CN1055111C - Composite strontium titanate electrically rheological liquid and its preparation - Google Patents

Abstract

The present invention relates to a technique for manufacturing composite dielectric materials, particularly to a technique for preparing electrorheological fluid with collochemistry methods. The present invention aims to provide applicable electrorheological fluid with stable structure, little sedimentation and high shear strength (7KPa) and a method. The present invention uses SrCl2, TiCl4, oxalate (or oxalic acid), citric acid, oxalic acid ester, acetamide, etc. as raw materials so as to prepare seasoning liquid, 0.1 to 0.9M% of acetamide as an accelerant is added after the seasoning liquid is seasoned again, centrifugated, washed, dried in vacuum and sintered, the solution is then uniformly mixed, and composite SrTiO3 electrorheological fluid is obtained after the solution is dried by evaporation in a water bath and sintered. Composite strontium titanate electrorheological fluid is prepared after the composite SrTiO3 electrorheological fluid, together with 200<#> silicon oil, is uniformly mixed and agitated according to different volume proportion. When the material is applied to a voltage of 2.5 KV/mm, the shear strength reaches 7KPa, and the sedimentation rate is 98% after the material is placed for 2 months.

Description

Composite strontium titanate electrically rheological liquid and preparation method thereof

The present invention relates to a kind of dielectric substance, particularly relate to and utilize the colloid chemistry method to prepare composite strontium titanate electrically rheological liquid and method.

Electrorheological fluid is very valued at present intelligent liquid, and when extra electric field, the viscosity of this liquid (being shearing resistance) increases 4-5 the order of magnitude (millisecond meter) immediately and becomes similar solid.In case remove external electric field, this material recovers original liquid state again, its shearing resistance approximate with square being directly proportional of extra electric field intensity, thereby can continuously change shearing resistance by the adjusting impressed voltage.The new kink characteristics of this material has important application prospects technically.Its major advantage be the time of response soon, continuously adjustable, energy consumption is low, be convenient to computer control.Can realize control, transmission, the damping of electromechanical integration.For example can make aspects such as vibroshock, clutch coupling, stepless speed regulation, brake, valve uses and uses at industrial sectors such as automatization, robot, automobile, aviations.

The shearing force of a kind of electro-rheologic fluid material that Japan National Oil Corporation releases in novel material exhibition in 1994 is 2Kpa (concrete material does not have open).Our country has minority unit to begin to carry out the research of electro-rheologic fluid materials such as silico-aluminate, polyacrylonitrile-radical, polyisobutene acid and application facet in the late nineteen eighties.But also can not find a kind ofly under low voltage at present in the world, shearing resistance is little up to steady chemical structure, the proportion of 5Kpa, is difficult for settled inorganic salt electro-rheologic fluid material.

China carried out a large amount of research work in this respect, as Chinese patent application: disclose a kind of strontium titanate current liquid and preparation method thereof No. 95107425.3.This method adopts the raw material of the above grade of chemical pure, uses SrCl ₂, TiCl ₄As cation group and MCl ₃(wherein M can be light rare earthss such as La, Y, Nd, Ce) is as doping agent; Oxalate as: oxalic acid potassium, sodium salt or oxalic acid are as anionic group; Can also add an amount of citric acid as sequestering agent, the pH value of regulating ageing solution is between 2-5; Also can add an amount of alcohol ester oxalate again and play the colloidal sol effect, press Sr as solvent _1-XM _XTiO ₃Form (wherein X=0-0.4) and come the proportioning weighing, get SrCl ₂Press Sr ²⁺0.05-0.4mol/l, TiCl ₄Press Ti ⁴⁺0.05-0.4mol/l; Oxalic acid is 0.1-0.8mol/l; And by Sr _1-XM _XTiO ₃The content of middle X is determined MCL ₃Weight, mix, this is an ageing liquid, again ageing liquid was placed in 50 ℃ of-70 ℃ of waters bath with thermostatic control ageing 10-50 minute, and used water-cooled then, centrifugal, after centrifugal throw out use the second distillation water washing again three times, after the general vacuum-drying, put into 950 ℃ of sintering 5-10 of retort furnace hours, can obtain white adulterated strontium titanate particle; It and silicone oil etc. are mixed SrTiO by the different volumes proportion by subtraction ₃+ silicone oil is proportion by subtraction by volume, promptly presses: $\mathrm{\&Phi;}=\frac{\mathrm{Vp}}{\mathrm{Vp}+V_f}$

