GERMANY: A new nanocoating developed for heat exchangers with anti-adhesive, anti-corrosive and anti-microbial properties could find ready acceptance in the air conditioning industry.

The Saarbrücken-based Leibniz Institute for New Materials is demonstrating the possibilities for the new coating at this year’s Hannover Messe which takes place from April 24-28.

The coating is aimed initially at the food industry where heat exchangers are used extensively by companies such as milk and juice processors. In order to ensure there is no risk to consumers, heat exchangers in these areas have to be free from microbes and must be cleaned at regular intervals using aggressive chemicals. These increase the sensitivity for corrosion, especially if mild steel is used as heat exchanger material.

According to Carsten Becker-Willinger, head of Nanomers at the Leibniz Institute for New Materials, the paint developed could also be used in other contexts, including air conditioning and water purification plants.

The developers achieve the anti-adhesive characteristics in the new coating by introducing hydrophobic compounds that are similar to common Teflon. These inhibit the formation of any undesired biofilm and allow residues to be transported out more easily before they clog up the channels of the heat exchangers. The coating also acts as a diffusion barrier, inhibiting corrosion by corrosive substances or aggressive cleaning agents. Colloidal copper is also used in the coating to prevent microbes, bacteria or fungus from adhering to surfaces.

“In addition, we can keep the paint chemically stable. Otherwise it would not withstand the aggressive chemicals that are required for cleaning,” explained Carsten Becker-Willinger.

The coating could also be adapted for special mechanical loads where, due to mechanical vibrations, the individual heat exchanger plates could be subjected to a certain amount of abrasion at points of contact.

The paint can be applied using standard methods such as spraying or immersion and subsequent hardening. It can be used on stainless steel, steel, titanium or aluminium.

The Leibniz Institute for New Materials is a leading centre for materials research, conducting research into nanocomposite technology, interface materials, and bio interfaces.