Research On Preparation And Properties Of 17Ni/?10NiO-NiFe₂O₄? Cermet With TiO₂ And WO₃ Compound Doping

NiFe₂O₄ based cermet with excellent thermal stability and corrosion resistance,is considered to be the most promising candidate of aluminum electrolysis inert anode material. Although the research and development of NiFe₂O₄ based cermet has gained certain achievements, but the density, mechanical properties and corrosion resistance of the material still can not meet the industrial production demand. With the support of international cooperation project?2010DFA52130?, choicing TiO₂ and WO₃ compound additives, the 17Ni/?10NiO-NiFe₂O₄? cermet doped with compound additives was prepared. Then by testing techniques such as DSC, SEM and XRD, the influence of TiO₂ and WO₃ compound additives on densification, phase composition,microstructure, mechanical properties, high temperature oxidation resistance and high temperature static corrosion resistance of cermet are investigated from the macroscopic and microscopic aspects. The main research results are as follows:1. The best preparation process of?10NiO-NiFe₂O₄? composite ceramic powder is as follows: sintering temperature is 1250 ?, holding time is 5h; and the best preparation technology of 17Ni/?10NiO-NiFe₂O₄? cermet doped with TiO₂ and WO₃ compound additives is as follows: adding a small amount of PVA, one-way thrust pressure is 300 MPa,vacuum sintering temperature is 1250?, holding time is 4h.2. There is no new phase generated with TiO₂ and WO₃ compound doping, still consist of NiO, Ni and NiFe₂O₄, instead of the compound additives solid solution to the NiFe₂O₄ lattice, producing the lattice distortion and vacancy, improving the diffusion coefficient and active, ultimately increasing density. When the TiO₂ and WO₃ content of2%?ratio of 3:1? and 3%?ratio of 1:3?, the samples have the highest density, than undoped sample increased 5.26% and 4.37% respectively.3. The density, grain boundary bonding strength and size of metal phase are improved obviously of the samples with TiO₂ and WO₃ compound doping, in order to improving the hardness, fracture toughness and bending strength of the sample in a certain extent.4. The preper TiO₂ and WO₃ compound additives can improve the high temperature oxidation resistance of the samples. When the TiO₂ and WO₃ content of 2%?ratio of 3:1?and 3%?ratio of 1:3?, the samples have the best high temperature oxidation resistance,the oxide layer thickness is about 80 um after 30 h oxidation, which is 38.46% less than the undoped sample.5. The corrosion resistance of the samples is not only related to material density, but also closely connected with the composition ratio of compound dopant. When the TiO₂ and WO₃ content of 3%?ratio of 1:3?, the samples have the best corrosion resistance, the high temperature static corrosion rate is 1.7080×10^-3g ? cm^-2 ? h^-1, which is 49.57% of the undoped sample.