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43 NACE INTERNATIONAL: VOL. 56, NO. 5 MATERIALS PERFORMANCE MAY 2017 COATINGS & LININGS ESSENTIALS Continued f rom page 40 phosphoric acid (H 3 PO 4 ), and an organic acid as a complexing agent. e more com- plexing agent they added, the more aniso- tropic the nanoparticles became. For more information, visit leibniz-inm. de/en. Cerium Dioxide Nanoparticles Prevent Seawater Fouling Chemists at Johannes Gutenberg University Mainz ( JGU) (Mainz, Germany) have devel- oped an effective, affordable, environmen- tally friendly method to reliably hinder haz- ardous seawater fouling. Protective coatings applied to vessels usually contain copper- based biocides, which may harm the envi- ronment and become ineffective due to re- sistance developed by organisms. To find an alternative, a JGU research team simulated a defense mechanism employed by algae, and established that cerium dioxide (CeO 2 ) nanoparticles can effectively prevent foul- ing. is discovery could lead to the produc- tion of new protective coatings that are much less environmentally harmful than antifouling coatings in use now. Marine algae utilize secondary meta- bolic products that provide a form of chem- ical defense against microorganisms and predators. ese halogenated secondary metabolites specifically prevent bacterial biofilms, other algae, and even barnacles from becoming attached to and developing on larger formations of algae, sponges, and other creatures. is natural defense pro- cess has been mimicked by the research team using CeO 2 nanoparticles. "Field tests have shown that cerium dioxide is an eco- logically acceptable alternative to cuprite, a substance that is used as a biocide together with copper thiocyanate and copper pyri- dine," explains Wolfgang Tremel, a professor with JGU's Institute of Inorganic Chemistry and Analytical Chemistry. Such copper compounds are toxic and accumulate in the environment, which motivated some coun- tries to impose strict limitations on the use of copper-based antifouling coatings. is new generation of antifouling coat- ings, which simulates the natural defense systems employed by marine organisms, is environmentally compatible. It is effective not only under laboratory conditions but also when actually used in the aquatic envi- ronment, says doctoral student Karoline Herget. Steel panels with CeO 2 coatings were exposed to seawater for weeks without be- coming covered by bacteria, algae, mollusks, or barnacles. Reference samples with con- ventional water-based coatings developed massive fouling over the same time period. e main problem with using biocides and antibiotics to combat biofilms is the risk of the organisms developing resistance to the chemicals. is drawback, the re- searchers say, could be effectively circum- vented in an ecologically acceptable man- ner by applying the surface coatings with CeO 2 particles. ey note this innovative technique has potential for many applica- tions, such as ship and exterior coatings, roof coverings, polymer membranes used for desalination, etc. For additional information, visit uni-mainz.de. n N o calibrat ion adjustment required for most applications – measure right out of the box! n Tough probes, robust housing and strong two year warranty on gage body and probe n All models include memory, U SB port, H iLo alarm, f ast measurement mode and Certificate of Calibration n Includes PosiSoft suite of software for viewing and reporting data n Advanced models connect to iOS or Android smart devices Co at in g Th ic k n e ss Gage s Simple. Durable. Accurate. 1-800-448-3835 www. d ef el sko. com DeFelsko Corporation l Ogdensburg, New York USA Tel: +1-315-393-4450 l Email: techsale@defelsko.com Award Winning Compatibility! The PosiTector gage accepts ALL coating thickness (6000/200), surface profile (SPG/RTR), environmental (DPM), ultrasonic wall thickness (UTG) and Shore hardness (SHD) probes.