Corrosion in the News: September 2, 2019 Roundup
This week's stories take a look at developments in nanomaterial technology, a city’s corroded drinking water tanks, and a new inspection method to monitor corrosion on bridges.
Welcome to the early September edition of the Corrosionpedia News Roundup. Rust never sleeps and neither do we as we work to provide you with the latest and most relevant corrosion news. In this edition, we highlight some exciting developments in nanomaterial technology with researchers using nanotubes and nanowires. Corrosion and a dead bird raise concerns about drinking water in a city in Ohio, and a new inspection method could save countless hours of corrosion monitoring on bridges. Enjoy this installment of our news roundup and come back in a couple of weeks for more corrosion-related headlines!
Nanotubes Used to Improve Corrosion Resistance
A research team recently discovered a breakthrough in coating technology when it used nanotubes to augment corrosion resistance. During the experiment, scientists loaded halloysite nanotubes with benzotriazole, an effective corrosion inhibitor and ultraviolet absorber.
Halloysite has become increasingly common as a raw material for nanotubes because of its relative affordability. Once doped with benzotriazole, the halloysite nanotubes are mixed with an anti-corrosive coating. Coatings that are mixed directly with a corrosion inhibitor often have their mechanical properties adversely affected. However, the use of halloysite nanotubes filled with benzotriazole in conjunction with a polybenzoxazine coating allows the coating to maintain excellent mechanical properties while also having improved corrosion resistance.
Bridge in Pennsylvania Becomes the First to Use New Corrosion Detection Method
The Coplay-Northampton Bridge replacement in eastern Pennsylvania will be the first bridge to use a newer, more effective nondestructive corrosion testing method on the post-tensioned tendons used in its construction. The method being used is known as the electrically isolated tendon system. Tendons in post-tensioned structures are typically protected from corrosion by surrounding them with a polymer sleeve. The effectiveness of this polymer sleeve and the corrosion of the tendons can be monitored over time via the electrically isolated tendon system by sending electricity through the tendons and measuring the impedance of the circuit. Changes in impedance over time could suggest that the corrosion protection materials are failing to do their job.
Neglect of Corrosion Leads to Potentially Unsafe Drinking Water
In Norwood, Ohio, two water tanks used for public drinking water have been steadily corroding for years. In fact, the interior protective coating hadn’t been repaired or replaced in decades. A recent inspection of the tanks by an outside firm revealed substantial corrosion and that animals have been going into the tanks. One inspector actually found a dead bird in one of the tanks. The team of inspectors didn’t outright declare that the water was hazardous to human health, but they did say that if left unattended there could be health risks for those who drink the water. The Environmental Protection Agency (EPA) recommended that city officials replace the tanks. The city officials are currently in the midst of a 30-day period at the end of which they are required to have a plan to resolve the issue.
New Test Method Helps Determine Orthopedic Implant Corrosion
Scientists at the Argonne National Laboratory, a facility run by the United States Department of Energy, have developed a new testing method that may be better able to determine how quickly and to what extent orthopedic implants will corrode inside the human body. The scientists mentioned that there may not be enough testing currently done on orthopedic device materials, which is a concern because corroded implants can cause severe health risks to medical patients. Using a variety of voltages and times, the new testing method applies an electrical current to an electrolytic solution in which the orthopedic implant material is integrated. By varying voltages and times, the new test method is thought to better mimic the varying conditions of oxidation within the body.
Nanomaterial Used to Prevent Photocorrosion of Solar Energy Semiconductors
Through the use of nanomaterial and specialized coatings, a team of researchers at the Brookhaven National Laboratory in Upton, NY developed an innovative way to potentially increase the useful life of solar energy semiconductors.
Photocorrosion has long been a hindrance to semiconductors used to generate hydrogen gas from water molecules. While these semiconductors work well at generating hydrogen initially, photocorrosion soon renders them less effective, resulting in costly repairs. However, the team of scientists has found a way to avoid this photocorrosion by using nanowires made of zinc oxide as a semiconducting material and coating them with a very thin layer of titanium dioxide. The combination of the high surface area of the nanowires, the zinc oxide, and the titanium coating create a semiconductor that is better suited to resist photocorrosion and continue to split hydrogen atoms from oxygen atoms.
U.S. Navy Begins Using New Pigment to Avoid Coating Discoloration
A new coating pigment developed by the United States Naval Research Laboratory is beginning to show promise by preserving the original color of the ships on which it has been used. Historically, the Navy has had problems maintaining the finish of their ships. While the previous coating pigments protected the ships from corrosion and other hazards, discoloration was still a concern. The new pigment can also be used to reduce the patchwork of colors seen on a ship as some portions of a ship receive a maintenance coating and others are left alone. Many companies have already begun integrating the new pigment in the coatings they supply to the US Navy.