掺减水剂尾砂膏体充填料浆流变参数的时效性研究（英文）

采用流变测试方法研究掺减水剂的胶结膏体随时间变化的流变参数,特别关注静态屈服应力和触变性。结果表明,随减水剂用量的增加,胶结膏体的静态屈服应力、动态屈服应力和触变性显著降低,塑性黏度几乎不变。养护时间对掺减水剂胶结膏体的静态屈服应力、动态屈服应力和触变性有显著影响,在2 h内分别提高了46.6%～87.1%、15.2%～35.6%和79.4%～138.2%。无减水剂胶结膏体的静态屈服应力、动态屈服应力和触变性在2 h内仅分别提高4.9%、6.3%和16.1%。无论是否添加减水剂,养护时间对胶结膏体的塑性黏度有较大影响,2 h内塑性黏度增大13.2%～19.7%。无论是否添加减水剂,胶结膏体的触变性随静态屈服应力、动态屈服应力呈线性函数增长。研究结果对掺减水剂胶结膏体的管道输送设计有一定的指导意义。     

复合材料的超微粒子在电流变液体中的应用

目的得到一种能够满足工程应用要求的高性能电流变液体,方法用微乳液法得到一种复合材料的超微粒子并作为分散相与硅油混合,得到3种不同体积分数的电流变液体,分别测试其在不同温度、电场强度、剪切率下电致应力和表观粘度的变化规律,结果大量的系统测试表明,用超微粒子制成的体积分数为30％的这种新型电流变液体具有明显的电流变效应,结论双电层极化对液体的电流变效应具有重要影响。     

基于固体浓度函数的尾砂膏体触变行为评估（英文）

尾砂膏体是高浓度料浆,表现出复杂的触变性。本研究通过一系列恒剪切速率实验研究了尾砂膏体的稳态和瞬态触变性行为。基于ZHANG等提出的触变性模型分析了固体浓度对尾砂膏体触变性的影响,建立了基于固体浓度的稳态流变参数经验模型,提出了描述固体浓度对瞬态屈服应力影响的时变性模型。上述模型实现了浓度影响下尾砂膏体稳态和瞬态剪切应力时变性演化的定量分析。     

电、磁流变及电磁复合流变测试装置

根据两个相对运动的平行板的流体处于简单剪切流状态的原理，设计制作了滑动平板式多功能流变体屈服应力测试装置．该装置用步进电机驱动，用单片机对步进电机进行精确定位和调速，并且由力传感器和应变仪来测量切应力数值,可以分别用于电流变液、磁流变液以及电磁流变液的测试．测试结果说明，该装置测量各种流变液都是有效的和实用的，且能保证一定的测量精度．     

电流变效应的等效平板电导模型

建立了计算两个轻微接触半球在非极性液体中吸引力的等效平板电导模型,把每个半球等效为有一定厚度的平板,给出了等效平板厚度的表达式,从而简化了颗粒之间相互作用力的计算方法。文中用等放平板厚度的概念讨论了各物理量对吸引力的影响。最后预测了电流变液的准静态屈服应力和实测值是符合的。     

电流变液及其性能研究

研制了两类不同重量比的电流变液,然后对基于硅油的几种配比的电流变液进行了微观结构研究,发现这一类电流变液的确存在链状结构,链的多少和粗细与液体的重量比和外加电场强度的大小有关。最后对两类电流变液分别进行了静态和动态特性实验,发现液体的重量比和外加电场强度对性能影响很大,所制得的电流变液可以认为是一种宾汉流体。     

乙二醇基铁/氧化钛纳米复合粒子的制备及其电流变性能

采用两步法制备出乙二醇基铁/氧化钛纳米复合粒子,并将制备的纳米复合粒子分散在硅油中得到一系列的电流变液。首先采用高温回流法制备出乙二醇基铁模板,然后分别用水解法和溶剂热制备出氧化钛纳米颗粒包覆在乙二醇基铁模板表面。使用X射线衍射仪(XRD),扫描电子显微镜(SEM),电流变仪等对纳米复合粒子进行结构的表征和性能的测试。研究了不同种类的表面活性剂复配体系对纳米复合粒子电流变性能的影响。通过对比,水解法得到纳米复合粒子相比于溶剂热在形貌和电流变性能方面都有所提高,水解法制备得到的纳米颗粒基的电流变液电流变效率可以达到200。     

