Research On Ni-Nano-Lu₂O₃ Composite Electroforming And Its Performance

In recent years,with the improvement of technology and manufacturing process,the electroforming technologyhas developed rapidly in the direction of complex,precise and high-performance.Nano-Lu₂O₃ particles have a high density and melting point,high temperature stability and excellent heat resistance,which areideal nano-particle additives.Nano-Lu₂O₃ particles have been widely used in the fields of ceramic materials,luminescent materials and tungsten and its alloys,and have achieved some results.It is expected that the composite layer with excellent performance can be obtained by co-deposition of nano-Lu₂O₃ particles and metal nickel.Therefore,it is very important to study the performance of nano-Lu₂O₃ composite electroforming to improve the performances of the products and expand the application of electroforming technology.Firstly,three electroforming parameters including the amount of Lu₂O₃ particles,cathode current density and stirring rate are chosen to determine their effects on mass fraction of Lu₂O₃ particles depositedon nickel layerby using orthogonal test.The experimental results show that Lu₂O₃ has the biggest influence on mass fraction of Lu₂O₃ particles,followed by stirring speed and cathodic current density.The best combination of process parameters is obtained: the amount of Lu₂O₃ particles addition 4g/L,stirring rate 800 rpmand cathode current density 3A/dm2.The results also indicate that the ultrasonic pretreatment can significantly improve the surface topography of Ni-Lu₂O₃ composite layer;the higherthe mass fraction of Lu₂O₃ particleis,the smoother the composite layeris.XRD analysis shows that the Lu₂O₃ particles havechanged the preferred orientation of composite layer.Then the effects of various amounts of Lu₂O₃ particles in the layer on micro-hardness,corrosion resistance and high-temperature oxidation resistance arestudied respectively.Results show that the micro-hardness of Ni-Lu₂O₃ composite layer increases with the increase of Lu₂O₃ particles in the layer,the micro-hardnessisup to 351.2HV,increased by 33.1% compared with pure nickel layer;when the cathodic current density and stirring rate are increasing,the micro-hardness of layer shows a trend of decrease after the first increase.Whilethe amount of Lu₂O₃ particles deposition is 2.99wt%,composite layer had the best corrosion resistance and oxidation resistance.Finally,the effects of LuCl3 on composite electroforming process and the performance of composite layer was also investigated based on Ni-Lu₂O₃ composite electroforming process.Results showed that the addition of LuCl3 can improve the co-deposition of Lu₂O₃ particles in the layer.As LuCl3 content is 2g/L,the surface of layer is the most dense and uniform,and it has the minimum micro-hardness,which is up to 0.149 μ m.When LuCl3 content is3g/L,the micro-hardness of the electroforming layeris up to 403.1HV,increased by53%compared with pure nickel.As the addition of LuCl3 is 2g/L,the composite surface isvery dense and has fewer defects,which lead to the best corrosion resistance and oxidation resistance.