| Aluminum alloy has a wide application market in the fields of building materials,automobile manufacturing,aerospace and navigation ships because of its low density,high specific strength and easy processing and forming,but its low hardness,poor wear and corrosion resistance have become the bottleneck restricting its wide application.Diamond-like carbon film(DLC)is a kind of amorphous multifunctional carbon film material,which has many excellent properties similar to diamond,such as high hardness,low friction coefficient,wear resistance and corrosion resistance,and is a good protective film.At present,the preparation methods of DLC films mainly include physical vapor deposition and chemical vapor deposition.Relatively speaking,liquid-phase electrochemical deposition technology has the advantages of simple equipment,mild reaction conditions and easy industrial production,and has broad development prospects.Based on this,the diamond-like carbon film was deposited on the surface of aluminum alloy by liquid-phase electrochemical deposition method,the suitable codoped elements were discussed,the electrolyte formula and deposition process parameters were optimized,and the electrochemical and friction and wear behaviors were studied,in order to improve the wear resistance,friction reduction and corrosion resistance of aluminum alloy and expand the application field of aluminum alloy.In this paper,single-layer and double-layer transition layer(Cu,Ni,Ni-Cu)DLC films and composite films doped with nano-CeO2 particles were designed and prepared on the surface of aluminum alloy by liquid-phase electrochemical deposition technology,and then the effects of transition layer and nano-CeO2 particle doping on the microstructure,surface morphology,microhardness,friction and wear properties and corrosion resistance of DLC films were studied.The main research contents and conclusions of this paper are as follows:(1)Hydrogen-containing DLC films were prepared by electrochemical deposition with deionized water as additive and ethanol as electrolyte with different concentrations.The results show that the more deionized water concentraion,the greater the current density and the faster the film deposition rate.Raman spectrum shows that the film is a typical diamond-like structure.When the content of deionized water is 35 mL/350 mL,the film surface is smooth and compact,and the micro-hardness,friction coefficient and wear loss are 178.2 HV,0.395 and 0.8×10-5 kg/m,respectively.The self-corrosion potential is the most positive and the corrosion current density is the smallest,which is-0.1874 V and 1.1069×10-6 A/cm2,respectively,showing good wear and corrosion resistance.(1)Transition layer(single layer Ni,Cu,double layer Ni-Cu)and DLC films were prepared by pulse electrodeposition and electrochemical deposition.The introduction of the transition layer has no significant effect on the microstructure of the film,but compared with the single-layer transition layer,the Ni-Cu-DLC film contains more sp3 hybrid bonds,with higher microhardness,lower friction coefficient and wear loss,which are 210.67 HV,0.264 and 0.4×10-5 kg/m,respectively.At the same time,the Ni-Cu-DLC film has positive corrosion potential,smaller corrosion current density and good corrosion resistance.(2)CeO2-DLC composite films were fabricated on aluminum alloy surface by doping CeO2 nanoparticles into ethanol aqueous solution by electrophoretic deposition technique.The results show that the microhardness of DLC film increases slightly after doping CeO2 nanoparticles.When the CeO2 doping amount in electrolyte is 0.07 g/350 mL,the composite film has smooth surface and uniform distribution of CeO2 nanoparticles.The microhardness,friction coefficient and wear loss are 228.64 HV,0.158 and 0.2×10-5 kg/m,respectively,showing the best wear resistance.The polarization curve and immersion test results show that the corrosion resistance of DLC composite films doped with CeO2 is obviously improved compared with pure DLC films.The composite films obtained with CeO2 doping amount of 0.07 g/350 ml have the highest self-corrosion potential,the lowest corrosion current density,and the lowest corrosion rate,which are-0.0839 V,6.2922×10-7 A/cm2 and 0.7854 g/m2·h,respectively. |
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