Research On Preparation And Properties Of 17（xCo-Ni）/（10NiO-NiFe₂O₄） Cermet

It is a trend to using inert anodes which is energy saving and environmental protection in the aluminum electrolytic replacing carbon anode material. Ni Fe2O4 based cermet has chemical stability, it has been considered to have the most promising as inert anode.Funded by the international science and technology cooperation and based on the preliminary findings of 17Ni/(NiFe2O4-10NiO) cermet, The purpose of this article is going to find a more suitable metal phase as the second phase with 10NiO-Ni Fe2O4 as matrix. The innovation of this article is to choose Co-Ni alloy replacing pure Ni as the metal phase of the cermet. 17(x Co-Ni)/(10NiO-NiFe2O4) cermet is prepared by Vacuum sintering. The influence of Co content on microstructure, phase composition, relative density, mechanical properties and high temperature oxidation resistance of cermet are investigated.The mainly conclusions and findings can be summarized as follows:1. The purity of 10NiO- NiFe2O4 matrix is high by using High Temperrature Solid State Reaction. The appropriate technological conditions are as follows: sintering temperature is 1200℃, holding time is 4 hours.2. 17(x Co-Ni)/(10NiO-NiFe2O4) cermet(x=0、10、20、30、40、50、70) is prepared by Cold pressing-Vacuum sintering. It is concluded that the optimum temperature is 1300℃.3. The 17(xCo-Ni)/(10NiO-NiFe2O4) cermet is composed of Co-Ni, NiFe2O4 and NiO. A part of Co reacted with ceramic matrix to form CoO and Fe2O3. They become more and more with the content of Co increases. Fe2O3 is located in the grain boundary between NiO and NiFe2O4, CoO is completely dissolved in the ceramic matrix. But the 17Ni/(10NiONiFe2O4) cermet is composed of Ni, NiFe2O4 and NiO.4. It can be concluded that the proper addition of Co can improve the relative density, mechanical properties and conductivly of 17Ni/(10NiO-NiFe2O4) cermet. All aspects of performance change trends are first increases and decreases afterwards with the content of Co increases. When the mass percent of Co was 20% of metal phase, the property of sample is the best. The density, hardness, bending strength, fracture toughness, thermal shock resistance were achieved 96.87%, 820.81N·mm-2, 163.65 MPa, 8.38MPa/m1/2, 73.42% respectively.5. The curve of oxidation kinetics of 17(xCo-Ni)/(10NiO-Ni Fe2O4) cermet follows parabolic rate law. When the mass percent of Co was 20% of metal phase, the high temperature oxidation resistance of sample is the best. The gain against per unit area is only 6.2164mg·cm-2 after oxidation of 48 h.