材料组分对电触头表面劣化的影响机理

Electrical contact material is one of the most important components for the power switchgears, which strongly affects the breaking capacity, service life and other performances of switchgear in power system. New materials with long service life and high working reliability are always expected and have been developed mainly until now through a large number of experiments, not theoretic design, to determine the composition of material and their respective percentages, which results in the waste of time and money. The basic reason for the above situation is we do not have the quantitative relationship between the electrical performance of electrode and the parameters of material. This project is to establish the relationship between the service life (sputter erosion) of electrode and the parameters of materials..Research indicates that material sputter erosion is with the characteristics of randomness and discreteness, and the sputter phenomena is mainly caused by the action of electromagnetic force against electrode, explosion of air bubble inside material as well as the boiling over of molten pool. Two models have been presented for the first time to predict the sputter erosion volume of different materials through the points of view of statistics and the competition between surface bondage energy of molten pool and the dynamic energy of molten drops. The models can systematically show how the sputter erosion of electrode is affected by heat capacity, density, latent heat of fusion, boiling point, electrical resistivity and other parameters of material. Theoretical simulation of sputter erosion are coincident well with the experiments for Ag, Cu, Ni, W, Mo, Cr, AgW, CuCr, CuW etc. Theoretical analysis also shows for the first time that the adhesion coefficient of liquid metal has a strong effect on sputter when it is between 0.1 and 1.0 but little effect when it is less than 0.1. .

研究多种触头材料在不同电流下的表面劣化实验并进行微观分析；计算触头材料温度场，并考虑两种相变及材料参数随温度的变化；研究触头金属液池流速场，包括电弧电磁力及液池阻尼的分析；建立液态金属喷溅模型，包括对液滴喷溅离散性、随机性的分析及利用能量涨落原理描述一次喷溅量方法。为新触头材料开发提供理论指导。