Sol-Gel Plating Healthier than Chrome

Speaking at an Institute of Physics conference in Chester, Robert Akid warns that workers are being exposed to chromium compounds that are potentially cancer-causing and says that a safer alternative is much needed.

Akid told the conference, Novel Applications of Surface Modification that he and his colleagues are developing just such an alternative. Their process will also be cheaper and allow industry to coat many other materials.

Akid of Sheffield Hallam University is developing a so-called “sol-gel technology” which is a colloid with nanoparticles in a solvent that can form a gel. A metal object is sprayed with or dipped into the sol-gel system and it quickly forms a gel-like layer on the object’s surface. The solvent is then removed by evaporation and the coating cured, or hardened.

“These inorganic-organic hybrid coatings have the potential to become an effective method of producing an alternative low-cost anti-corrosion or functional coating,” says Akid. The technology can be formulated and cured to give highly corrosion resistant, ceramic-based coatings. The method uses a range of cure temperatures and coatings are cured rapidly. The chemistry of the formulations has also been developed to provide sol-gel solutions that have a good shelf life.”

The team’s preliminary corrosion tests, showed that the coating possesses excellent corrosion resistance properties compared with uncoated samples and other pre-treatments. The researchers have also carried out mechanical tests and have shown with a simple scratch and bend tests that the coatings exhibit very good adhesion to the substrate. The coatings were also shown to be resistant to a nitric acid and chloride bath at pH1. This simulates the kind of corrosion that aluminium alloy aerospace components might experience.

Adapted from a news release researched and written by David Bradley on behalf of the IOP.