Materials Performance

MAY 2017

Materials Performance is the world's most widely circulated magazine dedicated to corrosion prevention and control. MP provides information about the latest corrosion control technologies and practical applications for every industry and environment.

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40 MAY 2017 MATERIALS PERFORMANCE NACE INTERNATIONAL: VOL. 56, NO. 5 COATINGS & LININGS ESSENTIALS Continued on page 43 Industrial insulation shaped by experts www.roxul-rti.com Experience our knowledge with ROXULASSIST ® , the online thermotechnical calculation tool This expert tool puts our extensive consulting skills and 75+ years of experience in the field of industrial insulation at your fingertips. Together, with our sustainable ProRox ® stone wool solutions, we can help you deliver the highest available protection against fire, heat, noise and energy loss while also reducing CO 2 emissions. Do the math and calculate the ideal insulation thickness with ROXUL ASSIST, our free online expert calculation program. Sign up at www.roxulassist.com or call (800) 265-6878 to help your business shape up. New ROXUL ASSIST online calculation tool EXPERT TOOL ROXULASSIST is available free of charge at www.roxulassist.com Flake-Shaped Zinc-Phosphate Particles Improve Corrosion Protection e large quantities of steel used in archi- tecture, bridge construction, and ship building are expected to be long-lasting and retain strength and safety qualities. For this reason, steel plates and girders used must have extensive and durable protection against corrosion caused by oxygen in the air, water vapor, and salts. Applying anti - corrosion coating layers with zinc-phos- phate particles is a common method for preventing corrosive substances from pene- trating into the material. Now, research scientists at Leibniz Institute for New Mate- rials (INM) (Saarbrücken, Saarland, Ger- many) have developed a more corrosion- resistant zinc-phosphate particle that is flake-like in shape with a length that is 10 times longer than its width. When compared to spherical particles, initial experiments with these new flake- shaped particles indicated better solubility because of their anisotropic properties— their properties are not the same in all di- rections, but are directionally dependent (i.e., they have different properties in differ- ent directions). is enables more phos- phate ions to be dissolved in a solution, and repassivation of the bare metal surface is better and faster, says chemist Carsten Becker-Willinger, who is head of the insti- tute's program division Nanomers † . "In first test coatings, we were also able to demonstrate that the flake-type particles are deposited in layers on top of each other, thus creating a wall-like structure. is means that the penetration of gas mole- cules through the protective coating is longer because they have to find their way through the 'cracks in the wall,'" Becker- Willinger explains. e result is a slower corrosion process than with coatings with spheroidal particles where the gas mole- cules can find their way through the protec- tive coating and reach the metal much more quickly. e scientists were able to validate the effectiveness of the new particles in an ad- ditional series of tests. Steel plates treated with coatings containing either spheroidal or flake-type zinc-phosphate particles were immersed in electrolyte solutions. After just a few hours in the electrolytes, the steel plates with spheroidal-particle coatings were showing signs of corrosion, whereas the steel plates with flake-type-particle coatings were still in perfect condition, even after three days. e flake-shaped zinc-phosphate parti- cles are synthesized in a controlled precipi- tation process developed at INM. e re- searchers created their particles using standard, commercially available zinc salts, † Trade name.

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