EFFECT OF RARE EARTH SUBSTITUTION ON ELECTRORHEOLOGICAL PROPERTIES OF TiO2

2002 ◽  
Vol 16 (17n18) ◽  
pp. 2371-2377 ◽  
Author(s):  
X. P. ZHAO ◽  
J. B. YIN ◽  
L. Q. XIANG ◽  
Q. ZHAO
Keyword(s):  
Shear Stress ◽  
Rare Earth ◽  
Silicone Oil ◽  
Anatase Phase ◽  
New Class ◽  
Dc Electric Field ◽  
Er Fluids ◽  
Er Fluid ◽  
Electrorheological Properties ◽  
Rare Earth Substitution

This paper describes a new class of water-free electrorheological (ER) fluids based on nonaqueous doped TiO 2 with rare earth (RE) in silicone oil. The thermal character and crystal structure of these materials are investigated with DSC, TG and XRD. The doped TiO 2 crystals possess anatase phase and their lattice spacing varies significantly with the content of rare earth. The rheological measurements show that the doped TiO 2 ER fluid exhibits an obviously higher shear stress than that of pure TiO 2 ER fluid under dc electric field. Especially, substitution with 10mol% cerium or 8mol% lanthanum for Ti can obtain a relatively high shear stress. On the basis of dielectric and conduction measurements, we preliminarily discuss the influence of the doping of rare earth on ER effects of TiO 2.

HIGH PERFORMANCE CALCIUM TITANATE NANOPARTICLE ER FLUIDS

2005 ◽  
Vol 19 (07n09) ◽  
pp. 1110-1113 ◽  
Author(s):  
XUEZHAO WANG ◽  
RONG SHEN ◽  
WEIJIA WEN ◽  
KUNQUAN LU
Keyword(s):  
High Performance ◽  
Silicone Oil ◽  
Calcium Titanate ◽  
Hydroxyl Group ◽  
Long Term Stability ◽  
Dc Electric Field ◽  
Wet Chemical ◽  
Er Fluids ◽  
Er Fluid

A type of calcium titanate (CTO) nanoparticles was synthesized by means of wet chemical method [1] without coating on the particles. The CTO/silicone oil ER fluid exhibits excellent electrorheological properties: high shear stress (~50-100 kPa ) under dc electric field, a low current density (less than 2μA/cm2 at 5kV/mm), and long term stability against sedimentation. Although there are not special additives in the ER fluids, it is found from the chemical analysis that a trace of alkyl group, hydroxyl group, carbonyl group and some ions is remained in the particles which may dominate the ER response.

ELECTRORHEOLOGICAL BEHAVIORS OF POLYANILINE-MONTMORILLONITE CLAY NANOCOMPOSITE

2002 ◽  
Vol 16 (17n18) ◽  
pp. 2521-2527 ◽  
Author(s):  
JUN LU ◽  
XIAOPENG ZHAO
Keyword(s):  
Dielectric Constant ◽  
Shear Stress ◽  
Electric Fields ◽  
Room Temperature ◽  
Silicone Oil ◽  
Weight Fraction ◽  
Influential Factors ◽  
Dc Electric Field ◽  
Er Fluid ◽  
Xrd And Tem

Polyanilline-montmorillonite nanocomposite (PANI-MMT) particles were synthesized by an emulsion intercalation method and characterized by IR, XRD and TEM spectrometry. TEM showed that the particle's size of MMT-PANI particles was about 100 mm. The dielectric constant of PANI-MMT nanocomposite was increased 2.4 times than that of MMT and 7 times than PANI, the conductivity of PANI-MMT particles was increased was increased 10 times than that of MMT. Meanwhile, the dielectric loss tangent was also increased about 1.36 times than that of PANI. The electrorheological behaviors of the suspensions of PANI-MMT nanocomposite in silicone oil with a 30% weight fraction were investigated under DC electric fields. In 3 kV/mm DC field at room temperature, the yield stress was 8.26 kPa (shear 5 s -1). In 4 kV/mm DC field, the shear strength was 8.30 kPa (γ = 103.1 s -1, T = 20°C), and much higher than that of pure polyaniline (PANI), montmorillonite (MMT) and mixture of polyaniline with clay (MMT + PANI). The sedimentation experiment showed that the PANI-MMT nanocomposite particles did not deposit during about two months. The relevant influential factors between shear stress and electric fields, between shear stress and shear rate, between shear stress and temperature was also discussed preliminarily. The results showed that the MMT-PANI ER fluid displays a notable ER effect under DC electric field.

