Video of REO hydrophobic surfaces in action. Credit: MIT News Office; YouTube.
I meant to write about this topic several months ago when the editors of Nature Materials published a remarkable paper about a relatively simple method to make a hydrophobic, which, in this case, are made from ceramic materials. The thrust of the paper was that rugged ceramic materials could be made to be intrinsically hydrophobic through the use of rare-earth oxides. The paper was written by a research group at MIT led by Kripa K. Varasani and I was again reminded of the topic last week when MIT Technology Review published a related story.
The pursuit of hydrophobicity has entailed everything from the studying of lotus leaves to the creation of fairly exotic coatings and films. In this case, however, the thrust of the investigators work was relatively straightforward: They wondered if the tendency of ceramics to be hydrophilic (e.g., with certain metal oxides, such as alumina, water gets bound when its oxygen atoms share electrons with the aluminum atoms, and, in turn, the oxygens in the ceramic share their electrons with hydrogen in the water) could be reversed by interfering with the hydrogen bonding and therefore prevent the ceramic from accepting electrons from water.
The investigators insight, according to the paper, is that rare-earth oxides, which have unfilled 4f orbitals, but these orbitals “are shielded from interactions with the surrounding environment by the full octet of electrons in the 5s2p6 outer shell.” The introduction of rare earths into the ceramic composition, then, might prevent the bonding and render the material hydrophobic.
Led by Varanasi, a materials scientist, the group tested their idea by making simple ceramic disks from powders composed of pure rare earth oxides (REOs) of 13 elements in the lanthanides series—from cerium oxide to lutetium oxide. The fourteenth, promethium oxide, was purposely skipped over because it is radioactive.
They gave a mirror finish to the disks by polishing in order to minimize roughness and texture effects, and then put them to several tests. Sure enough, the worked! The authors write, “As hypothesized, all the REOs are hydrophobic: water contact angels range between 100° and 115°. Also, the polar component of the surface free energy for all REOs was found to be negligible. Moreover, there is minimal variance in the wetting properties over the entire series.”
Moving closer to application-related properties, the group tested the disks with steam condensation, water droplet impingement, high-temperatures, and abrasion wear. These tests “demonstrated dropwise condensation, complete water droplet bounce-off [see video, above], and sustained hydrophobicity after high-temperature exposure and abrasion.”
Of course, demonstrating that some ceramics could be intrinsically hydrophobic was quite an accomplishment*, but Varanasi’s groups goal also had a practical side. They say, for example, that hydrophobic ceramics could play an important role by improving the efficiency of steam-based energy generation. In a separate Nature article about this research, Varanasi tells the publication that a problem with current generators is that steam condenses into water on the rotating blades of the turbine and causes the loss of energy. He says the efficiency loss from this effect could be as great as 30 percent. Likewise, with wind turbines, accumulated water can freeze on turbine blades, again creating efficiency losses and, perhaps, catastrophic failure. He says that in both examples, a superhydrophobic surface composed of the REOs could make an enormous difference.
As ceramists and other materials scientists and engineers know, there are many reliable methods for applying ceramics surfaces that could be employed to add hydrophobic surface to substrates, although the researchers caution that the effects of materials geometries and mismatches of coefficients of thermal expansion would have to be considered.
But, overall, using the REOs to achieve hydrophobic surfaces isn’t all that difficult, and, not surprisingly, Nature reports, “Varanasi is now working with energy and technology companies partnered with the MIT Energy Initiative, which co-funded his work, to test the ceramics in real-world applications.”
* Nature reports that credit for noticing the hydrophobicity of ceria may go to a research group led by Chin Li Cheung, working at the University of Nebraska-Lincoln’s Department of Chemistry and Nebraska Center for Materials and Nanosciences, that was focused on other topics and didn’t pursue the hydrophobic properties further.
By this time next year, Europe will be enforcing a tough, new standard on exhaust emissions from trucks and busses. Starting in September 2014, all new passenger and many lighter-weight commercial vehicles in regions covered by the European Commission’s rules will be required to have “Euro 6″-certified engines, and, in response, vehicle manufacturers and various research groups have been accelerating their filtration R&D. Switzerland’s Empa is of the institutions focusing on this issue, and researchers there say they are excited about some unconventional restructuring of the main filter components—typically ceramic substrates—that they say will enable manufacturers to meet pollution goals.
Heretofore, the standard diesel emissions filter is an extruded honeycomb-structure ceramic (e.g., cordierite) substrate that has a light coating of a catalytic material, such as platinum or palladium, which allows it to convert NOx and CO in the exhaust and capture soot. The honeycomb monolith substrate can withstand the stresses of temperature cycling during normal use and also during “regenerative” cycles when collected particulates (soot) are removed.
