Study of super-hard ceramics: "A discovery reported in the August 5 issue of Science could speed the design of materials that approach the hardness of diamond yet remain supple enough to be worked like metal. In a massive computer simulation involving 128 computer processors and nearly 19 million atoms, materials scientist Izabela Szlufarska of the University of Wisconsin-Madison and colleagues at University of Southern California demonstrated the precise atomic mechanisms that explain why "nanostructured" ceramic materials-some of the hardest substances known-also exhibit unusual pliability.
Unlike other exceptionally hard materials, these advanced ceramics tend to bend rather than break, meaning they could be shaped into extremely long-lasting yet lightweight parts for everything from automobile engines and high-speed machining tools to medical implants in the body.
Simulations can help to answer this by providing a level of detail unavailable to experiments. Using atomic-scale simulations, the team observed for the first time how atoms moved and interacted as a super-hard ceramic deformed under stress. The advance has not only provided unprecedented insight into the properties of these materials, but also a tool that researchers can use to systematically nano-engineer them. ..
The researchers next want to learn how to control the crossover point so as to engineer greater hardness into nano-crystalline silicon carbide without compromising pliability. For example, they could vary the volume of the grain boundaries or the size of the grains. Impurities, or dopants, might also be added to the grain boundaries to make the material stronger. Key to it all is the enormous computing power that allows scientists to simulate the material’s atomic details. "The experiments and devices have become smaller and smaller, while the simulations have grown larger and larger," says Szlufarska. "This is a unique time when the leading edge of materials design is exactly at the same length scale where fully atomic simulations are possible." " 2:21:50 PM
Towards a green nanotechnology: Review of the issues and early studies. "nanotechnology has been the subject of projections concerning its possible environmental risks well before its wide-scale commercialization. Raising such questions when nanotechnology is still in its infancy may result in better, safer products and less long-term liability for industry.
The rapidly developing nanomaterials industry is the nanotechnology that is most likely to affect our lives first. .. In the environmental technology industry alone, nanomaterials will enable new means of reducing the production of wastes, using resources more sparingly, cleaning up industrial contamination, providing potable water, and improving the efficiency of energy production and use. Commercial applications of nanomaterials currently or soon to be available include nano-engineered titania particles for sunscreens and paints, carbon nanotube composites in tires, silica nanoparticles as solid lubricants, and protein-based nanomaterials in soaps, shampoos, and detergents.
The production, use, and disposal of nanomaterials will inevitably lead to their appearance in air, water, soils, or organisms. Research is needed to ensure that nanomaterials, and the industry that produces them, evolve as environmental assets rather than liabilities. Unfortunately, little is known about the potential environmental impacts of nanomaterials...
An encouraging trend is that the methods used to produce nanomaterials often become “greener” as they move from the laboratory to industrial production. Setting aside the issue of nanomaterials’ toxicity, preliminary results suggest that fabricating nanomaterials entails risks that are less than or comparable to those associated with many current industrial activities. ..
It would be naïve to imagine that nanotechnology will evolve without risks to our health and environment. While attempting to halt the development of nanomaterial-inspired technologies would be as irresponsible as it is unrealistic, responsible development of these technologies demands vigilance and social commitment. " 2:05:03 PM