Squeeze-Strengthening Effect of Silicone Oil-based Magnetorheological Fluid

In order to study the squeeze-strengthening effect of silicone oil-based magnetorheological fluid （MRF）, theoretical basis of disc squeezing brake was presented and a squeezing braking characteristics test-bed for MRF was designed. Moreover, relevant experiments were carded out and the relationship between squeezing pressure and braking torque was proposed. Experiments results showed that the yield stress of MRF improved linearly with the increasing of external squeezing pressure and the braking torque increased three times when external squeezing pressure achieved 2 MPa.

ELECTRORHEOLOGICAL PROPERTIES OF DIATOMITE/SILICONE OIL SUSPENSIONS UNDER DC FIELDS

In this study, electrorheological （ER） behavior of suspensions prepared from 3.0 and 9.0 μm diatomite particulate, dispersed in insulating silicone oil （SO） medium was investigated. Sedimentation stabilities of suspensions （c = 5 wt%） prepared using these diatomite powders were determined to be 32 days （d = 3 μm） and 24 days （d = 9 μm）, respectively. ER activity of all the suspensions was observed to increase with increasing electric field strength, concentration and decreasing shear rate. Shear stress of diatomite suspensions increased linearly with increasing concentrations of the particles and with the applied electric field strength. Electric field viscosity of all the suspensions decreased sharply with increasing shear rate and particle size, showing a typical shear thinning non-Newtonian visco-elastic behavior. Effects of high temperature and polar promoter onto ER activity ofdiatomite/SO system were also investigated.

ELECTRORHEOLOGICAL PROPERTIES OF TALC POWDER/SILICONE OIL SUSPENSIONS UNDER DC FIELDS

In this study, the electrorheological （ER） behavior of suspensions prepared from d50 = 2.4 lam talc powder, dispersed in insulating silicone oil （SO） medium was investigated. Sedimentation stabilities of suspensions （c = 5 wt%） prepared using these talc powder powders were determined to be 78 days. The ER activity of all the suspensions was observed to increase with increasing electric field strength, concentration and decreasing shear rate. The shear stress of talc powder suspensions increased linearly with increasing concentrations of the particles and with the applied electric field strength. Electric field viscosity of all the suspensions decreased sharply with increasing shear rate and showed a typical shear thinning non-Newtonian visco-elastic behavior. Effects of frequency on the ER activity of talc powder/SO system were also investigated.

Purification of solar cell silicon materials through filtration

Silicon is the material most commonly used in the manufacturing of photovoltaic (PV) cells. In the current study, laboratory experiments of purification of solar cell silicon materials through filtration are carried out. Inclusion removal from silicon was investigated. The purpose is to achieve clean silicon materials for solar cells. Silicon samples and filter samples were analyzed using microscope observation, EPMA, and X-ray detection. Silicon nitride (Si3N4) and silicon carbide (SiC) particles are the main non-metallic inclusions present in top-cut silicon scrap. Almost all inclusions larger than 10 μm can be removed from silicon by the porous foam filter. In mass fraction, more than 90% inclusions are removed. Si3N4 particles are mainly removed on the top surface of the filter, and SiC particles are mainly removed by entering the pores and attaching to the filter material. SiC inclusions are not only simply attached on the surface of the filter material, but are found also inside the filter material. There are SiC bridges near the filter materials. These bridges may fill the spaces between filter material, and this will further retard inclusions passing through the filter. Three-dimensional turbulent fluid flow and inclusion motion in the filter was calculated. Both experimental observation and fluid flow simulation indicate that most of the inclusions are entrapped at the upper part of the filter.

Separation of methane from different gas mixtures using modified silicon carbide nanosheet: Micro and macro scale numerical studies

This research discusses the separation of methane gas from three different gas mixtures,CH4/H2 S,CH4/N2 and CH4/CO2,using a modified silicon carbide nanosheet(Si CNS)membrane using both molecular dynamics(MD)and computational fluid dynamics(CFD)methods.The research examines the effects of different structures of the Si CNSs on the separation of these gas mixtures.Various parameters including the potential of the mean force,separation factor,permeation rate,selectivity and diffusivity are discussed in detail.Our MD simulations showed that the separation of CH4/H2 S,and CH4/CO2 mixtures was successful,while simulation demonstrated a poor result for the CH4/N2 mixture.The effect of temperature on the diffusivity of gas is also discussed,and a correlation is introduced for diffusivity as a function of temperature.The evaluated value for diffusivity is then used in the CFD method to investigate the permeation rate of gas mixtures.

