$500 billion. That's a low estimate of how much friction and wear costs the U.S. every year. In fact, studies suggest that so-called "normal wear and tear" costs industrialized countries some 2 to 6 percent of their annual gross domestic product. How so? Nearly every machine ever created has at least one performance-critical sliding interface. Joints, bushings and bearings must operate reliably with low friction and low wear or the machine to perform as desired. When parts wear out, materials are wasted, quality suffers, and downtime and replacement expenses accrue on a massive scale, across all industry and consumer sectors. Apologies to William Shakespeare, but...ay, there's the rub. Dr. Brandon Krick is a tribologist - an expert in the study of the effects of friction on moving machine parts, and methods of easing those effects. "Tribology is absolutely integrated with everything we do daily, yet it is very poorly understood," he says. "The fact is that nothing - nothing -- would work without friction." 
Tribologist Brandon A. Krick and graduate student Mark Sidebottom will lead experimental efforts. (Image: Lehigh University) Professor Krick is partnering with colleagues from DuPont on a project that's recently won a "GOALI" grant from the National Science Foundation (NSF). The intent is to expand the Lehigh Tribology Lab's fight against friction, its war on wear. A 2013 addition to the mechanical engineering faculty at Lehigh University, Krick studies the fundamental origins of friction, wear, materials deformation, and adhesion on complex surfaces ranging from cells to nanocomposites, in environments ranging from space to thousands of feet under water. Netting a GOALI The NSF's Grant Opportunities for Academic Liaison with Industry (GOALI) program promotes university-industry partnerships by making project funds or fellowships/traineeships available to support an eclectic mix of industry-university linkages. According to the NSF Web site, special consideration is provided to interdisciplinary projects that create opportunities for faculty, postdoctoral researchers, and students to conduct research and gain experience in an industrial setting, while enabling industrial scientists and engineers to bring their perspective and skills to academia. Professor Krick says that the Lehigh-DuPont team will develop and study ultralow-wear composite materials suitable for manufacturability and usage in commercial and industrial settings. Krick will serve as principal investigator on the project, with DuPont scientists Christopher Junk and Gregory Blackman serving as co-principal investigators and Lehigh graduate student Mark Sidebottom leading the experimental efforts. "We'll be exploring how various material structures, composition, processing and operating conditions impact tribological performance," Krick reports. "We'll also gain a much more complete understanding of the mechanical and chemical processes involved in wearing down materials we're developing." "Working on this NSF GOALI proposal has been a truly collaborative, multidisciplinary process that could not have been completed without the help of our talented team members," say DuPont collaborators Junk and Blackman. "This project will focus on very fundamental questions, but with real applications in mind. Being on this team with Professor Krick has made us all better scientists and engineers, and we are eager to continue to build our partnership and help train new researchers along the way." According to the grant materials, "the research will use student-built instruments to directly validate the hypothesized mechanism that in situ tribochemical reaction products alter the properties of otherwise inert fluoropolymers. A multi-faceted characterization approach will systematically test the hypotheses and discover new mechanisms of these materials that could, ultimately, enable science-based design of new materials that are incredibly resistant to wear." The grant also calls for the development of outreach programs and educational opportunities in the field of tribology. Krick and his colleagues at DuPont have been partners fighting wear for several years. DuPont supported much of Krick's work as a student and researcher at the University of Florida, and the relationship has carried over into his activities at Lehigh. "DuPont is one of the world's premier industrial scientific communities," says Krick. "Working with the DuPont team has been one of the most productive and rewarding collaborations of my life." Krick was attracted to Lehigh due to its intense focus on interdisciplinary education and research and the power of its material characterization facility - the Center for Advanced Materials and Nanotechnology. "I'm in this field that relies heavily on collaboration, and I saw a lot of talented students and faculty here, and research capabilities that are right in my wheelhouse - the right place to build a research program," he says. Krick feels that the study of tribology gets far less credit than it deserves. "Lately there has been a large push for green manufacturing, new sources of energy, ways to make things more efficient. With tribology, we can make machines work more efficiently, significantly improving energy and material usage. If we can reduce the energy demands of machines and devices, we make use of alternative energy sources much more feasible."
