Research On Preparation And Properties Of 17Ni/（10NiO-NiFe₂O₄）Cermet With CoO And Cr₂O₃ Compound Doping

Al alloy plays a very important role in promoting China’s large-scale infrastructure construction and advancing the country’s progress,so the domestic aluminum electrolysis production industry must keep pace.However,the traditional aluminum electrolysis production process has the disadvantages of high energy consumption,high carbon consumption and environmental pollution.It is not consistent with the sustainable development path of China,so how to solve these problems is an urgent need.After a lot of research and research by many researchers,the key to solving the above problems is to find a new inert anode material-NiFe₂O₄ cermet,which can completely replace the traditional carbon anode.In this paper,with the support of the International Cooperation Project of the Ministry of Science and Technology（2010DFA52130）and the combination of previous research results achieved by our group,the improvement of properties of17Ni/（10NiO-NiFe₂O₄）by adding composite dopants is studied in detail.Composite dopants selections are CoO and Cr₂O₃,and composite doped cermet samples were prepared.This paper studied on the effects and mechanism of composite dopants on phase composition,densification degree,morphology of microstructure,comprehensive mechanical properties,high temperature oxidation resistance and molten salt corrosion resistance of cermet in detail by XRD,SEM and EDS.The main achievements are as follows:1.The process parameters of high temperature solid phase sintering for obtaining10NiO-NiFe₂O₄ ceramic powder:temperature 1200 C,holding time for 6h.The cold pressing-sintering method for 17Ni/（10NiO-NiFe₂O₄）cermet samples with CoO and Cr₂O₃composite doped is prepared as follows:unidirectional pressing force 300 MPa,holding time for 10 min,then vacuum sintering was carried out at 1250℃,holding time for 3h,vacuum degree 1.01×10² Pa.2.No new substances were produced in the cermet samples with CoO and Cr₂O₃composite dopants.The phases of all cermet samples were still composed of ceramics NiO,NiFe₂O₄ and metal Ni.The added CoO and Cr₂O₃ composite dopants can promoting the development of cermet densification.Among all cermet samples,the densification degree of1#cermet sample with the total amount of CoO and Cr₂O₃ doping of 1wt%（CoO:Cr₂O₃=2:1）is the highest,and its relative density is 98.46%.3.The comprehensive mechanical properties of cermet can be effectively improved by adding proper amount of CoO and Cr₂O₃ composite dopant.The hardness and the fracture toughness of 2#cermet sample with the total amount of CoO and Cr₂O₃ doping of 1wt%（CoO:Cr₂O₃=2:1）are the most prominent,which is 740.65Hv/N·mm^-22 and 9.61MPa·m^1/2.3#cermet sample with the total amount of CoO and Cr₂O₃ doping of 2wt%（CoO:Cr₂O₃=2:1）has the best bending strength which is up to 175.66 MPa.4.The high temperature oxidation resistance of 17Ni/（10NiO-NiFe₂O₄）cermets can be improved by adding appropriate amount of CoO and Cr₂O₃ composite dopants.The high temperature oxidation resistance of 1#cermet sample with the total amount of CoO and Cr₂O₃ dopants of 1wt%（CoO:Cr₂O₃=2:1）is the best,which is much better than 0#cermet.Its weight per unit area increased by only 3.1172 mg/cm².5.The corrosion resistance of high temperature molten salt of 17Ni/（10NiO-NiFe₂O₄）cerme can be improved by adding proper amount of CoO and Cr₂O₃ composite dopant.The corrosion resistance of high temperature molten salt of 1#cermet sample with the total doping of CoO and Cr₂O₃ is 1wt%（CoO:Cr₂O₃=2:1）is the best.And the corrosion rate and average annual corrosion depth are the lowest values,which are 1.8014×10^-3g?cm^-2?h^-1and 2.6876 cm?y^-1,respectively.Its overall resistance to high temperature molten salt corrosion was 58.47%higher than 0#cermet samples without doping.6.Considering the actual conditions and test results comprehensively,it is determined that the compound doping amount of 1wt%（CoO:Cr₂O₃=2:1）is the optimal doping component.