Preparation And Performance Study Of Highly Crystalline Nickel Nanopowders For MLCC

With good electrical conductivity,high reactivity and magnetic properties,nickel nanopowders are widely used in various fields such as electricity,magnetism,especially as the inner electrode material for MLCC.At present,commercial MLCC nano-nickel powder can only be prepared by PVD or CVD method,but these two methods use expensive equipment,complex process,preparation costs are very high,and it is difficult to produce highly dispersed nano-nickel powder below 100nm.The liquid phase reduction method and spray pyrolysis method are still in the laboratory research stage,and have the disadvantages of high toxicity of raw materials,serious agglomeration of particles and poor crystallinity.Therefore,it is important to study the suitable industrial,green and low-cost nano-nickel powder preparation technology.In this study,a salt-assisted sol-gel method is explored for the preparation of nickel nanopowders:a precursor film is coated on the surface of K₂SO₄particles using the sol-gel process,the gel film is transformed into nickel oxide nanoparticles by high-temperature calcination,nickel oxide is transformed into metallic nickel after high-temperature reduction again,and the dispersed nickel nanoparticles are obtained after water washing to remove the potassium sulphate salt.In this study,the physical phase transformation,particle size change and particle morphology evolution of nickel oxide nanoparticles are investigated.The effects of precursor concentration,plasticiser,surfactant and calcination temperature on the morphology,size and dispersibility of nickel oxide particles are investigated.The results show that the higher the concentration of precursors lead to larger particle size and more inhomogeneous in nickel oxide;with the increase of calcination temperature,the particle size of nickel oxide gradually increases and the particle size distribution becomes inhomogeneous;the addition of plasticisers and surfactants helps to maintain good size uniformity and dispersion of nickel oxide particles.The transformation process of nickel oxide particles into nickel and the morphological evolution of nickel nanoparticles during the reduction process are further investigated.The results show that the nickel nanopowder has good oxidation resistance and can be used at 300°C without oxidation,which is comparable to commercial submicron MLCC nickel powders.The salt-assisted sol-gel method used in this project has a low preparation cost,simple and easy to produce industrially.The prepared nickel nanopowders are small in size,well dispersed and good antioxidant properties.Further research and process optimisation of this method is expected to extend for the production of commercial MLCC nickel nanopowders.