氢分离单相钒基固溶体管状膜电塑成形和抗氢脆机理研究

The replacement of the commercially available palladium silver alloy with a higher hydrogen permeable vanadium alloy as the new hydrogen separation membrane material faces two challenges: difficult plastic formation at room temperature and its brittleness during hydrogen separation respectively. The effect of electroplating combined with the theories of dislocation slip and free electrons can be used to increase the plasticity of vanadium at room temperature thereby promoting its formation. The first-principles simulation calculation can be used to resolve the issue of hydrogen embrittlement by inhibiting the formation of hydride and controlling the solubility of hydrogen in the vanadium alloy by adding effective elements. This project will focus on aluminum-containing, single-phase vanadium based solid solution alloy membranes with no brittle hydride. High-energy pulse current parameters and the relationship between the stress flow behaviour and the microstructure of the tubular membrane deformation process are investigated in order to establish a coupled pulse current parameters of single phase vanadium-based solid solution electro-plastic constitutive equation. The micro-mechanism of electroplating of vanadium-based solid solutions would subsequently be revealed. Through the simultaneous use of environmental high-resolution transmission electron microscopy and synchrotron radiation source characterization techniques, the microscopic mechanism of hydrogen embrittlement in vanadium-based solid solutions is studied and a theoretical model will be constructed to reveal the mechanism of hydrogen embrittlement. This project establishes a strong foundation for the advancement in the new electroforming technology of tubular vanadium alloy membranes and the development of next generation of hydrogen separation alloy membrane material with a good combination of high resistance to hydrogen embrittlement and high hydrogen permeability.

针对以透氢率良好的钒合金替代商业鈀银合金作为新型氢分离膜材料开发过程尚存室温难塑性成膜和分离过程变脆的材料制备及应用难题，利用高能脉冲电流的电致塑性效应，结合位错滑移和自由电子理论促进室温塑性加工成膜；采用第一原理模拟计算，通过添加有效元素抑制氢化物形成同时调控氢在钒合金中的溶解度以解决氢脆问题。本项申请拟以固溶强化高而无脆性氢化物生成的含铝单相钒基固溶体合金膜为研究对象，研究高能脉冲电流参数与管材变形过程中应力流动行为及微观组织之间的作用规律，建立耦合脉冲电流参数的单相钒基固溶体电致塑性本构方程，揭示钒基固溶体电致塑性成形过程中的微观作用机理；同时借助环境高分辨透射电镜和同步辐射源表征技术，原位研究钒基固溶体氢脆微观机理，构建揭示氢脆机理的理论模型，为发展钒合金管状膜电致塑性成形新技术和研发集抗氢脆和高透氢率于一体的新一代钒合金氢分离薄膜材料奠定良好的理论基础。

氢能作为一种新型的零排放能源载体，已成为世界多国重要能源战略。目前，制氢方法无论化石燃料制氢、工业副产品制氢还是电解水制氢，都需要对这些含氢混合物的氢源进行分离纯化处理获得高纯氢气。纯化氢气主要有变压吸附法、低温分离和膜分离，其中金属膜分离技术以其纯度最高(>99.99999%)、操作简单、节能、高效、成本低等优点受到人们的青睐。虽然钯合金膜已经商业化，但实现大规模应用的成本太高，亟需开发新型非钯合金膜。第VB族难熔金属(V，Nb 和 Ta)合金膜比钯更便宜，渗透率也更高，有利于推进非钯合金膜分离提纯技术实用化。本项目将围绕非钯合金膜在氢分离膜技术领域中亟待解决的问题：针对氢致开裂，如何获得抗氢脆合金膜材料提高使用寿命而又保证氢渗透率高于商用钯合金；针对规模化合金膜制备，如何提高合金膜材料塑变成形性能，以便促进更薄合金膜的加工生产。项目主要研究了一系列V100-xAlx（x≤30 at%）固溶体合金的显微组织与氢渗透率、溶解度和扩散系数的关系，采用第一性原理探讨合金化元素Al及含量对氢在钒中溶解度和扩散的影响规律，并通过分析态密度图揭示Al在V中抗氢脆微观作用机理。采用同步辐射X光射线对V90Al10合金在室温至450°C范围内进行了原位衍射测量，研究脆性氢化物是否生成以及氢致峰宽化和位移的变化。以Nb-Ti-Zr单相固溶体为研究对象，通过厚度方向压下率和纵向延伸率评估铸态合金轧制成形能力，研究单相固溶体元素Ti、Zr及含量对冷轧塑性的影响，建立显微组织与成形性能的关系，筛选出能用冷轧途径制造薄膜的最佳合金成分。以V90-xTi10Mx (M=Y、Cu)双相组织为研究对象，分析这些合金的显微组织，研究Y和Cu含量对冷轧成形性能的影响，建立显微组织与氢渗透性能和抗氢脆之间的关系。研究成果主要有：Al元素添加有效降低氢在钒中的溶解度，并当含量为10at%时能抑制脆性氢化物的形成；开发出成形性能和抗氢脆性能双优的高性能合金，且能够用常规塑性成形技术规模化制备平面膜和管状膜。本项目科学意义在于深刻洞察了氢分离合金膜发生氢脆的内在机制，揭示了元素种类和含量对塑性影响的微观作用机理，为促进低成本工业化氢分离合金膜的工程化应用提供重要技术支撑。