硅粉反应活性与对撞粉碎效用

基于提高硅粉反应活性的研究,提出了硅粉粉碎技术要求,设计了一套新工艺和新设备并进行了验证。结果表明,这套技术的主要功效为:促使粉碎制粉技术发展,优化硅粉生产指标;为有机硅和多晶硅制品提供更优的原料;还为制订硅粉反应活性测试标准奠定了基础。     

反应物料对微型固定床反应器合成二甲基二氯硅烷的影响

利用微型固定床反应器,研究了直接法合成二甲基二氯硅烷的反应过程中硅粉质量、硅粉粒径及一氯甲烷流量对二甲基二氯硅烷的影响。结果表明,硅粉中杂质含量升高,反应出口气体中二甲基二氯硅烷的含量随之降低,硅粉中的Fe含量是影响二甲基二氯硅烷的主要因素;较小的硅粉粒径有助于反应初期缩短诱导期,但随反应的进行,硅粉的转化率和二甲基二氯硅烷的含量会下降;增加一氯甲烷流量,反应诱导期增长,硅粉转化率和二甲基二氯硅烷的含量均减小,但较小的流量在反应后期会出现二甲基二氯硅烷的含量严重下降的现象。     

多晶硅及其衍生产品前景展望

多晶硅是用工业硅(硅粉)通过化学、物理途径提纯制得,生产所用的主要配套原料是H_2和HCl。多晶硅主要用于生产单晶硅和卫星太阳能电池的材料。 单晶硅即硅半导体,是多晶硅的衍生产品,是制造集成电路和电子元件的优质材料。     

多晶硅生产中硅芯氧化问题探究

改良西门子法生产多晶硅中硅芯是多晶硅生长的载体,硅芯氧化会降低多晶硅产品品质,硅芯氧化的产品对下游铸锭、直拉均有不同程度的影响。目前硅芯氧化是影响多晶硅产品质量的一大问题。分析了硅芯氧化机理,针对相关因素开展了试验,提出了降低硅芯氧化率的措施。     

旋风分离器在多晶硅还原炉尾气除尘中的应用

在多晶硅生产中,还原炉尾气夹带硅粉,易造成尾气回收系统堵塞及设备严重破坏,同时还会导致系统物料的污染,影响多晶硅产品质量。介绍了一种采用旋风分离器对还原炉尾气进行除尘的方法,在一定程度上降低了尾气中的硅粉含量,提高了尾气回收系统的运行周期及稳定性。     

多晶硅无定型硅粉形成原因及控制

改良西门子法多晶硅生产过程中,若还原过程控制不当,会产生影响产品品质及系统运行的无定型硅粉。通过对还原过程温度控制、物料配比、二氯二氢硅含量、炉筒水温、尾气管结硅及换热情况等多方面因素研究,分析了无定型硅粉形成原因,提出了相关控制措施。     

硅粉加工粉尘爆炸危险性与预防措施

阐述国内多晶硅与有机硅产业中硅粉加工过程中出现的粉尘爆炸的危险性,从硅粉在粉碎、输送、分离、除尘等生产过程,论述了硅粉加工生产中存在较大粉尘爆炸危险因素,从厂房设计、工艺设计、安全技术管理等方面进行分析,指出了硅粉加工过程中预防发生粉尘爆炸的方法。     

硅粉密相气力输送技术在多晶硅生产中的应用

介绍某多晶硅厂对硅粉加料采用密相气力输送技术的输送方式和工艺流程,分析了该气力输送系统中主要设备和管道、阀门选型及设计时的考虑因素。     

多晶硅还原生产中变压器转档问题探讨

多晶硅反应从栽体硅芯到硅棒的这一生产过程中由于温度和硅棒直径的变化,硅棒电阻率时刻在发生变化,使得还原电源变压器在转档过程中出现诸多问题。如变压器温度升高、转档电流波动、调功柜熔断器烧坏甚至无法顺利转档等,这些问题的出现严重影响了多晶硅还原反应的正常进行,导致硅棒生长异常、产量降低、物料利用率低等一系列问题。本文通过生产实际,通过工艺和设备的调整,来有效控制多晶硅还原炉电气转档。     

多晶硅铸锭涂层用高纯Si3 N4微粉的研究进展与展望

本文根据国内外高纯氮化硅微粉制备的研究情况,综述了硅粉直接氮化法、硅亚胺热分解法、气相反应法等几种氮化硅粉末的主要制备方法,介绍了各种制备方法在生产多晶硅铸锭涂层用氮化硅微粉的优缺点,并从产品质量、成本等角度分析比较了各种制备方法的特点,指出了制备多晶硅铸锭用氮化硅粉末的主要发展方向.     

