Study On The Influence Of Soot And Dust Particles On The Fretting Performance Of Electrical Contact

There are a large number of electronic connections in electronic equipment and power systems.The reliability of electronic connections directly affects the reliability of the whole machine.The working environment,contact materials,structure and other factors affect the electrical contact interface.It results in a very complex failure mechanism involving chemical,physical,mechanical,electrical and many other disciplines.The probability of electronic connection failure caused by atmospheric particles intruding into electronic devices is significantly higher than that caused by other factors.Therefore,research on the effects of soot and dust particles on the fretting wear performance of electrical contacts can not only improve the failure of electronic equipment,but also play a vital role in deepening the mechanism of electrical contact fretting wear.In this paper,a soot/dust layer was prepared on the copper surface by spraying.Based on the electro-contact fretting wear device independently developed by the Institute of Tribology,Southwest Jiaotong University,the service conditions of the copper contact in the presence of soot/dust were simulated,the effects of particle concentration and load on the electro-contact fretting wear performance were studied.The ball-plane contact mode was used in the experiment.The wear area was analyzed by means of optical microscope(OM),scanning electron microscope(SEM),white light interferometer and other equipment.Combining the contact resistance(ECR)curve,friction coefficient(COF)curve and friction-displacement amplitude(Fτ-D)curve,the influence mechanism of soot and dust particles on fretting wear behavior of copper in electrical contact was systematically revealed.The conclusions are as follows:(1)Soot particles play an anti-friction and anti-wear role in fretting wear of copper,and the higher the concentration,the more obvious the anti-wear effect.When the soot concentration is C=1g/L,the wear scar width and the maximum depth are reduced by 1.3 and 4.2 times compared with the dust-free smooth interface.The particle size of dust is larger,and the friction coefficient of dust particles increases after contact,but it also plays an anti-wear role on the surface of samples.When the dust concentration is C=1g/L,the wear scar width and maximum depth decrease by 1.7 times and 3.4 times compared with the dust-free smooth interface.(2)When the load is small,the contact resistance value is large and extremely unstable.The metal oxide deposits in the contact area to form contact spots with extremely high resistance,which is the fundamental reason for the sharp rise of contact resistance.As the load increases,the area of the contact spots becomes larger,and the contact resistance decreases.Under large load,the contact area matches well,and the contact resistance of metal materials is stable.Fretting wear changes the contact surface condition and increases the contact resistance of metal.Under the condition of small load(2-6N),the COF curve has obvious running-rising-falling-stabilizing periods.For larger loads(8-10N),there are only rising and stable periods.The higher contact load makes the contact area in a good matching state.The two contact surfaces reach the equilibrium point in a very short time,and the friction coefficient is relatively stable.