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用溶胶-凝胶法制备了系列锐钛矿型掺杂稀土元素二氧化钛粉粒,在干态下对其所配制的电流变液进行了力学性能测试及其温度效应研究。结果表明,掺杂后的电流变液性能远优于同条件下所制纯二氧化钛电流变液。温度效应明显优化,在10 ℃~100 ℃均有较强的电流变活性,使用温度范围比纯二氧化钛电流变液大幅度加宽,80℃剪切应力达到最大。材料中的RE/Ti摩尔比对电流变效应影响显著,不同温度下RE/Ti=0.07~0.11之间电流变液呈现最佳的电流变效应,RE/Ti摩尔比引起电流变液介电性质的改变是电流变效应增强和不同的起因。 相似文献
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Yan-Li Shang Yun-Ling Jia Fu-Hui Liao Jun-Ran Li Ming-Xiu Li Juan Wang Shao-Hua Zhang 《Journal of Materials Science》2007,42(8):2586-2590
New nano-sized TiO2 electrorheological (ER) materials doped with different metal (M = Na, Zr, Ce, Al, Ca, Zn) oxides have been prepared. Relationships
between the composition, microstructure, conductivity, dielectric property and ER effect of these materials have been studied.
The results show that doping Na2O, ZrO2, Al2O3 or CeO2 can enhance the ER performance of the TiO2 material, whereas, doping CaO or ZnO would decrease the ER activity of the material. The shear stress (τE) of the suspension (25 wt%) of Na-doped TiO2 in dimethyl silicone oil reaches 1.6 kPa at the electric field strength E = 4.2 kV/mm and shear rate γ = 300 s−1, and its τr value of 54.6 (τr = τE/τ0, where τ0 is the shear stress at no electric field) is seven times higher than that of pure TiO2 suspension. This high τr value is very advantageous to the use. The dielectric loss tangent (tanδ) plays a dominant role in influencing the ER performance
of a particle material, and the effect of the surface area (pore volume, especially) and grain size should be taken into account. 相似文献
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合成并表征了平面梯形聚合物聚喹吖(2,3-b)啶-7,14(5,12)二酮(聚线型反式喹吖啶酮,PTQA);以PTQA为基础粒子,溴代二苯甲烷(BDPM)为分散介质制备了无水型电流变流体(ERF),考察了其电流变性能。研究了体系中粒子浓度、外加电场强度、剪切速率等对电流变流体的剪切应力、屈服应力和表观黏度的影响,考察了电流变流体的温度效应。结果表明,PTQA-BDPM体系是一种性能优良的电流变流体,粒子质量分数为30%的流体室温屈服应力达到6.0 kPa(3 kV/mm);体系的剪切应力随温度升高而增大,且在高温区间具有较强的温度效应。 相似文献
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以间苯二胺,2,5-二氧环己二甲酸二甲酯为原料,经缩合、闭环、氧化等反应,制得了聚喹吖(2,3b)啶-12,14(5,7)二酮(PQA)并进行了表征;并以PQA为基础粒子制备了无水型电流变流体(ERF),研究了其电流变性能。考察了溴代二苯甲烷(BDPM)-PQA体系中粒子浓度、电场强度、剪切速率等对电流变流体性能的影响,并从聚合物粒子的分子结构特点出发,对该体系的电流变效应进行了解释;对比了不同分散介质(BDPM及硅油)对电流变效应的影响。结果表明,PQA在BDPM中具有较佳的电流变效应,当粒子的质量分数为30%,外加电场为3 kV/mm时,屈服应力达4.0 kPa。 相似文献
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Cr离子改性氧化钛/丙烯酰胺纳米电流变液及其性能研究 总被引:1,自引:0,他引:1
采用醇盐水解法, 合成了铬离子改性氧化钛/丙烯酰胺纳米颗粒. XRD、TEM、粒度分析显示颗粒为无定型态, 平均粒径为140nm, Cr离子与十二烷基苯磺酸钠的同时加入对粒径的减小有协同作用. 粒径减小可引起颗粒浸润性的改善. 当Cr/Ti摩尔比为10%时, 所得颗粒配制的电流变液显示出极好的电流变效应: 在4kV/mm直流电场下, 该电流变液的静态剪切应力高达152kPa. 离子掺杂与浸润性的改善是电流变液力学性能提高的原因. 相似文献
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结合改进的水解法和溶胶-凝胶法,制备了丙三醇/羧甲基淀粉/改性纳米氧化钛复合颗粒,分析表明羧甲基淀粉和纳米氧化钛之间存在有相互作用;同时,介电测试表明此颗粒配制的电流变液的介电极化特性有很大改善.经流变学测试,此复合颗粒电流变液的动态剪切应力在颗粒质量分数为25%,剪切速率为100s-1,3kV/mm DC下为960Pa,剪切增幅比为35.同时,此电流变液的静态屈服应力在更高浓度,5kV/mm DC下可达到18kPa,比同等条件下改性氧化钛和CMS电流变液的静态屈服应力均有所提高.此外,这种电流变液还表现出较好的抗沉降性能. 相似文献
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聚邻苯二胺/蒙脱土纳米复合材料的合成及其电流变效应 总被引:2,自引:2,他引:0
用乳液共混插层法制备了聚邻苯二胺/蒙脱土纳米复合材料微粒,通过IR、XRD及TEM对其结构进行了表征。 结果发现,邻苯二胺插入蒙脱土层间聚合后,导致蒙脱土片层之间的剥离,形成纳米复合材料。 将其分散在甲基硅油中(体积分数,22%)配制成无水电流变液,该复合材料表现出较大的协同效应,具有较好的电流变行为。实验结果表明在外加电场下,其电流变效应比聚邻苯二胺、蒙脱土均有显著提高。 在3 kV/mm(DC, 74.5 s-1)时,剪切强度达8.27 kPa;同时抗沉降性极好,静置60 d沉淀率小于3%。介电性能测试表明,聚邻苯二胺/蒙脱土纳米颗粒的介电常数和介电损耗较蒙脱土和聚邻苯二胺均有一定提高,电导率也达到了最佳范围。 相似文献
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Zhi-Wei Pan Yan-Li Shang Jun-Ran Li Song Gao Yan-Li Shang Rui-Li Huang Juan Wang Shao-Hua Zhang Yuan-Jing Zhang 《Journal of Materials Science》2006,41(2):355-362
A new class of electrorheological (ER) material, rare earth (RE = Ce, Gd, Er and Y) complexes of phosphate cellulose, has