磁流变液剪切屈服应力的数值分析

为了改善单链模型的准确性，从颗粒间的磁相互作用能出发，建立了磁流变液多链计算模型．考虑链内颗粒和相邻链中颗粒的影响，利用磁能密度的变化，得到了磁致剪切应力应变关系，由剪切应力应变曲线的最大值来确定磁流变液的剪切屈服应力．对于链状结构，研究了链间距与链内相邻颗粒距离之比对磁流变液剪切屈服应力的影响；对于柱状结构，通过确定柱的大小及相邻柱的间距，构建了BCT结构计算模型，对含柱状结构的磁流变液的剪切屈服应力进行了分析．计算结果表明，当比值较大时，多链模型与单链模型趋于一致；比值较小时单链模型的误差不能忽略．传统的单链模型高估了磁流变液的剪切屈服应力，铁磁颗粒体积比浓度较小时，链状结构有比柱状结构更高的剪切屈服应力；而当颗粒体积比浓度较大时，柱状结构优于链状结构．     

混炼胶的粘弹性本构模型

根据混炼胶的两种典型流变性能(屈服应力与剪切变稀),建立了一种新的混炼胶的粘弹性本构关系.此方程说明材料的屈服应力是剪切变稀行为的一个主要原因,解释了某些材料存在的双牛顿区现象,并证明第一牛顿区的剪切粘度大于第二牛顿区的,同时也说明屈服应力也是幂律方程流动指数不稳定的一个重要原因,应用时应剔除屈服应力的影响.     

海上稠油流变特性及热处理技术的实验研究

为了获得稠油的流变特性对海上油藏的开采、管输等影响数据,利用旋转流变仪对海油样本的黏度、屈服应力进行测量,绘制黏温曲线和流变曲线。并用MATLAB拟合黏温方程、流变方程和屈服应力与温度曲线方程。根据拟合曲线方程,说明该油样具有剪切稀释性,为Herschel-Bulkley流体,随着温度的增加屈服应力逐渐减小。同时,热处理技术可改善稠油的流动性,利用水浴和微波2种加热方式及采用2种加热温度(中温段和高温段)对降黏效果进行研究,结果表明,在微波加热50℃时降黏效果最显著,为最优的热处理条件。     

A New Modified Conductivity Model for Prediction of Shear Yield Stress of Electrorheological Fluids Based on Face-center Square Structure

A new modified conductivity model was established to predict the shear field stress of electrorheo-logical fluids (ERF). By using a cell equivalent method, the present model can deal with the face-center squarestructure of ERF. Combining the scheme of the classical conductivity model for the single-chain structure, a new formula for the prediction of the shear yeld stress of ERF was set up. The influences of the separation distance ofthe particles, the volume fraction of the particles and the applied elects‘field on the shear yield stress were investigated.     

Electro-rheological Effect of Barium Titanate Particles Coated with Urea and Suspended in Methyl Silicone Oil

Barium titanate nano-powders were synthesized under defined conditions.The surface of these particles was successfully modified by coating with urea.The characteristics of these composite particles were studied by X-ray diffraction, transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy.The electro-rheological (ER) effects of these particles suspended in methyl-silicone oil were measured.The particle, methyl-silicon oil ratio was 30%-35% weight percent.The experimental results indicate that these ER particles exhibit a remarkable ER effect.The ER fluid shows Bingham characteristics and the static shearing stress increases with an increase of the electric field strength.The highest static shearing stress under a 4 MV/m electric field is 13.2 kPa at room temperature, an increase of about 8.7 kPa compared to untreated BaTiO(C2O4)2 powders.     

Effect of Carrier Liquid on Electrorheological Performance and Stability of Oxalate Group-modified TiO_2 Suspensions

By using oxalate group-modified TiO_2 nanoparticles as the dispersing phase, different kinds of silicone oil with various viscosities and terminal groups(hydroxyl, hydrogen, and methyl) were used as the dispersing media to prepare different electrorheological(ER) fluids. Their zero-field viscosity, yield stress under direct current electric fields, ER efficiency, shear stability, leakage current density, and sedimentation stability were tested to study the effect of carrier liquid on the properties of ER fluids. The results indicate that the zerofield viscosity, the yield stress, and the leakage current density increase with increasing viscosity of the silicone oils. The effects of the viscosity on the ER efficiency, the shear stability, and the sedimentation ratio depend on the competition between the viscous resistance and the aggregation of the particles. Among the three ER fluids prepared with silicone oil with different terminal groups, hydroxyl-terminated oil based sample has the highest zero-field viscosity, the highest field-induced yield stress and ER efficiency, the largest current density, and the best sedimentation stability.     