ELECTRORHEOLOGY OF DISPERSIONS OF BaxSr(1-x)TiO3 IN SILICONE OIL UNDER AC OR DC ELECTRIC FIELD

2012 ◽  
Vol 26 (14) ◽  
pp. 1250081 ◽  
Author(s):  
GLAUBER M. S. LUZ ◽  
ANTONIO J. F. BOMBARD ◽  
SILVIO L. M. BRITO ◽  
DOUGLAS GOUVÊA ◽  
SHEILA L. VIEIRA
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Electric Field ◽  
Silicone Oil ◽  
Ferroelectric Materials ◽  
Dc Electric Field ◽  
Ac Fields ◽  
Er Fluid ◽  
Constant Shear Rate

Electrorheology (ER) of ferroelectric materials such as nanometric BaTiO 3 is still not fully understood. In this paper, nanoparticles of Ba x Sr (1-x) TiO 3 (where x = 0.8, 0.9 or 1.0) were synthesized using the method of Pechini, calcinated at 950°C, and after, lixiviated under pH 1 or pH 5. A controlled stress rheometer (MCR-301) was used to make the ER characterization of dispersions made of Ba x Ti 1-x O 3 in silicone oil (30% w/w), where (a) shear stress as a function of DC electric field (under constant shear rate) or (b) shear stress as a function of shear rate (under constant AC or DC electric field) were measured. We observed that electrophoresis occurred under electric field DC, creating a concentration gradient which induced phase separation in ER fluid. On the other hand, under AC fields above 1 kV/mm, the ER effect is stronger than for DC field, and almost without electrophoresis. Furthermore, there is an AC frequency, dependent on the disperse phase, where the ER effect has a maximum.

YIELD PROCESS OF ELECTRORHEOLOGICAL FLUID WITH POLYANILINE PARTICLE

1994 ◽  
Vol 08 (25) ◽  
pp. 1563-1575 ◽  
Author(s):  
KIYOHITO KOYAMA ◽  
KEIJI MINAGAWA ◽  
TAMOTSU YOSHIDA ◽  
NORIYUKI KURAMOTO ◽  
KATSUFUMI TANAKA
Keyword(s):  
Shear Stress ◽  
Electric Field ◽  
Particle Concentration ◽  
Silicone Oil ◽  
Electrorheological Fluid ◽  
Yield Behavior ◽  
Wide Range ◽  
Dc Electric Field ◽  
Er Fluid ◽  
Flow Experiments

Electrorheological behaviors of polyaniline/silicone oil suspension were observed by using a modified Couette type rheometer with high resolution for shear stress. The yield behaviors were examined over a wide range of shear strain. The storage modulus and loss tangent were determined under a constant dc electric field. It was clarified that the polyaniline-based ER fluid yields two different strain amplitudes, i.e. about 1% and 50%. The stress-strain curves obtained from shear flow experiments also suggested the existence of two-step yield process. The yield process was found to be dependent on the electric field strength and the particle concentration in different manners. The yield behavior observed is discussed in relation to the structure of particle clusters which causes the ER effect.

Dependence of the shear stress on particle properties in electrorheological fluids

2001 ◽  
Vol 15 (06n07) ◽  
pp. 938-946 ◽  
Author(s):  
Kunquan Lu ◽  
Yucheng Lan ◽  
Shouqiang Men ◽  
Xiaoyu Xu ◽  
Zhao Xianpeng ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Shear Stress ◽  
Silicone Oil ◽  
Theoretical Calculations ◽  
Ferroelectric Material ◽  
Electrorheological Fluids ◽  
Particle Properties ◽  
Er Fluids ◽  
Er Fluid ◽  
Curie Temperature Tc

