiO2氧化膜,因而TiB2的加入明显改善了Al2O3陶瓷材料 摩擦磨损 相似文献
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用煅烧石油焦作填料,煤沥青作粘结剂,钛粉和硅粉作添加剂,采用热压工艺制备了一系列双组元掺杂再结晶石墨.考察了不同质量配比的添加剂对再结晶石墨的热导率、电阻率和抗弯强度的影响以及微观结构的变化.实验结果表明,与相同工艺条件下制备的纯石墨材料相比较,掺杂15wt%钛粉再结晶石墨的传导以及力学性能有较大幅度的提高.在掺杂钛粉15wt%、硅粉<2wt%时,双组元再结晶石墨的常温热导率随着硅粉的掺杂量的增加有所提高.当掺杂钛粉及硅粉分别为15wt%和2wt%时,再结晶石墨RG-TiSi-152的常温热导率可达494W/m·K.但是当掺杂钛粉15wt%、硅粉>2wt%时,随着硅粉的继续增加,再结晶石墨的常温热导率反而降低.而双组元掺杂钛硅再结晶石墨的导电以及力学性能却随着硅粉的掺杂量的增加而降低.XRD分析表明,对于双组元掺杂钛硅再结晶石墨而言,钛元素最终在材料中以碳化钛形式存在,而硅元素则大都以气态形式被逸出,XRD物相图谱中未发现硅及其碳化物的存在.材料RG-TiSi-152的微晶尺寸La以及晶面层间距d002分别为864和0.3355nm. 相似文献
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以聚脲材料为壳材包覆可膨胀石墨(EG),并在囊壁上嵌入CuO提高壁材的导热性能,从而获得可膨胀石墨微胶囊(EG@PO),然后将制备的EG@PO与聚磷酸铵(APP)复合应用于阻燃天然橡胶(NR)。通过SEM、热失重和红外光谱分析等手段对EG@PO进行表征。通过极限氧指数、垂直燃烧测试、热失重测试、锥形量热仪和导热系数测定仪等手段测试不同添加量的EG@PO对NR热稳定性、阻燃性、产烟性和热传导性等的影响。结果表明,成功利用聚脲材料包覆EG,并在囊壁上嵌入CuO。EG@PO和APP协同作用提高了NR的阻燃性能和热稳定性。当EG@PO添加量为6 g时,EG@PO/NR复合材料的极限氧指数为28.3%,垂直燃烧法测试结果达到V-0级,600℃时的残炭量达到27.5%。且热释放速率和总热释放量均出现大幅下降,相比于纯天然橡胶,最大热释速率和总热释放量分别降低了49.8%和25.7%,分别为467.7 kW/m2和48.4 MJ/m2。与此同时,镶嵌在微胶囊囊壁中的CuO有助于热量在NR基体和EG之间的传递,EG@PO/NR复合材料的导热系数最高为0.266 W/(m·K)。 相似文献
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用溶胶-凝胶法制备了SrBi_4Ti_4O_(15)陶瓷材料,研究了烧结温度、铋含量及掺杂Nd对SrBi_4Ti_4O_(15)陶瓷结构、热扩散率及介电性能的影响.结果发现,SrBi_4Ti_4O_(15)陶瓷材料的热扩散率和介电常数随烧结温度的升高而增大,最佳烧结温度为1100℃,铋含量过量达10%时,SrBi_4Ti_4O_(15)陶瓷的热扩散率和介电常数最大.随着掺杂量Nd的增加,SrBi_4Ti_4O_(15)陶瓷的热扩散率和介电常数随之增大. 相似文献
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采用水热合成法制备了由纳米棒组成的微米级球形Bi2S3颗粒, 然后通过放电等离子烧结技术(SPS)将不同摩尔比例的BiCl3/Bi2S3复合粉末制备成块体。加入适量的BiCl3不仅提高了Bi2S3样品的导电率, 而且降低了其热导率。Bi2S3复合0.5mol%BiCl3的样品在762 K电导率最大, 达到45.1 S·cm-1, 远高于此温度下纯Bi2S3样品的电导率(12.9 S·cm-1)。Bi2S3复合0.25mol% BiCl3的样品在762 K时热导率最低, 为0.31 W·m-1·K-1, 低于同一温度下纯Bi2S3的0.47 W·m-1·K-1。在762 K下, Bi2S3复合0.25mol% BiCl3的样品获得最大ZT值(0.63), 比纯Bi2S3样品(0.22)提高了大约2倍。 相似文献
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A. Smontara J. C. Lasjaunias R. Maynard H. Berger F. Lévy 《Journal of Low Temperature Physics》1998,111(5-6):815-840
We report on thermal conductivity measurements of the quasi-onedimensional single crystals (Ta
1–x
Nb
x
Se
4
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I (x = 0, 0.008, 0.01) between 50 mK and 6 K. The thermal conductivity of a (TaSe
4
)
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I sample obeys a cubic variation below 0.8 K, in good agreement with the boundary scattering regime. For two Nb doped samples, the thermal conductivity between 0.1 K and 1 K obeys a quasiquadratic regime, which is ascribed to extended linear or planar defects, specific to this one-dimensional structure, and introduced either by doping or by successive thermal cycling, while it obeys a cubic variation below 0.1 K, as in the case of pure (TaSe
4
)
2
