SAPO-34/SiO_2催化甲醇制烯烃

采用水热法合成了SAPO-34分子筛,并用X射线粉末衍射仪和扫描电子显微镜对SAPO-34分子筛的结构进行了表征,同时探讨了黏合剂种类、甲醇分压、催化剂粒径和硅源等对SAPO-34分子筛催化甲醇制烯烃(MTO)反应性能的影响。实验结果表明,在MTO反应中,三烯(乙烯、丙烯和丁烯)选择性在反应初期存在明显的诱导期;以S iO2为黏合剂合成的SAPO-34/S iO2催化剂不但可缩短MTO反应的诱导期,三烯选择性也较未添加黏合剂或以A l2O3为黏合剂时高1~2个百分点;且当催化剂活性明显下降时,三烯选择性下降的幅度较小。催化剂粒径、甲醇分压及硅源对催化剂的诱导期也有明显的作用。在甲醇分压低于19kPa、催化剂粒径0.25~0.38mm、S iO2为黏合剂、硅酸四乙酯为硅源时,SAPO-34/S iO2催化剂的MTO性能明显提高。     

Effect of chloride ions on immersion plating of copper onto porous silicon from a methanol solution

The effect of chloride ions (Cl⁻) during the immersion plating of copper onto porous silicon (PS) from a methanol (MeOH) solution has been studied. The presence of Cl⁻ in the Cu²⁺ solution was found to slow down the rate of copper deposition, as confirmed by inductively coupled argon plasma emission spectroscopy and X-ray photoelectron spectroscopy measurements. The threshold concentration of Cl⁻ at which the deposition of copper is very severely diminished was found to be 0.1 M. The inhibition effect is discussed on the basis of the rest potential values of PS and polarization curve measurements. They revealed that the rest potential of PS upon dipping in these solutions appears to direct the metal deposition. Current density-potential curves show that at Cl⁻ concentrations higher than 0.1 M, the reduction of Cu ions proceeds in two steps; the reduction of Cu(II) to Cu(I) followed by the reduction of Cu(I) to Cu(0). This suggests that Cu(I) species in MeOH solution can be stable over a certain potential range and this stability of Cu(I) is responsible for the inhibition of metal deposition. Fourier transform infrared spectroscopy and scanning electron microscopy (SEM) were also performed to investigate the structural changes and characterizations of PS samples after the plating process.     

Effect of Lateral Cracks on Fracture Toughness Determined by the Surface-Crack-in-Flexure Method

The surface-crack-in-flexure (SCF) method uses a Knoop indenter to create small, semielliptical surface precracks in beam specimens. Lateral cracks may interfere with the primary median crack and cause errors of up to 10% in determination of fracture toughness, particularly for materials for which the fracture toughness is ∼3 MPa·m^1/2 or less. Although the residual-stress-damage zone is ground or polished away by hand by removing 4.5–5 times the indentation depth, this amount may not be sufficient to completely remove the lateral cracks in low-fracture-toughness materials. A series of tests were conducted on sintered alpha silicon carbide with different amounts of material removed after indentation. Once the lateral cracks were fully removed, the SCF results concurred with single-edged-precracked-beam and chevron-notched-beam data collected in accordance with ASTM Designation C1421. A simple remedy for the SCF method is to examine the outer ground surface for remnants of lateral cracks before fracture and to remove more material if necessary.     

建设宁夏石嘴山千吨级多晶硅产业基地的有利条件及优势研究

多晶硅是重要的电子与半导体原材料,建设千吨级硅产业基地具有重要的战略意义与经济效益。通过对建设千吨级多晶硅宁夏石嘴山产业基地的基础条件与优势进行探讨,认为在宁夏石嘴山建设千吨级多晶硅产业基地具有得天独厚的优势与条件,是必要和可行的。     

Dependence of Silicon Carbide Product Morphology on the Degree of Mechanical Activation

Mechanical activation before carbothermic reduction can substantially enhance the formation of SiC from SiO₂and carbon mixtures. However, the morphology (e.g., particles or whiskers) of SiC formed from mechanically activated SiO₂and carbon mixtures is dependent of the degree of mechanical activation and the condition of the subsequent carbothermic reduction. These phenomena are investigated and rationalized based on the increased reactivity of the reactants and SiC formation mechanisms.     

VHF-PECVD制备微晶硅材料的均匀性及其结构特性的分析

采用VHF-PECVD技术在多功能系统(cluster tool)中制备了系列硅薄膜，研究薄膜的均匀性及电学特性和结构特性。结果表明：气压和功率的合理匹配对薄膜的均匀性有很大的影响；材料的喇曼测试和电学测试结果表明微晶硅薄膜存在着纵向的结构不均匀，在将材料应用于器件上时，必须要考虑优化合适的工艺条件；硅烷浓度大，相应制备薄膜的晶化程度减弱，即薄膜中非晶成分增多。     

A novel integration approach for combining the components to minimize a micro-fuel cell

This work employs porous silicon as a gas diffusion layer (GDL) in a micro-fuel cell. Pt catalyst is deposited on the surface of, and inside, the porous silicon by the physical vapor deposition (PVD) method, to improve the porous silicon conductivity. Porous silicon with Pt catalyst replaces traditional GDL, and the Pt metal that remains on the rib is used to form a micro-thermal sensor in a single lithographic process.     

TFT有源矩阵α－Si∶H薄膜PECVD淀积工艺研究

分析了α－Ｓｉ∶Ｈ薄膜的质量和厚度对α－Ｓｉ∶ＨＴＦＴ关键性指标的影响，深入、详细地讨论了其ＰＥＣＶＤ淀积工艺，并在实验的基础上确定了最佳淀积工艺参数，从而获得了高性能的７５ｍｍ３７２×２７６像素α－Ｓｉ∶ＨＴＦＴ有源矩阵     

草酸二甲酯加氢合成乙二醇反应的研究

在微型管式反应器中,采用Cu/SiO2催化剂,在温度190～210℃、压力1～3MPa、草酸二甲酯(DMO)与氢气的摩尔比(氢酯比)40～120、DMO空速6.0～25.0mmol/(g.h)的条件下,对DMO加氢制乙二醇的反应进行了研究。实验结果表明,高温、高压、高氢酯比和低DMO空速都能提高DMO的转化率和乙二醇的收率,但同时也增加了副产物的选择性。较适合的反应条件为:压力2MPa,温度205～210℃,氢酯比80～100,DMO空速10.0mmol/(g.h)。动力学研究表明,DMO加氢反应符合Langmuir-Hinshelwood吸附反应动力学模型,表面反应为速率控制步骤,氢气不解离吸附,由此得到了相应的动力学方程及参数。统计检验结果表明,该模型对DMO加氢反应高度适定。