Ion implantation of stainless steel heater alloys for anti-fouling applications

Ion implantation of fluorine and silicon ions into stainless steel heater alloys inhibits the accumulation of CaSO₄ deposits when used in an saturated aqueous solution of 1.6 g/l concentration. This anti-fouling action leads to an increase in the heat transfer coefficient by more than 100% under a heat flux of 200 kW/m² and 200% under a heat flux of 100 kW/m² when compared to unimplanted heater elements. Heat transfer data indicate that following a heating cycle of 4000 minutes a thick layer of CaSO₄ deposit remain on unimplanted heater surfaces. Similar CaSO₄ deposits also formed on the implanted alloys initially but did not remain after 1000 minutes causing a significant recovery in the heat transfer coefficient. Ion implanting these alloys leads to surface energy reduction and hence the anti-fouling action observed