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Innovative heat- and corrosion-resistant coating approaches, applicable in indirect-food-contact outdoor environments, have been developed. Two systems, a direct-to-metal single-layer, polysiloxane-based, oven-dried system and a bilayer, zinc phosphate active pigment-containing, ambient-cured system were developed to overcome the shortcomings of the traditional bilayer, zinc-rich primer-based heat-resistant surface-protective solutions for outdoor cooking equipment, such as barbecue grills. This case study aims to optimize the application conditions, measure and evaluate the impact of surface preparation and compare thermo-resistant and anticorrosive properties of different coating systems focusing on eco-efficiency. The anticorrosion efficiency of the coatings was characterized using salt-spray chamber corrosion tests and electrochemical impedance spectroscopy. The thermo-resistant character of the coatings was tested by cyclic and constant heat treatment, after which the physical integrity of the coatings was evaluated by optical microscopy. In the overall performance of the coatings, the roughening of the steel substrate surface and the thickness of the coatings were also considered as influential parameters. The study revealed that the newly developed coatings have superior anticorrosion performance to the usually applied Zn-rich coating. The Single-layered Coating has excellent corrosion resistance under certain conditions and has the advantage of fast layer application. The Bilayered Coating showed excellent heat- and corrosion-resistance properties even on a surface without sand-blasting. [ABSTRACT FROM AUTHOR]

Abstract: This work presents the preparation of nano-structured silver coatings on TiAl6V4 and CoCrMo alloys by a pulse current technique and the study of time dependent electrochemical behaviour of silver coated metallic implants. EIS data as a function of immersion time in 0.9wt% NaCl solution have been obtained to clarify the electrochemical processes occurring in the system. During early stage immersion (1–2 days), the impedance response shows near capacitive behaviour. As the time passes, the electrolyte gradually penetrates the silver coating and the sandblasted metallic implants. The silver comes into contact with the electrolyte and the conditions for galvanic corrosion are fulfilled. Due to the potential difference between silver coating and the metallic alloy, discrete anodic and cathodic areas are formed, which result in the release of silver, since the silver acts as an anode in galvanic cells. The cathode process is the reduction of the dissolved oxygen at the surface of the substrate. For antimicrobial applications of nanosilver coated TiAl6V4 and CoCrMo alloys, it is very important to maintain the continuous release silver ions. Degradation of silver coatings have been traced and confirmed by different methods such as SEM micrographs, EDX analysis, EIS measurements and solution analysis by ICP-MS methods. [Copyright &y& Elsevier]