The conventional approach to engineering these filters is to allow exhaust gasses to pass through relative easily while providing maximum exposure to the surfaces bearing the catalyst. Turbulence was a thing to be avoided.
However, one research group at Empa, its Internal Combustion Engines Laboratory, says there is a downside to the honeycomb monolith: The flow of the exhaust gasses is distributed unevenly. Most of the exhaust gasses pass through the center section of the filter, creating a high-temperature zone and leaving much of the outer regions of the honeycomb relatively unused. To compensate for the unused regions, Empa says the honeycomb filters have to be relatively long (besides adding general manufacturing costs, the extra length also means the use of extra expensive catalytic material).
Empa claims that the impetus for rethinking the filter design was the viewing of a diesel filter whose central section had partially melted (see photo). The researchers’ novel idea, which began to emerge a few years ago, was to embrace the turbulence of the exhaust and put it to use to distribute the gasses more evenly.
But, a rugged ceramic substrate to support the catalyst would still be needed, and the Internal Combustion Engines Lab turned to researchers in Empa’s High-Performance Ceramics Laboratory. Instead of relying on the straight-through openings of a honeycomb, the ceramics group began to tinker with a special catalyst-coated ceramic foam, which they subsequently named Foamcat. The structure of the foam would encourage the turbulence needed to more evenly distribute the exhaust through the filter.
To filter engineers, the Empa approach probably raises several questions, especially in regard to the mechanical strength of a ceramic foam and to the negative effects of the turbulence, i.e., loss of engine performance due to back pressures from the exhaust. In response, a news release from the institute says
[S]cientists succeeded in increasing the mechanical strength of the material many times over. Currently the research team is working to optimize the structure of the ceramic—the foam substrate has a greater air resistance than the monolith that results in a slight comparative increase in fuel consumption. Using sophisticated computer simulation techniques, the Empa team has developed foam structures which reduce the air resistance without affecting the necessary turbulence.
According to Empa, the bottom-line benefit is that the surface area of the Foamcat substrate is much more efficiently used than with a honeycomb monolith. It claims that the efficiency is improved so much that the Foamcat filter can match the performance of a honeycomb filter at half the length and only requires one third of the expensive catalysts.
Whether vehicle manufacturers ultimately embrace the ceramic foam design remains to be seen. The problem of the expense of noble metal catalysts is vexing to manufacturers and other groups have been trying to find substitutes such as acicular mullite.
Nevertheless, Empa says it has been partnering for over a year with catalyst-maker Umicore and diesel engine manufacturer Fiat Powertrain Technologies to do field tests with a Foamcat filters. It also says that Swiss electrical utility IWB has been testing a vehicle fitted with the Foamcat filter for 18 months.
The stakes are high. According to a document (pdf) on the Euro 6 standards prepared by Cummins, all NOx emissions will have to be 75 percent less and particulate matter will have to be 66-95 percent less than current “Euro 5″ limits.
Climate change is in the news frequently these days. Researchers are investigating ways that new anthropogenic activity can balance or mitigate existing or future anthropogenic activities that contribute to pollution and climate issues. Examples include clean energy, green manufacturing, sustainability, design for recyclability, etc.
While social behavior will certainly be involved, too, my sense is that we plan to engineer our way out of climate trouble.
Ancient humankind was forced to react to severe climate change, too, most notably in the Late Pleistocene era when the most recent ice age or period of glaciation occurred. The Pleistocene era covers the time span from 2.6 million to 11,700 years before present (an interesting definition of time worth looking up).
Today we distinguish between pottery as an art form as distinct from technical ceramics for engineered applications. However, in ancient times, pottery was the engineered innovation that met the needs of the contemporary people. “Pottery was a hunter-gatherer innovation that first emerged in East Asia between 20,000 and 12,000 calibrated years before present,” write the authors in the abstract of a new letter in Nature.
Ceramic pottery gives anthropologists and archaeologists a way to study the lives and influences of ancient peoples. Last summer, for example, we reported on the discovery in China of the oldest known pottery that provides solid evidence of pottery being used by hunter-gatherer societies long before agrarian lifestyles were established.
The Nature letter reports on how an ancient society inhabiting the Japanese islands used pottery in the Late Pleistocene era as severe climate changes influenced their lifestyles. The timeframe known as the Jōmon period spanned from about 14,000 BC to 300 BC and overlapped with the ice age climate change that characterized the Late Pleistocene era. The region’s hunter-gatherer culture was fairly complex and produced a plethora of pottery for practical and ceremonial uses.
