| Titanium and its alloys are ideal"marine metal"materials because of their low density,light weight,excellent mechanical,chemical and corrosion resistance.However,due to the problems of low hardness,poor friction and wear performance,and cyclic corrosion in the harsh marine environment,titanium materials are limited to serve in a large area in the marine environment.In recent years,the preparation of modified layer on titanium substrate has become a hot spot in this field at home and abroad.However,the research shows that the single modification method is still difficult to meet the application of titanium materials in complex working conditions.In order to improve the wear-resistant and corrosion-resistant properties of titanium,the Ru/Ti gradient composite coating was prepared on the surface of industrial pure titanium TA2 by surface mechanical grinding,magnetron sputtering and thermal oxidation.Firstly,nanocrystalline layer was prepared on the surface of TA2 substrate by mechanical grinding,and then gradient Ru/Ti coating was prepared on the surface of industrial pure titanium and titanium material after surface mechanical grinding by magnetron sputtering.Finally,the gradient coating was heat oxidized.The kinds and contents of the elements before and after the thermal oxidation of the coating were determined by Energy Dispersive Spectrometer?EDS?,the phase composition before and after the thermal oxidation of the coating was determined by X-ray diffraction?XRD?and laser confocal Raman spectrometer,and the surface morphology and roughness before and after the thermal oxidation of the coating were observed by Field Emission Scanning Electron Microscope?FE-SEM?and Atomic Force Microscope?AFM?.The corrosion resistance and wear resistance of the coating were tested by electrochemical workstation and friction and wear testing machine respectively,and the mechanism of improving the corrosion resistance and wear resistance of the coating was analyzed.The results show that the surface structure of the gradient coating is compact without defects and cracks,and the crystal structure is typical columnar crystal.Before the thermal oxidation treatment,the coating is well combined with comerical pure titanium and titanium material after surface mechanical grinding.Ti gradient coating is mainly composed of?-Ti,FCC Ti and oxide Ti2O;Ti/Ru gradient coating is mainly composed of?-Ti,FCC Ti,Ru and a small amount of Ru oxide.The coating particles on the industrial pure titanium substrate are smaller than those on the surface after mechanical grinding,and the change of roughness is consistent with the change of particle size.After thermal oxidation treatment,Ti gradient coating is mainly composed of?-Ti,FCC Ti,Ti O and rutile Ti O2;the phase in Ti/Ru gradient coating is almost the same as before.In the Ti/Ru coating,the surface of the coating is complete because Ru can inhibit the oxidation of Ti.The corrosion resistance of Ti/Ru gradient composite coating sputtered and thermally oxidized on the surface of mechanically ground titanium material is improved obviously.The highest corrosion potential is-0.347 V,and the lowest corrosion current density is 3.18×10-7A·cm-2.The reason for the improvement of the corrosion resistance of the coating is that the interface stress of Ti/Ru coating is small and the stability is good.The presence of Ru in the coating makes the thermodynamics of the sample surface more stable.The other is that the platinum group element Ru itself has excellent corrosion resistance.Under 0.5 N load,the friction coefficient of titanium material after surface mechanical grinding is the lowest,which is 0.21;under 1n load,commerical pure titanium and titanium material after surface mechanical grinding sputter Ti/Ru gradient composite coating and after thermal oxidation,the friction performance is improved,and the friction coefficient is 0.40. |
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