By measuring the shear stress of a ferroelectric particle/silicone oil ER fluid varying with the temperature across Tc, the dependence of ER effect on permittivity mismatch is quantitatively obtained. The dielectric property of ferroelectric material behaves a dramatic change at Curie temperature (Tc) either in the dielectric constant and the conductivity. TGS and KNO 3 ferroelectric particles are chosen for studying the dielectric constant and conductivity dependence of the shear stress in ER fluids respectively. The measured results are more reliable, because the conditions, such as size, shape, composition of particles, especially chemical nature of particles and interface property between particles and liquid, all are same. The available theoretical calculations can not well fit our measured results. In order to consider the properties of whole suspensions, the orientation of the particles with spontaneous polarization under an electric field was studied in advance.

Measurement of Interaction Forces at Small Distance under Electric Field in a Smectite Dispersed Silicone Oil Based ER Fluid

2001 ◽  
Vol 15 (06n07) ◽  
pp. 811-816 ◽  
Author(s):  
Toyohisa FUJITA ◽  
Toshio MIYAZAKI ◽  
Toshiharu TANAKA ◽  
Ke Jun Liu ◽  
Eiich KUZUNO ◽  
...  
Keyword(s):  
Electric Field ◽  
Silicone Oil ◽  
Small Distance ◽  
Surface Forces ◽  
Attraction Force ◽  
Interaction Forces ◽  
Repulsive Energy ◽  
Inflection Points ◽  
Dc Electric Field ◽  
Er Fluid

The apparatus to measure interaction forces under an electric field at small distance between a conductive hemisphere and a flat plate has been developed. The surface forces at small distance sandwiched ER fluid dispersing ultrafine smectite particles (20 to 50 nm thickness) in silicone oil has been measured. This fluid shows 0.7 kPa of apparent yield stress by applying 2.5 kV/mm of DC electric field. When an electric field applies to this ER fluid, the repulsive energy curves shows inflection points at about 0.2 μ m distance periodically at small distance of less than 1 μ m because the repulsion force decreases for a vacancy of particles after the particles are pushed out and the dipole attraction force acts between hemisphere and plate. On the other hand, when the electric field becomes off and it passes enough time, the inflection points is observed more shorter distance of about 0.15 μ m periodically. The coagulated particle size is estimated about 0.15 μ m under no electric field and becomes larger by applying electric field.

LANTHANUM TITANATE NANOPARTICLES ER FLUIDS WITH HIGH PERFORMANCE

2012 ◽  
Vol 26 (13) ◽  
pp. 1250079 ◽  
Author(s):  
DE WANG ◽  
RONG SHEN ◽  
SHIQIANG WEI ◽  
KUNQUAN LU
Keyword(s):  
Yield Stress ◽  
Silicone Oil ◽  
Heating Temperature ◽  
Hydroxyl Group ◽  
Lanthanum Titanate ◽  
Different Temperatures ◽  
Static Yield ◽  
Er Fluids ◽  
Er Fluid ◽  
Static Yield Stress

A new type of electrorheological (ER) fluid consisting of lanthanum titanate (LTO) nanoparticles is developed. The ER fluids were prepared by suspending LTO powder in silicone oil and the particles were fabricated by wet chemical method. This ER fluid shows excellent ER properties: The static yield stress reaches over 150 kPa under 5 kV/mm with linear dependence on the applied DC electric field, and the current density is below 10 μA/cm2. In order to investigate the affect factor on the ER behavior, the LTO powder were heated under different temperatures. The ER performances of two particles treated under different temperatures were compared and the composition changes for those particles were analyzed with TG-FTIR technique. It was found that the static yield stress of the suspensions fell from over 150 kPa to about 40 kPa and the current densities decreased prominently as the rise of the heating temperature. TG-FTIR analysis indicated that polar groups remained in the particles such as alkyl group, hydroxyl group and carbonyl group etc., contribute to the ER effect significantly. The experimental results are helpful to understand the mechanism of the high ER effect and to synthesize better ER materials.

