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New research reveals how corrosion happens on the atomic level. When water vapor meets metal, the resulting corrosion can lead to mechanical problems that harm a machine's performance. Through a process called passivation, it also can form a thin inert layer that acts as a barrier against further deterioration. Either way, the exact chemical reaction is not well understood on an atomic level, but that is changing thanks to a technique called environmental transmission electron microscopy (TEM), which allows researchers to directly view molecules interacting on the tiniest possible scale. Professor Guangwen Zhou -- a faculty member at Binghamton University, State University of New York's Thomas J. Watson College of Engineering and Applied Science -- has been probing the secrets of atomic reactions since joining the Department of Mechanical Engineering in 2007. Along with collaborators from the University of Pittsburgh and the Brookhaven National Laboratory, he has studied the structural and functional properties of metals and the process of making "green" steel. Their latest research, "Atomistic mechanisms of water vapor induced surface passivation," was published in November in the journal Science Advances. Co-authors included Binghamton PhD students Xiaobo Chen, Dongxiang Wu, Chaoran Li, Shuonan Ye and Shyam Bharatkumar Patel, MS '21; Na Cai, PhD '12; Zhao Liu, PhD '20; Weitao Shan, MS '16, and Guofeng Wang from the University of Pittsburgh; and Sooyeon Hwang, Dmitri N. Zakharov and Jorge Anibal Boscoboinik from the Brookhaven National Laboratory. In the paper, Zhou and his team introduced water vapor to clean aluminum samples and observed the surface reactions. "This phenomenon is well-known because it happens in our daily lives," he said. "But how do water molecules react with aluminum to form this passivation layer? If you look at the [research] literature, there's not much work about how this happens at an atomic scale. If we want to use it for good, we must know, because then we will have some way to control it." They discovered something that had never been observed before: In addition to the aluminum hydroxide layer that formed on the surface, a second amorphous layer developed underneath it, which indicates there is a transport mechanism that diffuses oxygen into the substrate. "Most corrosion studies focus on the growth of the passivation layer and how it slows down the corrosion process," Zhou said. "To look at it from an atomic scale, we feel we can bridge the knowledge gap." The cost of repairing corrosion worldwide is estimated at $2.5 trillion a year, which is more than 3% of the global GDP -- so developing better ways to manage oxidation would be an economic boon. Additionally, understanding how a water molecule's hydrogen and oxygen atoms break apart to interact with metals could lead to clean-energy solutions, which is why the U.S. Department of Energy funded this research and Zhou's similar projects in the past. "If you break water into oxygen and hydrogen, when you recombine it, it's just water again," he said. "It doesn't have the contamination of fossil fuels, and it doesn't produce carbon dioxide." Because of the clean-energy implications, the DOE regularly has renewed Zhou's grant funding over the past 15 years. "I greatly appreciate the long-term support for this research," Zhou said. "It's a very important issue for energy devices or energy systems, because you have a lot of metallic alloys that are used as structural material."

Photo Credit: Unsplash/Marcel Strauß The U.S. Department of Energy (DOE) has announced an award of $2,849,000 to the Composites Manufacturing Simulation Center (CMSC) of Purdue University (West Lafayette, Ind., U.S.) and its industry partners, Thermwood Inc. (Dale, Ind., U.S.), TPI Composites Inc. (Scottsdale, Ariz., U.S.), Dassault Systèmes (Waltham, Mass., U.S.), Dimensional Innovations (Overland Park, Kan., U.S.) and Techmer PM (Clinton, Tenn., U.S.). The DOE-funded Purdue program, “Additive Manufacturing of Modular Tools with Integrated Heating for Large-Scale Wind Blade Manufacturing,” is led by Eduardo Barocio, director of the Composites Additive Manufacturing and Simulation (CAMS) Industrial Consortium. “The primary goal of the program is to develop the foundation for automation in manufacturing of tooling for large-scale wind blades that can accommodate continuous changes in blade geometry and scale,” Barocio says. “This will be accomplished through modular construction, wherein modules are 3D printed with carbon fiber-reinforced thermoplastic composites by a technology called extrusion deposition additive manufacturing, which was first developed at the DOE’s Manufacturing Demonstration Facility in the Oak Ridge National Laboratory [ORNL].” Specific targets for the program include developing a module design for wind blades equal to or greater in length than 80 meters; reducing the time required to manufacture and assemble wind blade tooling by at least 40% over conventional tool manufacture; enhancing tool performance by at least 15%; effecting weight reductions by a minimum of 25% over conventional tools; and lowering the manufacturing cost of a wind blade tool by at least 35%. Barocio is founder and director of the Thermwood Large-Scale Additive Manufacturing (LSAM) Research Lab at the Indiana Manufacturing Institute in Purdue Research Park. He is also founding director of the Composites Additive Manufacturing and Simulation Industrial Consortium, whose mission is to shape the future of LSAM by providing education, simulation tools, characterization and best practices. “The proposed program provides the foundation for automated manufacturing technology in wind blade tooling manufacture,” Barocio adds. “These same technologies can be applied to manufacturing of all the elements of the wind energy system and, as such, the program provides a pioneering development that can leverage technology within the United States for a major source of clean energy, wind.” The program will develop and demonstrate seven specific innovations. These include automating the 3D printing of large-scale modules and developing robust joining technology and inline heating elements deposition for conduction heating. Others include 3D printed cooling channels for convective cooling; new composite materials systems for economy and performance; support frame weight reduction; and tool deformation prediction and control, with decision-making by a digital twin for 3D printing design and manufacturing. Overall, the DOE awarded $30 million for 13 projects across 10 states that will reshape the design, materials and sustainability of large wind blades for offshore and land-based applications. Large wind blades face significant challenges in design and materials, particularly for offshore applications. The selected projects will tackle these challenges, focusing on sustainability, efficiency and technological advancements to make wind energy more viable and effective. Importantly, the DOE projects were picked for their potential to bolster the manufacturability and robustness of composite materials, which are essential to the future success of wind energy technologies. The projects focus on three primary challenges: large wind blade additive manufacturing (AM), AM of wind turbine components and advanced manufacturing, materials and sustainability for large wind blades. “These projects, alongside the Purdue program, will address the remaining challenges in wind turbine manufacturing and build on previous work in automation, digitalization, wind blade sustainability and modular blade construction and joining,” R. Byron Pipes, executive director of the Composites Manufacturing Simulation Center at Purdue, says. “Successful demonstration of automation in the manufacture of alternate energy systems can enhance their wider use while sustaining the industry in the U.S.”