Clarification of abrasive jet precision finishing with wheel as restraint mechanisms and experimental verification

According to the critical size ratio for the characteristic particle size to film thickness between grinding wheel and work, the machining mechanisms in abrasive jet precision finishing with grinding wheel as restraint can be categorized into four states, namely, two-body lapping, three-body polishing, abrasive jet machining and fluid hydrodynamic shear stress machining. The critical transition condition of two-body lapping to three-body polishing was analyzed. The single abrasive material removal models of two-body lapping, three-body polishing, abrasive jet finishing and fluid hydrodynamic shear stress machining were proposed. Experiments were performed in the refited plane grinding machine for theoretical modes verification. It was found that experimental results agreed with academic modes and the modes validity was verified.     

Effect of carrier liquid on electrorheological performance and stability of oxalate group-modified TiO<Subscript>2</Subscript> suspensions

By using oxalate group-modified TiO₂ nanoparticles as the dispersing phase, different kinds of silicone oil with various viscosities and terminal groups (hydroxyl, hydrogen, and methyl) were used as the dispersing media to prepare different electrorheological (ER) fluids. Their zero-field viscosity, yield stress under direct current electric fields, ER efficiency, shear stability, leakage current density, and sedimentation stability were tested to study the effect of carrier liquid on the properties of ER fluids. The results indicate that the zero-field viscosity, the yield stress, and the leakage current density increase with increasing viscosity of the silicone oils. The effects of the viscosity on the ER efficiency, the shear stability, and the sedimentation ratio depend on the competition between the viscous resistance and the aggregation of the particles. Among the three ER fluids prepared with silicone oil with different terminal groups, hydroxyl-terminated oil based sample has the highest zero-field viscosity, the highest field-induced yield stress and ER efficiency, the largest current density, and the best sedimentation stability.     

具有聚苯胺高分子体系电流变流体的静力学性能

对聚苯胺高分子体系的电流变流体的力学特性进行了实验研究,结果表明：电流变流体在电场作用下其力学特性是变化的,并表现出复杂的非线性,随着电场强度的增加,电流变流体出现由液态向固态转化的趋势。应力 应变实验表明,电流变流体在屈服阶段出现重复屈服强化现象。     

新型电流变抛光工具开发及其抛光实验

针对当前电流变抛光研究中所用尖锥状工具要求抛光间隙为μm级、对设备定位精度要求高及抛光非导体需加辅助电极等不足,研制了一种新型的电流变抛光工具——集成电极工具。介绍了集成电极工具的结构,并对其电场分布进行了计算。新工具不仅可以抛光导体工件,而且也可以抛光非导体工件。工具与工件之间的抛光间隙可以大到mm数量级。以碳化钨(WC)和光学玻璃为对象,分别进行了抛光实验,并通过单因素实验给出了电压、转速、磨料浓度、抛光时间等因素与表面粗糙度的关系曲线。实验结果表明:抛光10min后,WC的表面粗糙度由Ra66.48nm下降到Ra33.18nm;光学玻璃的表面粗糙度由Ra11.02nm下降到Ra3.67nm。     

Electro-rheological properties of montmorillonite particles coated with titania in methyl silicone oil

Montmorillonite particles coated with titania were synthesized by means of a sol-gel method to use with elec-tro-theological material. The characteristics of these composite particles were studied by X-ray diffraction, scanning electron mi-croscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). The electro-rheological (ER) effects were measured after these particles were mixed with methyl-silicon oil by 20% and 30% (weight percent). The experimental results show that these montmorillonite/titania particles exhibit a marked ER effect compared with pure montmorillonite particles under a DC electric field.The highest static yield stress is up to 4.28 kPa, which is an increase of about 3.13 kPa over that of untreated montmorillonite pow-der under the electrical field strength of 3.2 kV/mm at room temperature.