Previously, the authors write, it was thought that ceramic pottery provided hunter-gatherers with “attractive new strategies for processing and consuming foodstuffs.” The interdisciplinary team from the UK, Japan, the Netherlands, and Sweden used modern chemical analysis tools to study the char residue in Jōmon pottery and found lipids that are “unequivocally derived from processing freshwater and marine organisms.” A study of 101 char deposits shows that “Productive aquatic ecotones were heavily exploited by late glacial foragers.” In other words, the ancient Japanese ate a lot of fish.
In a press release, Oliver Craig from the Department of Archaeology at the University of York, UK, describes the use of pottery by a foraging society as a “revolutionary new strategy for the processing of marine and freshwater fish, but perhaps most interesting is that this fundamental adaptation emerged over a period of severe climate change.” He speculates that the abundance of food in the ecotone “provided the initial impetus for an investment in producing ceramic containers…”
While advanced ceramics are currently being developed and used to help solve pollution and climate challenges, what are the new applications in which ceramic materials might become a “revolutionary new strategy” and worthy of investment to meet today’s climate challenges?
Thermo-Calc Software AB announced the release of Thermo-Calc 3.0, which constitutes the third generation of its popular computational thermodynamics software. Thermo-Calc is a powerful software package used to perform thermodynamic and phase diagram calculations for multi-component systems of practical importance. Calculations are based on thermodynamic databases produced using the CALPHAD method. Databases are available for Steels, Ti-, Al-, Mg-, Ni-alloys, multi-component oxides and many other materials. ”Our main ambitions for this new version of Thermo-Calc have been to unify the two earlier versions of Thermo-Calc (i.e. Thermo-Calc Classic and Thermo-Calc Windows) into one application, and to create a framework that is suitable for future extension with additional modules and functionality that will integrate more closely with our other software tools such as DICTRA and TC-PRISMA,” says Anders Engström, CEO of Thermo-Calc Software AB.
When Ghrepower, a Shanghai-based manufacturer of small and medium-size wind turbines, decided to set up a subsidiary in Swansea, Wales, in 2011 to tap into the British wind turbine market, it did not realize how much of an impact it would make on the local community. One thing of great help to Ghrepower was the GO Wales Work Placements scheme, created to help Welsh graduates find work. Graduates participating in the scheme work at companies located in Wales for between six to 10 weeks, during which time the Welsh government contributes up to 100 pounds. When the placement period ends, the employers can offer the workers long-term jobs if they wish to. “We expanded overseas because the wind turbine market in China is restricted by China’s immature smart grid system, which is the infrastructure essential for delivering energy generated from wind farms to people’s homes,” Deng says. “As our products are manufactured in China, we have certain cost advantages. For example, a crucial material for the wind turbines battery is a magnet, which in turn relies on rare earth materials. As China produces rare earths, we have a cost advantage,” he says. At the same time, Deng points out that some of its extra functions single it out from its competitors. For example, the wind turbines’ propeller blades can change shape in response to the amount of wind available. “This technology is common for large scale wind turbines, but quite rare for small and medium-scale turbines, and makes us unique.
Cabot Corp. completed an expansion project at its fumed silica facility in Barry, Wales. Production capacity at the site has been increased by 25 percent. The expansion is part of a three-year plan started in 2011 to increase Cabot’s global fumed metal oxide capacity by 35-40 percent. This expansion project is an extension of Cabot’s long-term relationship with Dow Corning. Furthermore, the increased production capacity supports Cabot’s growth in the rising global silicones market. This market is poised to grow at 6-9 percent per year over the coming decade. Through the expansion project, Cabot can now use a wider range of silane raw materials to make a broader portfolio of products to meet silicones and other market needs. Cabot and Dow Corning have worked closely together in Barry since 1991, when Cabot built its fumed silica facility adjacent to Dow Corning’s silicone monomer plant. As part of a highly interdependent and collaborative “fence-line” relationship, Dow Corning provides Cabot with silanes that are converted to fumed silica for Dow Corning’s compounded silicones applications, as well as for other customers and applications including electronics, adhesives, and composites.
Orbite Aluminae Inc. and Veolia Environmental Services signed an exclusive worldwide collaborative agreement for the treatment and recycling of red mud generated by industrial alumina production using the Bayer process. The terms of the partnership include the construction of the first plant to treat red mud using Orbite’s patented process. Red mud often remains stored in situ, which increases the risk of accidental spills. To meet this environmental and complex challenge facing the aluminum industry, Orbite and Veolia Environmental Services endeavour to bring the solution to treat the red mud stockpiled around the world in an economically and socially sustainable manner. These technologies allow for the extraction of smelter-grade alumina and high-purity alumina, as well as other products such as rare earths and rare metals, from various feedstocks including aluminous clay and bauxite, all without producing red mud. Veolia Environmental Services is the only worldwide integrated operator covering the entire value chain of waste management (collection, sanitation, treatment and recovery).
