Ferroalloys and Stainless Steels with Low Carbon Footprint via Hydrogen Reduction of Oxide Blends

该奖项支持与先进炼钢相关的基础研究，从而大幅减少导致全球变暖的二氧化碳（CO2）排放及其对美国土地和人口的影响。使用绿色氢代替焦炭（碳的一种形式），铁和其他矿石在单一步骤中直接转化为合金钢，例如广泛用于消费者和高科技应用的不锈钢（含有铁、镍和铬）。氢气是通过可再生电力分解水获得的。本研究利用原位x射线绕射与理论模拟，探讨铁与其他金属氧化物混合物氢还原的热力学与动力学。该项目支持国内氢经济的发展，并有助于工业脱碳。它提高了美国钢铁工业的现代化和竞争力，从而使美国经济和社会受益。该过程利用各种学科，包括制造，冶金和X射线衍射科学，从而带来新的教育机会。该项目扩大了妇女和代表性不足的群体在研究中的参与，并培训了促进国内高价值合金钢生产所需的下一代工程师。氢还原Fe_2O_3是一个复杂的过程，因为存在过渡相FeO和Fe_3O_4，还原过程中体积变化很大。氧化物共混物的氢还原以在单个步骤中产生铁合金和合金钢引入了额外的复杂性，因为铁的氧化物与其他元素（例如镍、铬、钨、钼和锰）之间的相互作用导致还原动力学的加速、热力学稳定性的转变以及进一步的瞬态相的形成。本研究研究了这些影响的机制以及最终合金的微观结构和性能，寻求更深入地了解直接氢还原，因为它适用于各种合金钢和铁合金。该项目研究如何一步，一锅氢还原氧化物混合物，以创建合金钢和铁合金，大大提高了还原动力学，同时也比多步工艺更有效，其中单个合金元素被创建，然后与铁结合，以制造合金钢。该项目发展了对铁和合金元素的氧化物混合物的共同还原的基本理解，以获得可用于生产各种钢的金属二元和三元铁合金。通过原位X射线衍射研究氧化物混合物的氢还原，以评估反应动力学和相形成，并通过CALPHAD、相场和有限元建模来提高对反应机理的理解和预测。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This award supports fundamental research related to advanced steelmaking, enabling a drastic reduction of carbon dioxide (CO2) emissions responsible for global warming and its impact on the US land and population. Using green hydrogen, instead of coke (a form of carbon), iron and other ores are directly transformed, in a single step, to alloy steels, such as stainless steel (containing iron, nickel and chromium) which is used extensively in consumer and high-tech applications. The hydrogen is obtained by splitting water with renewable electricity. This research investigates the thermodynamics and kinetics of hydrogen reduction of blends of iron and other metal oxides using in situ x-ray diffraction and theoretical modeling. This project supports the development of a domestic hydrogen economy and contributes to industrial decarbonization. It improves modernization and competitiveness of the US steel industry, thus benefiting the US economy and society. The process leverages various disciplines including manufacturing, metallurgy, and x-ray diffraction science leading to new educational opportunities. The project broadens participation of women and underrepresented groups in research and trains the next generation of engineers needed to boost domestic production of high-value alloyed steels. Hydrogen reduction of Fe2O3 is a complex process due to the presence of transient phases, FeO and Fe3O4, and large volume changes during reduction. Hydrogen reduction of oxide blends to create, in a single step, ferroalloys and alloy steels, introduces additional complexity, as the interactions between oxides of iron and the other elements, such as nickel, chromium, tungsten, molybdenum and manganese, lead to acceleration of reduction kinetics, shift in thermodynamic stability, and formation of further transient phases. This research studies the mechanisms underlying these effects and the microstructures and properties of the final alloys, seeking a deeper understanding of direct hydrogen reduction as it applies to various alloyed steels and ferroalloys. This project studies how one-step, one-pot hydrogen reduction of oxide blends to create alloy steels and ferroalloys greatly improves the reduction kinetics while also being more efficient than a multiple step process where individual alloying elements are created and then combined with iron to make alloy steels. The project develops a fundamental understanding of co-reduction of oxide mixtures of iron and alloying elements to achieve metallic binary and ternary ferroalloys useful for production of various steels. Hydrogen reduction of oxide blends is studied via in-situ x-ray diffraction to assess the reaction kinetics and phase formation and CALPHAD, phase-field, and finite-element modeling to improve the understanding of and provide predictions of reaction mechanisms.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.