超细SiO2表面改性及在孔结构材料合成中的应用

从回收利用二氧化硅废料颗粒的角度出发,用硅烷类偶联剂对废料颗粒进行表面改性,并将其作为合成有序硅基孔结构材料的原料。傅里叶红外光谱、热重分析、激光光散射结果表明达到了改性目的。然后用TEM和SEM研究了晶化温度对硅基孔材料形态的影响,发现优化合成条件可以得到有序结构材料,为超细二氧化硅废料的回收利用提供了可能。     

磷矿伴生硅资源制备单质硅的探讨

综述了国内外以四氟化硅、氟硅酸钠（钾）、无定SiO2为硅源制备单质硅的主要方法,并对以无定SiO2为硅源制备单质硅的工艺条件进行了研究与探索。     

二羟基硅酞菁合成方法的研究

对二氯硅酞菁的合成进行了研究,并采用甲醇析出法分离出生成的二氯硅酞菁。利用二氯硅酞菁硫酸溶液冰水析出法将二氯硅酞菁转化为二羟基硅酞菁,收率达到77%,比文献的醇解法收率有较大提高,并通过红外分析对两种化合物的结构进行了确认。     

Growth of Alumina/Metal Composites into Porous Ceramics by the Oxidation of Aluminum

Alumina/metal composites were grown into the pores of porous alumina, porous aluminosilicate, and porous silicon carbide substrates through the oxidation of Al–Si (5 wt%) powder compacts coated with magnesia powder (11 mg/ cm²). The thickness of the resulting composite increased with oxidation time and temperature, and was proportional to (pore size)^0.5 on using porous alumina. The composite thickness was more than 2 times larger in the silicon carbide and about 4 times larger in the aluminosilicate than in the alumina at 1523 K for 1 h. The products using these three types of substrates consisted of alumina, aluminum, and silicon, except that a silicon carbide phase occurred when using the silicon carbide substrate. Silica and mullite in the aluminosilicate substrate changed to silicon and alumina, and silica in the silicon carbide substrate changed to silicon because of the reduction by aluminum.     

Verfahren zur Herstellung von Solarsilicium

Production of solar silicon. Economic exploitation of solar energy using solar cells made of crystalline silicon is dependent upon a considerable drop in the cost of the silicon raw material which is nowadays produced by standard methods of the semiconductor industry. New procedures for producing less expensive solar silicon can be divided into four groups characterized by different physico-chemical purification techniques: (1) reduction of volatile Si-H-Cl compounds; (2) purification of technical grade silicon (98–99%); (3) reduction of hexafluorosilicates; (4) reduction of silicon dioxide. Among the ten solar silicon processes under discussion, the purification of technical grade silicon and the carbothermal reduction of silicon dioxide have the greatest scope for cost reduction; however, it remains to be established whether the necessary purity can be achieved on an industrial scale.     

碳化硅材料中游离硅及游离碳对性能的影响

研究了全碳粉反应渗硅碳化硅（PCRBSC）材料的结构与力学性能的关系。分析了渗硅碳化硅材料中游离硅（fsi),游离碳（fc)含量对抗折强度的影响。结果表明：参硅碳化硅材料中随游离硅（fsi)含量的增加,其抗折强度下降,并且二者呈直线关系,符合线性复合规划,另一方面,游离碳（fc)含量较高的渗硅碳化硅材料,尽管游离硅（fsi)含量低,但其抗折强度低于等量或较多游离硅（fsi)含量的渗硅碳化硅材料的抗折强度。     

Effect of crystal plane orientation on the friction-induced nanofabrication on monocrystalline silicon

Although monocrystalline silicon reveals strong anisotropic properties on various crystal planes, the friction-induced nanofabrication can be successfully realized on Si(100), Si(110), and Si(111) surfaces. Under the same loading condition, the friction-induced hillock produced on Si(100) surface is the highest, while that produced on Si(111) surface is the lowest. The formation mechanism of hillocks on various silicon crystal planes can be ascribed to the structural deformation of crystal matrix during nanoscratching. The silicon crystal plane with lower elastic modulus can lead to larger pressed volume during sliding, facilitating more deformation in silicon matrix and higher hillock. Meanwhile, the structures of Si-Si bonds on various silicon crystal planes show a strong effect on the hillock formation. High density of dangling bonds can cause much instability of silicon surface during tip disturbing, which results in the formation of more amorphous silicon and high hillock during the friction process. The results will shed new light on nanofabrication of monocrystalline silicon.     

