立方相纳米氮化钒粉体制备方法

中国科学院上海硅酸盐研究所近日向社会推出立方相纳米氮化钒粉体制备方法。据介绍 ,这种制备立方相纳米氮化钒粉体的方法 ,主要特征是以沉淀法制备的一水合五氧二钒 (V2 O5·H2 O)粉体为原料、在氨气气氛中将一水合五氧二钒粉体于管式反应炉中高温氮化制得立方相纳米氮化钒粉体。通过改变氮化温度、氮化时间等工艺条件、可获得小于 5 0nm的不同晶粒尺寸的纳米氮化钒粉体。氮化反应温度控制在 5 0 0～80 0℃ ,氮化保温时间 3～ 5h ,氮化升温速率为 5～ 10℃ /min。在优化条件下 ,可得到立方相纳米氮化钒粉体。立方相纳米氮化钒粉体制备方…     

[C4H7N2]3·PMo12O40配合物晶体的形貌模拟及其最佳纳米化计算的探讨

采用量子化学计算软件Material Studio的Morphology模块BFDH法则模拟了[C4H7N2]3·PMo12O40配合物晶体生长稳定外形,以晶体模拟形貌为基础,运用纳米计算方法通过对[C4H7N2]3·PMo12O40的不同纳米微粒总晶胞数、总原子数、比表面积、单颗粒表面原子数、单颗粒表面晶胞数及表面活性原子比例的计算,得出了[C4H7N2]3·PMo12O40纳米微粒的最佳纳米尺度为135 nm,认为晶体纳米化过程中[C4H7N2]3·PMo12O40制备到该尺度范围,理论上[C4H7N2]3·PMo12O40的活性和稳定性会达到均衡的最佳状态.     

[C4H7N2]3·PMo12O40配合物晶体的形貌模拟及其最佳纳米化计算的探讨

采用量子化学计算软件Material Studio的Morphology模块BFDH法则模拟了[C4H7N2]3·PMo12O40配合物晶体生长稳定外形，以晶体模拟形貌为基础，运用纳米计算方法通过对[C4H7N2]3·PMo12O40的不同纳米微粒总晶胞数、总原子数、比表面积、单颗粒表面原子数、单颗粒表面晶胞数及表面活性原子比例的计算，得出了[C4H7N2]3·PMo12O40纳米微粒的最佳纳米尺度为135nm，认为晶体纳米化过程中[C4H7N2]3·PMo12O40制备到该尺度范围，理论上[C4H7N2]3·PMo12O40的活性和稳定性会达到均衡的最佳状态。     

Eu2O3纳米晶形貌模拟及其最佳纳米尺度计算

采用量子化学计算软件Material Studio的Morphology模块,运用BFDH法则对单斜Eu2O3颗粒的纳米晶形貌进行详细的预测,对其纳米化的最佳尺度进行充分的探讨,模拟计算显示单斜Eu2O3纳米晶的(001)面为最易外显面,显示几率为41.64%.通过对其纳米晶尺度的探讨,得出单斜Eu2O3纯组分的最佳粒径为130nm.     

氮化钒合金在400MPa级钢筋中的应用

介绍了攀钢采用氮化钒合金化与钒铁合金化生产400MPa级含钒钢筋(20MnSiVⅢ级钢筋)的对比试验结果,研究了钒、氮微合金化对钢筋的性能和组织的影响,探讨了氮化钒的强化机理,比较了使用两种合金的生产成本。     

氮化钒/纳米硅/碳复合微球的制备及其储锂性能

硅(Si)因拥有高的比容量,资源丰富等优势有望成为下一代高性能锂离子电池负极材料,但其导电性差和循环过程中体积膨胀严重等缺陷限制了其进一步应用。采用喷雾干燥法,以玉米淀粉、纳米硅和NH₄VO₃作为原料,经碳化与氮化后获得氮化钒/纳米硅/碳复合微球(Si@VN/C)。氮化钒的引入提供了电子/离子快速传输通道,提高了纳米硅的导电率,并使纳米硅保持了良好的结构稳定性。碳层将作为纳米硅颗粒的保护层,避免纳米硅与电解液直接接触,有效缓解纳米硅充放电后的体积膨胀。Si@VN/C展现出良好的循环性能,在0.2 A·g^-1电流密度下循环130圈后容量为818 mAh·g^-1,在0.5 A·g^-1高电流密度下循环300圈后可逆容量仍保持580.5 mAh·g^-1。     

