International.
Research scientists at the INM – Leibniz Institute for New Materials, developed a special type of zinc phosphate nanoparticles. In contrast to conventional, spheroidal zinc phosphate nanoparticles, the new nanoparticles are flake-shaped. They are 10 times longer and thicker. As a result of this anisotropy, the penetration of gas molecules into the metal slows down.
"In the first coating tests, we were able to show that flake-type nanoparticles are deposited in layers on top of each other, thus creating a wall-shaped structure," explained Carsten Becker-Willinger, Head of Nanomers® at INM. "This means that the penetration of gas molecules through the protective layer is longer because they have to find their way through the cracks in the wall."
The result, he said, is that the corrosion process was much slower than with coatings with spherical nanoparticles where gas molecules can find their way through the protective layer to the metal much more quickly.
In other series of tests, the scientists were able to validate the efficacy of the new nanoparticles. To do this, steel plates were immersed, both in electrolytic solutions with zinc-spheroidal phosphate nanoparticles and with flake-type zinc phosphate nanoparticles in each case. After only half a day, the steel plates in the electrolytes with spherical nanoparticles were showing signs of corrosion while the steel plates in the electrolytes with flake-like nanoparticles were still in perfect condition and bright, even after three days. The researchers created their particles using standard commercially available zinc salts, phosphoric acid and an organic acid as a complexing agent. The more complexing agent is added, the more anisotropic the nanoparticles will become.
Source: INM – Leibniz Institute for New Materials
