剪切速率和静置时间对Fe-Al-Mg-MMH/钠质蒙脱土复合触变性体系触变性的影响

研究了测定条件对R=0.051的Fe-Al-Mg型混合金属氢氧化物(简称MMH)/钠质蒙脱土(简称MT)复合触变性悬浮体性质的影响.主要考察了高速剪切分散后,测定粘度(η)随时间(t)变化时采用的剪切速率(DL)和测定η前的静置时间(ts)的影响发现DL和ts的影响很复杂,ts=0,低DL时(10和170s-1)呈现复合触变性的体系,在高DL时(340、511和1022s-1)可呈现正触变性;DL增加,体系η逐渐降低.在所研究的ts范围内(0～2h),随ts的增加,体系分别由低DL时(10和170s-1)的复合触变性和高DL时(340、511和1022s-1)的正触变性皆转变为负触变性.低DL时(10和170s-1),η随ts逐渐降低;高DL时(340、511和1022s-1),η随t逐渐增高.对影响机理进行了初步探讨.     

牙膏增稠的理论和增稠剂

深入阐述了牙膏增稠的流变学理论，同时，介绍了用于生产牙膏的儿种主要增稠剂的性能及其在牙膏配方中的应用。流变学理论和黏合剂化学技术的有机结合直接导致了新型牙膏配方产品的诞生。     

高黏度苯丙乳液的制备

为了制备高性能的苯丙乳液，研究了乳化剂、助剂DZ-1及丙烯酸对苯丙乳液黏度及触变指数等性能的影响。研究结果表明：乳化剂用量低反应生成的凝聚物较多，用量大乳液的气泡较多。乳液的黏度和触变指数随DZ—1用置增大而大幅度提高。乳液黏度随丙烯酸用量的增加而提高，但用量超过3％后，耐水性能变差。乳化剂用量为1．0％，DZ-1用量为4．5％，酸用量为3．0％时合成的苯丙乳液黏度和触变指数较高。用该苯丙乳液配制的涂料黏度高、触变性好，耐擦洗及耐水性好，综合性能优良。     

Quantification of different effects occurring during fatigue tests on bituminous mixtures

Quantification of different effects (nonlinearity, heating, thixotropy, and fatigue) occurring during fatigue tests on bituminous mixtures is presented in this paper. A focus is given on the nonlinearity phenomenon. Continuous fatigue tests and a test with specific protocol (called fatigue tests to estimate biasing effects) were performed in tension/compression mode on cylindrical samples of the same material. The analysis of results reveals that reversible effects (nonlinearity, heating, and thixotropy) are important (more than 90% decrease at 100,000 cycles for a strain amplitude of 100 μm/m at 10 Hz) and cannot be ignored when interpreting classical fatigue tests. The nonlinearity effects respect the time‐temperature superposition principle, and they are more pronounced at “high” temperature (at the same frequency). Direction of nonlinearity curve in the Cole‐Cole axes is shown to be independent of temperature and frequency for the considered range.     

Application of a material fatigue damage model in 4PB tests

The fatigue property of an asphalt mix is an important issue in pavement design. This property is often determined with the aid of a four-point bending (4PB) test in controlled deflection mode. The fatigue property is related to the decrease in the calculated complex stiffness modulus, however, due to the non- homogenous stress and strain field in the beam, the measured response does not represent the stiffness modulus of the material but a weighted stiffness value. For a correct interpretation, a fatigue damage material model like the Asphalt Concrete Pavement-Fatigue model is needed. After integration, the calculated and measured responses are compared. By varying the model parameters, an excellent comparison between the two responses is obtained up to a certain number of cycles. This number of cycles is denoted as the fatigue life N _PH . The accumulated dissipated energy at the surface of the beam in the midsection can be expressed as a constant times the fatigue life N _PH to the power z and also as a constant times the product of the fatigue life N _PH and the initial dissipated energy in the first cycle. Using these two findings, a Wöhler curve was established similar to the one directly based on the strain amplitudes and fatigue life data.     

Evolution of Globular Microstructure in New Rheocasting and Super Rheocasting Semi‐Solid Slurries

Based on the solidification theory for metal alloys, a simple recipe for the controlled processing of globular microstructures without external stirring is presented: Firstly, small solidification nuclei must be distributed homogeneously throughout a melt. In New Rheocasting (NRC) these nuclei are formed by forced homogeneous nucleation due to partial quenching of the melt, while in Super Rheocasting (SRC) the nuclei are “second phase particles” in specially designed alloys, which are grown in a controlled fashion in a certain temperature range. Potential alloy compositions for SRC are provided. Secondly, given these melts with small particles in them, globular growth can be assured by utilizing the Gibbs‐Thomson “self healing effect” and slow further cooling to allow diffusion in the melt and to suppress constitutional supercooling. This simple recipe is applicable to various ferrous and non‐ferrous alloys. If an SRC alloy is cooled more rapidly than necessary for globular growth of the primary phase, but is held sufficiently long in the SRC range for dispersoid formation, these dispersoids can act as potent grain refiners and possibly enhance elevated temperature properties. A combination of both processes by using SRC alloys in the NRC equipment may lead to pressure tight castings with low porosity and finer grain structure than can be achieved with NRC on its own, and consequently, better mechanical properties.     

混凝土流变参数十字搅拌轴测试方法

采用十字搅拌轴剪切仪测定混凝土拌和物的流变参数（屈服应力τ0和塑性黏度η）更具准确性.通过推导给出了自制十字轴流变仪扭矩与转速关系,得出了流变参数计算公式;试验所得混凝土拌和物流变参数与已有相关理论和试验具有良好的一致性,并能量化分析混凝土触变性能,可满足施工现场连续测定混凝土工作性需求.     

基础油对锂基润滑脂流变性的影响

为考察基础油对锂基润滑脂流变性的影响,在稳态剪切流和小幅振荡剪切流下研究不同黏度基础油制备的锂基润滑脂的流变参数。通过分析触变性、屈服应力,表观黏度、储存模量和应变幅度等流变参数,探讨基础油黏度对流变性的影响。结果表明:基础油的黏度越小,锂基润滑脂的黏弹性表现更加显著,破坏其结构所需要的能量越大,其结构更加稳定。     

超高性能混凝土流变特性及其调控研究

为了实现超高性能混凝土(UHPC)流变特性的高效调控,采用膨润土作为辅助胶凝材料并对制备的UHPC进行了性能评估,包括UHPC浆体的流动度、静态屈服应力、动态屈服应力、塑性黏度和触变性,并系统分析了不同掺量的膨润土对UHPC浆体流变性能的影响。结果表明:随着膨润土掺量增加,UHPC浆体的流动度整体表现为下降趋势,下降幅度逐渐增大;当膨润土掺量由0%增加到15.0%(质量分数)时,UHPC浆体静态屈服应力、动态屈服应力和塑性黏度均显著增大,分别提高了约17.05倍、5.78倍和1.16倍;随着膨润土掺量增加,滞回环面积和触变指数增大,触变性得到明显改善。同时,掺入膨润土后仍然满足UHPC的优异力学性能要求。