纳米磷酸钒钠的制备及其储钠性能研究

基于磷酸钒钠制备条件苛刻、颗粒粒径大、电导率差等问题,提出了一种制备纳米磷酸钒钠的新方法。通过碱性沉钒形成羟基氧化钒,再利用PO₄^3-、F^-等阴离子与OH^-的原位离子交换,从而得到纳米化的磷酸钒钠。借助XRD、SEM、FTIR等方法,分析了纳米磷酸钒钠的形成机理,优化了合成条件。电化学测试结果表明,磷酸钒钠的纳米化提升了电子/离子输运能力,使得所制备的纳米磷酸钒钠表现出优异的储钠性能。当电流密度为10 mA/g时,其放电比容量为106.68 mAh/g,并且循环20次循环充放电后,仍能保持80.85 mAh/g的放电比容量。     

铁元素在氮化钒铁中的赋存状态

采用化学分析,XRD,SEM等检测手段,对闪速燃烧工艺制备的氮化钒铁中铁元素的赋存状态进行了系统研究。实验结果表明:以FeV80为原料,高温下进行氮化反应,FeV80颗粒的钒原子氮化形成氮化钒包覆层,随着氮化反应的进行,氮化钒含量和铁含量相对增多,钒的氮化难度逐渐增大。实验产品中,铁主要以Fe形势存在,不均匀分布于氮化钒颗粒内部。     

纳米碳化钒强化TWIP钢加工硬化机制研究

弥散分布的纳米碳化钒颗粒能明显提高TWIP钢的屈服强度,但同时将在一定程度上降低加工硬化率。采用一个修正的物理模型来研究纳米碳化钒颗粒对一种实验室等级的FeMnC奥氏体TWIP钢加工硬化率的影响。试验发现在塑性变形过程中弥散分布的纳米碳化钒颗粒会加快位错累积速率,但也会降低孪晶形成速率。与不含析出相的TWIP钢相比,在小应变时含纳米碳化钒颗粒的TWIP钢加工硬化率较高,但随着应变量的增加其硬化率减小的速度高于不含析出相的TWIP钢,因此在高应变条件下含纳米碳化钒颗粒的TWIP显示出较低的钢加工硬化率。     

使用氮化钒铁合金生产高强度钢筋的工业试验

介绍了使用氮化钒铁合金生产4批159炉高强度钢筋的工业试验结果,基本工艺为100 t氧气转炉冶炼→165 mm×165 mm方坯连铸→热连轧(Φ20～32 mm),试验中以使用钒铁或氮化钒合金化作为对照试验.结果表明:(1)使用氮化钒铁合金化成分控制稳定;(2)使用氮化钒铁合金化钒的收得率高于使用钒铁或氮化钒;(3)钢中钒含量、钒的加入量对钢材机械性能的影响规律性非常明显,所得定量经验式可用于合金成分设计参考;(4)使用氮化钒铁合金化完全可满足HRB400～500高强度钢筋的生产,有降低合金用量和合金化成本的前景.     

Prospects for using carbonitride-forming elements in carbon steels to increase their mechanical properties

The effect of carbonitride-forming elements on the structure and mechanical properties of a carbon steel (0.65% C) is studied. A thermodynamic calculation is applied to plot solubility curves for the carbides and nitrides of titanium, aluminum, niobium, and vanadium. The optimum concentrations of these elements are determined to form dispersed carbide and nitride particles of the required number and sizes to impede austenite grain growth. Data on the effect of additions of various carbonitride-forming elements on the austenite grain growth and the impact strength are received. The intrduciton of carbonitride-forming elements in carbon steel in certain combinations and concentrations is shown to improve its mechanical properties.     

