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Experimental studies and computer simulation of the preparation of nanoporous silicon-carbide membranes by chemical-vapor infiltration/chemical-vapor deposition techniques.

机译：通过化学气相渗透/化学气相沉积技术制备纳米多孔碳化硅膜的实验研究和计算机模拟。

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摘要

Silicon carbide (SiC) is a material with very attractive properties. Its excellent mechanical strength, high chemical stability and thermal conductivity, strength and abrasion resistance at high temperatures, low thermal expansion, biocompatibility, and resistance to acidic and alkali environments, have made SiC a great candidate for use as material for the preparation of high-temperature membranes.;The focus of the present Thesis is to prepare SiC microporous membranes by a chemical-vapor deposition technique (CVD), using tri-isopropylsilane as the precursor and Ar or He as inert carrier gas. In the experiments we prepared membranes with a He permeance ~10-7 mol/m2 .s.Pa and a He/Ar ideal separation factor ~10.0. We envision the SiC membranes that we prepare to be eventually utilized in reactive separation applications with the water-gas shift and methane steam reforming reactions, where the membrane must function in the presence of high-temperature steam.;A pore network model was also developed in order to describe the preparation of microporous SiC membranes by the CVD technique. The membrane's pore space was represented by a three-dimensional network of interconnected pores, in which the effective size of the pores was distributed according to a pore size distribution. The chemical reaction, the various transport processes, and the evolution of the pore sizes due to the deposition of SiC on the pores' internal surface during the CVD process were included in the model. The Maxwell-Stefan equations were used for describing the pore level transport processes, which include the Knudsen and hindered diffusion, as well as viscous flow. The effect of pore blockage was also taken into account. The simulator monitors the PSD as the membrane's structure evolves. Also computed was the carrier gas' permeance during the CVD process. Good agreement was found between the simulation results and our single-gas experimental permeation data. The results also indicate the fundamental significance of the pore blockage (i.e., the percolation effect) to the evolution of the membrane's structure.;We also used the CVD technique to prepare SiC nanotubes and to characterize their properties using the BET, XRD, and TEM techniques. The SiC nanotubes have a number of potential uses as components of mixed-matrix membranes and catalyst supports, as well as for electronic and sensor applications. In the preparation of the SiC nanotubes we utilized as substrates, Anopore(TM) inorganic membranes (Anodisc(TM)), which are composed of a high purity alumina matrix prepared by the electrochemical anodization of aluminum.
机译：碳化硅（SiC）是一种具有非常吸引人的性能的材料。 SiC具有出色的机械强度，高化学稳定性和导热性，高温下的强度和耐磨性，低热膨胀性，生物相容性以及对酸性和碱性环境的耐受性，使SiC成为制备高碳钢的理想材料。本论文的重点是通过化学气相沉积技术（CVD），以三异丙基硅烷为前驱体，以Ar或He为惰性载气，制备SiC微孔膜。在实验中，我们制备的膜的He磁导率约为10-7 mol / m2.s.Pa，He / Ar理想分离系数约为10.0。我们设想了准备制备的SiC膜，该膜最终将用于水煤气变换和甲烷蒸汽重整反应的反应分离应用中，其中膜必须在高温蒸汽存在下起作用。;还开发了孔网络模型为了描述通过CVD技术制备微孔SiC膜。膜的孔空间由相互连接的孔的三维网络表示，其中孔的有效尺寸根据孔尺寸分布而分布。该模型包括化学反应，各种传输过程以及在CVD过程中由于SiC沉积在孔内表面上而导致的孔径变化。用麦克斯韦-斯特凡方程描述孔隙水平的迁移过程，其中包括克努森和受阻扩散以及粘性流。还考虑了孔堵塞的影响。随着膜结构的演变，模拟器会监视PSD。还可以计算出CVD过程中的载气渗透率。在模拟结果和我们的单气体实验渗透数据之间发现了很好的一致性。结果还表明了孔堵塞（即渗透作用）对膜结构演变的根本意义。我们还使用CVD技术制备了SiC纳米管，并使用BET，XRD和TEM表征了它们的性能。技术。 SiC纳米管具有多种潜在用途，可作为混合基质膜和催化剂载体的成分，以及用于电子和传感器应用。在制备SiC纳米管时，我们将Anopore™无机膜（Anodisc™）用作基材，该膜由通过铝的电化学阳极氧化制备的高纯度氧化铝基质组成。

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  • 作者

    Mourhatch, Ryan.;

  • 作者单位

    University of Southern California.;

  • 授予单位 University of Southern California.;
  • 学科 Engineering Chemical.
  • 学位 Ph.D.
  • 年度 2010
  • 页码 173 p.
  • 总页数 173
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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