Influence Mechanism And Optimization Method Of Interface Oxidation Characteristics On Current-carrying Friction And Wear Performance

After entering the electrical age,current-carrying friction pairs have gradually become an indispensable part of daily life due to the demand for dynamic power transmission.With the emergence of extreme operating conditions such as high speed and large current,and extreme service environments such as high temperature and humidity,the interface oxidation state has become increasingly complex,abnormal wear occurs frequently,and service life is seriously affected.The interface oxidation has an important influence on the current-carrying friction and wear.The first is to isolate the actual contact and inhibit the material transfer,which shows the lubricating protection effect;the second is to raise the temperature and electrical ablation,showing the effect of aggravating wear.The competition mechanism between the two effects is still unclear,and relevant research is urgently needed.At the same time,the existing service performance optimization methods of current-carrying friction pairs have a single application scenario.It is necessary to explore new efficient and universal active optimization methods.Firstly,the influence mechanism of interface oxidation on current-carrying friction and wear performances was explored by quantitatively controlling the oxide film thickness.In static electrical contact,the contact resistance increases with the increase of oxide film thickness until it enters the insulating state.The main reason is that the temperature rise and electrical ablation brought by the oxide film will destroy the conducting channels between the friction pairs.In the sliding electrical contact,the friction coefficient and its fluctuation,wear rate,contact resistance,arc discharge energy and its duration all first decrease and then increase with the increase of oxide film thickness,and the current-carrying efficiency first increases and then decreases,that is,there is an appropriate oxide film thickness to minimize the loss of interface materials.The appearance of the minimum value can be explained by the mutual competition mechanism between oxide film lubrication and protection,temperature rise and ablation.And a continuous and uniform oxide film is the key to show the effect of lubrication and protection.Subsequently,the influence mechanism of the magnetic field on the oxidation kinetics of copper was studied.It was found that the surface oxidation activation energy of copper could be reduced by an external magnetic field.Finally,a magnetic field optimization method for the service performance of current-carrying friction pairs based on interface oxidation regulation is proposed.It was found that the axial magnetic field could decrease the friction coefficient and its fluctuation.With the increase of the magnetic induction intensity,the friction coefficient first decreased and then increased,and wear rate continued to reduce.Different magnetic field polarities showed little difference in reducing friction and wear.When the magnetic induction intensity is low,the deterioration degree of electrical contact properties is small,but after increasing to the critical value,the current-carrying friction and wear performance of the contact pairs deteriorates rapidly.The magnetic field promotes the transition from severe wear to mild wear by promoting oxide film formation,accelerating the discharge of hard wear debris from the contact area,and reducing arc energy density.The effect of interfacial oxidation explored in this paper perfects the current-carrying tribology.The proposed method for optimizing the service performance of the currentcarrying friction pairs could work in most environments.And it provides technological support for safeguarding the secure and steady operation of the current-carrying friction pairs in engineering,and minimizes the cost of operation and repair.