溶胶-凝胶法制备纳米碳化硅粉末的研究

以工业硅溶胶和炭黑为主要原料，采用溶胶一凝胶法和碳热还原法制备了纳米碳化硅粉末，研究了原料组成和制备工艺对超细粉末质量的影响。结果表明：该方法可直接制备纯度较高，颗粒直径分布范围小，粒径在一定范围内可控制的纳米碳化硅粉末。     

新型高比表面积碳化硅的制备及其在多相催化中的应用进展

综述了近年来新型高比表面积碳化硅的制备方法、合成原理及其在多相催化中的应用。主要阐述了形状记忆法、碳热还原法、纳米铸造法、镁热还原法等制备碳化硅的原理、过程和结果,分析了其作为催化剂载体在多相催化反应中的性能特点和存在问题,并对今后此方面的研究提出了一些建议。     

研发动态

高比表面积多孔碳化硅渭南师范学院的王冬华以康醇为碳源、正硅酸乙酯为硅源、含氢硅油为结构助剂,通过溶胶-凝胶法制备了碳化硅前驱体;再经碳热还原法得到高比表面积多孔碳化硅。研究发现,含氢硅油的特殊结构有利于形成多孔碳化硅,且对碳化     

镧对碳化硅超细粉合成温度与粒度的影响

众多研究表明,提高反应物起始原料的均匀混合程度、添加适量的添加剂是改善碳热还原法制备碳化硅超细粉体的有效途径。由于稀土元素对众多的化学反应都能起到有效的促进作用,于是,以纳米二氧化硅和活性炭为起始原料,以稀土镧为添加剂,采用碳热还原法制备碳化硅超细粉体,并借助X射线衍射仪和激光粒度仪分别对合成的粉体进行物相和粒度分析,实验结果表明:添加一定量的稀土镧有助于降低碳化硅超细粉的合成温度及粉体粒度。     

核用碳化硼制备工艺研究进展

碳化硼是一种被广泛应用在耐火材料、模具、轴承、喷嘴和核工业中的新型材料,主要介绍了有关制备碳化硼的工艺,其主要包括碳热还原法、自蔓延热还原法、化学气相沉积法和溶胶-凝胶碳热还原法。通过对比指出各种方法的优缺点,探讨了碳化硼制备的研究现状、存在的问题及发展方向。     

Al2O3-SiC复相陶瓷材料制备方法的研究现状

简要论述了Al2O3-SiC复相陶瓷材料的常用制备方法,如无压烧结法、热压烧结法、气压烧结法和溶胶-凝胶法等,重点介绍了碳热还原法。对以不同原料制备Al2O3-SiC复相陶瓷材料的碳热还原法进行了比较,指出了这方面研究的不足之处和下一步研究的方向。     

锆催化的碳化硅纳米线的制备及表征

以酚醛树脂为碳源、正硅酸乙酯为硅源、硝酸锆为催化荆,通过溶胶-凝胶法和碳热还原法制备出碳化硅纳米线.用X射线衍射仪和透射电子显微镜进行了表征.结果表明,通过此法制备的碳化硅为β - SiC,具有光滑的表面、长而直的线状结构;氧化锆在低于熔点时也起到液相催化作用,为碳化硅的生长提供有利生长点.     

纳米碳化硅对染料罗丹明B的光降解性能研究

以石墨作为碳源，正硅酸乙酯作为硅源，硝酸钴作为催化剂，采用溶胶-凝胶法和碳热还原法制备纳米碳化硅，并对其光催化性能进行研究。讨论了不同Si C用量、不同p H值、不同光源下纳米碳化硅对罗丹明B的光催化降解效果。结果表明：在250W紫外灯照射条件下，当p H=1，催化剂量为100mg时，罗丹明B的光降解效果最好，最高降解率可达58.52%。     

磷肥副产硅胶生产碳化硅的实验研究

磷肥副产硅胶产量可观,其主要成分是二氧化硅,是加工硅系列产品很好的原料.碳化硅属第三代半导体材料,经济价值高,应用前景好.概述了以二氧化硅为硅源制备碳化硅粉体的主要方法,并介绍利用磷肥副产硅胶碳热还原法生产碳化硅的实验研究.     

氮化铝粉末制备方法研究进展

综述了AIN粉末制备方法的特点和研究进展,包括直接氮化法、碳热还原法、电弧熔炼法、气相反应法、等离子体法、裂解法、自蔓延高温合成法、高能球磨法和微波合成法。根据合成的原理及反应物的状态对这些方法进行了归类,重点论述了直接氮化法和碳热还原法的研究动态。     

Novel SiC synthesis method applicable to SiC solid phase sintering

Most of the present production processes of SiC sintered bodies require some powder mixing using a mechanical milling process (ball milling, and so on). In this case, relatively long hours are required, and there is the problem of contamination during the preparation process. To avoid these problems, we developed a new process for obtaining a self-sinterable, stoichiometric SiC powder, whose precursor material is water-soluble; the precursor material was synthesized from aqueous silica and citric acid containing a small amount of aluminum compound. In order to obtain the stoichiometric SiC composition, the above aqueous precursor material was adequately cured in air (200°C-400°C); subsequently carbonization reaction (~800°C) in nitrogen atmosphere, carbothermal reduction (~1600°C) in argon atmosphere, and pressureless sintering (~1900°C) were performed. Among these processes, the curing process (cross-linking process) is very important for obtaining the equivalent composition (silica and carbon) for the subsequent carbothermal reduction. In this study, the adequate curing temperature and suitable preparation condition for the carbothermal reduction were investigated for the production of stoichiometric self-sinterable SiC powder. The pressureless sintered body achieved using the obtained SiC powder demonstrated a desirable trans-crystalline fracture behavior.     

