| Aluminum for the advantages of low density, good plasticity and ductility, good thermal conductivity properties, corrosion resistance and so on, is widely used in various fields. The traditional method of aluminum electrolytic is Hall-Herout which uses carbon as the anode.In the electrolysis process, O2is released by the Al2O3decomposition and at the high temperature it reacts easily with carbon anode production of carbon dioxide.With the CO2pouring into the air, the carbon anode consumption will increase and the environment will be polluted.It is a new production of aluminum industrial production method which use the inert anode instead of the carbon anode, and the choice of inert anode materials is the high-profile difficulties. Domestic researches on the inert anode materials are mainly concentrated in metal materials and Ni-Fe-Cu-Co alloy has achieved good experiment results, but the performance still cannot meet the needs of industrial production for the imperfection of the high temperature oxidation resistance and corrosion resistance. This experiment by adding the Si and B elements in the alloy to improve and enhance the high temperature properties of the Ni-Fe-Cu-Co alloy.This article adopt the method of vacuum smelting, semi-solid electromagnetic stirring to prepare the different contents of Si and B Ni-Fe-Cu-Co alloy.Through the SEM, XRD, EDS and OM analysis methods, research the different contents of Si and B elements the existing forms and the influence on the microstructure and impact mechanism in Ni-Fe-Cu-Co alloy.The high temperature oxidation resistance of alloy experiment is to analyze the oxide film morphology and phase composition of the Si and B elements of Ni-Fe-Cu-Co alloy organization and the influence law of high temperature oxidation resistance.Result shows that:When the addition of silicon is less than1.5wt%, silicon exists in the form of substitutional solid solution in the Ni-Fe-Cu-Co alloy and increases the supercooling degree of the solidification process. The Ni-Fe-Cu-Co alloy within silicon will form heterogeneous multilayer oxide film on the alloy surface and from the inside to the outside of the film layer, cobalt oxide and iron oxide content increase gradually, nickel oxide and silicon oxide content decrease. The oxide film formed part is similar to the spinel ferrite nickel material which has certain protective oxide film layer. When the silicon content is less than1wt%, along with the increase of the content of silicon, the alloy organization change into tiny isometric from bulky isometric. It shows silicon refine the alloy isometric and reduce the oxidation of alloy. When the silicon content is higher than lwt%, the structure transfers into the dendritic structure. Silicon is an active element and easy to combine with oxygen, for another reason the diffusion speed of Si is slow in Ni, so silicon make alloy produced serious internal oxidation and weight the oxidation, reducing the oxidation resistance of alloy. When the silicon content is lwt%, the alloy increases the Ni-Fe-Cu-Co alloy under the condition of850℃/latm O2oxidation resistance which is of the tiny grains, lesser internal oxidation degree, smaller fold oxide film surface, low porosity and protective, oxidation weight minimum.When the B element content is less than0.5wt%in Ni-Fe-Cu-Co alloy, the alloy grain will be refined and spheroidized for B is a strong grain boundary partial element. The oxidation film of the Ni-Fe-Cu-Co alloy within B element is mainly composed of iron oxide, cobalt oxide, nickel oxide and oxide film formed in some substance similar to the nickel ferrite spinel, having certain protective oxide film layer. When B content is less than0.1wt%, the refine of grain size effect is small, because B gathers in the grain boundary and increases the oxygen diffusion speed along the boundary. So the alloy will have a bad oxidation resistance. When B content is higher than0.3wt%, alloy is of small dendritic structure and forms the second phase, Fe23B6phase, The oxide film is loose and high void ratio,and the oxidation resistance is similar to the original alloy. Only for the amount of B is about0.1wt%, the alloy within small grains, B in grain boundary less, oxide film formed on the surface smooth, better integration with the alloy matrix, improve the oxidation resistance of alloy. |
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