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...     

Study on Isothermal Precipitation Behavior of Nano‐Scale (Nb,Ti)C in Ferrite/Bainite in 780 MPa Grade Ultra‐High Strength Steel

In order to precisely control the nano‐scale (Nb,Ti)C precipitate in hot‐rolled 780 MPa Nb–Ti microalloying C–Mn steel, isothermal precipitation behavior of nano‐scale (Nb,Ti)C precipitate in the ultra‐high strength steel was investigated by the thermal simulation experiments. The results indicated that defects of deformed supercooled austenite became the preferential nucleation sites of nano‐scale (Nb,Ti)C precipitate and ferrite, so there was a competition mechanism for austenitic defects between ferritic transformation and precipitate nucleation. Bainitic transformation could effectively freeze austenitic defects, and additional defects are formed because of volume expansion in bainitic transformation process, so bainitic transformation could promote precipitate nucleation. However, precipitate was impacted by both nucleation driving force and atom diffusibility, so the peak temperature of nano‐scale (Nb,Ti)C precipitate was 550°C. On the basis of the above theoretical results, hot rolling experiments results showed that when the coiling temperature was 550°C, the yield strength and tensile strength were 710 and 790 MPa, respectively, and the microstructure of hot‐rolled steels was mainly bainitic ferrite, and a large number of <10 nm nano‐scale (Nb,Ti)C precipitates were obtained. Precipitation strengthening contribution to reached 325 MPa.     

Effects of second-phase particles on coarsening of austenite in 0.15 Pct carbon steels

The effects of second-phase particles formed by the addition of vanadium, nitrogen, and aluminum on the austenite grain coarsening behavior of 0.15 pct carbon steels were studied. The oxidation and etching technique has been adopted to reveal the prior austenite grain boundaries. The specimens were austenitized at intervals of 50°C within the range of 900°C to 1150°C under high vacuum (<10⁻⁴ torr) for half an hour, toward the end of which they were oxidized for about one minute by introducing oxygen at about 250 mm Hg to reveal the grain boundaries, and then quenched into iced water. The variation of prior austenite grain size with temperature in these steels indicates that vanadium carbonitride, V(C, N), is much more effective in austenite grain refinement than vanadium carbide, VC, at all temperatures. The effect of vanadium carbonitride in austenite grain refinement is more or less the same as that of aluminum nitride. AlN, at temepratures below 1000°C, but this effect of vanadium carbonitride in austenite grain refinement decreases with increasing temperature. Above 1000°C, aluminum nitride is a much better grain refiner than vanadium carbonitride. The presence of the V (C, N) and AlN particles in the same steel causes moderate grain growth of austenite. MD. Mohar Ali Bepari, formerly with the Department of Metallurgy, The University of Sheffield, Sheffield, England, is Associate Professor of Department of Metallurgical Engineering, Bangladesh University of Engineering and Technology, Dhaka, Bangladesh.     

Progress in the study of high-nitrogen corrosion-resistant aging nonmagnetic vanadium steels

Studies of the structure and properties of high-nitrogen corrosion-resistant aging nonmagnetic vanadium steels have been analyzed. The hardening of these steels by fine vanadium nitride and carbonitride particles is considered. The mechanisms of the discontinuous decomposition of austenite supersaturated by nitrogen upon heat treatment are described. Methods for the removal of the negative effect of the discontinuous decomposition on the mechanical properties of high-nitrogen steels have been found. Steels with an overequilibrium nitrogen content are shown to exhibit superplasticity. The dependences of the microstructure and properties of high-nitrogen vanadium austenitic steels on their alloying and the conditions of thermal and thermoplastic treatments are considered.     