Porosification-reduced optical trapping of silicon nanostructures

Metal-assisted chemical etching (MACE) was carried out to fabricate solid silicon nanowires (s-SiNWs) and mesoporous silicon nanowires (mp-SiNWs). Total reflection and transmission were measured using an integrated sphere to study optical properties of the MACE-generated silicon nanostructures. Without NW aggregation, mp-SiNWs vertically standing on a mesoporous silicon layer trap less light than s-SiNWs over a wavelength range of 400-800 nm, owing to porosification-enhanced optical scattering from the rough inner surfaces of the mesoporous silicon skeletons. Porosification substantially weakens the NW mechanical strength; hence the elongated mp-SiNWs aggregate after 30 min etching and deteriorate optical trapping.     

硅粉加入量对碳纤维增强铝碳耐火材料显微结构和强度的影响

以电熔白刚玉、石墨、硅粉和碳纤维为主要原料,通过固定刚玉细粉和硅粉总含量(29%),改变硅粉加入量(0～20%)制得了六组碳纤维增强铝碳耐火材料.采用XRD、SEM及EDS等研究了硅粉加入量对不同温度处理后材料物相组成、显微结构及强度的影响.结果表明:(1)220 ℃热处理后,硅粉含量低于8%时,抗折耐压强度变化不大;硅粉的含量高于8%时,抗折与耐压强度均降低.(2)1400 ℃热处理后,当硅粉含量从0增加到8%时,耐压强度与抗折强度均得到明显改善.而当硅粉量进一步增加时,试样出现裂纹,强度显著下降.(3)综合考虑,硅粉的最佳加入量为8%,此时经220 ℃、1400 ℃热处理后材料具有最好的抗折强度及耐压强度.     

云南省水稻增施硅肥肥效及优化施肥量研究

通过全省近１０ａ（１９８８ ～１９９９）硅肥在水稻上施用的结果及土壤化验资料分析,研究了土壤有效硅、硅肥用量与硅肥肥效的相关性,提出了水稻增施硅肥的土壤硅素的丰缺指标及优化施肥量。     

碳化硅在聚合物中的应用

综述了碳化硅（SiC）在用填充改性、表面包覆改性、离子注入改性和聚合物表面接枝改性等方法所制得的复合材料中的应用，并对纳米SiC改性环氧树脂、纳米微晶SiC改性聚乙烯基咔唑和香豆素共混物、聚吡咯包覆改性SC、硅离子注入改性聚对苯二甲酸乙二醇酯薄膜及丙烯酰胺接枝改性SiC等进行了详细讨论     

Effect of some technological parameters on structure formation in materials based on reaction-sintered silicon carbide

Results of petrographic, x-ray, chemical, and spectral investigations of the structure and composition of materials based on SiC fabricated by reaction sintering of preforms pressed from grainy silicon carbide and its mixtures with petroleum coke in molten and volatilized silicon are presented. It is shown that the structure and composition of reaction-sintered silicon carbide materials can be controlled by changing the proportion of silicon carbide and petroleum coke in the pressed preform, the coarseness of carbide and carbon particles, the density of the pressings, and the temperature of reaction sintering. It is established experimentally that secondary silicon carbide formed as a result of the reaction between petroleum coke and silicon binds the grains of the initial carbide into a dense silicon carbide skeleton, whereas the retained pores are filled with free silicon. A single-phase material consisting entirely of silicon carbide can hardly be obtained by the method of reaction sintering. In practice, this method gives double-phase (SiC-Si) and triple-phase (SiC-Si-C) materials with a maximum content of the principal phase (SiC) equal to 94–96% (mass fractions).Translated from Ogneupory i Tekhnicheskaya Keramika, No. 8, pp. 2–8, August, 1996.     

