Original scientific paper
https://doi.org/10.5599/jese.2709
In situ electrochemical impedance spectroscopy of TiN-based hard coatings
Izabela Martinez
; Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Ivana Lučića 5, 10000 Zagreb, Croatia
*
Božidar Matijević
; Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Ivana Lučića 5, 10000 Zagreb, Croatia
* Corresponding author.
Abstract
Hard coatings are thin, wear-resistant films, typically composed of ceramic or metal-based compounds, that enhance surface durability and corrosion resistance. Advancing hard coatings depends on incremental improvements driven by extensive experimentation, which could be significantly enhanced by a fast, reliable, and non-destructive method for assessing coating barrier efficiency. A previously developed electrochemical impedance spectroscopy (EIS) press-on cell with a chloride-free, pH-neutral paste electrolyte, originally validated on stainless steel, bronze, coated bronze, and Corten steel, was adapted to determine barrier effectiveness of four coating/substrate combinations (TiN/TiCN and TiN/TiBN on 42CrMo4 and 32CrMoV12-10 steels) produced via plasma-assisted chemical vapor deposition and characterized by glow discharge optical emission spectroscopy and scanning electron microscopy (SEM). Impedance spectra were evaluated by equivalent circuit fitting, and the contributions of resistive and capacitive elements were analysed in detail. SEM image analysis using statistical features and binarization revealed an inverse relationship between grain boundary density and total coating resistance across the barrier spectrum, from ~kΩ cm² to ~MΩ cm². The EIS results aligned with literature data for similar hard coatings in neutral electrolytes, supporting the method’s validity. The paste electrolyte method enables rapid, non-destructive screening of coatings with distinct barrier properties, offering a practical alternative to conventional destructive techniques.
Keywords
Plasma-assisted chemical vapor deposition; coating barrier efficiency; paste electrolyte; impedance spectra
Hrčak ID:
333186
URI
Publication date:
12.5.2025.
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