Aluminum Aerospace Coating May Replace Toxic Chromates
A materials engineering research team at the University of Nevada, Reno has developed an environmentally friendly, self-healing coating for aluminum that could replace toxic chromates. (Source: University of Nevada, Reno/Mike Wolterbeek)
Agreed. These types of advances will also help compliance to environmental requirements such as RoHS and others. Good to see reseach and development being performed in this area to give designers more options.
As a manufacturer of aluminum connectors for harsh environments the subject of what coating to use for corrosionprotection is a constant. Especially today with RoHS and REACH activities. Needless to say I am imensely interested and was hoping you can provide contact information for Chidambaram or a path to learn more?
Thanks, Dave, for the summary and all those links. Performance is often the main issue with environmentally friendly substitutes, whether it's coatings or fuel, that are candidates for replacing toxic ones. This one sounds like it's pretty close.
Good discussions. Non-toxic alternatives to chromate coatings of aluminum can move us closer to the overall environmental objectives of such programs as RoHS. Looking at overall lifecycle costs is important when considering a process change as you noted. Chromates consume resources in the disposal of spent coating residues.
TJ, I mentioned those specific alloys because the sources did, as the coating was developed specifically for mil/aero applications. But they also stated that this coating works on "all aluminum products." That sounds like all aluminum alloys.
@TJ McDermott: The same thing that makes 7075 and 2024 so much stronger than other aluminum alloys also makes them less resistant to corrosion: copper. The copper-containing intermetallic particles that are responsible for these alloys' high strength create tiny galvanic cells within the material itself.
In general, if you can protect 7075 and 2024 against corrosion, 6061 will be easy.
Chuck, I wish we could get more cost info on some of these new technologies. As usual, not much is known yet until it's in use in industrial quantities. OTOH, the fact that it's non-toxic may be worth a cost differential.
@Ann: Thanks for a good article on a timely topic. It would be interesting to see polarization curves and salt spray testing results for the molybdate coatings.
There is a wide variety of non-chromate conversion coatings, including permanganates, zirconates, titanates, cerates, and others. There are also conversion coatings based on trivalent chromium. Some of these have been around for many years, while others are newer. However, to the best of my knowledge, none of them provide corrosion resistance that is quite as good as that of hexavalent chromate.
Electrodeposited coatings can meet or exceed the performance of chromate, but it is challenging to coat internal passages with electrodeposited coatings, and they don't have the self-healing characteristics of conversion coatings.
The U.S. military has a great on-line database with information about alternatives to chromate conversion coatings.
More often than not, with the purchase of a sports car comes the sacrifice of any sort of utility. In other words, you can forget about a large trunk, extra seats for the kids, and more importantly driving in snowy (or inclement) weather. But what if there was a vehicle that offered the best of both worlds; great handling and practicality?
Science fiction author Isaac Asimov may have the best rules for effective brainstorming and creativity. His never-before-published essay, "On Creativity," recently made it to the Web pages of MIT Technology Review.
Much has been made over the potentially dangerous flammability of lithium-ion batteries after major companies like Boeing, Sony, and Tesla have grappled with well-publicized battery fires. Researchers at Stanford University may have come up with a solution to this problem with a smart sensor for lithium-ion batteries that provides a warning if the battery is about to overheat or catch fire.
Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.