Engineers are placing low-powered sensors in the reflective raised pavement markers that are already used to help drivers identify lanes. Microchips inside the markers transmit information to passing cars about the road shape to help autonomous driving features function even when vehicle cameras or remote laser sensing, called LiDAR, are unreliable because of fog, snow, glare or other obstructions. Self-driving electric vehicles still face steep hills on the road to reliability. Researchers from the Department of Energy's Oak Ridge National Laboratory and Western Michigan University are working together to drive solutions from outside the car: sensors and processing embedded in road infrastructure. Working with partners, ORNL engineers are placing low-powered sensors in the reflective raised pavement markers that are already used to help drivers identify lanes. According to a paper in IEEE Sensors by ORNL researcher Ali Ekti with lead author Sachin Sharma of WMU, microchips inside the markers transmit information to passing cars about the road shape. They are effective even when vehicle cameras or remote laser sensing called LiDAR are unreliable because of fog, snow, glare or other obstructions. "We are working to make autonomous driving features accurate and safe in more remote areas," Ekti said. "And we are doing it by converting a dummy piece of infrastructure into something with many more uses." Not only does the technology provide more accurate information about the driving environment, but it also shifts some of the processing load from the car's software onto infrastructure. This saves electric vehicle battery power, extending driving range to promote wider EV adoption. Compared with a leading camera and LiDAR-based autonomous driving technology, the chip-enabled pavement markers can reduce navigational power consumption by up to 90%, the authors reported in a technical paper. The technology has potential for use with not only tomorrow's self-driving vehicles, but also today's common autonomous driving features, such as lane assist. The effort is part of a larger project led by WMU, which is teaming with research and industry partners to develop related sensor and autonomous driving technologies such as radar retro-reflectors, high-definition mapping, computational offloading and weather sensing. WMU researchers are also using a vehicle driving on a closed course to measure the reduction in vehicle energy use that is enabled by these technologies, said Zachary Asher, assistant professor of mechanical and aerospace engineering and director of the WMU Energy Efficient and Autonomous Vehicles Lab. ORNL researchers experimented to find the best combination of transceiver, battery and antenna for the sensor package inside standard road markers, as well as those that are designed to withstand snowplows. They then utilized a communications protocol that involves hopping across a particular radio frequency spectrum up to 50 times a second. "It's hard to detect, works well against interference, is low cost and doesn't consume a lot of power," Ekti said. Adjustments to the equipment could ensure its battery would last for the same replacement cycle as the pavement markers, typically a year. Ekti's team created algorithms that triangulate among the GPS coordinates of lane markers to reconstruct an image of the drivable area. One algorithm is embedded in a microchip inside the pavement marker, while a decoding algorithm is incorporated into the car's software. ORNL researchers field-tested the sensor platform in a variety of weather conditions and in a remote national park in Montana with no wireless access. They found that it transmits more than five times beyond the original 100-meter goal. "It's amazing how far it can transmit -- over hills, in snow. It's a big deal," Asher said. "Every step of the way, we're surprised at how well this technology is working, and we're finding some really cool ways it could be integrated." The sensors could also signal temporary lane shifts or closures in construction zones when high-definition maps might be out of date. Marker sensors could eventually convey information about temperature, humidity and traffic volume, Ekti said. The project team plans to work with students to build a smaller microchip for the markers as a substitute for more expensive off-the-shelf products. Asher is planning road demonstrations for stakeholders including the Tennessee and Michigan departments of transportation, the Michigan Office of Future Mobility and the City of Chattanooga. These government agencies decide which technologies are implemented in infrastructure, so their involvement in the development process is critical, Asher said. Venture capitalists and Silicon Valley have typically regarded self-driving vehicles as a software problem, Asher said. "With the hindsight of 10 years of highly- funded development, we now know that software and cameras alone don't provide an easy solution," he said. "Perhaps a more patient approach, using infrastructure-based hardware in coordination with government transportation agencies, is the way to achieve zero-accident vehicles which actually use energy sustainably." Part of the ORNL research was conducted at DOE's National Transportation Research Center. The Vehicle Technologies Office under DOE's Office of Energy Efficiency and Renewable Energy provided funding. Contributing ORNL researchers include Ross Wang, Jason Richards, Elizabeth Piersall, David Pesin, Ozgur Alaca and Shean Huff.