Experimental Study On The Preparation Of Vanadium Carbonitride By Direct Reduction Of Vanadium Pentoxide

Vanadium and vanadium compounds are widely used in the field of iron and steel metallurgy.The carbon and nitrogen elements in the steel are combined with vanadium and precipitated in the form of vanadium carbide and nitride.Vanadium carbide and vanadium nitride can refine the steel structure and grain,improve the strength of the steel,prepare vanadium carbonitride from vanadium oxide,and improve the toughness,wear resistance,plasticity,corrosion resistance and other properties of the steel.Therefore,it is widely used in steel.In this paper,vanadium carbonitride was prepared by high temperature vacuum carbothermal reduction nitridation with vanadium pentoxide as raw material and coke as reducing agent under certain vacuum and nitrogen atmosphere.Based on the thermodynamics of VCN,the optimization of VCN preparation process by direct reduction of V₂O₅ was analyzed,and the influencing factors such as carbon distribution coefficient,reaction temperature,reaction time,nitrogen flow and pressure were studied.The following conclusions were drawn through the research:（1）Through thermodynamic analysis and calculation of V₂O₅ reduction process and theoretical calculation and simulation with factsage software,the results show that the nitriding reaction of vanadium carbide is carried out step by step,and the reaction process of vanadium carbonitride is:V₂O₅→V₂O₄→V₂O₃→VC→VCN.According to the thermal mechanics research,V₂O₃ is directly reduced to VC when the carbonation reaction occurs,and the theoretical temperature is 1375K.VCN is obtained when the nitridation reaction occurs,and the theoretical nitriding temperature is 1540K,Due to the influence of CO partial pressure and N₂ partial pressure,the gas partial pressure will affect the reaction temperature during the preparation of VCN from V₂O₅.The carbonization temperature was 1173K,the nitriding temperature was 1723K～1823K,and the optimum reaction temperature was 1753k under other conditions.（2）Through the optimization and analysis of the process parameters of preparing VCN,such as carbon ratio,sample pressure,reaction temperature,reaction time and nitrogen flow rate,the XRD composition of the product was detected.With the increase of carbon content,vanadium content and nitrogen content increased first and then decreased,and the best carbon distribution coefficient was 35%,;With the increase of temperature,the content of vanadium and nitrogen increased first and then decreased.The optimum reaction temperature was 1753K;With the increase of reaction time,vanadium content and nitrogen content increased first and then tended to be flat,and the optimal reaction time was 180min;With the increase of nitrogen flow rate,vanadium content gradually increased,nitrogen content first increased and then decreased,and the best nitrogen flow rate was 300sccm;With the increase of pressure,the vanadium content and nitrogen content continued to rise,and the best pressure was 20MPa.（3）Through the optimization test of vanadium pentoxide direct reduction process for the preparation of VCN,the content of VCN products is V75.55%,N13.91%and C4.96%.