Materials Performance

AUG 2018

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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13 MATERIALS PERFORMANCE: VOL. 57, NO. 8 AUGUST 2018 "Metals can be compressed to 10 or 20 percent strain, no problem, but ceramics often fracture into pieces if you compress them to less than 2 to 3 percent strain," Zhang says. "We show that f lash-sintered ceramics can be compressed to 7 to 10 per- cent without catastrophic fracture." The Purdue-led research is supported by the U.S. Off ice of Naval Research (Ar- lington, Virginia, USA), in collaboration with the University of California, Davis (Davis, California, USA) and Rutgers University (New Brunswick, New Jersey, USA). For more information, visit w w w.purdue.edu. Gel-Like Pads Detect Steel Corrosion Successful nondestructive field tests to de- tect corrosion on stainless steel (SS) were recently conducted using a novel gel-like pad system developed by the German In- stitute for Materials Research and Testing (Berlin, Germany), and made available by TÜV SÜD Chemie Service (Leverkusen, Germany). In the presence of water and oxygen, a chromium oxide (Cr 2 O 3 ) layer typically forms on the surface of SS, which helps prevent dissolution of the underlying ma- terial. However, certain conditions in manufacturing, transport, or storage op- erations can result in defects of the passive layer. The KorroPad system tests the Cr 2 O 3 layer within 15 min. The system can be used on assets such as piping systems or tanks that are frequently exposed to ex- treme environmental conditions, includ- ing f luids with high concentrations of chloride; acids; or corrosive gases. Wherever the passive layer is missing or defective, a potassium hexacyanoferrate indicator in the test pad reacts with the iron ions. These ions, present at the sites of defects, cause a chemical reaction that changes the test pad's color at the exact point of damage. Results are documented by either taking photographs of the af- fected area or scanning it. Field tests were carried out on austen- itic chromium nickel steels as well as mar- tensitic, ferritic, and duplex steels. Since surface quality plays a key role in whether a material is prone to corrosion, the tests used steels that are considered particu- larly resistant or prone to corrosion. Test- ing was carried out both on materials as delivered and on steels subjected to dry or wet grinding in manual and machine processing. Results of the testing conf irmed the effectiveness of the method and corre- lated well with results obtained through electrochemical measurements. For more information, visit w w w.tuev-sued.de/ chemieservice.

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