In the Vp=particle cumulative volume formula

V _fThe volume of=oil is made into adulterated strontium titanate current liquid.This method is because its temperature effective is good inadequately, and shearing resistance is reduced to 2Kpa (2.5KV/mm) in the time of 60 ℃, and it is very big to be higher than 60 ℃ of temperature down cut intensity reductions, can't use.Therefore this method has limitation, and material property is not ideal enough.

The objective of the invention is to overcome the shortcoming and defect of above-mentioned technology, in order to improve the overall target of electrorheological fluid performance, a kind of Stability Analysis of Structures is provided, sedimentation hardly, temperature effective is good, shearing resistance is higher, and more than 90 ℃, 2.5KV/mm (DC) shearing resistance reaches the composite strontium titanate electrically rheological liquid of making electrorheological fluid components and parts (using value being arranged as vibroshock, clutch coupling etc.) of 7Kpa and a kind of method that simply is suitable for suitability for industrialized production is provided.

The object of the present invention is achieved like this:

One, composite strontium titanate electrically rheological liquid of the present invention is by number being the SrTiO that 95107425.3 methods make by Chinese patent application ₃Add the 0.1-0.9M/L acetamide solution in the homodisperse particle and do electric rheological effect promotor, make the composite strontium titanate electrically rheological liquid material, its molecular formula: (SrTiO ₃) _1-Y(CH ₃CONH ₂) _YY=0.1-0.7 wherein.

Two, method

It is to adopt SrCl that the present invention prepares the composite strontium titanate electrically rheological liquid method ₂, TiCl ₄, oxalate (or oxalic acid), citric acid, alcohol ester oxalate, ethanamide etc. are made raw material, press Sr _1-XM _XTiO ₃The ratio weighing, M=La wherein, Y, Nd, Ce, the X=0-0.4 mixing and stirring is made into ageing liquid, ageing liquid was placed in 50 ℃ of-70 ℃ of waters bath with thermostatic control ageing 10-50 minute, use water-cooled then, centrifugal, the gained throw out is used the second distillation water washing three times again after centrifugal, after vacuum-drying, put into retort furnace at 950 sintering 5-10 hours, can obtain the adulterated strontium titanate particle of white spheroidal particle, concentration 0.1-0.9M% acetamide solution is mixed, acetamide solution is a kind of promotor of electric rheological effect, and when conductive ion was not enough, ethanamide self can produce certain conductive ion NH ⁺ ₄So, add ethanamide and can promote electric rheological effect.Because 221.2 ℃ of ethanamide boiling points all can strengthen current effect more than 100 ℃.The white spheroidal particle strontium titanate doping that mixes current effect promotor is stirred,, put into 700 ℃ of following sintering of retort furnace 4 hours, take out back and 200 at 65 ℃ of water bath methods ^#Silicone oil mixes, and its blending ratio 0.23-0.65 by volume mixes and is composite strontium titanate electrically rheological liquid.

The advantage of composite strontium titanate electrically rheological liquid of the present invention and method is:

1, when applying low voltage 2.5Kv/mm, the shearing resistance of this material is up to 7Kpa

2, this material sedimentation was hardly placed more than 550 hours, and its subsidence rate reaches 99%, and placing 2 months subsidence rate is 98%;

3, null field viscosity is approximately zero:

4, steady chemical structure;

5, the particle of this material chain porous spherical in shape shape; Can be used for preparing vibroshock, clutch current becomes the liquid components and parts;

6, this method preparation is simple, easy handling and suitability for industrialized production, yield rate height.