Optimization of Reaction Conditions in a Fluidized‐Bed for Silane Pyrolysis

The fluidized‐bed chemical vapor deposition (CVD) process for polycrystalline silicon production is considered to be the most attractive alternative to the conventional bell‐jar process. In order to obtain stable operation, high space‐time‐yields and high purity of the product several obstacles have to be eliminated. Reaction conditions must be optimized to avoid the homogeneous decomposition of silane and minimize silicon dust formation. The effect of temperature, silane partial pressure, gas velocity and the size of bed particles has to be identified. These dependencies and the interaction between hydrodynamics and kinetics of homogeneous and heterogeneous CVD‐reactions were studied in a laboratory‐scale fluidized‐bed reactor.     

四氯化硅水解制纳米二氧化硅粉体工艺研究

多晶硅合成过程中副产大量四氯化硅。以四氯化硅为硅源,通过水解反应成功合成了二氧化硅粉体。探讨了反应温度、四氯化硅的加料速度、四氯化硅和水的加料比、循环比等条件对二氧化硅比表面积的影响,并利用X射线粉末衍射仪、傅里叶红外光谱仪、比表面测定仪和粒度分析仪等测试工具对所制备的二氧化硅的结构、粒径等参数进行了表征。实验结果表明：在温度为50 ℃,四氯化硅的加料速度为2.0 L/min,加料比［m（四氯化硅）∶m（水）］为0.10~0.15,循环比为10 h-1的条件下,可制得满足橡胶补强剂要求的二氧化硅粉体。     

冶金法制备太阳能硅过程的湿法提纯研究

湿法提纯作为冶金法路线制备太阳能级硅的前处理工序,可以去除大部分金属杂质,提高最终产品收率。考察了硅粉粒径、浸出剂浓度、温度、时间、搅拌等因素的影响,采用ICP、SEM等对产品进行了表征。当工艺条件为:硅粉平均粒径44μm、w(HCl)=5%、温度80℃、时间6h,处理后产品中杂质w(Fe)=2.4×10-5,去除率为99.2%,杂质w(Al)=6.4×10-5,去除率为80%。描述了酸浸过程在前后不同阶段分别为受反应速度和内扩散控制历程。为太阳能级硅制备工业化开发,大幅度降低成本提供了参考。     

Diffusion in porous silicon: effects on the reactivity of alkenes and electrochemistry of alkylated porous silicon

Alkenes are known to react with hydrogen-terminated silicon surfaces to produce robust organic monolayers that are attached to the surface via covalent SiC bonds. In this report we investigate the dependence of the rate of alkylation of porous silicon samples on the reaction time using photochemical initiation. The kinetics of the photochemical alkylation of hydrogen-terminated porous silicon by undec-1-ene in toluene were observed to be pseudo first order, however the apparent rate constant decreased as the concentration of undec-1-ene increased. This behaviour is opposite to what would be expected if the rate-limiting process was an elementary chemical reaction step involving the alkene. Instead, it suggests that transport of the alkene to reactive sites and in the correct orientation is the rate-limiting step. Comparison of the rates of alkylation of porous silicon by undec-1-ene and dimethoxytrityl (DMT)-undecenol is consistent with such an interpretation as the bulky DMT headgroup gives a lower rate of alkylation. The diffusion of some simple redox-active probe molecules in porous silicon was investigated using a scanning electrochemical microscope (SECM). The probe molecules are converted at diffusion-controlled rate at an inlaid disk ultramicroelectrode (UME) consisting of the cross-section of a microwire sealed in glass. If the microelectrode is placed a short distance above the porous silicon, the microelectrode current depends on kinetics of the electrochemical reactions at the porous silicon and the mass transport properties within the open thin layer cell formed by the microelectrode and the alkylated porous silicon. In order to differentiate the effects of finite heterogeneous kinetics at silicon from diffusion limitations, current-distance curves were fitted over a wide range of applied potentials (on the Si) and it was observed that the diffusion coefficient in the porous layer was strongly anisotropic. The measured diffusion rates are comparable to those in bulk water along the pores, but with negligible diffusion between pores. This indicates that few pore-pore interconnections exist in the porous silicon.     

