This award by the Division of Materials Research to University of Houston is to study the role of microscopic heterogeneities in the corrosion of metal alloy surfaces. This Materials World Network award is cofounded and managed by the Metals and Metallic Nanostructures program. This proposed research involves the use nonlinear optical spectroscopy and scanning probe techniques to study the atmospheric corrosion of a model metal alloy surface based on Cu:Zn alloy. Main objectives of the project are: 1) Study the local atmospheric corrosion of Cu:Zn alloys; and 2) Compare the reactions on protected alloys surfaces with the initiation of corrosion reactions. To probe local regions of the alloy surface, Sum Frequency Generation Imaging Microscopy will be used as a local probe on the surface species formed under reaction conditions. This technique has the ability to identify sub-monolayer of surface adsorbates based on their vibrational spectra. In addition, Scanning Electrochemical Microscopy will be used to identify cathodic and anodic regions of the surfaces where the corrosion process occurs. These techniques will be applied to bare and protected surfaces to study the effect of inhibition on local corrosion. These studies will be carried out in collaboration with scientists at Royal Institute of Technology, Stockholm, Sweden. The results from these studies are expected to provide chemical maps of corrosion activity related to molecular speciation in those locations, and thus a molecular-level description of local corrosion events. Students on this project will be developing experimental and scientific skills through designing of the research project, and writing and presenting results at national meetings. International exchange, travel, research experience by students and faculty in the collaborating institutions are salient features of this collaborative multidisciplinary research.
This multidisciplinary research program is expected to positively impact both undergraduate and graduate student members of the research team In addition, students will be exposed to in the use and application of a number of analytical methods including advanced spectroscopic methods to study the atmospheric corrosion at the surface. They also will be trained in material surface characterization with an emphasis on the chemistry of corrosion at a microscopic level. Finally, this project will greatly enhance our younger scientist skills and development using modern laser techniques. The knowledge gained will provide a detailed model on the local chemistry of corrosion that has been very difficult to characterize until now. The planned International collaboration with Royal Institute of Technology in Sweden will provide opportunities for students and faculty to do research in the collaborating laboratories.
Our goal in this project was to understand how the nonuniform nature of the metal surface affected its ability to resist. This approach was to use lasers to study the surface of brass and steel, two important metals in common use. The corrosion or oxidation of metals is fundamentally an oxidation process so we planned to use electrical methods with our lasers together to understand the underlying microstructure, and ultimately its relation to the corrosion process. In our lab we have invented a laser microscope that is able to probe the surface of the metal and identify the molecules adsorbed onto it. These molecules are able to help the metal resist oxidation and corrosion. This is like paint but 1000x thinner, so impossible to see without the laser techniques. The laser techniques are also able to identify the molecules based on their spectrum, whether or not they can absorb light of different colors. The microscope was used in conjunction with an electrical probe the can measure the resistance on the surface of the metal. Some areas have more or less resistance depending on if the molecules are adsorbed there or not. The two techniques are complimentary in information gained and similar in their probe resolution, 1 micrometer. The results will be chemical maps of corrosion activity related to molecular speciation in those locations, and thus a molecular-level description of local corrosion events. These techniques will be applied to bare and protected surfaces to study the effect of corrosion inhibition on microscopic scale. Studies on these metal alloys surfaces help us to identify how molecules spread n the surface and help protect it for corrosion. These results are expected be valuable to corrosion engineers and materials scientists. The knowledge gain will provide a detailed model on the local phenomenon that has been very difficult to characterize until now. Engineers and scientist have long recognized that their materials that they want to use are quite varied in chemical make-up across the surface. But until recently there was no good way to understand how they varied. The laser microscope methods that were used her were able to describe in detail how the molecules adsorb with different properties at various position across the surface. These variations were useful to understanding their ability to protect the metal from corroding. This study also represents the first combine use of vibrational spectroscopic imaging with probe microscopy, two complimentary and powerful techniques. The success of our next generation of scientists and engineers will depend on their ability to integrate ideas and techniques developed by focused yet multidisciplinary research. This philosophy motivates the interdisciplinary nature of this research program and will positively impact both undergraduate and graduate student members of the research team. The proposed research also presents a valuable opportunity to learn and experience collaborative multidisciplinary research -- a current emphasis of science and engineering education. In addition the students were able to work on a very important project that using the most modern cutting edge techniques in surface chemistry. This project served as a platform for undergraduate and high school students that conduct research in our group. The project was well suited for beginning scientist to conduct meaning research by conducting electrochemical measurements and more. Several students that have participated in our group have succeeded in publishing papers, winning national awards, and moving on to prestigious university studies in science.