Below in conjunction with drawings and Examples the present invention is described in detail:

Fig. 1, compound SrTiO ₃Spherical chain, porous shape particulate transmission electron microscope photo.

Fig. 2, compound SrTiO ₃The electrorheological fluid shearing resistance is to the change curve (under the differing temps) of extra electric field.

Fig. 3, compound SrTiO ₃Electrorheological fluid subsidence rate curve.

Fig. 4, compound SrTiO ₃The electrorheological fluid shear rate curve.

Table 1 is that electrorheological fluid international standard and electrorheological fluid performance of the present invention compare.Embodiment 1: prepare compound (SrTiO ₃) _0.7(CH ₃CONH ₂) _0.3Electrorheological fluid:

With 120ml concentration is that the oxalic acid solution of 1mol adds that to contain 50ml concentration be 1mol/l SrCl ₂And 50ml concentration is 1mol/l TiCl ₄, citric acid 10g in the acetate two alcohol ester 10ml aqueous solution, adds water 770ml, makes to mix consisting of of back system: 0.05mol/l Sr ²⁺, 0.05mol/l Ti ⁴⁺, the 0.12mol/l oxalic acid, dissolve in 17.7 the gram ethanamides stir, this ageing liquid is placed 65 ℃ of water bath with thermostatic control ageings 50 minutes, water-cooled, centrifugal.The gained throw out is with second distillation water washing three times, vacuum-drying, and 700 ℃ of sintering 4 hours, products therefrom 6 grams are with 200 ^#5 milliliters of silicone oil by volume proportion by subtraction 0.30 are mixed into electrorheological fluid, and the relation of its shearing resistance and extra electric field as shown in Figure 2.Working temperature is up to more than 80 ℃, and subsidence rate as shown in Figure 3.This composite strontium titanate electrically rheological liquid is suitable for making components and parts such as vibroshock.

Embodiment 2: prepare a kind of compound (Sr that contains Y _0.8Y _0.2TiO ₃) _0.5(CH ₃CONH ₂) _0.5Electrorheological fluid.

With 240ml concentration is that the oxalic acid solution of 1mol/l adds that to contain 100ml concentration be 1mol/l SrCl ₂And 100ml concentration is 1mol/l TiCl ₄, 20ml concentration is 1mol/l YCl ₃, citric acid 209 in the alcohol ester oxalate 10ml aqueous solution, adds water 510ml, makes consisting of of mixed back system: 0.1mol/l Si ²⁺, 0.1mol/lTi ⁴⁺, 0.24mol/l oxalic acid, 0.02mol/l Y ³⁺, dissolve in 29.5 gram ethanamides, stir, this ageing liquid is placed 60 ℃ of water bath with thermostatic control ageings 30 minutes, can add citric acid ageing liquid pH value is transferred between the 2-5.Through water-cooled, centrifugal after the gained throw out with second distillation water washing three times, vacuum-drying, 700 ℃ of sintering 4 hours in retort furnace then, promptly get original proportioning is (Sr _0.8Y _0.2TiO ₃) _0.5(CH ₃CONH ₂) _0.5White particle be composite strontium titanate electrically yttrium particle, claim its 7 gram with 200 ^#5 milliliters of silicone oil by volume proportion by subtraction are 0.38 to be mixed with electrorheological fluid.The yttrium composite strontium titanate electrically rheological liquid composite of performance index of mixing of the present invention's preparation all reaches when applying 2.5KV/mm voltage, and its shearing resistance is up to 7Kpa.

