Design And Properties Investigation Of Ni-Mo Composite Coating Reinforced With Duplex Nanoparticles

The Ni coating and the Ni-based composite coating are the most widely used protective metal coatings due to their high hardness,wear resistance and corrosion resistance.They are widely used in ships,automobiles,and aircraft.In order to further enhance the performance of the coating and broaden its application field,adding nanoparticles with excellent properties to the matrix metal to prepare a nanocomposite coating can obtain the common characteristics of the matrix metal and the nanoparticles.In this study,6061 aluminum alloys and closed-cell aluminum foams were selected as substrates.Ni-Mo coating and Ni-Mo-SiC-TiN nano-composite coating were prepared by voltage-stabilized electrodeposition respectively,to explore the optimal process parameters.Study effect of nanoparticles on the morphology,structure and properties of the Ni-Mo coating,and the enhancement effect of the nanocomposite coating on the matrix properties.The results show that when the electrodeposition voltage is 6.5V,a dense and uniform nanocomposite coating can be obtained.The structure of Ni-Mo-SiC-TiN nanocomposite coating is a typical face-centered cubic(FCC)Ni-Mo phase.After adding Si C and Ti N nanoparticles,the surface roughness of the Ni-Mo coating increased from 4.3?m to 7.6?m,and the grain size decreased from 17.22 nm to 12.54 nm.The mechanical properties were tested by Vickers microhardness tester and pin-disk friction and wear experiments.Due to the addition of Si C and Ti N particles,the microhardness of the coating increased from 268 HV to 385 HV,and the friction coefficient was greatly reduced from 0.35 to 0.2.Polarization experiment shows that the corrosion potential of the Ni-Mo coating moved positively after adding nanoparticles,and the corrosion current density decreased.The immersion experiment proves that the nanoparticles reduced the corrosion rate.After electrodepositing Ni-Mo-SiC-TiN nano-composite coatings on the surface of 6061aluminum alloys,the hardness of the substrate increased by 251 HV,the friction coefficient and the wear loss were reduced,the self-corrosion potential shifted positively,the corrosion current density decreased,and the corrosion rate in 3.5wt%Na Cl solution was reduced by 82%.The performance of aluminum alloy is significantly improved.The Ni-Mo-SiC-TiN nanocomposite coating was electrodeposited on the surface of closed-cell aluminum foams.It was found that when the electrodeposition voltage was 6.0V,a nanocomposite coating with complete substrate coverage and good deep plating ability could be prepared on the surface of aluminum foams.The quasi-static compression experiments show that the electrodeposition time affected the mechanical properties of aluminum foam.When the electrodeposition time was increased from10min to 40min,the W _v of aluminum foams increased from 0.852 J to 2.520 J,and the?_sincreased from 1.06 MPa to 2.99 MPa.The enhancement of compressive properties of aluminum foams by adding nanoparticles is not obvious.The corrosion resistance of aluminum foams had been significantly improved.The self-corrosion potential,pitting potential,and potential for primary passivation were positively shifted by 294 mV,99 mV,and 301 mV,respectively.