been synthesized using microcrystalline cellulose, phosphoric acid, urea and RE(NO3)3 solutions as starting materials. The ER properties of suspensions of microcrystalline cellulose, phosphate cellulose [cellulose-P-ONH4] and the [cellulose(-P-O)3RE] complex particle materials in silicon oil have been investigated under DC electric field. The formation of rare earth
complexes helps to decrease the shear stress and viscosity at zero electric field, and to enhance the ER effect of the materials.
The shear stress (τE) of the ER fluid (20% weight fraction) of a typical yttrium complex [cellulose(-P-O)3Y], the yttrium content of which is 0.04 mol/100 g, is 2.3 kPa at 4.2 kV/mm and 300 s−1 with a τr value (τr = τE/τ0, where τ0 is the shear stress at no electric field and 300 s−1) of 34.3, which is 18 times higher than that of pure microcrystalline cellulose suspensions. The improvement of dielectric
loss tangent of the material, due solely to the formation of rare earth complexes, resulted in an enhancement in the ER effect
of the material. In addition, the cellulose(-P-O)3RE materials possess better thermal stability, and their suspensions are more stable in the anti-sedimentation than that of
the cellulose-P-ONH4 material. 相似文献
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Electrorheological (ER) properties of synthesized, pristine poly(p-phenylene) (PPP) particles without any dopant treatment was investigated via flow curves including shear viscosity and yield stress. The ER characteristics were examined as functions of both particle concentration and applied electric field strengths. This undoped, PPP based suspension exhibited normal ER characteristics displayed by conventional semi-conducting polymeric ER materials with doping. The yield stress, which is an important design parameter for ER fluids, satisfied a universal scaling function. We found that the critical electric field strength for the undoped PPP suspension was much higher than the doped PPP suspension. These undoped particles can be used as a model system to test the doped system at low concentration via a universal scaling function. 相似文献
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Ling ZHENG Yinong LIState Key Laboratory of Mechanical Transmission Chongqing University Chongqing ChinaAssoc. Prof. Ph.D. 《材料科学技术学报》2005,21(1):83-86
Graphite/TiO2 composite particles were obtained by sol-gel technique in this paper. The structure and characteristic of the composite particles are analyzed by XRD, SEM and TG-DTA. The electrorheological properties of the ER fluid containing the particles were measured by a Couette-type rheometer under shear rates of 1~136 s-1 and AC electric fields of 0~3 kV/mm. The experimental results show that the leaking current density of the ER fluid is higher than that of pure titanium dioxide particles dispersed in damping oil. The shear yield stress of the ER fluid increases with increasing electric field and exhibits a typical Bingham flow behavior. The suspension demonstrates an excellent ER performance (τ/τ0=1200) compared with conventional ER fluids (τ/τ0 ≤500). The sedimentation of the ER fluid is improved obviously due to the coating effect of the particles. 相似文献
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Pumice particles-based electrorheological (ER) suspensions were prepared in silicone oil and its ER behavior was investigated
as a function of shear rate, electric field strength, concentration and temperature. Sedimentation stabilities of suspensions
were determined. ER activity of all the suspensions was observed to increase with increasing electric field strength, concentration
and decreasing shear rate. Yield stress of pumice suspensions increased linearly with increasing applied electric field strength
and with concentrations of the particles. The pumice suspensions show a typical shear thinning non-Newtonian viscoelastic