液相还原法制备超细铜粉的研究进展

超细铜粉具有特殊的性能及广泛的应用前景,针对应用较广泛的液相还原法制备超细铜粉的研究进行了阐述,介绍了液相还原法制备超细铜粉工艺的研究进展以及铜粉表面改性的工艺方法,提出了目前尚存在的问题及对未来的展望。     

碳化硼材料的制备技术

本文综述了国内外碳化硼粉末和碳化硼陶瓷制备技术的研究现状与进展情况,重点介绍了碳管炉、电弧炉碳热还原法、自蔓延高温合成法、激光诱导化学气相沉积法、溶胶凝胶碳热还原法合成碳化硼粉末以及热压、热等静压、无压烧结、放电等离子烧结和反应烧结制备碳化硼陶瓷的研究进展。     

纳米二氧化钛的制备及应用研究

纳米二氧化钛作为一种新型的高性能材料,近年来受到了国内外研究人员的关注,并在相当广泛的领域中得到应用。本文从制备工艺和应用两方面详细阐述了国内外纳米二氧化钛的研究进展和发展现状。且对现存的制备方法进行比较,并指出了其优缺点;并对其发展前景进行了展望。     

Effect of SiC nanoparticles on in-situ synthesis of SiC whiskers in corundum–mullite–SiC composites obtained by carbothermal reduction

Corundum–mullite–SiC composites were synthesised using a carbothermal reduction method. The effects of SiC nanoparticles and sintering temperatures on the phase transformation of the composites and the synthesis of SiC whiskers were studied by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Results indicated that corundum, mullite, and SiC whiskers were produced as final products at 1600–1650 °C. SiC whiskers were formed through the vapor–solid mechanism. The added SiC nanoparticles worked as nucleating agents to facilitate the carbothermal reduction of aluminosilicates and formation of SiC whiskers. The sample with the added SiC nanoparticles exhibited a high yield of β-SiC of 17.1%. Furthermore, the SiC nanoparticles decreased the formation temperature of SiC whiskers from the original 1600 °C to 1500 °C, and the porosity of the composites was increased from 56.7% to 64.7% by increasing the partial pressure of SiO gas. This study provides an insight into the more efficient synthesis of composites with SiC whiskers through the carbothermal reduction of aluminosilicates.     

纳米氧化锌的制备与应用

纳米氧化锌作为一种功能材料，有着许多优异的性能和广泛的应用价值。对纳米氧化锌在国内外的研究现状、制备技术(固相法、液相法和气相法)及其应用状况进行了较为系统的评述，并提出了进一步研究的方向，对纳米氧化锌的形成机理及微观结构进行探讨，寻求行之有效的制备高纯、均匀纳米氧化锌的方法，以及制备各种性能的氧化锌粉体。     

碳热还原ZrSiO_4制备ZrO_2(Y_2O_3)粉末和SiC纳米粉末

ZrO 2(Y 2O 3) powder and SiC nanopowder were prepared by carbothermal reduction of ZrSiO 4. With the existence of additive Y 2O 3 and other impurities, ZrSiO 4 was dissociated into ZrO 2 and SiO 2 in the condition of 1450—1550?℃. ZrO 2(Y 2O 3)powder was thus obtained via the removal of SiO 2 as silicon oxide (SiO) gas during carbothermal reduction process. SiC nanopowder and small amount of SiC whisker were synthesized form the gas-phase reaction between SiO vapor and supplied CH 4 gas.     

Pd-CeO2/SiC催化剂的制备及其在CO和C3H6氧化反应中的催化性能

分别以蔗糖和硅酸钠为碳源和硅源,硫酸为催化剂,采用溶胶-凝胶法和碳热还原法合成SiC;以其为载体,Pd为活性组分,CeO₂为助剂,采用浸渍法制备Pd-CeO₂/SiC催化剂。考察催化剂制备方法、助剂CeO₂添加量和还原温度等对催化剂在CO和C₃H₆氧化反应中活性的影响。结果表明, 采用分步浸渍法制备的催化剂具有较高活性, CeO₂添加质量分数2%时制备的0.5%Pd-2%CeO₂/SiC催化剂经200 ℃预还原后,对CO和C₃H₆氧的最低完全转化温度分别为210 ℃和215 ℃,CeO₂助剂可显著提高金属Pd在催化剂表面分散度,与Pd产生相互作用,使Pd还原峰向低温移动,提高了催化剂活性。     

Improvement in the properties of low carbon MgO-C refractories through the addition of graphite-SiC micro-composite

Graphite–SiC micro-composites have been prepared in–house by carbothermal reduction process. Controlling the process parameters including the weight ratio of SiO₂ to graphite as well as carbothermal reduction temperature during the micro-composite preparation favors the homogeneous formation of SiC with preferred morphologies like ribbons and whiskers/fibers. The micro-composite modified low carbon MgO-C refractories have exhibited significantly improved bulk properties over the standard composition. To understand the beneficial role of SiC reinforcement on hot strength performance under air oxidizing conditions, we propose a scaling parameter known as strength factor (fs) based on the ratio of hot strength (HMOR) to cold strength (CCS). Correlating the strength factor data (fs) with oxidative damage provides new insights into the reinforcing effects of distinct SiC morphologies in this new class of micro-composite fortified refractory systems over the standard compositions.