竖式中频炉加工氮化钒VN16技术研究

研究了利用竖式中频炉加工氮化钒VN16产品的技术。通过对氮化钒合成过程中的反应机理、反应条件等试验分析,结合工业化试验,实现了利用竖式中频炉将VN12以低成本加工成VN16产品,使氮化钒产品达到了增值的目标。     

溶质钒原子与铁的[100](001)位错的相互作用

采用改进分析型EAM模型（MAEAM）研究了溶质钒与铁的[100]（001）位错的相互作用.对铁的[100]（001）位错及掺杂结构用分子动力学方法进行了弛豫.计算了钒在这些掺杂格点上的能量,以及溶质钒与铁的[100]（001）位错缺陷系统的能量,发现在位错芯区域钒的格点能高,随着钒与位错芯之间距离的增加,其格点能降低;溶质钒替代拉伸区位错芯位置的铁原子时,钒与位错的相互作用能最强,缺陷系统的能量最低、结构最稳定.     

中碳V、Ti微合金钢连轧圆坯表面裂纹的研究

为了减少中碳V、Ti微合金钢连轧圆坯的表面裂纹,在实验室条件下,测定了中碳V、Ti微合金钢的高温塑性和脆性温度范围,分析了影响中碳V、Ti微合金钢铸坯、连轧圆坯表面裂纹的因素,确认在900～820％温度范围内,随温度的下降,钢中V、Ti氮化物和碳氮化物在奥氏体晶界大量析出,弱化了晶界的变形能力,是造成中碳V、Ti微合金钢连轧圆坯表面裂纹的主要原因。结合实际生产过程,对现行生产工艺提出了改进建议。     

Structure of continuously cooled low-carbon vanadium steels

The structures of four 0.15 pct carbon steels containing vanadium, nitrogen, and aluminum separately and together were studied systematically, with the help of transmission electron microscopy, by cooling suitable steels at four different rates ranging from 120 °C/min to 3.6 °C/ min from temperatures giving a common austenite grain size of 35 μm. Except for the steel containing only vanadium and that containing only aluminum and nitrogen cooled at the fastest rate used, the observed microstructures were all essentially mixtures of polygonal ferrite and expected amounts for pearlite. For all the steels studied, except the one containing aluminum and nitrogen, it was found that general precipitation was more common than interphase precipitation, although the extent of the latter increased at lower cooling rates. Moreover, in some cases, both general and interphase precipitation were present in the same area. The presence of aluminum was observed to enhance the formation of interphase precipitates at all cooling rates, and the spacing between parallel rows of precipitates increased as the cooling rate was decreased. The dislocation density was high at all cooling rates in all the steels, but it was found to decrease with decreasing cooling rates. Very fine precipitates were found in all the steels, except the steel containing aluminum and nitrogen. At the fast cooling rates, the segregation of vanadium and interstitial elements, which led to locally lower transformation temperatures and higher supersaturations, resulted in clusters of fine particles of vanadium carbonitride, V(C, N). At the slower cooling rates, all the steels showed severe heterogeneity in precipitate morphology which was more pronounced in the steel containing aluminum and nitrogen, while a needlelike morphology of V(C, N) precipitate was occasionally found in steels containing either vanadium and nitrogen or vanadium, nitrogen, and aluminum. As the cooling rate decreased, particle coarsening and growth occurred, causing a reduction in the number of particles/unit area. The coarsening rate of V(C,N) in the presence of aluminum is considerably lower than that of vanadium carbide, VC, or of V(C, N) in the absence of aluminum. Because of the unfavorable precipitation kinetics, any aluminum nitride (A1N) formed during cooling did not nucleate separately but was deposited on the pre-existing A1N particles, thus causing them to be coarsened very rapidly with decreasing cooling rate. Formerly with the Department of Metallurgy, The University of Sheffield, Sheffield, England     

氮化钒制备技术的发展及应用

简要介绍了氮化钒的物理化学性质,详细介绍了国内外氮化钒制备技术的发展历程.氮化钒主要有两种制备方法,即高温真空制备和高温非真空制备,近年来也出现了一些新方法.对氮化钒的应用进行了综述,它不仅成为了微合金钢中重要的合金添加剂,还开拓了催化剂、工具涂层和微电子等应用领域.