Embodiment 3: preparation contains the compound (Sr of Nd _0.9Nd _0.1TO ₃) _0.9(CH ₃CONH ₂) _0.1Strontium titanate current liquid

Described the same with embodiment 2 technologies, according to Sr _1-XM _XTiO ₃It is Nd that composition is chosen M ₂O ₃0.02mol/l, add ethanamide 5.9 grams, stir, this ageing liquid is placed 60 ℃ of water bath with thermostatic control ageings 30 minutes, through water-cooled, centrifugal after, the gained throw out is with second distillation water washing three times, vacuum-drying, sintering 4 hours in retort furnace promptly gets original proportioning and is (Sr then _0.9Nd _0.1TiO ₃) _0.9(CH ₃CONH ₂) _0.1White particle, get 6 gram above-mentioned product and 5ml200 ^#Silicone oil mixes (the volume integral ratio is 0.3), stirs and makes the strontium titanate current liquid of compound neodymium-doped.

Embodiment 4, and preparation technology is fully with embodiment 1, but the ethanamide that dissolves in is 29.5 grams, and the original proportioning of white composite strontium titanate electrically particle of gained is (SrTiO ₃) _0.5(CH ₃CONH ₂) _0.5Take by weighing 6 gram above-mentioned composite titanic acid strontium particles and 200 ^#Silicone oil 4ml mixes (the volume integral ratio is 0.4) and makes composite strontium titanate electrically rheological liquid.

Table 1 electrorheological fluid international standard and electrorheological fluid performance of the present invention are relatively

	The electrorheological fluid international standard	Composite strontium titanate electrically rheological liquid
			Maximum subtracts shearing stress	2-5 kPa	＞7 kPas (2.2 kvolts/millimeter)
Maximum field	～4 kvolts/millimeter (being limit) by breaking down field strength	～4 kvolts/millimeter (being limit) by breaking down field strength
			Current density	＜20 microamperes/centimetre 2	＜20 microamperes/centimetre 2
Temperature limit	+ 10to+90 ℃ (ionic, direct current)-25to+125 ℃ (non-ionic type interchange)	+10to90℃
			Stability	Impurity can not be arranged	Subsidence rate 99% (more than 550 hours) inclusion-free, do not decompose
Time of response	≤ several milliseconds	≤ several milliseconds
			Density	The 1-2 gram per centimeter 3	2.28 gram per centimeter 3
Viscosity	0.2-1 handkerchief. second	＜1 handkerchief. second

Claims (4)

1, a kind of composite strontium titanate electrically rheological liquid, it is characterized in that: it consists of (SrTiO ₃) _1-Y(CH ₃CONH ₂) _Y, Y=0.1-0.7 wherein.

2, a kind of method for preparing the described composite strontium titanate electrically rheological liquid of claim 1 comprises and adopts SrCl ₂, TiCl ₄, MCl ₃, oxalate does raw material, presses Sr _1-XM _XTiO ₃The ratio weighing, wherein M=La, Y, Nd, Ce, X=0.1-0.4; Mixing and stirring is made into ageing liquid, ageing liquid was placed in 50 ℃ of-70 ℃ of thermostat(t)ed waters ageing 10-50 minute, use water-cooled then, centrifugal, the gained throw out is used 2 distilled water washs three times again after centrifugal, after vacuum-drying, put into retort furnace at 950 ℃ of sintering 5-10 hours, can get the adulterated strontium titanate particle of white spheroidal particle, it is characterized in that: after the acetamide solution of white spherical strontium titanate doping and 0.1-0.9M% is mixed, at 65 ℃ of water bath methods, put into 700 ℃ of sintering of retort furnace 4 hours, take out (SrTiO ₃) _1-Y(CH ₃CONH ₂) _YWith 200 ^#Silicone oil compares uniform mixing by the 0.23-0.65 volume integral.

3, by the described method for preparing the strontium titanate doping electrorheological fluid of claim 2, it is characterized in that: described oxalate raw material is oxalic acid potassium, sodium oxalate.

4, by the described method for preparing the strontium titanate doping electrorheological fluid of claim 2, it is characterized in that: at SrCl ₂, TiCl ₄, MCl ₃, add citric acid in the ageing liquid for preparing of oxalate, the pH value of solution remains between the 2-5.

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