权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

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.

在高阻粉尘层中粒子-粒子-接触之间存在导电的情况下，静电粘附力的产生与固体中的电传输机制强烈耦合。高场强导致粘附力显著增加。对于电阻率，观察到明显的非欧姆行为，具有很强的时间效应。该项目的目的是通过微观尺度上的实验和模拟来研究其潜在的机制。我们以前的研究表明，高阻粒子层中的电荷传输机制与驻极体材料中的机制相一致。在电流传输过程中，正负电荷载流子被注入材料中，并形成显著的静电空间电荷。时间效应可以通过电荷注入机制和粒子体积内电荷的固定来解释。在接触间隙和空隙中，电荷输运可能通过热电子场发射和气体放电机制发生。尽管在微观层面上会产生很强的静电附着力，但宏观上的空间电荷过剩会导致高阻粉尘层因静电排斥而发生机械破坏。在项目的继续实施中，单颗粒-颗粒接触的成功测量将得到改进和继续。在这里，电流吸收和接触力被测量(时间分辨率)作为颗粒直径、接触间隙距离、颗粒材料和施加电压的函数。应通过观察光和气体离子的发射来验证通过触点间隙的电荷传输机制。在该项目的模拟部分，正在开发一个包含固体中和接触间隙中电荷传输机制的模型。通过局域电势、场强、载流子密度和电流密度，可以得到间隙中的导电或放电机制和接触力。在这里，时间效应的适当建模也是一项重要的任务。模拟将使用单粒子实验的结果进行验证。最后，我们将尝试模拟链状粒子排列，作为宏观粒子层的模型。此外，还将在粒子层和块状(介电)材料层上进行实验。