behavior, in which viscosity of suspension decreased sharply with increasing shear rate. Effect of high temperature onto ER
activity of pumice/silicone oil system was also investigated. 相似文献
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Toemphong Puvanatvattana Datchanee Chotpattananont Piyanoot Hiamtup Sumonman Niamlang Ruksapong Kunanuruksapong Anuvat Sirivat Alexander M. Jamieson 《Materials science & engineering. C, Materials for biological applications》2008,28(1):119-128
Electrorheological properties of polythiophene/polyisoprene suspensions were investigated in the oscillatory shear mode under electric field varying from 0 to 2 kV/mm. Poly(3‐thiophene acetic acid) particles were synthesized via an oxidative polymerization and doped with perchloric acid in order to vary electrical conductivity. ER responses can be enhanced with increasing electric field strength, particle electrical conductivity, and particle concentration. The storage modulus (G′) increases dramatically by 3 and 4 orders of magnitude, with the variations of particle conductivity and particle concentration as the electric field strength is increased from 0 to 2 kV/mm The results can be interpreted in terms of the difference in the polarizability between the particles and the matrix, and the particle agglomeration existing at high particle electrical conductivity and high particle concentration. The suspensions exhibit the transitions from the fluid‐like behavior to the solid‐like behavior at the critical electric field strengths. In particular, the sol‐to‐gel transitions occur at lower electrical field strengths with higher particle electrical conductivity and at higher particle concentration. 相似文献
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温度对电流变液体流变行为的影响 总被引:2,自引:0,他引:2
研究了温度对硅铝酸盐、沸石、高分子、钛酸钡悬浮相电流变液体(ERF)抗剪强度及表观粘度的影响规律,结果表明,温度的作用规律主要受外加电场强度和悬浮相数量的影响,与剪切速率的大小无明显关系。温度升高,在高的外加场强下,硅铝酸盐系ERF和沸石系ERF的抗剪强度有明显峰值出现;高分子材料悬浮相ERF也有峰值现象;BaTiO3悬浮相ERF的抗剪强度则单调下降。 相似文献
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Rong Shen Xuezhao Wang Yang Lu De Wang Gang Sun Zexian Cao Kunquan Lu 《Advanced materials (Deerfield Beach, Fla.)》2009,21(45):4631-4635
Recent works on the development of various electrorheological (ER) fluids composed of TiO2, Sr? Ti? O, and Ca? Ti? O particles coated with C? O/H? O polar groups are summarized, in which an extremely large yield stress up to 200 kPa is measured and the dynamical yield stress reaches 117 kPa at a shear rate of 775 s?1. Moreover, unlike that of traditional dielectric ER fluids, the yield stress displays a linear dependence on electric field strength. Experimental results reveal that it is the polar molecules adsorbed onto the dielectric particles that play the decisive role: the polar‐molecule‐dominated ER effect arises from the alignment of polar molecules by the enhanced local electric field in the gap between neighboring particles. The pretreatment of electrodes and the contrivance of new measuring procedures, which are desirable for the characterization and practical implementation of this material, are also discussed. The successful synthesis of these fluids has made many of the long since conceived applications of the ER effect available. 相似文献
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代少俊 《中国材料科技与设备》2012,(1):30-32
制备了偶联剂修饰的稀土离子掺杂TiO2,将其与羟基硅油反应,制备得到了ERF;利用红外分析、热分析、透射电镜和电子能谱对其结构进行了分析,结果表明,稀土离子被引入,偶联剂对粒子结构有影响;对电流变效应测试结果表明偶联剂和稀土离子对该体系的电流变有较大影响;高电场强度下,偶联剂KH-570的电流变液明显优于偶联剂A-151和KH-401,而稳定性则相反;稀土Ce和Eu比稀土La掺杂的效果更明显。 相似文献
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研究试制了乳状电流变基液,以二甲基硅油为基体,二甲基亚砜作添加剂,在超声波的作用下使二甲基亚砜分散于硅油中形成稳定的乳状液,测试了该乳液的介电常数,电导率及介电损耗。以此乳液作基液,与稀土改性TiO2和BaTiO3等固体颗粒配成电流变液,并对其流变性能进行测试。实验结果表明:用该乳液作基液配制的电流变液化用纯硅油作基液配制的电流变液介电性能有较大的改善,电流变性能显著提高。 相似文献