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Tribologist Brandon A. Krick and graduate student Mark Sidebottom will lead experimental efforts. (Image: Lehigh University) Professor Krick is partnering with colleagues from DuPont on a project that's recently won a "GOALI" grant from the National Science Foundation (NSF). The intent is to expand the Lehigh Tribology Lab's fight against friction, its war on wear. A 2013 addition to the mechanical engineering faculty at Lehigh University, Krick studies the fundamental origins of friction, wear, materials deformation, and adhesion on complex surfaces ranging from cells to nanocomposites, in environments ranging from space to thousands of feet under water. Netting a GOALI The NSF's Grant Opportunities for Academic Liaison with Industry (GOALI) program promotes university-industry partnerships by making project funds or fellowships/traineeships available to support an eclectic mix of industry-university linkages. According to the NSF Web site, special consideration is provided to interdisciplinary projects that create opportunities for faculty, postdoctoral researchers, and students to conduct research and gain experience in an industrial setting, while enabling industrial scientists and engineers to bring their perspective and skills to academia. Professor Krick says that the Lehigh-DuPont team will develop and study ultralow-wear composite materials suitable for manufacturability and usage in commercial and industrial settings. Krick will serve as principal investigator on the project, with DuPont scientists Christopher Junk and Gregory Blackman serving as co-principal investigators and Lehigh graduate student Mark Sidebottom leading the experimental efforts. "We'll be exploring how various material structures, composition, processing and operating conditions impact tribological performance," Krick reports. "We'll also gain a much more complete understanding of the mechanical and chemical processes involved in wearing down materials we're developing." "Working on this NSF GOALI proposal has been a truly collaborative, multidisciplinary process that could not have been completed without the help of our talented team members," say DuPont collaborators Junk and Blackman. "This project will focus on very fundamental questions, but with real applications in mind. Being on this team with Professor Krick has made us all better scientists and engineers, and we are eager to continue to build our partnership and help train new researchers along the way." According to the grant materials, "the research will use student-built instruments to directly validate the hypothesized mechanism that in situ tribochemical reaction products alter the properties of otherwise inert fluoropolymers. A multi-faceted characterization approach will systematically test the hypotheses and discover new mechanisms of these materials that could, ultimately, enable science-based design of new materials that are incredibly resistant to wear." The grant also calls for the development of outreach programs and educational opportunities in the field of tribology. Krick and his colleagues at DuPont have been partners fighting wear for several years. DuPont supported much of Krick's work as a student and researcher at the University of Florida, and the relationship has carried over into his activities at Lehigh. "DuPont is one of the world's premier industrial scientific communities," says Krick. "Working with the DuPont team has been one of the most productive and rewarding collaborations of my life." Krick was attracted to Lehigh due to its intense focus on interdisciplinary education and research and the power of its material characterization facility - the Center for Advanced Materials and Nanotechnology. "I'm in this field that relies heavily on collaboration, and I saw a lot of talented students and faculty here, and research capabilities that are right in my wheelhouse - the right place to build a research program," he says. Krick feels that the study of tribology gets far less credit than it deserves. "Lately there has been a large push for green manufacturing, new sources of energy, ways to make things more efficient. With tribology, we can make machines work more efficiently, significantly improving energy and material usage. If we can reduce the energy demands of machines and devices, we make use of alternative energy sources much more feasible."
High-energy gold ions impact the crystal surface from above at the sites indicated schematically by dashed circles. Measurement of the strength of superconductivity in this same field of view, as shown on the lower panel, reveals how the impact sites are the regions where the superconductivity is also annihilated. In additional studies, the scientists discovered that it is in these same regions that the strongest pinning of quantized vortices occurs, followed at higher magnetic fields by pinning at the single atom crystal damage sites. Pinning the vortices allows high current superconductivity to flow unimpeded through the rest of the sample. (Image: Brookhaven National Laboratory) The work is a product of the Center for Emergent Superconductivity, a DOE Energy Frontier Research Center established at Brookhaven in partnership with Argonne and the University of Illinois to foster collaboration and maximize the impact of this research. "This study opens a new way forward for designing and understanding high-current, high-performing superconductors," said study co-author J.C. Séamus Davis, a physicist at Brookhaven Lab and Cornell University. "We demonstrated a procedure whereby you can irradiate a sample with heavy ions, visualize what the ions do to the crystal at the atomic scale, and simultaneously see what happens to the superconductivity in precisely the same field of view." Argonne physicist Wai-Kwong Kwok led the effort on heavy ion bombardment. "Heavy ions such as gold can create nearly continuous or discontinuous column shaped damage tracks penetrating through the crystal. As the very high-energy ions traverse the material, they melt the crystal at the atomic scale and destroy the crystal structure over a diameter of a few nanometers. It's important to understand the details of how these atomic-scale defects affect local electronic properties and the macroscopic current carrying capacity of the bulk material," he said. The scientists were particularly interested in how the nanoscale defects interact with microscopic magnetic vortices that form when iron-based