【作者】 李燕；

【导师】 扈玫珑；

【作者基本信息】 重庆大学 ， 工程（冶金工程）（专业学位）， 2021， 硕士

【摘要】 金属钒熔点高、硬度大,具有良好的导热性和化学稳定性,广泛应用于钢铁、有色冶金、航空航天、化学及新能源等领域。我国具有丰富的钒资源,占全世界可开采储量的19.6%,但钒资源综合利用水平较低,传统钒及钒合金制备工艺能耗高、成本高,在一定程度上限制了钒及钒合金的利用。熔盐电解法可实现由金属氧化物到金属的短流程制备,有望降低钒及钒合金生产成本,提高钒资源综合利用水平。但熔盐电解制备金属及其合金工艺目前仍存在电流效率低的难题。本文采用熔盐电解工艺制备钒合金,并针对钒合金制备过程工艺电流效率低的问题,从电解体系界面作用和宏观电解槽结构改进两方面开展了研究,降低工艺过程碳负面影响并提高工艺电流效率。在此基础上,进一步开展了电解过程中利用碳直接制备陶瓷复合材料的探索性研究。论文得到主要结论如下:（1）熔盐电解钒等金属氧化物混合物可直接制备钒合金。熔盐电解制备钒合金工艺以碳质材料为阳极时,会造成严重的熔盐和产物的碳污染,并且熔盐表面碳的积累导致阴阳极短路从而降低了电解过程电流效率。（2）V₂O₅电解脱氧历程主要有四个阶段:（ⅰ）V₂O₅直接得电子脱氧生成V₂O₃,脱除的O^2-被熔盐中的Ca²⁺捕获生成CaO,CaO会和V₂O₃反应生成中间相CaV₂O₄;（ⅱ）CaV₂O₄和V₂O₃进一步电解脱氧生成VO_x;（ⅲ）VO_x得电子深脱氧形成钒氧固溶体（V-O）;（ⅳ）V-O缓慢脱氧。（3）CaCl₂-KCl混合熔盐体系可改善熔盐与石墨电极间的润湿性,在CaCl₂熔盐中加入30 wt%的KCl熔盐对降低熔盐碳污染效果较好。该体系能抑制电解过程中的阴极析碳反应,降低碳对阴极产品的影响以及提高电解过程的电流效率,其中CaCl₂熔盐中加入30 wt%的KCl的熔盐体系与纯CaCl₂熔盐体系相比,阴极产品中的碳含量降低了68.64%,电流效率提高了38.99%。（4）改进电解槽结构可在一定程度上降低碳对工艺电流效率的影响,U型电解槽结构较复杂,不利于加工和进一步放大;阴极套管电解槽虽可降低熔盐碳污染,提高电流效率,但结构较复杂,可操作性不强;加隔板电解槽既可避免电解槽短路,又可在一定程度上降低熔盐碳污染,且加工、放大均较简单,易实现,工艺电流效率可提高44.38%。（5）熔盐电解工艺采用碳质材料为阳极时,可实现氧化物电解脱氧和金属碳化耦合直接制备VC陶瓷层复合材料,且该复合材料的陶瓷层与基体呈一整体,为碳化物陶瓷层制备提供了新思路。更多还原

【Abstract】 Metal vanadium has a high melting point,high hardness,good thermal conductivity and chemical stability,which is widely used in steel,non-ferrous metallurgy,aerospace,chemistry and new energy fields.China has abundant vanadium resources,accounting for19.6%of the world’s recoverable reserves,but with a low comprehensive utilization level.The traditional preparation processes of vanadium and vanadium alloys have high energy consumption and high cost,limiting vanadium and vanadium alloys to a certain extent of use.The molten salt electrolysis method can realize the short-process preparation from metal oxide to metal,which is expected to reduce the production cost and promote the comprehensive utilization of vanadium resources.However,preparing metals and their alloys by molten salt electrolysis still has a problem of low current efficiency.In this paper,the molten salt electrolysis process is used to prepare vanadium alloys.Focus on the problem of low current efficiency and the negative impact of carbon in the process.studies have been carried out from two aspects:the interface effect of the electrolysis system and the improvement of the macro electrolytic cell structure.Further exploratory research on the use of carbon to prepare ceramic composite materials in the electrolysis process directly has been carried out on this basis.The main conclusions of the paper are listed as follows:（1）Molten salt electrolysis of vanadium and other metal oxide mixtures can directly prepare vanadium alloys.When the carbonaceous materials are used in the molten salt electrolysis method as the anode,it will cause serious molten salt and carbon pollution of the products.The accumulation of carbon on the surface of molten salt causes the short circuit,which reduces the current efficiency of the electrolysis process.（2）V₂O₅ electrolytic deoxidation process mainly has four stages.（ⅰ）V₂O₅ direct electron deoxidation to generate V₂O₃,the removal of O^2-is captured by Ca²⁺in molten salt to generate CaO,CaO will react with V₂O₃to form the mesophase CaV₂O₄;（ⅱ）CaV₂O₄ and V₂O₃ are further electrolytically deoxidized to produce VO_x;（ⅲ）VO_x gets electrons to deep deoxidize to form vanadium oxide solid solution（V-O）;（ⅳ）V-O slowly deoxidizes.（3）CaCl₂-KCl mixed molten salt system can improve the wettability between molten salt and graphite electrode.The addition of 30 wt%of KCl to CaCl₂ molten salt is beneficial to reduce the carbon pollution of molten salt.The carbon content in the cathode product has been reduced by 68.64%,and the current efficiency has been increased by 38.99%.The CaCl₂-KCl system can suppress the cathodic carbon evolution reaction during the electrolysis process,reduce the influence of carbon on the cathode product and improve the current efficiency of the electrolysis process.（4）Improved cell structure can reduce the influence of carbon on the current efficiency of the process to a certain extent.The U-shaped electrolytic cell structure is more complex,which is not conducive to process and further enlarget.Although the cathode sleeve electrolytic cell can reduce molten salt carbon pollution and improve current efficiency,the structure is more complicated,and the operability is not strong.The electrolytic cell with a separator can avoid the short circuit,and reduce the molten salt carbon pollution,and the processing and amplification are relatively simple and easy to realize.The current efficiency increased 44.38%with a separator in the electrolytic cell（5）When the molten salt electrolysis process uses carbonaceous materials as the anode,the VC ceramic layer composite material can be directly prepared.The ceramic layer of the composite material is integrated with the matrix via the coupling of oxide electrolytic deoxidation and metal carbonization,provides a new idea for a carbide ceramic layer preparation.更多还原