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1、3.2.1 液体电介质的离子电导 3.2.1 Ionic conductance of liquid dielectrics 3.2.2 液体电介质的电泳电导与华尔屯定律 3.2.2 Electrophoresis conductance and Walden laws of liquid dielectrics 3.2.3 液体电介质在强电场下的电导 3.3.3 Conductance of liquid dielectrics in high field strength,3.2 液体电介质的电导 3.2 Conductance of liquid dielectrics,本节内容 Con
2、tents in this section,本征离子是指由组成液体本身的基本分子热离解而产生的离子。 Intrinsic ionic refers to ionic produced by the basic molecule of liquid in thermal dissociation. 杂质离子是指由外来杂质分子或液体的基本分子老化的产物离解而 生成的离子。 Impurity ionic refers to the ionic produced by dissociation of external impurities and liquid basic molecule agein
3、g. 极性液体分子和杂质分子在液体中仅有极少的一部分离解成为离 子，可能参与导电。 Only a small part of polarity liquid molecule and impurity molecule will dissociate to ionic, and may be in conduction.,2.2.1 液体电介质的离子电导 2.2.1 Ionic conductance of liquid dielectrics,1. 液体电介质中离子的来源 The source of ions in liquid dielectrics,离子电导可分为本征离子电导和杂质离子电
4、导。 Ionic conduction can be divided into intrinsic and impurity ionic conduction,2.液体电介质中的离子迁移率 Ion mobility of liquid electrolyte,液体分子之间的距离远小于气体而与固体相接近，其微观结构与非晶态固体类似，液体分子的结构具有短程有序性。另一方面，液体分子的热运动比固体强，分子有强烈的迁移现象。 The distance between liquid molecules much less then gas but close to solid, and the micr
5、ostructure is similar to non-crystalline solid, featured in short-distance and orders. On the other hand, the thermal motion of liquid molecule is faster than solid while the molecular migration is intensive.,液体中的离子所处的状态与分子相似，可用如图3-5 的势能图来描述液体中离子的运动状态。 Ionic in liquid is in a state like molecular, a
6、vailable potential energy diagram in Figure 3-5 describes the movement of ions in liquid.,可以认为液体中的分子在一段时间内是与几个邻近分子束缚在一起，在某一平衡位置附近作振动；而在另一段时间，分子因碰撞得到较大的动能，使它与相邻分子分开，迁移至与分子尺寸可相比较的一段路径后，再次被束缚。 It can be assumed that liquid molecule is bound up with other molecules nearby for a while, and vibrates at a
7、certain balance position. Sometimes molecule obtains great kinetic energy from collision, and will be separated from nearby molecules ,then be bounded up again after transfers somewhere.,设离子为正离子，它们处于A、B、C等势能最低的位置上作振动，其振动频率为，当离子的热振动能超过邻近分子对它的束缚势垒时，离子即能离开其稳定位置而迁移，这种由于热振动而引起离子的迁移，在无外电场作用时也是存在的。,图3-5 液体
8、电介质中的离子势能图 Figure 3-5 in the ionic liquid dielectric potential energy diagram,Provided positive ions located in A, B, C of the lowest potential energy and vibrate at a frequency , when the ion thermal vibration can exceed the shackles of the neighboring molecules, the ion will be able to migrate fro
9、m stable position, such kind of migration caused by thermal vibrations still exists in the absence of external electric field.,设离子带正电荷q，电场强度沿x正方向。离子由A向B迁移所需克服的势垒将降低，而由B向A迁移所需克服的势垒相反将上升u，如图3-6所示，即 Ion charged of positive q, electric field intensity along the x-axis positive direction. If ions migrate
10、 from the A to B, the potential barrier needed to overcome will be reduced, contrarily while migration from B to A, potential barrier will increase u, as shown in Figure 3-6, that is,(3-5),图3-6 液体电介质中离子跃迁时所要克服的势垒模型 Figure 3-6 Potential barrier model of ionic transition in liquid dielectric (a)无外电场时
11、(b)有外电场时 (a) Without external electric field (b) External electric field applied,3. 液体电介质电导率与温度的关系 Relationship between conductance and temperature in liquid dielectrics,一般工程纯液体介质在常温下主要是杂质离子电导，此时 Generally in practical engineering, at normal temperature purity liquid medium mainly consider impurity
12、ionic conduction, as,(3-6),当外加电场强度远小于击穿场强时，液体介质的离子电导率是常数。而电导率随温度的增加如式(3-6)所示。 When the applied field strength is much smaller than the breakdown field intensity, the ionic conductance of liquid medium is constant. The conductance increases with temperature as shown in Eq (3-6).,即ln与（1/T）的关系具有线性关系。 N
13、amely, ln and (1/T) are in linear relationship.,可忽略系数项随温度的变化，近似写成 Ignore the influence of temperature on coefficients, can be rewritten approximately like,3.2.2 液体电介质的电泳电导与华尔屯定律 3.2.2 Electrophoresis conductance and Walden laws of liquid dielectrics,工程应用中，液体介质中加入的树脂部分可能呈胶粒状悬浮在液体介质中，形成胶体溶液，此外，水分进入某些液
14、体介质也可能造成乳化状态的胶体溶液。 In engineering application, part of resin added in liquid medium may suspend like tagma, then becomes colloidal solution. Besides, some liquid medium when mixed with some water may change into emulsifying colloidal solution . 胶粒均带有一定的电荷，当胶粒的介电常数大于液体的介电常数时，胶粒带正电；反之，带负电。 All colloid
15、al particles with charges, when colloidal permittivity is larger than liquids, then colloids in positive electricity. On the contrary, with negative electricity.,设胶粒呈球形，球体半径r，液体的相对介电常数为 ，胶粒的带电量q，它在电场E的作用下，受到的电场力为 Provided colloid as sphericity with radius r, relative permittivity and charged of q, a
16、n electric field force will be exerted on it under electric field E, that is,胶粒相对于液体的电位一般是恒定的（约为0.050.07V），在电场作用下定向的迁移构成“电泳电导”。胶粒为液体介质中导电的载流子之一。 Relative to the potential of liquid which is usually a constant (about 0.05V-0.07V)and consitutes “electrophoresis conductivity” in the effect of electric field. Colloidal is one of the electric charge carriers in liquid medium.,(3-9),(3-11),(3-10),电泳电导率 Electrophoresis conductance,液体电介质的黏度。 -Viscosity of liquid dielect
