The Study Of Atomic Oxygen Effect On Graphene Films

In recent years,the severity of space environment and its effect on spacecraft has been gradually understanding.Low earth orbit(200 km--700 km)is the main satellite orbit of ship,space shuttle.Atomic oxygen(AO)is the main composition of low earth orbit environment atmosphere,accounts for about 80%,as the highest levels in the environment of low earth orbit,its harm is huge for the spacecraft.The cause of atomic oxygen big harm basically has the following two aspects: on the one hand,atomic oxygen has strong chemical activity,can react with materials directly;on the other hand,when the spacecraft is in orbit,the running speed is very high,at a speed of 8 km/s,the energy that atomic oxygen acting on the surface of the spacecraft is about 4e V,when these atomic oxygen with strong oxidizing,large flux,high energy Interact with materials,it will have some influence in materials' surface morphology and performance,thus affect the normal operation of the spacecraft and service life.So far,people haven't understand the mechanism of atomic oxygen effect very fully,researchers concern the following several aspects mainly: the loss of the material's weight is due to desquamate or more complex chemical reaction;The relationship between material surface and the crash angle;The influence of material surface temperature in the reaction;What is produced by the degradation reaction;The atomic oxygen effect is limited in material surface or could extend to the body.Graphene research value is mainly manifested in two aspects: the one is as the basic structure of the sp~2 hybrid carbon materials unit,it can be used as a model material;On the other hand,graphene has many excellent properties,such as high specific surface area,high carrier mobility,high conductivity,high heat conductivity,high light transmittance,high strength,etc.,thus it has great potential applications in many fields.In fact,graphene as the sp~2 hybridized carbon materia's basic structure unit,the regular pattern of atomic oxygen reaction for other kinds of carbon film sensor atomic oxygen reaction condition also have basic guidance;At the same time,due to determine the structure and properties of graphene has,also very suitable forcarbon materials as a model to research on the laws of the atomic oxygen reaction in the first place.The first part of the work,we use oxidation-reduction method prepared two sets of different reduction degree of graphene films,and the content of oxygen containing groups of the films is controllable during the preparation.Put the films for the irradiation of different atomic oxygen flux,calculate the quality of the samples and analysis the denudation rate,the results showed that graphene film has lower atomic oxygen erosion rate,compared with carbon,graphite,Kapton,Teflon,epoxy resin,the common space materials,has better atomic oxygen resistance.And the degree of reduction of graphene films showed different degrees of atomic oxygen resistance,high degree of reduction of film has better atomic oxygen resistance,so it can through regulating thin films during the preparation of reduction to the preparation of graphene film with the proper atomic oxygen resistance.To investigate the change of the conductivity of graphene films under the atomic oxygen irradiation environment,we adopt the method of graphene oxide conductive adhesive to platinum wire connected to the ends of the graphene films,formed the graphene membrane resistance,study the changes of membrane resistance conductivity under the irradiation of atomic oxygen environment,the experimental results show that the membrane resistance stable time can be 149 h,the corresponding atomic oxygen flux is 1.3×1021atom/cm2,and its effective working time can be controlled as graphene membrane resistance reduction degree in the process of preparation.The second part,through a series of test methods for characterizing the physical and chemical properties,graphene film contrast different irradiated by atomic oxygen flux changes of graphene films,analyse the interaction between graphene and atomic oxygen,the test results show that the effect of atomic oxygen on the graphene membrane included its physical sputtering and chemical reaction on the surface of the material,physical sputtering resulted in the erosion of graphene film surface,two-dimensional plane structure gradually appear holes,chemical reactions lead to membrane surface oxygen content increased gradually,atomic oxygen react with graphene undermine the original sp~2 hybridization carbon-carbon bonds,and graphenegradually formed C = O,epoxy bond,gradually became sp~3 hybridized carbon atoms.