Study On Electric Conductive Materials To Protect Corronsion And Oxidation In High Temperature Fluorides Bath

In Aluminum industry,inert anodes attract more and more attention for their low cost and being friendly to the environment. This academic's purpose is to study inert anodes which are used in aluminum electrolysis. In the recent two decades, cermets as the promising materials were used to fabricate inert anodes especially cermets based on spinels which presented a bright future in industrial application. The dissertation's mainly focused on the hot-pressing manufacture of cermet inert anode based on NiFe2O4-M and WC-M and testing their corrosion resitance during electrolysis.The project of cermets, used as the inert anodes for aluminum electrolysis, has been carrying out combined with low corrosion of oxides and perfect conductivity of alloy.NiFe2O4-based cermets were prepared by compositing the NiFe2O4 ceramic matrix with the mixed powders of M as the electrical conducting metallic elements.Another inert anode is made by plasma thermal spraying. The effcts of technics parameters, such as the sintering time, the sintering temperature and the contents of metallic phase on the relative density and electrical conductivity of the cermets were studied.The electrical conductive mechanism of NiFe2O4-based cermets was investigated.The mainly conclusions and findings can be summarized as follows:(1) The synthetical conditions of NiFe2O4 is found to be suitable as NiFe2O4 and NiO calcined at 1000℃for 6 hours;(2) Put the powder into the mold. Press the mold in one direction. For the sample to be sintered can be NiFe2O-M inert anodes.(3) WC-M inert anode is made by plasma thermal spraying. In aluminum electrolysis,the electrical conductivity of WC-M inert anode is good, current density is 1A/cm2. Corrosion rate of WC-M inert anode is 29.0mm/year.(4) The electrical conductivity of NiFe2O4-M inert anode is availuble too, current density is lA/cm2. Corrosion rate of the inert anode is 19.5mm/year. (5) The two kind materials both can be used as inert anode.The purity of aluminum product is above 98%.Corrosion resistance of inert anode of NiFe2O4-M is better than inert anode of WC-M,but its fabrication technologies are very difficult. So we will develepo the NiFe2O4-M inert anode in the future.