Graphene-based Anti-fouling and Protective Coatings for Heat Exchangers

Purpose and goal

The main goal is to develop a Graphene or Graphene Related Material (GRM) based coating system as a viable w ay to obtain heat conducting corrosion protection and anti-biofouling of stainless steel for Plate Heat Exchangers (PHEs) in demanding aqueous applications. To suit most aqueous applications PHEs, it should be corrosion resistant in highly demanding marine environment up to 90 °C as w ell as prevent biofouling in process water from for example the food industry. The coating should be available for validation of the technology by Alfa Laval by targeted customers during 2018.

Expected results and effects

A surface coating with GRM has been optimized mainly with regard to adhesion at high temperatures in saline water. Variables tested were pre-treatment, primer, type of GRM and top-coat choice. GRM with 20-30 µm flakes have better heat conductivity than 0.5-2 µm with 2% oxygen, tested as a dispersion in binders, but they were too large for the thin coatings used in this application. The pre-treatment of the stainless steel is best done with degreasing, and without airplasma treatment or sand-blasting, both of which deteriorate the properties of stainless steel.

Planned approach and implementation

An outside partner has been hired to apply the coating to the plates to be tested by Alfa Laval. RISE, Nanoinnova and PC3 have developed a graphene or graphene-related (GRM) nano-composite formulation intended to be applied directly to metal (DTM). The top layer can be optimized with GRM to get anti-fouling properties. The long-term barrier properties were planned to be evaluated by KTH and Nanoinnova while Alfa Laval would carry out testing of coated plate heat exchangers, but spray coating the plates was not successful.