superconductors are placed in a strong magnetic field -- the type that would be present in turbines and other energy applications. "These quantum vortices are like eddies in a river moving across or counter to the direction of flow," Davis said. "They are the enemy of superconductivity. You can't prevent them from forming, but scientists as long ago as the 1970s found you can sometimes prevent them from moving around by shooting some high-energy ions into the material to form atomic-scale damage tracks that trap the vortices." But random bombardment is, literally, hit-or-miss. Scientists developing materials for energy applications would like to take a more strategic approach by developing a quantitative and predictive theory for how to engineer these materials. "If a company comes to us and says we are developing these superconductors and we want them to have this current at a certain temperature in this type of magnetic field, we'd like to be able to tell them exactly what type of defects to introduce," Kwok said. To do that they needed a way to map out the defects, map out the superconductivity, and map out the locations of the vortices -- and a quantitative theoretical model that describes how those variables relate to one another and the material's bulk superconductivity. A precision spectroscopic-imaging scanning tunneling microscope (SI-STM) developed by Davis is the first tool that can map out those three characteristics on the same material. Under Davis' guidance, Brookhaven Lab postdoctoral fellow Freek Massee (now at University Paris-Sud in France) and Cornell University graduate student Peter Sprau -- the two lead co-authors on the paper -- used the instrument's fine electron-tunneling tip to scan over the material's surface, imaging the atomic structure of the landscape below and the properties of its electrons, atom by atom. The precision allows the scientists to scan the same atoms repeatedly under different external conditions -- such as changes in temperature and ramped up magnetic fields -- to study the formation, movement, and effects of quantum vortices. Their atomic-scale imaging studies reveal that vortex pinning -- the ability to keep those disruptive eddies in place -- depends on the shape of the high-energy ion damage tracks (specifically whether they are point-like or elongated), and also on a form of "collateral damage" discovered by the researchers far from the primary route traversed by each ion. Collaborating theorists at the University of Illinois are now using the experimental results to develop a descriptive framework the scientists can use to predict and test new approaches for materials design. "These studies will really help us solve at which temperature which type of defects will be best for carrying a particular current," Kwok said. "The ability to achieve critical current by design is one of the ultimate goals of the Center for Emergent Superconductivity."
Schematic of the ionic polymer-graphene composite (IPGC) actuator or “motor”. When an electric field is applied, the redistribution of ions causes the structure to bend. (Image: Korea Advanced Institute of Science and Technology) In a paper published in ("Durable and Water-Floatable Ionic Polymer Actuator with Hydrophobic and Asymmetrically Laser-Scribed Reduced Graphene Oxide Paper Electrodes"), researchers from the Korea Advanced Institute of Science and Technology report the development of a thin-film electrode based on a novel ionic polymer-graphene composite (IPGC). Graphene is a single-atom-thick layer of carbon with exceptional mechanical, electrical and thermal properties. The new electrodes have a smooth outer surface that repels water and doesn’t have apparent cracks, which makes them nearly impermeable to liquids. They also have a rough inner surface, which facilitates the migration of ions within the membrane to stimulate bending. The new IPGC actuator demonstrates exceptional durability without apparent degradation, even under very high input voltage. It shows promise for use in biomedical devices, “biomimetic” robots that mimic movements occurring in nature, and flexible soft electronics. The researchers acknowledge that there are still many challenges and more research is needed to realise the full potential of the graphene-based electrodes and their subsequent commercialisation. In 2015, they plan to further enhance the bending performance of the actuators, their ability to store energy and their power. They also plan to develop a biomimetic robot that can walk and jump on water like a water strider. They will do this by constructing floatable IPGC actuators with a reliable bending performance that can continue for a period of six hours without any apparent change in durability.
A device is remotely triggered to self-destruct. A radio-frequency signal turns on a heating element at the center of the device. The circuits dissolve completely. (Image: Scott White, University of Illinois) "We have demonstrated electronics that are there when you need them and gone when you don't need them anymore," White said. "This is a way of creating sustainability in the materials that are used in modern-day electronics. This was our first attempt to use an environmental stimulus to trigger destruction." White's group teamed up with John A. Rogers, a Swanlund chair in materials science and engineering and director of the Frederick Seitz Materials Laboratory at Illinois. Rogers' group pioneered transient devices that dissolve in water, with applications for biomedical implants. Together, the two multi-disciplinary research groups have tackled the problem of using other triggers to break down devices, including ultraviolet light, heat and mechanical stress. The goal is to find ways to disintegrate the devices so that manufacturers can recycle costly materials from used or obsolete devices or so that the devices could break down in a landfill. The heat-triggered devices use magnesium circuits printed on very thin, flexible materials. The researchers trap microscopic droplets of a weak acid in wax, and coat the devices with the wax. When the devices are heated, the wax melts, releasing the acid. The acid dissolves the device quickly and completely. To remotely trigger the reaction, researchers embedded a radio-frequency receiver and an inductive heating coil in the device. The user can send a signal to cause the coil to heat up, which melts the wax and dissolves the device. Watch a video of the researchers demonstrating and explaining the devices:
