五氧化二钒制备氮化钒的过程研究

对还原氮化法制备氮化钒的过程进行了理论分析和实验探讨，结果表明，五氧化二钒还原过程中同时发生了直接还原和间接还原，在高温氮化条件下已生成的氮化钒又转化为碳化钒，本试验条件下直接还原的开始温度为656K，氮化的开始温度为1160K，氮化钒转化为碳化钒的温度为1560K，间接还原发生的可能性与配碳系数有关，配碳系数越大，其发生的可能性越大。     

由三氧化二钒制备碳氮化钒的研究

以V2O3为原料，采用真空还原方法制备出碳化钒，生成的碳化钒直接进行渗氮制备出碳氮化钒，结果表明，原料中的配碳量是控制反应产物中氮含量的关键因素。氮化温度影响产物中氮含量，低温条件下，随氮化温度提高氮含量增加，但当反应温度高到一定程度，氮含量不再随温度提高而增加，氮化温度在1400℃时，4h可以氮化完全。     

一步法制备碳氮化钒的工艺优化试验

围绕开发连续、高效、低成本的一步法合成碳氮化钒的技术，在总结氮化钒生产工艺过程研究的基础上，以V₂O₅为原料，焦炭为还原剂，经过破碎、混料和压制成块、烘干后进行还原氮化过程，在高纯氮气气氛下探索了高温碳热还原一步法制备碳氮化钒的最佳生产工艺条件。通过对V₂O₅的还原过程进行热力学分析计算并利用FactSage热力学软件对其进行理论研究，采用XRD、SEM等测试方法对反应温度、反应时间、氮气流量、制样压力等影响因素进行单因素试验分析，结果表明，碳化钒的氮化反应是逐级进行的，碳氮化钒的反应过程为V₂O₅→V₂O₄→V₂O₃→VC→VCN。试验中产生的CO会改变炉内气体分压，会对碳化温度和氮化温度产生影响，因此反应过程中应严格控制体系的CO和N₂分压；反应时间和氮气流量对反应产物的钒、氮、碳含量产生不同的影响，钒含量和氮含量随着反应时间的增加和氮气流量的...     

偏钒酸铵一步法制备氮化钒研究

在热力学计算基础上,通过热重—差热试验的分析,对偏钒酸铵碳热还原制备氮化钒的过程进行了探索,研究了原料配碳比和反应温度对产物物相和成分的影响。结果表明,配碳比为理论碳比时氮化产物氮含量最高,碳含量随着配碳比增加而升高。一步法制备氮化钒的过程是钒氧化物的碳热还原和氮化同时进行的耦合反应。     

用三氧化二钒制取氮化钒试验研究

对三氧化二钒用碳还原氮化制备氮化钒的反应过程进行了热力学与动力学条件分析,在此基础上,对承钢公司氮化钒车间制成的球团料进试验,研究了三氧化二钒用碳热还原氮化温度和时间的关系,并确定了最佳的反应温度和时间,为生产提供理论指导。     

碳热还原氮化法制备氮化钒

以V2O5为原料,采用碳热还原法制备氮化钒,通过扫描电镜(SEM)和X射线衍射(XRD)观察与分析还原氮化产物的形貌与组成,分析产物的碳、氮、氧含量,研究原料配碳量、氮化温度和氮化时间等对还原氮化产物的影响。结果表明:还原氮化产物为碳氮化钒的固溶体。原料配碳量是影响反应产物中氮含量的关键因素,配碳比(质量分数)约为21%时还原氮化产物具有最高的氮含量14.76%;氮化温度应控制在1 400~1 420℃范围内,氮化时间达到4 h即可实现氮化完全。     

微波碳热还原法制备氮化钒的研究和实践

利用微波高温炉常压碳热还原渗氮法制备了氮化钒，并进行了试生产。实验结果表明微波加热法可以采用V2O5为原料一步反应制得氮化钒，配碳量和温度是影响产物成分的重要因素。试生产结果表明，产品理化指标满足炼钢的要求。与传统加热方式相比，微波加热缩短了反应时间，简化了工艺，因而大幅度地降低了成本。     

V2O5还原氮化制备VN过程中的化学反应动力学

研究以碳作为还原剂,还原氮化五氧化二钒制备氮化钒过程中的还原氮化反应动力学。在分别通入高纯氮气和氩气所得热重曲线的基础上,通过数据处理和回归分析得出了各步还原反应和氮化反应的反应活化能和频率因子,进而提出了各反应的速度常数(K)和反应温度(T)的经验公式。     

碳化钒、碳氮化钒生产工艺条件的实验室研究

在碳热还原钒氧化物(V_2O_5)反应体系平衡组成计算的基础上,进行了实验研究工作,确定了制取碳化钒(V_2C)的生产工艺条件.采用正交设计方法,研究了对碳化钒的渗氮过程,制定出碳氮化钒的生产工艺条件。     

还原氮化一步法制备氮化钒

以钒页岩提钒工艺的中间产品反萃液作为钒源,在沉钒之前加入碳黑,对加碳沉钒所得的混合物进行还原氮化制备氮化钒。结果表明,碳黑与V_2O_5的质量比为0.30时,产物的氮含量达到最大值;随着反应温度的升高,产物的氮含量先迅速增加后基本稳定,选择最佳的反应温度为1 150℃,反应1.0h即可获得较高的氮含量;最佳的氮气流量和造块压力分别为300 mL/min和10kN。在最佳工艺条件下,XRD谱显示产物均由VN相组成,制得的氮化钒纯度较高,满足GB/T 20567—2006中牌号VN16的化学成分要求。     

Effects of vanadium and nitrogen on recovery and recrystallization during and after hot-working some HSLA steels

The effects of vanadium/nitrogen additions on dynamic and static recovery and recrystallization have been studied in a set of aluminum-killed HSLA steels containing 0.1 pct carbon, 0.01 to 0.02 pct nitrogen, and either vanadium (0.1 or 0.2 pct), niobium (Cb) (0.03 pct), or vanadium and niobium together. Most, but not all, of the tests were carried out at 1173 K (900°C), a temperature at which precipitation of VN might be expected under some conditions. The net effect of dynamic recovery, recrystallization, and precipitation was monitored by measuring the change in compressive flow stress with strain at a constant temperature. Static changes were followed by measuring the change in compressive flow stress on isothermally holding unloaded specimens after a hot precompression. These kinetic data were supplemented by metallographic and electron-microscopic examinations of quenched specimens and of carbon extraction replicas taken from them. Evidence is presented which indicates that, at a holding temperature of 1173 K (900°C), static recrystallization occurs in vanadium steels containing 0.1 pct vanadium before any precipitation is detected. The progress of this recrystallization is arrested by the precipitation of vanadium nitride. At a higher vanadium concentration, 0.2 pct, recrystallization does not start. The effects of V/N ratio, austenitizing temperature (between 1373 K (1100°C) and 1523 K (1250°C), and isothermal holding temperature (between 1173 K (900°C) and 1273 K (1000°C)) on the kinetics of static softening and hardening are compared in some vanadium steels and plain-carbon and niobium steels of similar base-composition.     

减少转炉提钒过程碳烧损

摘要：为了有效减少了转炉提钒过程的碳烧损量,在硅钼炉内进行氧化性炉渣与铁水在不同温度下的渣金反应实验,发现炉渣与铁水的反应速率随温度的升高而加快;温度越高铁红(Fe2O3)将钒氧化到极值的速度越快,但达到极值后钒会被还原回铁水中,且还原速度也随温度的升高而提高;温度越高钒渣中的钒被铁水中碳还原的量越大。根据实验结果对转炉提钒工艺进行了优化,吹炼温度为1340～1350℃时加入冷却剂,控制较低的终点温度,在钒氧化率不降低的情况下,碳烧损率从19.39%降到17.91%、碳烧损量从0.82%减少到0.76%,有效减少了转炉提钒过程的碳烧损。     

Resource-saving direct alloying of steel

The development of the alloying and modification of steel by oxides, including natural materials, is very promising. Potential materials include barium–strontium carbonate ores, nickel concentrates, and vanadium converter slag, which may be used to produce steel with improved properties, without the expensive process of producing ferroalloys and intermediate alloys. Considerable research is required to improve steel-making processes. Thermodynamic modeling may be used for that purpose. In the present work, thermodynamic modeling is used for elementary systems involved in the extraction of barium, strontium, vanadium, and nickel from their oxides by means of different reducing agents. The results indicate that microalloying and modification of steel by inexpensive materials is possible; and permit the determination of the type of reducing agent and the optimal quantities employed. The Terra software used in thermodynamic modeling permits the determination of the equilibrium composition of the multicomponent heterogeneous system for high-temperature conditions, on the basis of the maximum-entropy principle. The reducing agents considered are carbon, silicon, and aluminum. The influence of the temperature and reducing-agent consumption on the reduction processes is investigated. The results regarding the reduction of barium and strontium show that silicon or aluminum is the best reducing agent when barium-bearing oxide materials are employed. The optimal reducing-agent consumption corresponding to maximum reduction of the barium and strontium is determined. The possibility of reducing nickel by carbon is confirmed. It is found that vanadium may be reduced by silicon or carbon or a complex process in which carbon is the predominant reducing agent. The results permit the development of a resource-saving technology based on oxides for the alloying, microalloying, and modification of Fe–C systems.     

低碳锰铁 FeMn 84C 0.4 氮化的实验研究

应用真空电阻炉高温渗氮、X射线衍射分析等实验测试方法，研究了粒度、温度、气相组成等因素对低碳锰铁氮化的影响。工业用气态氮作为渗氮气体的主要气相组成，可同时发生锰铁的氮化和氧化，生成 Mn4N 和 MnO 化合物；随渗氮温度的提高，锰氧化物的含量相应增高。渗氮气氛中配加氨气，使氮气的分压相应降低，平衡吸附浓度降低，渗氮试样的含氮量降低。     

Reduction of vanadium oxide by carbon in stainless steelmaking slags

Simultaneous reduction of chromium, iron and vanadium oxides by carbon has been studied by conducting experiments on typical stainless steelmaking slags in the temperature range of 1823 to 1923 K. In‐situ gas generated due to the reduction led to several phenomena such as foam/emulsion formation, change in foam height, size of gas bubbles and rate of gas generation. The kinetics of vanadium oxide reduction by carbon are studied under the influence of the above mentioned phenomena and the presence of chromium and iron oxides.     

The isothermal reduction kinetics of chromium-bearing vanadium–titanium magnetite sinter

The reduction of chromium-bearing vanadium–titanium magnetite sinter (CVTMS) by CO was investigated at 1123–1223?K. The reduction degree increased with increasing temperature. The isothermal reduction kinetics of CVTMS was analysed, according to Sharp analysis and ln–ln analysis, the kinetic mechanism of reduction process for all samples in different basicity can be represented as f(α)?=?1.61(1?α)[?ln(1?α)]^1–1/1.61. The reaction activation energy of all samples (R?=?1.9, 2.1, 2.3, obtained according to the components of the materials burdening used in sintering process) at different reaction degrees were calculated by the model-free method. And the pre-exponential factors of reaction also were calculated by the mathematical method. The rate controlling step for the reduction process under the present reduction condition was chemical reaction.