Study On Preparation And Properties Of NiFe₂O₄ Based Anode Material Reinforced By Fiber

At present, there are two problems in using NiFe₂O₄ spinel as anode material: 1. its property of thermal shock is unsatisfactory, and this increases the corrosion rate and decreases the endurance of the anode; 2. the strength and the toughness of the NiFe₂O₄ spinel are relatively low, which make it easy to break when it is carried and connected with conductor pole. In order to solve these problems this thesis studied the preparation of NiFe₂O₄ based anode material reinforced by SiC whisker and SiC fiber.At first, NiFe₂O₄ spinel was synthesized using NiO and Fe₂O₃. The sintering temperature was 900℃, and holding time was 6h. In the next place, NiFe₂O₄ based anode material was prepared by adding SiC whisker and SiC fiber.This thesis studied the preparation of SiC_W/NiFe₂O₄ ceramic composite materials by adding SiC whisker for the first time. The results of thermodynamic calculation and XRD analysis showed that when the temperature was lower than 1200℃, NiFe₂O₄ and SiC_W were consistented with each other. The experiment determined the appropriate sintering technology of SiC_W/NiFe₂O₄ composite materials: sintering temperature was 1180℃; holding time was 6h. The test results of mechanical property showed that the bending strength of SiC_W/NiFe₂O₄ composite materials with 3% SiC_W was increased about 200% than that of NiFe₂O₄ sample. This indicated that the SiC whisker had strengthening effect. The property of thermal shock of SiC_W/NiFe₂O₄ composite materials declined, and the bending strength retention of the sample with 3% SiC_W was decreased by 14%. The decrease of the property of thermal shock was related to the bonding state of the interface of SiC_W/NiFe₂O₄ composite materials. The thermodynamic calculation and XRD analysis showed that silicate compound 2FeO·SiO₂ was formed at the interface of SiC_W/NiFe₂O₄. The thermal expansion coefficient of 2FeO·SiO₂ changed...