Oxygen Incorporation in Czochralski Growth of Silicon under a Horizontal Magnetic Field

A mechanism of oxygen transportation in Czochralski growth of silicon crystals under a horizontal magnetic field (HMCZ) is proposed. Oxygen depleted surface melt, driven to the growth interface by the thermal Marangoni flow, determines oxygen concentration in the grown crystals. Systematic study was carried out to investigate effects of growth parameters on oxygen incorporation into crystals.

Removal of SiC particles from solar grade silicon melts by imposition of high frequency magnetic field

Non-metallic particles and metallic impurities present in the feedstock affect the electrical and mechanical properties of high quality silicon which is used in critical applications such as photovoltaic solar cells and electronic devices. SiC particles strongly deteriorate the mechanical properties of photovoltaic cells and cause shunting problem. Therefore, these particles should be removed from silicon before solar cells are fabricated from this material. Separation of non-metallic particles from liquid metals by imposing an electromagnetic field was identified as an enhanced technology to produce ultra pure metals. Application of this method for removal of SiC particles from metallurgical grade silicon （MG-Si） was presented. Numerical methods based on a combination of classical models for inclusion removal and computational fluid dynamics （CFD） were developed to calculate the particle concentration and separation efficiency from the melt. In order to check efficiency of the method, several experiments were done using an induction furnace. The experimental results show that this method can be effectively applied to purifying silicon melts from the non-metallic inclusions. The results are in a good agreement with the predictions made by the model.

纳米流体和两性表面活性剂改善钻井液性能实验研究

本文研究了碳化硅纳米流体和表面活性剂对水基钻井液物理和化学性质(热稳定性、黏度、表面张力和滤失特性)的影响。将碳化硅纳米流体、表面活性剂溶液和水基钻井液混合形成表面活性剂——碳化硅(Si C)钻井液,分别用流变仪、张力仪和压滤机对混合钻井液的黏度、表面张力和滤失性等性质进行了研究。实验结果表明,与常规表面活性剂相比,两性表面活性剂对钻井液黏度的增量最大,此外,混合钻井液具有更好的热稳定性,随着温度的升高,黏度平均变化率为9%,表面张力和滤失性分别下降了31.0%和22.2%。

硅片盒喷雾清洗装置设计

为减少在半导体产业中因硅片盒洁净度引起的硅片清洗质量问题,提高硅片盒清洗效率并减少化学液用量,课题组设计了一种硅片盒喷雾清洗装置。该装置采用上部喷雾、下部浸入的化学液湿法清洗方式,结合雾化理论对喷嘴结构进行了参数设计,并对化学液喷雾硅片盒清洗机的骨架、槽体和化学液喷雾装置进行建模及仿真分析。研究结果表明:该装置在保证清洗效果的前提下,可以避免因硅片盒洁净度的不足而影响硅片的表面质量,同时减少了化学液的用量和废气的排放。该设计为硅片盒清洗提供了一种更高效且经济的参考方案。

剪切增稠液胶囊增强硅橡胶复合材料抗冲击性能的数值模拟研究

冲击会对实战条件下武器的安全性和可靠性带来影响,因此必须使用抗冲击材料来提高武器系统的安全性。随着武器装备的高速发展,传统的聚合物抗冲击材料已逐渐不能满足要求,因此需要开发兼顾高效、轻质、智能、多次防护、多功能的抗冲击防护材料。将剪切增稠液(STF)胶囊分散在硅橡胶中制备了新型抗冲击复合材料,应用LS-DYNA程序ALE算法对落锤冲击STF/硅橡胶复合材料的过程进行了动力学建模,通过数值模拟研究了复合材料的抗冲击性能,并讨论了冲击速度、STF液滴分布结构以及吸能液体对复合材料抗冲击性能的影响。