硅切割废砂浆制备硅溶胶及回收碳化硅的工艺研究

以硅切割废砂浆中硅粉为来源,制备较高浓度硅溶胶,并回收得到高纯度碳化硅。结果表明,制备硅溶胶的最佳实验条件为:反应温度90℃,硅粉活化时间5 min,反应时间1 h,废油砂∶蒸馏水∶碱=10∶30∶0.6(质量比)。     

高纯、单分散二氧化硅纳米粒子的制备

本文以单晶硅粉作为硅源,氨水作为催化剂,制备了二氧化硅纳米粒子.研究了单晶硅粉制备二氧化硅纳米粒子时反应条件对反应产率和粒径的影响,并通过单因素实验法和正交设计法获得了最佳实验条件.通过激光粒度分析仪、电感耦合等离子体-质谱(ICP-MS)、扫描电子显微镜(SEM)等方法对纳米二氧化硅粒子的纯度、形貌、粒径进行了表征,得到了高纯、单分散的二氧化硅纳米粒子.     

Reactions of Alkynes Using Heterogeneous and Homogeneous Cationic Gold Catalysts

The use of both heterogeneous and homogeneous gold catalysts for the reactions of alkynes is described. The reaction of ethyne with hydrogen chloride to make vinyl chloride monomer is initially described using gold supported on activated carbon. This reaction involves Au³⁺ as the reactive species and it is now known that higher alkynes can also be hydrochlorinated with the products of Markovnikov addition being formed. Subsequently, there is now a rich chemistry involving cationic gold or gold complexes as homogeneous catalysts for a very broad range of reactions involving alkynes, and some examples are discussed, including the nucleophilic addition of amines and alcohols to alkynes. Given the range of reactions that gold catalyses as a homogeneous catalysts this may be indicative that many more heterogeneously catalysed reactions using gold can be expected to be discovered.     

冶金法制备太阳能硅过程的湿法除硼研究

湿法提纯作为冶金法路线制备太阳能级硅前处理工序,可去除大部分铁铝等碱金属及硼杂质,提高最终产品收率。实验考察了湿法除硼过程主要工艺因素:浸出剂浓度、温度、时间、搅拌等对产品纯度的影响,采用SEM对产品进行表征。当工艺条件为c(HNO3)=6.5 mol/L,c(H2SO4)=6 mol/L,温度120℃、时间4 h,处理后产品中杂质质量分数为3.574×10-6,湿法过程单元的去除率为44.58%。实验结果为高等级太阳能级硅制备工业化开发大幅度降低成本提供了技术基础。     

Silica to Silicon: Key Carbothermic Reactions and Kinetics

The primary carbothermic reactions for the reduction of silica to produce silicon were defined and the reaction kinetics were determined. Most possible reactions between silicon oxide and carbon or carbon compounds were studied by a series of thermogravimetric analyses at temperatures up to 2000°C. Four key sequential reactions occur with SiC and SiO as intermediate reactants; two reactions involve SiO₂ and two involve SiO. Reaction rate versus temperature, activation energy, and preexponential factors were determined for each of six reactions involving SiO₂ or SiO. These kinetic studies show that SiO, when combined with either carbon or Sic, reacts in the gaseous state, and the sublimation of SiO is not the rate-limiting reaction for forming silicon.     

化妆品中用硅粉、硅悬浮液的最新技术(日)

硅是化妆品生产不可缺少的原料之一。介绍了硅粉、硅悬浮液用于化妆品生产的最新技术, 特别是毛发调理产品中的应用。硅粉作为固体原料有望成为化妆品中新产品的生产原料。