Opreparation Of Chromium Oxide Hydrogen Permeation Penetration Coatingand Its Properties

In hydrogen storage and fusion environments,hydrogen and its isotopes will infiltrate the substrate surface.Hydrogen embrittlement and other hazards are caused by the hydrogen permeate.On the one hand,it will affect the material properties which result in the lower reliability of the instrument.On the other hand,it will lead to the serious accidents causing casualties and environmental pollution.In order to avoid the generation of the above hazards,we generally adopt one or more hydrogen resistant coating growing on the surface of the substrate to prevent the hydrogen permeation.Therefore,the research pay attention to preparing the chromium oxide coating with different methods.Furtherly,the better scheme for the preparation of chromium oxide coating was selected by evaluating the different coating performance.First,the surface morphology of chromium oxide coatings were characterized by optical microscope,scanning electron microscopy?SEM?and atomic force microscope?AFM?before and after hydrogenation;the phase of the coating was analyzed by X-ray diffraction?XRD?technology and Raman technology;the surface chemical state and the variation of element content with depth of the different coatings were analyzed by the X-ray photoelectron spectroscopy?XPS?and Auger Electron Spectroscopy?AES?,respectively;the defects and forbidden band of the different coatings were tested by the ultraviolet luminescence luminosity and photoluminescence technology.Second,the global electrochemical properties of different coatings were analyzed including open circuit potential?OCP?,I-t curves,potentio-dynamic polarization?PDP?,and electrochemical impedance spectroscopy?EIS?before and after hydrogen permeation.Finally,in order to further verify the electrochemical performance,the surface work function and the surface local corrosion current density were tested by using the local scanning electrochemical workstation system.The results show that the performance of the water plasma chromium oxide coating is the best and its surface roughness is the smallest.The main phase of the coatings prepared with different methods is Cr₂O₃.Meanwhile,the water plasma chromium oxide coating has the highest crystallinity.The high-valence chromium content of the water plasma oxide coating is the lowest.As well as,the defects and the thickness are the smallest when compared with other chromium oxide coatings.As for the water plasma oxide coating,the open circuit potential is the highest,which means the integrity of the coating is the best.The local corrosion current density of the water plasma chromium oxide coating is the lowest within the testing range,which means the corresponding corrosion hazard is the weakest.In addition,the water plasma chromium oxide coating has the lowest self-corrosion current density,the lowest corrosion rate,and the highest corrosion resistance.All of these characters mean that water plasma chromium oxide coating has a better electrochemical performance to hinder the ions in the electrolyte to contact with the substrate.The surface work function furtherly verify the results that the performance of the water plasma chromium oxide coating is the most stabilizing.