SCIART: Collaborative Research: Protection of Silver Objects from Corrosion using Atomic Layer Deposited Barrier Coatings

SCIART：合作研究：使用原子层沉积阻挡涂层保护银制品免受腐蚀

• 批准号: 1041809
• 负责人: Raymond Phaneuf
• 金额: $ 33万
• 依托单位: University of Maryland, College Park
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-15 至 2015-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1041809&HistoricalAwards=false
• 关键词: SCIART; Collaborative; Research; Protection; Silver

NONTECHNICAL DESCRIPTION The corrosion of silver artifacts, especially polished silver surfaces, is a monumental problem for art collections throughout the world. As objects in major museums are typically one of a kind, conservation methods and techniques require overwhelming evidence of treatment effectiveness, improvement over existing methods, and reversibility. This research will develop a novel multilayer, multifunctional transparent barrier coating for silver using a very powerful technique known as "atomic layer deposition" (ALD), which allows for the creation of nanometer thick layers of metal oxides with an exquisite level of control, literally at the atomic level. The resulting multilayer films will be optimized to reduce the rate of silver corrosion, while complying with the rigorous standards of art conservation practice. This museum and university partnership will result in an effective, low-cost strategy to reduce silver artifact corrosion, which also preserves artifact appearance and composition without precluding future conservation-treatment strategies. These benefits will be shared with the global museum conservation community through publications and presentations.TECHNICAL DETAILS In this work multilayer-structured, multifunctional atomic layer deposition (ALD) films for conservation of silver art objects are fabricated, characterized and optimized. Tarnishing of silver is a critical problem, presently producing irreparable damage to priceless art objects in museum collections throughout the world. The approach is based upon ALD: an innovative, thermally activated gas phase process for synthesizing nanometer-thick solid films by sequential exposure to 2 or more gas reactants to induce self-limited chemisorbed surface reactions, which reduces the rate of oxidant arrival at the underlying surface by orders of magnitude. Multiple compositions and layer structures are explored to optimize barrier performance and optical clarity. Tarnishing is evaluated via reflectance spectroscopy, and using x-ray photoelectrons spectroscopy (XPS) to measure the amount of sulfur on the surface subsequent to stripping the oxide after a series of exposures. Accelerated transport of oxidants through the film and reaction at the silver surface, using both exposure to atmospheres with controlled, elevated concentrations of H2S, and increasing the temperature of ALD coated samples are employed to establish the characteristic time scales, likely decades or longer. The reversibility of ALD metal oxide coatings is evaluated to determine if either the deposition or the removal of thin layers of metal oxides on silver changes the physical characteristics or chemical composition of the silver surface. The direct impingement of oxidant molecules through pinholes in barrier coatings is prevented by depositing multiple layers of alternating oxides of aluminum and titanium. Novel oxidant gettering functionality is introduced via deposition of buried layers of platinum into the films. Patterning of silver substrates is used to quantify the effect coatings have on the optical properties of micro and macro features and evaluation of the role of the starting topography on the topographical and compositional stability of the surfaces of art objects during ALD oxide deposition, removal, and on the local rate of tarnishing. Students at both the graduate and undergraduate level are trained in cutting-edge ALD film fabrication and characterization techniques, and in museum conservation practices in this collaboration between the Walters Art Museum and the University of Maryland.

非技术描述银器的腐蚀，尤其是抛光的银色表面，是全世界艺术收藏的巨大问题。由于主要博物馆中的物体通常是一种，因此保护方法和技术需要压倒性的治疗效率证据，改善现有方法以及可逆性。这项研究将使用一种非常强大的技术“原子层沉积”（ALD）开发出一种新型的多功能透明屏障涂层，以使其具有精美的控制水平，从而在原子水平上产生了精美的控制水平。 最终的多层膜将被优化，以降低银腐蚀的速度，同时遵守严格的艺术保护实践标准。该博物馆和大学的伙伴关系将产生一种有效的低成本策略，以减少银色伪影腐蚀，这也可以保留人工制品的外观和构图，而不会阻止未来的保护策略。 这些好处将通过出版物和演示与全球博物馆保护界分享。技术细节在这项工作中，多层结构，多功能原子层沉积（ALD）膜用于保护银艺术对象，制造，表征和优化。白银的破坏是一个关键问题，目前在世界各地的博物馆收藏中对无价艺术品造成了无法弥补的损害。 该方法基于ALD：一种创新的，热活化的气相工艺，用于通过顺序暴露于2个或更多气体反应物来诱导自限制的化学化学表面反应，以降低氧化剂到达的氧化度速率，从而降低下层表面上的氧化剂到达的速率。探索了多个组成和层结构，以优化屏障性能和光学清晰度。通过反射光谱法评估了粉刷，并使用X射线光电子光谱（XP）来测量一系列暴露后剥离氧化物后表面上硫的量。 氧化剂通过膜和在银表面的反应加速运输，两者都暴露于具有控制浓度的H2s的大气中，并使用升高ALD涂层样品的温度来建立特征时间尺度，可能是数十年或更长的时间。评估ALD金属氧化物涂层的可逆性，以确定银色的沉积或去除金属氧化物的薄层会改变银表面的物理特性或化学成分。 通过沉积铝和钛的多层交替氧化物，可以防止通过屏障涂层中的针孔直接撞击氧化分子。 新颖的氧化剂获取功能是通过将铂层埋入层的沉积引入膜中引入的。 银基质的模式用于量化涂料对微观和宏特征的光学特性的影响，并评估起始地形在ALD氧化物沉积，去除ALD氧化物对象的地形和组成稳定性以及对局部速率的作用。 毕业生和本科生的学生都接受了尖端的ALD电影制作和特征技术的培训，以及在沃尔特斯艺术博物馆和马里兰大学之间合作的博物馆保护做法中。