Nitridation of Silica Characterized by High-Energy X-Ray Diffraction Technique

The structure of amorphous silicon oxynitride formed under nitridation conditions using ammonia gas, before the onset of silicon nitride crystallization, is determined employing high-energy X-ray diffraction (HEXRD) technique. The derived real-space function suggests that smaller ring structures, especially 3R and 4R (R: ring), which are the dominant rings in crystalline silicon nitride, are not major species in amorphous silicon oxynitride, and form in the latter part of the silicon nitride crystallization.     

硅溶胶—苯丙乳液复合路标涂料的研制

采用正硅酸乙酯(TEOS)为主要原料,以聚合溶胶法制备硅溶胶,制得的硅溶胶与苯丙乳液冷拼复配得到复合基料,再以该基料制得硅溶胶—苯丙复合路标涂料。通过正交试验分别确定了制备硅溶胶、硅溶胶—苯丙复合乳液和硅溶胶—苯丙复合路标涂料的最优方案。     

Template-free fabrication of silicon micropillar/nanowire composite structure by one-step etching

A template-free fabrication method for silicon nanostructures, such as silicon micropillar (MP)/nanowire (NW) composite structure is presented. Utilizing an improved metal-assisted electroless etching (MAEE) of silicon in KMnO₄/AgNO₃/HF solution and silicon composite nanostructure of the long MPs erected in the short NWs arrays were generated on the silicon substrate. The morphology evolution of the MP/NW composite nanostructure and the role of self-growing K₂SiF₆ particles as the templates during the MAEE process were investigated in detail. Meanwhile, a fabrication mechanism based on the etching of silver nanoparticles (catalyzed) and the masking of K₂SiF₆ particles is proposed, which gives guidance for fabricating different silicon nanostructures, such as NW and MP arrays. This one-step method provides a simple and cost-effective way to fabricate silicon nanostructures.     

Characteristics and surface energy of silicon-doped diamond-like carbon films fabricated by plasma immersion ion implantation and deposition

Diamond-like carbon (DLC) films doped with different silicon contents up to 11.48 at.% were fabricated by plasma immersion ion implantation and deposition (PIII-D) using a silicon cathodic arc plasma source. The surface chemical compositions and bonding configurations were determined by X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The results reveal that the sp³ configuration including Si–C bonds increases with higher silicon content, and oxygen incorporates more readily into the silicon and carbon interlinks on the surface of the more heavily silicon-doped DLC films. Contact angle measurements and calculations show that the Si-DLC films with higher silicon contents tend to be more hydrophilic and possess higher surface energy. The surface states obtained by silicon alloying and oxygen incorporation indicate increased silicon oxycarbide bonding states and sp³ bonding states on the surface, and it can be accounted for by the increased surface energy particularly the polar contribution.     

Stoichiometry of the C + SiO2 Reaction

The reaction of one-to-one molar carbon/silica powder mixtures was studied using simultaneous thermogravimetric analysis and mass spectroscopy with crystalline and amorphous silica. Reaction proceeded via a two-stage path in which there are at least three identifiable competing global reactions. During the first stage, silicon carbide is formed along with small amounts of silicon monoxide. The most likely reaction path during this stage is the following: SiO₂( s ) + C( s ) → SiO( g ) + CO( g ); SiO( g ) + 2C( s ) → SiC( s ) + CO( g ). The second stage consists of reactions between silica with silicon carbide which form silicon monoxide and, where conditions permit, may also form silicon metal. The major reaction during this stage is 2SiO₂( g ) + SiC( s ) → 3SiO( g ) + CO( g ).     

