In this research, Cr-C composite coatings were electro-codeposited in sulfuric acid-based nano/micro carbon black particles containing solutions. After deposition the samples annealed under different conditions and the microstructure of the coatings rehabilitated with this additional heat-treatment. The effect of heat-treatment conditions on the carbide/nitride phase formation for both the nano and the micro carbon black reinforced composite coatings and their microstructure-corrosion behavior relation was investigated by means of XRD, SEM, and Potentiostat. Another aim of this study is to introduce a relatively new technique, “In-situ Codeposition Method”. The obtained results showed that the Cr-C composite coatings can be fabricated successfully and with an additional heat-treatment, it is possible to obtain a Cr-Cr23C6/Cr2N composite structure by in-situ codeposition method. Therefore, change in the microstructure and corrosion behavior suggests the improvement of properties due to the formation of Cr23C6/Cr2N. Besides, residual stress state changed from tensile to compressive. According to the detailed inspections, it is assigned that the definite results are directly correlate with both the magnitude and the direction of the residual stresses. As a result, the corrosion resistance of the in-situ electro codeposited coatings is believed to be controlled by microstructure and surface properties of the metallic chromium layer, which is modified by the formation of carbide and/or nitride phase, and can be used for many engineering applications instead of traditional metallic coatings.
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