Electric Conduction, Adhesion Forces and Discharge Processes in a Particle-Particle-Contact - Highly Resistive Materials

颗粒-颗粒接触中的导电、粘附力和放电过程 - 高电阻材料

基本信息

批准号：
169555597
负责人：
Professor Dr.-Ing. Ulrich Riebel
金额：
--
依托单位：
Lehrstuhl Mechanische Verfahrenstechnik
依托单位国家：
德国
项目类别：
Priority Programmes
财政年份：
2010
资助国家：
德国
起止时间：
2009-12-31 至 2016-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/169555597?language=en
关键词：
Electric Conduction Adhesion Forces Discharge

项目摘要

In case of electrical conduction across the particle-particle-contacts in highly resistive dust layers, the generation of electrostatic adhesion force is strongly coupled to the mechanisms of electrical transport in the solid. High field strengths lead to a significant increase of adhesive forces. For the electrical resistivity, a pronounced non-ohmic behaviour with strong time effects is observed. Aim of the project is to investigate the underlying mechanisms by experiments and simulations on the microscopic scale. Our previous investigations have shown that the mechanisms of charge transport in highly resistive particle layers correspond to those in electrete materials. During current transport, positive and negative charge carriers are injected into the material, and significant electrostatic space charges are formed. The time effects are explained by the mechanisms of charge injection and by the immobilization of charges in the particle volume. In the contact gaps and pore spaces, charge transport can occur by the mechanisms of thermionic field emission and gas discharge. Even though strong electrostatic adhesion forces are generated on the microscopic level, the macroscopic space charge excess can lead to a mechanical failure of highly resistive dust layers by electrostatic repulsion. In the continuation of the project, the successful measurements on single particle-particle contacts shall be improved and continued. Here, the current uptake and the contact force are measured (time-resolving) as a function of particle diameter, contact gap distance, particle material and applied voltage. The mechanism of charge transport across the contact gap shall be verified by observing the emission of light and gas ions. Within the simulation part of the project, a model incorporating the mechanisms of charge transport in the solid and in the contact gap is being developed. Via local potentials, field strengths, charge carrier densities and current densities, the conduction or discharge mechanisms in the gap and the contact force are to be obtained. Here as well, the appropriate modelling of time effects is an important task.The simulations will be verified using results from the single particle experiments. Finally, we will try to simulate chain-like particle arrangements as a model for macroscopic particle layers. Additionally, experiments on particle layers and on massive layers of (dielectric) materials will be made.

如果在高电阻性灰尘层中跨颗粒粒子接触的电导传导，则静电粘附力的产生与固体中电运转运的机制密切相关。高场强度导致粘合力显着增加。对于电阻率，观察到具有强烈时间效应的明显非欧味行为。该项目的目的是通过微观量表通过实验和模拟来研究基本机制。我们先前的研究表明，高电阻颗粒层中电荷转运的机理与elemente材料中的电荷相对应。在当前运输过程中，将正电荷载体注入材料中，并形成明显的静电空间电荷。时间效应是通过电荷注入机制和粒子体积中电荷固定的固定来解释的。在接触间隙和孔隙空间中，可以通过热场排放和气体排放的机制发生电荷传输。即使在微观水平上产生了强静电粘附力，宏观空间电荷过量也会导致高度电阻式灰尘层通过静电排斥而导致机械故障。在项目的延续中，应改进并继续进行单个粒子触点的成功测量。在这里，测量当前的摄取和接触力（时间分解）作为颗粒直径，接触间隙距离，粒子材料和施加电压的函数。跨接触间隙的电荷运输机理应通过观察光和气体离子的排放来验证。在项目的仿真部分中，正在开发一个模型，该模型正在开发固体和接触间隙中的电荷运输机理。通过局部电势，田间强度，电荷载体密度和当前密度，将获得间隙和接触力中的传导或放电机制。同样，适当的时间效应建模是一项重要的任务。将使用单个粒子实验的结果来验证模拟。最后，我们将尝试模拟链状粒子排列作为宏观颗粒层的模型。此外，将进行粒子层和（介电）材料的大量层的实验。