2023年国外有机硅进展

根据公开发表的相关资料,综述了2023年国外有机硅行业的发展概况及有机硅产品的研发进展。

臭氧催化氧化在单晶硅切削液废水处理的工程应用

单晶硅切削液废水具有COD高、可生化性差等特点。针对某单晶硅生产企业废水,目前拟采取将其在企业内经过气浮、生化、曝气生物滤池等工艺处理至达到接管标准后,与其他污水混合进入污水处理厂进行生化处理的措施,这存在着对下游污水处理厂水质冲击问题,影响其稳定运行。对此,在污水处理厂生化工艺段前增设臭氧催化氧化处理工艺段对废水进行预处理,以提升生化段进水水质。根据企业外排废水出水COD设置不同的臭氧投加量,连续运行15 d,分析了臭氧消耗量、出水COD和下游污水处理厂出水COD,结果表明,随着单位质量COD的臭氧投加量(臭氧投加比)的提高,出水COD显著降低,但过高的臭氧投加量会造成臭氧尾气破坏装置高负荷运行及高能耗。实验条件下,当臭氧投加比在0.98~1.39 mg/mg内变动,平均1.20 mg/mg时,臭氧工艺段出水COD平均为83 mg/L,下游污水处理厂最终出水COD平均为17 mg/L,实现了出水稳定达标。

硅油基磁流体润滑轴承液膜静态特性分析

采用磁流体作为润滑介质可优化滑动轴承的性能,实现可控的动压润滑。为提高磁流体的油膜特性,对性能较优的硅油基磁流体进行油膜静态特性研究。针对硅油基磁流体润滑的滑动轴承,考虑空化效应,采用数值分析方法研究不同工况下润滑膜的静态特性。结果表明:转速对油膜承载力的提升有限,摩擦力随着转速的提升而增大;偏心率对油膜压力及油膜承载力的提升效果显著,最高压力区域随着偏心率的增大逐渐向最小油膜厚度方向移动,摩擦力随偏心率增大而略微减小;磁场强度的增加可以提高油膜承载力,但增幅取决于转速与偏心率,最大增幅随偏心率的增大而增大以及随转速的增大而减小。研究结果可为磁流体轴承的设计提供一定参考。

破碎地层护壁防塌剂研制及性能评价

针对顺北奥陶系碳酸盐岩地层揭开后坍塌掉块严重,遇阻卡钻频发的难题,以二甲基二烯丙基氯化铵、N,N-二甲基丙烯酰胺及自制含甲氧基硅烷基团的有机硅单体为原料,合成了可与碳酸盐岩地层发生键合反应的抗高温有机硅护壁防塌剂SMHB-1。通过红外光谱、核磁共振氢谱及热重等表征了产物的分子结构及稳定性,并评价了其搭接抗剪切强度、降滤失性能及封堵性能等进行了研究。结果表明,1.5%SMHB-1溶液处理过的碳酸盐岩岩心片的搭接抗剪强度可达到0.2 MPa, 160℃老化16 h后1%SMHB-1可使4%土浆滤失量降低60.7%,SMHB-1可降低体系渗透率降约61.68%,并且与现场钻井液的配伍性能好。以SMHB-1为核心的水基护壁防塌钻井液体系在顺北X井奥陶系地层进行应用,奥陶系井壁稳定性好,没有掉块产生,扭矩平稳,起下钻顺利,无阻卡,试验井段平均井径扩大率8.6%~11.4%。

高效有机硅消泡剂的制备

针对气田钻井液发泡问题,从钻井液发泡原因和消泡机理出发,在综合考察现今国内外各种消泡体系的基础之上,研制了一种以有机硅为主体的乳液型消泡剂LS。通过L16正交实验确定了影响消泡剂LS产品性能的条件,得出各因素对反应的影响次序为:有机硅质量分数>乳化温度>乳化剂质量分数>乳化时间;优化的合成条件为:有机硅质量分数15%,乳化剂质量分数5%,乳化温度80℃,乳化时间20 m in。通过性能评价实验,证明该消泡剂具有用量少(质量分数为0.2%)、消泡效果好(密度恢复率为98.96%)、抑泡能力强(抑泡密度恢复率为99.13%)、无毒无污染等优点,作为一种高效环保型的钻井液消泡剂,具有广阔的发展应用前景。LS已工业化生产,现场应用效果良好。

