Role of Selected Major and Minor Alloy Alloying Elements in Copper Alloys on Copper Ion Release and Oxide Formation for Anti-Microbial Functionality

技术概述：耐甲氧西林金黄色葡萄球菌（MRSA）具有抗生素耐药性，通过手与金属表面接触传播，经常导致医院患者感染。铜（Cu）和银（Ag）具有抗菌能力，这是由于在潮湿空气中汗盐沉积潮解形成的复杂表面环境下，通过电化学过程释放氧化的Cu或Ag离子。由于手汗会导致铜表面迅速失去光泽，目前在医院不受欢迎。具有抗菌能力和颜色稳定性的铜合金对于高接触表面是非常理想的，现在使用不锈钢，但没有抗菌能力。理想的合金表面以合金化介导的速率释放Cu离子。然而，对铜合金的电化学氧化、钝化和释放的科学认识还存在空白。以往的研究很少关注主、次合金元素对Cu析出的影响。先前对工业合金的研究证实了合金元素的复杂影响；合金元素可能抑制或促进Cu离子的释放，其机制目前尚不清楚。目的是阐明Cu在合金元素系统变化下的释放特性和机制。通过系统添加选定的合金元素合成的二元和三元铜合金，研究合金化对铜释放、钝化和颜色稳定性的影响。腐蚀/释放行为将与合金元素在氧化过程中命运的原子尺度测量有关。使用各种技术的全球和高分辨率表面和原子尺度实验研究将跟踪金属中Cu的命运，氧化物以及释放的通量。智力上的优点包括对主要和次要合金元素在这些过程中所起作用的固体/液体界面的新认识。改进试错法的功能性合金设计的基础将会出现。非技术总结：该项目涉及发展材料科学，使更好地设计具有抗菌功能的铜和银基合金，从而最终控制医院获得性感染。例如，耐甲氧西林金黄色葡萄球菌（MRSA）具有抗生素耐药性，通过手与表面接触传播，经常导致感染。铜（Cu）和银（Ag）金属合金具有抗菌功能，这是由于金属离子在人体汗液等复杂化学环境下的释放。铜在医院不受欢迎，因为手出汗会迅速失去光泽。不锈钢耐变色，但不具备任何抗菌能力。该项目旨在确定和了解控制合金性能的因素，这些因素能够同时实现抗菌功能和颜色稳定性。这些特性对于高接触表面是非常理想的。本项目将研究选定合金元素介导的Cu合金中Cu的释放特性和机制。智力上的优点包括对合金元素在人体汗液中铜合金氧化/离子释放中的作用有了新的认识。这将使合金成分的智能设计具有理想的抗菌功能和最小的光泽。更广泛的影响包括开发必要的洞察力，以便在抗菌应用中使用多功能铜合金，以减少致病细菌的传播。这可以对世界健康产生积极影响，也有助于了解其他应用中的金属释放。材料科学和工程以及腐蚀科学领域将出现重大的人力资源开发——这是STEM培训的关键缺口，也是美国国家科学院确定的国家需求。材料科学领域的研究生将接受教育，并充分融入所有研究任务。本科生和高中生也将参加。与美国铜发展协会和各种铜合金生产商的合作正在进行中。

TECHNICAL SUMMARY: Methicillin-resistant Straphylococcus aureus (MRSA) is antibiotic-resistant and spread by hand-to-surface contact with metal surfaces, often leading to hospital patient infection. Copper (Cu) and silver (Ag) possess anti-microbial capability due to the release of either oxidized Cu or Ag ions via electrochemical processes in response to complex surface environments formed during deliquescence of perspiration salt deposits in humid air. Cu surfaces are not presently favored in hospitals due to rapid tarnishing caused by hand perspiration. A Cu alloy that has antimicrobial capability and color stability is highly desirable for high touch surfaces where stainless steel is now used but has no antimicrobial capabilities. The ideal alloy surface releases Cu ions at rates mediated via alloying. However, there is a gap in scientific understanding of electrochemical Cu oxidation, passivity and release from copper alloys. Few past studies focus on the role of major and minor alloying elements on Cu release from alloys. Prior research on commercial alloys confirms the complex effects of alloying elements; alloying elements may either suppress or enhance release of Cu ions by mechanisms which are presently unknown. The objective is to elucidate the Cu release characteristics and mechanisms in selected Cu alloys as mediated by systematic variation of alloying elements. The effects of alloying on copper release, passivity and color stability will be investigated using binary and ternary Cu alloys synthesized with systematic additions of selected alloying elements. Corrosion/release behavior will be connected with atomic scale measurements of the fate of alloying elements during oxidation. Both global and high resolution surface and atomic scale experimental studies using a variety of techniques will track the fate of Cu in the metal, the oxide as well as the flux released. Intellectual merits include new solid/liquid interfacial understandings of the role of major and minor alloying elements on these processes. A foundation for functional alloy design that improves trial and error approaches will emerge.NON-TECHNICAL SUMMARY: This project concerns developing the materials science which enables better design of copper and silver based alloys that have anti-microbial functionality as a way to ultimately control hospital acquired infections. For instance, Methicillin-resistant Straphylococcus aureus (MRSA) is antibiotic-resistant and spread by hand-to-surface contact, often leading to infection. Copper (Cu) and silver (Ag) metallic alloys possess anti-microbial function due to the release of metal ions in response to complex chemical environments such as human sweat. Cu is not favored in hospitals due to rapid tarnishing caused by hand perspiration. Stainless steels resist tarnishing but do not possess any antimicrobial capability. This project seeks to identify and understand factors controlling alloy properties that enable both antimicrobial function and color stability. These properties are highly desirable for high touch surfaces. This project will conduct research to define the Cu release characteristics and mechanisms in selected Cu alloys as mediated by selected alloying elements. Intellectual merits include new understandings of the role of alloying elements on copper alloy oxidation/ion release in human perspiration. This will enable intelligent design of alloy compositions for ideal anti-microbial function and minimal tarnishing. Broader implications include development of the insight necessary to enable use of multi-functional copper alloys in anti-microbial applications to reduce the spread of disease-causing bacteria. This can positively affect world health, and also contribute to understanding of metal release in other applications. Significant human resource development will occur in the fields of materials science and engineering as well as corrosion science - crucial gaps in STEM training and a national need identified by the US National Academy. Graduate students in the materials science area will be educated and fully integrated with all research tasks. Undergraduate as well as high school students will also participate. Collaboration is underway with the Copper Development Association of America and various copper alloy producers.