氢化物加氢脱氧法对金属镧靶材的脱氧机理研究

This project is based on the technical bottleneck and key problems of the existing deoxidize methods of rare earth metal target, introduce the hydrogenation vacuum smelting technology aims to study the deep deoxidization behavior and mechanism of lanthanum target. First, the occurrence state, micro area distribution and diffusion coefficient, distribution coefficient of oxygen impurity in La target will be deeply studied by various analytical methods and thermodynamic calculation softwares such as SEM, XAFS, BL15U1, FACTSAGE and CALPHAD et al. Next, Study the Optimization hydride process of hydrogenated lanthanum and hydrogenated Calcium. In addition hydride hydrogenation deoxidization preparation of high purity metal lanthanum target material process. Finally, the separation behavior and transferring law of oxygen impurity in La target during the purification process will be explored by combine the difference of their existence form and thermodynamic parameters before and after the hydrogenation refining with the hydrogenated lanthanum and hydrogenated Calcium. The success of this project will be helpful to expand the research methods and results of oxygen impurities to other impurities (C, N and O et al.), realize the efficient synchronization separation of kinds of impurities, which will lay the groundwork for the new energy, efficient and economy purification technology route of rare earth metal target and make a significant theoretical and practical contribution to innovation the existing purification technologies and ptomoting sustainable development of the rare earth industry in the near future.

本项目基于现有稀土金属靶材制备的技术瓶颈和关键问题，引入加氢脱氧真空熔炼工艺，以稀土金属镧靶材为研究对象，分别通过间充型氢化镧和离子型氢化钙引入两种不同类型氢源，研究其熔炼过程深度脱氧行为与机理。首先，协同SEM、TEM、XAFS、上海光源BL15U1等多种分析手段与FACTSAGE、CALPHAD等热力学计算软件研究镧靶材中氧的赋存状态、微区分布与扩散系数、活度等热力学特性；其次，优化氢化物制备、氢化物加氢脱氧法制备高纯度金属镧靶材工艺；最终，结合加氢脱氧前后镧中氧杂质的存在形式、热力学参数的差异性，与熔炼过程挥发气体形态，探索氧杂质的迁移和脱除规律。本项目的实施可以起到以点带面的作用，即通过O杂质这个点带动其它气体杂质（C、N、S）的整个面，实现多种气体杂质的高效分离，对创新节能高效的高纯稀土金属靶材技术路线，推动稀土产业深加工和稀土产业的发展都具有重要的意义。

高纯金属La靶材作为信息存储、集成电路等电子器件的关键原材料，其关键核心制备技术长期以来一直被国外公司掌握，制约了我国稀土薄膜新材料的原始创新与应用开发。本项目针对高纯La靶材制备过程中氧杂质含量偏高的问题，开展了氢化物加氢脱氧法对金属镧靶材的脱氧工艺及其机理研究，获得了新型、高效的稀土金属靶材制备技术，主要研究结论如（1）探索稀土金属La 靶材中氧元素的赋存状态和微区分布特征，氧杂质在金属La靶材以间隙杂质的形式均匀分布，不存在明显的偏析现象。（2）研究了间隙型氢化镧和离子型氢化钙制备工艺，获得了不同颗粒的La4H12.19和CaH2稳定化合物；通过TGA、XRD、SEM等手段深入研究了氢化镧和氢化钙分解热力学和动力学。（3）研究了不同比例的氢化镧对真空悬浮熔炼和电子束熔炼等超洁净熔炼过程中脱氧效果，实验结果表明氢化镧加入量为1wt.%时，真空悬浮熔炼后金属镧靶材中的氧含量趋于最低值，相比不添加氢化镧效率提升了42%；氢化镧加入量为1wt.%时，电子束熔炼后金属镧靶材中的氧含量趋于最低值，相比不添加氢化镧效率提升了65%.（4）获得了氢化物加氢脱氧法对金属镧靶材的脱氧机理，氢化镧在高温条件下分解为La原子和具有强烈的还原性H原子，H原子通过扩散作用与熔融液中O原子发生反应结合成H2O分子，迁移至金属镧熔融液的表面挥发除去；同时，剩余的H原子将结合形成H2，不会引起二次污染问题。（5）本课题共发表论文3篇，申请国内外发明专利6项、已获授权专利4项，制定行业标准1项、企业标准1项。