Research On Plasma Sprayed TiB₂ Coating On Cathode Surface Of Aluminum Electrolysis Cel

Most carbon cathodes electrolytic cell exist some problem such as resistance to low sodium corrosion rate,larger resistivity,short life of cathode,it needs to spend a lot of time that parking electrolytic cell for repairing,and will increase the cost of production,this will restrict the development of aluminum industry.In order to overcome the disadvantages of aluminum electrolytic tank,we need the development of new aluminum inert wettability cathode material,a large number of scholars have conducted in-depth research.TiB2 material is popular because it has good electrical conductivity,liquid aluminum wettability,and the advantages of corrosion resistance to molten salt.This paper main research the preparation of aluminum electrolytic cell wettability TiB2 inert cathode by plasma spraying,and TiB2 cathode coating materials,plasma spraying process and coating related properties,the main research contents and results are as follows:(1)DH-2080 plasma spraying equipment in preparation for about 2mm TiB2 coating with pure TiB2 powder as raw material and cathode carbon blocks as matrix,the analysis and testing of the properties of the coating,and the reasonable plasma spraying process parameters is determined.And the spraying process with related coating performance are studied,to obtain the influence law of Spraying distance,spray current and main gas flow on the coating porosity and the deposition rate.The results show that the factors of influencing the coating bond strength is in turn,spraying current,spraying distance,the main gas pressure,and feed powder rate;(2)Through XRD composition analysis and oxygen content analysis is carried out on the coating,we find the coating existing oxide,although use argon as working gas in the process of spray and powder gases,but there are still some TiB2 powder oxidation.So we research the TiB2 powder oxidation behavior at high temperature.The results show that at low temperature,the surface of TiB2 can form a layer of protective film oxide,the oxidation reaction is not occurs or response is very slow to TiO2 material was not oxidation;When the temperature between 765K and 1430K,the solid phase of TiO2 and liquid phase B2O3 will be produced,liquid phase B2O3 covers on the surface of oxide layer,it can isolate oxygen,TiB2 material has good oxidation resistance;When the temperature of T higher than 1430K,the oxidation products of solid phase TiO2 and gas phase B2O3,because of B2O3 steam volatile,it speeds up the process of TiB2 powder with oxygen contact,the oxidation resistance of TiB2 material gradually decline.(3)This paper researchs the wettability of TiB2 coating and liquid aluminum,sodium corrosion principle,and the conductivity.The results show that the TiB2 coating with liquid aluminum has good wettability;TiB2 coating and liquid aluminum layer can with prevent or slow sodium penetration into cathode carbon material,sodium corrosion resistance is superior to the semi graphite cathode;At room temperature,the resistivity of TiB2 coating is larger,above for the half graphite cathode carbon block’s resistivity.TiB2 content is higher,the resistivity is smaller at room temperature,and when high temperature,the resistivity of TiB2 coating is below graphite cathode carbon block’s.