Electrorheological Properties of Ni-Group Nano Particles and Multilayer Compound Polar Molecule Modify

2012 ◽  
Vol 476-478 ◽  
pp. 1749-1752
Author(s):  
Suo Kui Tan ◽  
Xiao Ping Song ◽  
Song Ji ◽  
Hong Zhao ◽  
Min Wu ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Shear Stress ◽  
Polar Molecule ◽  
Nano Particles ◽  
Core Shell ◽  
Shell Particles ◽  
The Relationship ◽  
Er Fluid ◽  
Electrorheological Properties ◽  
Molecule Type

This paper emphasis has researched the ER properties of Ni group core-shell nano particles modifier with Urea，SDBS and other polar molecule，analysis the relationship among ER properties and polar molecule type ，compound modifier under different electric field or magnetic field. It is found that the shear stress increasing with adding polar molecule, compound polar molecule modify can marked advance the properties of Ni group core-shell particles ER fluid.

Effect of Urea Content on Properties and Microstructure of Ni/TiO2 Group Particles ER Fluid

2012 ◽  
Vol 496 ◽  
pp. 25-29 ◽  
Author(s):  
Suo Kui Tan ◽  
Xiao Ping Song ◽  
Hong Zhao ◽  
Song Ji ◽  
Hong Yan Guo ◽  
...  
Keyword(s):  
Electric Field ◽  
Mass Ratio ◽  
Microstructure Observation ◽  
Urea Content ◽  
Column Structure ◽  
Dc Electric Field ◽  
Er Fluids ◽  
Er Fluid

This paper emphasis have researched the effect of Ni/TiO2group particles modifier with Urea by properties and microstructure，it has showed that ER activity of the particles were closely associated with urea content. When the mass ratio of urea/Ti is 30%, The microstructure observation of the ER fluids under DC electric field showed that the particles aggregated to form thicker and dense column structure when the mass ratio of Urea/Ti is 30%, while the column structure were broken when excessive urea (>30%) was added. A thin and loose column structure was formed in non-urea added ER fluid.

Electrorheological Properties of Suspensions Based on Polyaniline-montmorillonite Clay Nanocomposite

2002 ◽  
Vol 17 (6) ◽  
pp. 1513-1519 ◽  
Author(s):  
Jun Lu ◽  
Xiaopeng Zhao
Keyword(s):  
Dielectric Constant ◽  
Dielectric Loss ◽  
Yield Stress ◽  
Electric Fields ◽  
High Dielectric Constant ◽  
Silicone Oil ◽  
Transmission Electron ◽  
High Dielectric ◽  
Er Fluid ◽  
Electrorheological Properties

It is thought that high-dielectric constant, suitable conductivity, and dielectric loss dominate electrorheological (ER) effects. According to this viewpoint, the polyaniline/montmorillonite nanocomposite (PANI-MMT) particles with high-dielectric constant and suitable conductivity were synthesized by an emulsion intercalation method. The electrorheological properties of the suspensions of PANI-MMT particles in silicone oil have been investigated under direct current electric fields. At room temperature, it was found that the yield stress of PANI-MMT ER fluid was 7.19 kPa in 3 kV/mm, which is much higher than that of pure polyaniline (PANI), that of pure montmorillonite (MMT) as well as that of the mixture of polyaniline with clay (PANI+MMT). In the range of 10–100 °C, the yield stress changed only 6.5% with the variation of temperature. The sedimentation ratio of PANI-MMT ERF was about 98% after 60 days. The structure of PANI-MMT particles was characterized by infrared, x-ray diffraction (XRD), and transmission electron microscopy (TEM) spectrometry, respectively. The XRD spectra show that the inner layer distance of PANI-MMT can be enhanced to 1.52 nm when the PANI was inserted into the interlayer of MMT, whereas it is only 0.96 nm for free MMT. TEM shows that the diameter of PANI-MMT particles is about 100 nm. The dielectric constant of PANI-MMT nanocomposite was increased 5.5 times that of PANI and 2.7 times that of MMT, besides, the conductivity of PANI-MMT particle was increased about 8.5 times that of PANI at 1000 Hz. Meanwhile, the dielectric loss tangent can also be increased about 1.7 times that of PANI. It is apparent that the notable ER effect of PANI-MMT ER fluid was attributed to the prominent dielectric property of the polyaniline-montmorillonite nanocomposite particles.

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