I. In the vicinity of 1 K and 2 K for pure and 1 at. % Nb doped samples, thermal conductivity shows a very sharp peak, which exceeds the low-temperature cubic boundary Casimir regime, or the quasi quadratic regime, respectively. The presence of the peak in these systems is explained by a phonon Poiseuille flow, originating from their strong anharmonicity, amplified by the lattice anisotropy. 相似文献
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Sarabjeet Singh Sidhu Malkeet Singh Preetkanwal Singh Bains 《Particulate Science and Technology》2018,36(3):324-331
The present study investigates the thermal conductivity of bimodal SiC particulate distribution in aluminum matrix composites fabricated via powder metallurgy route. The effects of the SiCp reinforcement size distribution and processing parameters such as sintering time and temperature on the thermal conductivity have been examined. The Box–Behnken experimental array was employed to identify the effects of selected variables on the thermal conductivity of the composite. A reasonable augmentation in the thermal conductivity was observed with an increase in sintering time and %volume fraction of fine SiC particulates. It has been demonstrated that the matrix doped with fine SiC particulates (37?µm) occupied interstitial positions and formed continuous SiC–matrix network resulting in minimizing the micropores that contributed for good thermal conductivity, that is, 235?W/mK. Scanning electron microscopy (SEM) and x-ray diffraction (XRD) were conducted to evaluate the microstructure architecture and interfacial phase formation. 相似文献
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以YbH2-MgO体系为烧结助剂, 采用两步法烧结制备了高热导率高强度氮化硅陶瓷, 研究了YbH2-MgO对氮化硅致密化行为、相组成、微观形貌、热导率和抗弯强度的影响。在预烧结阶段, YbH2在还原SiO2的同时原位生成了Yb2O3, 进而形成“缺氧-富氮”液相。该液相不仅有利于晶粒的生长, 更有利于阻碍晶格氧的生成, 相较于Yb2O3-MgO助剂体系, β-Si3N4晶粒尺寸更大, 晶格缺陷更少, 低热导晶间相更少, 在1900 ℃保温24 h后, 热导率最优可达131.15 W·m-1·K-1, 较Yb2O3-MgO体系提升13.7%。用YbH2代替Yb2O3, 在低温条件下烧结制备得到的氮化硅抗弯强度有所改善, 在1800 ℃保温4 h的抗弯强度可达(1008±35) MPa; 但在高温烧结时强度略有下降, 这与微观结构的变化密切相关。研究表明, YbH2-MgO体系是制备高热导率高强度氮化硅陶瓷的有效烧结助剂。 相似文献
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Sensitivity to Combustible Gas for ZnO Thin Films 总被引:1,自引:0,他引:1
A fine polycrystalline ZnO thin film with 0.3~0.6 μm grain size was obtained by sol-gel process and a consequential heat treatment at 500℃. The process of preparing ZnO thin film was analysed. The sensitivity and conductivity of ZnO thin films as combustible gas (CO, CH4,H2) sensor as well as the influence of catalyst and pH value of the precursor on its sensitivity were studied in detail. The structure characteristics of ZnO thin film by different process were irlvestigated by X-ray diffraction, thermal analysis and photoelectron spectrometer. The atomic ratio of Zn to O on the surface of ZnO thin film was found to be 1.14:1 measured from XPS result. The conductivity of the thin film increases greatly when doped with Al3+ ion but decreases while doped with Na+ ion 相似文献