A research team at the University of Nevada, Reno has developed a new environmentally-friendly coating for aluminum to replace the carcinogenic chromate coatings used in aerospace applications. The chromate conversion coatings have been used for more than 50 years to protect aluminum from corrosion.
The team presented their research last week at the international Pacific Rim Meeting on Electrochemical and Solid-State Science in Hawaii.
"It was well received at the conference," Dev Chidambaram, lead scientist and assistant professor of materials science and engineering at the University of Nevada, said. "There is no question that this will be able to replace the chromate-based coating. Even though the coating formulation is yet to be optimized, the coating has shown exceptional performance."
Attempts to replace chromate coatings with non-toxic coatings have been underway since the 1980s. The awareness on effects of chromates was brought to the forefront in 1993 by the real-life incident involving Erin Brokovich and depicted in the movie released in 2000 of the same name. Although the use of chromates for consumer and automotive applications has been banned, it is still in use by the defense and aerospace industries under various exemptions.
The carcinogenic coatings were exempted from the ban due to unavailability of suitable replacement combined with the high human and financial cost of failure from corrosion. The search for a suitable replacement has been elusive primarily due to one main characteristic of the coating referred to as "self-healing," the ability of the coating to heal itself after being damaged or scratched.
When scratched, the coating components from nearby sites migrate to the damaged region and re-protect the underlying alloy. A short video of the coating formation is on Chidambaram's website, www.electrochemical.org/ under the heading "Cool Videos."
Chidambaram's formulation performs comparably to the chromate formula in its ability for self-healing, which is important to the defense and aerospace industry. The coating can be applied to all aluminum products. The new formula creates an environmentally-benign molybdate-based coating that provides corrosion protection to aluminum, used for aircraft and spacecraft. These coatings, when damaged, will re-heal themselves.
The University of Nevada, Reno team developed and tested more than 300 coatings before arriving at this formulation. They used a complimentary suite of advanced surface analytical techniques such as Raman microspectroscopy, Fourier transform infrared spectroscopy, energy dispersive spectroscopy, secondary ion mass spectroscopy and X-ray photoelectron spectroscopy to conclusively prove the presence of molybdate in the scratched region. Further, using electrochemical testing, the team showed the coating re-protected itself via self-healing upon scratch test.
The team includes graduate student David Rodriquez, who conducted the extensive testing on the materials, and undergraduate aerospace engineering major at the University of Colorado, Boulder intern Roshan Misra, who began the project as a high school summer intern from Reno High School. The team is still working to optimize the coating formulation for even better protection.
"This has taken 14 years of work, continuing on work I did at the State University of New York at Stony Brook and the Brookhaven National Laboratory," Chidambaram said.
Chidambaram, as the director of the University's Materials and Electrochemical Research Laboratory (MER Lab), has obtained nearly $3 million in externally-funded research grants in the past three years and directs eight doctoral students and one postdoctoral associate. He is also the director of the materials science and engineering graduate program and the Chemical and Materials Department in the College of Engineering.
Nevada's land-grant university founded in 1874, the University of Nevada, Reno has an enrollment of 18,000 students and is ranked in the top tier of the nation's best universities. Part of the Nevada System of Higher Education, the University has the system's largest research program and is home to the state's medical school. With outreach and education programs in all Nevada counties and with one of the nation's largest study-abroad consortiums, the University extends across the state and around the world. For more information, visit www.unr.edu.
Mike Wolterbeek | EurekAlert!
Dresdner scientists print tomorrow’s world
08.02.2017 | Fraunhofer-Institut für Werkstoff- und Strahltechnik IWS
New technology for mass-production of complex molded composite components
23.01.2017 | Evonik Industries AG
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
23.03.2017 | Life Sciences
23.03.2017 | Power and Electrical Engineering
23.03.2017 | Earth Sciences