Abstract
Carbon nanostructured films were synthesized by chemical vapor deposition (CVD) on H18 stainless steel (AISI 440C) sheets with an H2/CH4/N2 gas mixture at various substrate temperatures. During the synthesis, the iron and chromium oxide layer was formed between the steel and carbonaceous layer. The carbon films exhibited wall-like and spherical morphologies and structures, as characterized by scanning electron microscopy and Raman spectroscopy. It was found that the synthesis temperature affects the microsphere density and, therefore, also in the electrochemical behavior. The electrochemical behavior of nanostructured carbon coatings strongly depends on the CVD deposition conditions. The best corrosion resistance (Rp = 11.8 MΩ·cm2, Icorr = 4.4 nA·cm−2) exhibits a nanostructured carbon sample with a moderate amount of sp2-C-rich carbon microspheres CμSs synthesized at 700 °C. The corrosion resistance of the nanostructured carbon coating is better than raw stainless steel.
Highlights
IntroductionNanostructured carbon coatings for steel electrodes, due to their remarkable characteristics, such as high electrical conductivity, hydrophobicity, and chemical inertness, have found a place in many applications as proton-exchange membrane fuel cells [1], porous current collectors for lithium-ion batteries [2], and as an effective support to grow carbon nanotubes [3,4,5], vertically-oriented graphene [6], carbon fibers [5] and micro-sized carbon spheres [5]
The formation of CμSs is affected mainly by two factors: firstly, they preferably grow close to carbon-rich non-catalytic sites, which are covered by amorphous carbon, acting as a carbon buffering layer [21] and, secondly, high temperatures inhibit their formation
In this study, nanostructured carbon coatings were deposited on AISI440C steel using chemical vapor deposition
Summary
Nanostructured carbon coatings for steel electrodes, due to their remarkable characteristics, such as high electrical conductivity, hydrophobicity, and chemical inertness, have found a place in many applications as proton-exchange membrane fuel cells [1], porous current collectors for lithium-ion batteries [2], and as an effective support to grow carbon nanotubes [3,4,5], vertically-oriented graphene [6], carbon fibers [5] and micro-sized carbon spheres [5]. Diamond-like carbon coating, deposited after plasma nitriding, was found to enhance corrosion resistance [7], while carbon nanotubes and nanofibers, may accelerate intergranular corrosion, due to the chromium depletion of the near-surface steel region and chromium carbide precipitation at grain boundaries [8]
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