Transient Oxidation Stages of Metals

目标是获得对氧化阶段的新认识，其中金属表面条件和杂质受到高度控制。铜和铝的一系列原位TEM实验解决了瞬态氧化中的开放问题，包括初始氧化物形成的动力学。样品制备，初始的非原位表征和氧化实验，以及数据分析和建模，在匹兹堡大学进行。氧化的初始阶段之后是在伊利诺伊大学厄巴纳-香槟分校（UIUC）材料研究实验室进行的原位超高真空透射电子显微镜。与橡树岭国家实验室（ORNL）腐蚀科学与技术（CS&amp；T）小组的密切互动是该计划不可或缺的一部分。目前，金属表面上氧原子的行为是通过表面技术，如低能电子衍射（LEED）和超高真空扫描隧道显微镜（UHV-STM）来观察的，这些表面是高度控制的，或者通过研究在高温和低温下发生的宏观氧化物生长，在原子水平上的表面清洁度是极具挑战性的。计划中的实验提供了在这两个极端之间架起桥梁的重要信息。表面氧化过程在环境稳定性、高温腐蚀、电化学、某些催化反应和薄膜生长以及极端燃料反应中起着至关重要的作用。关于氧与金属表面的相互作用，以及热力学稳定的氧化物的宏观生长，我们知道得很多。然而，目前，从金属氧化物成核到形成热力学稳定的氧化物的瞬态氧化阶段，是一个具有科学挑战性和技术重要性的领域

9902863YangThe goal is to gain new understanding of the stages of oxidation where metal surface conditions and impurities are highly controlled. A coordinated series of in-situ TEM experiments on copper and aluminum address open issues in transient oxidation, including the kinetics of initial oxide formation. Sample preparation, initial ex-situ characterization and oxidation experiments, as well as data analysis and modeling, are conducted at University of Pittsburgh. The initial stages of oxidation are followed by in-situ ultrahigh-vacuum transmission electron microscopy performed at the Materials Research Laboratory, University of Illinois at Urbana-Champaign (UIUC). Close interaction with the Corrosion Science and Technology (CS&T) Group at Oak Ridge National Laboratory (ORNL) is integral to this program. At present the behavior of oxygen atoms on metal surfaces are observed by surface techniques such as low energy electron diffraction (LEED) and ultra-high vacuum-scanning tunneling microscopy (UHV-STM), where the surfaces are highly controlled, or by studies of macroscopic oxide growth occurring at high and low temperatures, where surface cleanliness at the atomic level is extremely challenging to achieve. The planned experiments provide essential information that bridges the gap between these two extremes.%%%Surface oxidation processes play critical roles in environmental stability, high temperature corrosion, electrochemistry, certain catalytic reactions and thin film growth as well as extreme fuel reactions. Much is known about oxygen interaction with metal surfaces and about the macroscopic growth of thermodynamically stable oxides. At present, however, the transient stages of oxidation, from the nucleation of the metal oxide to the formation of the thermodynamically stable oxide, represent a scientifically challenging and technologically important area.***