Sacmi has recently added to its long list of innovations for the sanitaryware sector with the introduction of a new brand, Reco2. The machine technical specifications allow for very considerable savings, minimization of energy consumption and reduction of polluting emissions. Sacmi’s system solutions which provide pre-drying stations enabling the energy consumption of the production line to be further reduced while, at the same time, improving health and safety in the workplace. With Sacmi’s plants customers can count on a reduction in production cycle times of 40%, in storage space requirements of 30% and in total energy costs of the complete pre-drying and drying process of up to 50%. Furthermore, the presence in glazing booths of innovative dry filters provides for the elimination of waste water and, therefore, treatment costs.
PPG Industries has launched the PPG Glass Education Center, a comprehensive website to help architects, specifiers, students, and construction industry professionals learn more about designing, specifying and building with glass. Divided into three sections—glass topics, glass FAQs and glossary—the PPG Glass Education Center features a compelling mix of videos, colorful illustrations and educational features that address issues such as preventing thermal glass breakage, specifying IGUs, how low-e glass works, and how heat-treated glass differs from heat-strengthened glass. The Glass Education Center is not designed as a promotional or marketing tool. The site’s existing content is based on the most frequently asked questions PPG fields on its website, during sales calls and through its call center, and new educational material will be added continually. In addition to hosting five short videos (3 to 6 minutes each), the Glass Education Center contains an extensive glossary of industry terms and nearly two dozen frequently asked questions covering low-e glass, glass safety issues and more. Six more videos will be added to the site before July, along with content driven by architects’ questions and input.
I am not sure how much (if any) of this could be affected by the sequestration decisions, but this is a reminder that NIST has issued a call for grant proposals covering the institute’s interests in measurement science and engineering (MSE), spanning eight research units:
- The Material Measurement Laboratory grants: Support research in the fields of materials science and engineering, materials measurement science, biosystems and biomaterials, biomolecular measurements, chemical sciences, and applied chemicals and materials;
- The Physical Measurement Laboratory grants: Support research in the areas of mechanical metrology, semiconductors, ionizing radiation physics, medical physics, biophysics, neutron physics, atomic physics, optical technology, optoelectronics, electromagnetics, time and frequency, quantum physics, weights and measures, quantum electrical metrology, temperature, pressure, flow, far-UV physics, and metrology with synchrotron radiation;
- The Engineering Laboratory grants: Support research in the fields of machine tool and machining process metrology; advanced manufacturing; intelligent systems and information systems integration for applications in manufacturing; structures, construction metrology and automation; inorganic materials; polymeric materials; heating, ventilation, air conditioning and refrigeration equipment performance; mechanical systems and controls; heat transfer and alternative energy systems; computer-integrated building processes; indoor air quality and ventilation; earthquake risk reduction for buildings and infrastructure; smart grid; windstorm impact reduction; applied economics; and fire research.
- The Information Technology Laboratory grants: Support research in the areas of advanced network technologies, big data, cloud computing, computer forensics, information access, information processing and understanding, cybersecurity, health information technology, human factors and usability, mathematical and computational sciences, mathematical foundations of measurement science for information systems; they also support a metrology infrastructure for modeling and simulation, smart grid, software testing and statistics for metrology;
- The NIST Center for Neutron Research grants: Support research involving neutron scattering and the development of innovative technologies that advance the state of the art in neutron research;
- The Center for Nanoscale Science and Technology grants: Support research in the field of nanotechnology specifically aimed at developing essential measurement and fabrication methods and technology in support of all phases of nanotechnology development, from discovery to production; they also support collaborative research with NIST scientists, including research at the CNST NanoFab, a national shared resource for nanofabrication and measurement; and supporting researchers visiting CNST;
- The Office of Special Programs grants; Support research in the broad areas of greenhouse gas and climate science measurements, and law enforcement standards; and
- The Associate Director for Laboratory Programs grants: Support research in chemistry, materials science, physics, engineering, infrastructure, information technology, neutron research, and nanotechnology.
In 2012, these programs supported $31.5 million in research. Funds can also be used to support conferences, workshops, or other technical research meetings that are relevant to NIST’s work.
NIST says proposals for all programs—except the EL grants—will be considered on a continuing/rolling basis. Proposals received after 5 p.m. Eastern Time on June 3, 2013 may be processed and considered for funding in the current fiscal year or in the next fiscal year, subject to the availability of funds.
Note: the primary deadline for applications to the EL Grant Program is Friday, March 1, 2013. EL will continue to accept applications on a continuing/rolling basis in the current fiscal year and the next fiscal year, depending on available funds.
The grants.gov website has details of scope, anticipated award sizes, requirements and the proposal submission and review process for each of the grant programs. Search under “Opportunity Number” 2013-NIST-MSE-01.