| Electrical contact structure is widely used in various fields of electronic equipment.Its function is to ensure the effective transmission of electrical signals within the equipment components.The stability of its performance is one of the basic conditions to ensure the efficient operation of electronic equipment.The performance degradation of electrical contact structures is affected by contact materials,working parameters and environmental factors.Electronic equipment is inevitably required to serve in some complex and extreme environments.The environmental factors will accelerate the degradation of electrical contact structure performance,leading to the reduction of service life of electronic equipment.Therefore,the study on the influence of complex environmental factors on electrical contact performance is of great significance to improve the reliability of electronic equipment.In this paper,the atmosphere environment simulation platform and the external vibration simulation platform were built based on the milli Newtons-level electric contact test device independently developed by the research group.The electrical contact performance of copper/brass sliding electrical contact pair under complex simulated environment were studied by these two platforms.The root cause and mechanism of the degradation of electrical contact performance was analyzed with the wear mark morphology,cross section profile and chemical composition.This paper draws the following conclusions:(1)By studying the electrical contact performance of the samples before and after storage in the atmospheric environment and x98-11 atmosphere environment,the following conclusions are drawn: In x98-11 atmosphere environment,the initial contact resistance was higher under low load(50 and 100 m N),and lower and stable under high load(200 m N).The aerosol in the atmosphere has certain lubricity and reducing wear.The polluted layer after storage has a certain effect of reducing wear.The wear mark depth of polluted sample was less than that of the original sample.However,the polluted layer did not change the wear pattern of the contact pair in the final stage of the test.Under the joint action of aerosol and polluted layer,the electrical contact performance under low load condition is further deteriorated due to the barrier of pollutants.Under the condition of high load,the friction of the contact pair can effectively remove the interface pollution and reduce the contact resistance.(2)By studying the influence law of vibration amplitude on electrical contact performance,the following conclusions are drawn: In the vibration environment(vibration amplitude?2 mm,vibration frequency=5 Hz),the overall level of contact resistance did not change significantly.However,due to the incomplete separation of the contact pair in the vibration environment,the instantaneous maximum value of the contact resistance existed.As the vibration amplitude increased,the frequency by the maximum value also increased.This resulted in an increase in the standard deviation of the contact resistance.When the amplitude was 2 mm,the standard deviation of contact resistance could reach 7?9 times of that under non-vibration condition.(3)By studying the coupling effects of storage pollution and external vibration on electrical contact performance,the following conclusions are drawn: the acetal adhesive polluted layer has certain insulation,viscosity and wear reduction properties.When the volume fraction of adhesive was not less than 30%,the initial state of the contact pair was insulated.External vibration can lead to incomplete separation of contact pair,which increase contact gap and decrease contact stability.The wear capacity of the contact pair was reduced in vibration environment.This resulted friction to fail to remove the interface pollution.Under the coupling action of polluted layer and external vibration,high resistance materials such as oxides were retained on the surface of the sample,which leaded to the continuous increase of contact resistance. |
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