Physiological and Proteomic Analysis in Chloroplasts of Solanum lycopersicum L. under Silicon Efficiency and Salinity Stress

Tomato plants often grow in saline environments in Mediterranean countries where salt accumulation in the soil is a major abiotic stress that limits its productivity. However, silicon (Si) supplementation has been reported to improve tolerance against several forms of abiotic stress. The primary aim of our study was to investigate, using comparative physiological and proteomic approaches, salinity stress in chloroplasts of tomato under silicon supplementation. Tomato seedlings (Solanum lycopersicum L.) were grown in nutrient media in the presence or absence of NaCl and supplemented with silicon for 5 days. Salinity stress caused oxidative damage, followed by a decrease in silicon concentrations in the leaves of the tomato plants. However, supplementation with silicon had an overall protective effect against this stress. The major physiological parameters measured in our studies including total chlorophyll and carotenoid content were largely decreased under salinity stress, but were recovered in the presence of silicon. Insufficient levels of net-photosynthesis, transpiration and stomatal conductance were also largely improved by silicon supplementation. Proteomics analysis of chloroplasts analyzed by 2D-BN-PAGE (second-dimensional blue native polyacrylamide-gel electrophoresis) revealed a high sensitivity of multiprotein complex proteins (MCPs) such as photosystems I (PSI) and II (PSII) to the presence of saline. A significant reduction in cytochrome b6/f and the ATP-synthase complex was also alleviated by silicon during salinity stress, while the complex forms of light harvesting complex trimers and monomers (LHCs) were rapidly up-regulated. Our results suggest that silicon plays an important role in moderating damage to chloroplasts and their metabolism in saline environments. We therefore hypothesize that tomato plants have a greater capacity for tolerating saline stress through the improvement of photosynthetic metabolism and chloroplast proteome expression after silicon supplementation.     

反应烧结碳化硅的显微组织及其导电性的研究

研究了液态硅参与下的反应烧结碳化硅的工艺参数、显微组织对其电阻率的影响.随着烧结气氛压力和成型压力增加,反应烧结碳化硅中游离硅量减少,电阻率增加.其烧结机理以碳的溶解及碳化硅的淀析过程为主.     

Comparison of the Pyrolysis Products of Dichlorodimethylsilane in the Chemical Vapor Deposition of Silicon Carbide on Silica in Hydrogen or Argon

A chemical analysis of the pyrolysis gases and solids formed during the deposition of silicon carbide from the decomposition of dichlorodimethylsilane in argon and hydrogen is reported. Depositions were performed at 1 atm pressure, temperatures from 700° to 1100°C, and a mean residence time of approximately 1 min. The chemical analysis shows that, under reactor conditions, the gases formed were mainly methane, hydrogen, silicon tetrachloride, trichloro-silane, and trichloromethylsilane. The presence of hydrogen chloride was not examined. The use of hydrogen, as a carrier gas, decreased the trichloromethylsilane and solid aerosol (smoke) in the reaction products, compared to that present in the argon system, and increased methane, trichlorosilane, and silicon production. Primarily, silicon and silicon carbide were deposited when hydrogen was used as the carrier gas. When argon was used, a complex mixture of silicon carbide and organosilicon compounds was formed. It is hypothesized that, when hydrogen was used as the carrier gas, silicon carbide formed from chlorosilanes and methane, which were products from the decomposition of dichlorodimethylsilane. These products subsequently reacted to form silicon, which then reacted with methane to form silicon carbide. In argon, however, it is hypothesized that silicon carbide can be formed in two ways: (1) from the pyrolysis of solid organosilicon compounds which are products from the pyrolysis of dichlorodimethylsilane in argon and (2) as the reduction of dichlorodimethylsilane to chlorosilanes and methane, caused by the hydrogen produced from the pyrolysis of dichlorodimethylsilane in argon.