Microvisualization of Pitting Precursor Sites on Metals

金属上点蚀前驱体位点的显微可视化

• 批准号: 9509766
• 负责人: William Smyrl
• 金额: $ 30.27万
• 依托单位: University of Minnesota-Twin Cities
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-08-01 至 1998-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9509766&HistoricalAwards=false
• 关键词: Microvisualization; Pitting; Precursor; Sites; Metals

DMR-9509766, PI-Smyrl: The objective is to develop microvisualization methods to locate and identify precursor sites for pitting corrosion and other forms of localized corrosion. These methods will be used to monitor the effectiveness of treatments to remove or passivate the sites and thereby mitigate local attack. Scanned, gold-coated, optical fibers are employed to carry out combined photoelectrochemical and electrochemical microscopy (SPECM) to identify precursor sites on titanium and titanium alloys. This technique has been successfully used to reveal precursor sites for high purity titanium. The precursor sites are more highly electroactive than the surrounding surface, but the sites have lower photocurrent activity. In order to extend the measurements to higher resolution, tapered optical fiber tips are used. The ultimate resolution for the latter measurements is on the order of 10-20 nanometers, as demonstrated by near-field optical microscopy. Studies are performed in the 100-200 nanometer level as a first step before going to the 10-20 nanometer range. The confocal laser scanning microscope (CLSM) is used to obtain rapid photoelectrochemical images to complement the above studies. CLSM is also used for fluorescence microscopy on aluminum alloys to locate copper-rich areas. The latter are sites for cathodic reduction of oxygen, and their removal from the surface has been shown to improve the corrosion resistance and pitting resistance of aluminum alloys. ***This project demonstrates the capability of fluorescence microscopy with the CLSM to monitor the surface treatment processes designed to remove cop per inclusions that cause pitting corrosion on aluminum. The combination of the techniques will enable a study of nonuniform reactivity on metal surfaces over lateral dimensions from tens of nanometers to tens of micrometers and will extend understanding of the nature of pitting precursor sites on titanium and other metals.***

DMR-9509766，PI-Smyrl：目的是开发显微可视化方法，以定位和识别点蚀和其他形式局部腐蚀的前驱部位。 这些方法将用于监测治疗的有效性，以去除或钝化部位，从而减轻局部攻击。 扫描，镀金，光纤进行组合光电化学和电化学显微镜（SPECM），以确定钛和钛合金的前体网站。 该技术已成功地用于揭示高纯钛的前体部位。 前体位点比周围表面具有更高的电活性，但该位点具有较低的光电流活性。 为了将测量扩展到更高的分辨率，使用锥形光纤尖端。 后者的测量的最终分辨率是在10 - 20纳米的顺序，如近场光学显微镜所示。 研究在100 - 200纳米水平进行，作为进入10 - 20纳米范围之前的第一步。 共聚焦激光扫描显微镜（CLSM）被用来获得快速的光电化学图像，以补充上述研究。 CLSM还用于铝合金的荧光显微镜检查，以定位富铜区域。 后者是氧的阴极还原的位点，并且它们从表面的去除已被证明可以改善铝合金的耐腐蚀性和耐点蚀性。 * 该项目展示了CLSM荧光显微镜监测表面处理工艺的能力，该工艺旨在去除导致铝点蚀的铜夹杂物。 这些技术的结合将使研究金属表面上从几十纳米到几十微米的横向尺寸上的不均匀反应成为可能，并将扩大对钛和其他金属上点蚀前体位点性质的理解。