纳米二氧化硅改善钻井液滤失性能的实验研究

泥页岩地层井壁失稳的主要原因是泥页岩吸水后发生膨胀和掉块。针对这种情况提出了使用纳米二氧化硅封堵泥页岩纳米级孔喉、降低其渗透率从而减缓水分侵蚀的思路。在前期研究基础上，通过透射电镜分析、钻井液常规性能测试和扫描电镜分析等手段，评价了不同温度下纳米二氧化硅对钻井液滤失性的改善效果。结果表明：纳米二氧化硅可以有效地降低淡水基浆和膨润土基浆在升温过程中的失水量：室温下失水量降低率为56．25％，140℃时失水量降低率为78％，而对低固相基浆则效果一般；相对于纳米二氧化硅的质量浓度5％，其质量浓度为10％时可以使钻井液形成较为连续而致密的滤饼，封堵能力加强。由此可见，纳米二氧化硅可以有效改善淡水基浆和膨润土基浆的降滤失性能，且在温度升高过程中（室温～160℃）表现较好。

LED封装用液体交联剂的制备与表征

报道了一种功率型发光二极管(LED)封装用液体高分子交联剂的制备方法。将甲基氢环硅氧烷与八甲基环四硅氧烷、甲基苯基混合环体等环硅氧烷,在甲苯溶剂中,40℃~80℃,用阳离子交换树脂催化其开环共聚,并以适量四甲基二氢硅氧烷封端。产物为澄清透明的甲基苯基含氢硅油,其苯基含量(Ph/Si,molar ratio)为0.30~0.60,活泼氢(Si-H)含量为0~0.5%,折光指数为1.39~1.51(25℃),动力黏度为100 mPa.s^550 mPa.s(25℃)。

江苏东海水晶矿床成因初探:流体包裹体和硅氧同位素证据

东海水晶矿床位于苏鲁超高压变质带中,它的成因机制及其与超高压变质作用的关系一直是大家关注的问题。本文运用流体包裹体、硅氧同位素地球化学以及微量元素地球化学,对东海水晶矿床的成因进行了初步研究。结果显示,舍晶石英脉中流体包裹体主要有单液相、气液两相以及H2O-CO2流体包裹体,其中以气液两相流体包裹体为主,大小在5-50μm,但在含金红石发晶的水晶中气液两相流体包裹体最大可达300μm。其形成温度可以分为3个区间,即100℃-120℃, 160℃-220℃和240℃-260℃;而其盐度也集中于0-2wt％NaCl,4-12wt％NaCl和14-16wt％NaCl三个区间,反映了多期流体的叠加作用。激光拉曼和流体包裹体群成分分析可知,流体包裹体中除了H2O和CO2外,还有N2、CH4、H2S和C2H6等,并且在不同的爆裂温度情况下,流体包裹体所释放的成分有所差别。东海水晶矿床中不含金红石发晶的石英的δ18O变化范围在-5．6～+4．6‰,δ34Si变化范围在-0．2-+0．2‰之间;而含金红石发晶的石英的δ18O变化范围在10．5-14．9‰,δ34 Si变化范围在-0．2-+0．1‰之间。相对来说,与水晶热液作用有关的鳞片状黑云母比斜绿泥石更加富集Nb、Cr、Fe、V、W、Ti和Zr等。本文认为东海水晶矿床的形成在富含石英的榴辉岩在大陆板块俯冲折返过程中及其以后,由不同时期、不同性质、不同成分流体叠加作用下的结果,而含金红石发晶的形成则是叠加富Nb、Fe流体的结果。

含氢硅油的最新研究进展

综述了近20年来含氢硅油的研究成果,对全含氢硅油和部分含氢硅油的制备方法进行了分析及比较。展望了含氢硅油的发展方向。

金属过滤器用高性能碳化硅泡沫陶瓷的制备

介绍了一种适用于大规模工业化生产高强度金属过滤用碳化硅泡沫陶瓷的方法。采用商用SiC粉体和聚氨酯泡沫通过2次挂浆工艺可以制备出最大平均抗弯强度达到2.87 MPa,平均孔径在3 mm左右,同时具备优良的抗热震性能和高达1700℃耐火度的碳化硅泡沫陶瓷。探讨了浆料的粘度、流变性能对挂浆性能的影响及第2次挂浆对强度的增强机理,说明1次浆料的触变性能和适当固相含量的2次浆料是高强度泡沫陶瓷制备的关键,而2次挂浆工艺对强度提高的主要贡献来源于第2次浆料对1次挂浆烧结后留下空洞的有效弥补。