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[Display omitted] • The Cr-Al-C coatings with different crystallization states were manipulated here. • The partially crystallized Cr-Al-C coatings exhibited the best performance. • Mechanism of conductive corrosion resistance was clarified by HAADF and EPR. • Partially crystallized Cr-Al-C coatings were promising candidate in BPs protection. Metal bipolar plates (BPs) with excellent corrosion resistance and good conductivity have been becoming one of key issues to explore proton exchange membrane fuel cells (PEMFCs). Here, we fabricated the high-performance protective Cr-Al-C coatings on stainless steel 316L using a combined cathodic arc and magnetron sputtering deposition with subsequent annealing. The electrochemical measurements in 0.5 M H 2 SO 4 + 5 ppm HF solution and interfacial contact resistance (ICR) tests indicated that all the coatings exhibited enhanced corrosion resistance and excellent conductivity. As the annealing time increased, enhanced conductivity and corrosion current density were observed. Particularly, the sample annealed at 550 °C for 2 h exhibited the best comprehensive performance in balancing the corrosion current density of 3.02 × 10-7A cm−2 and ICR of 4.5 mΩ cm2 under 140 N cm−2, respectively. The present work provides the alternative strategy to apply the promising Cr-Al-C coatings for high-performance metal BPs used in PEMFCs. [ABSTRACT FROM AUTHOR]

The corrosion of metallic Bipolar Plates (BPs) has become a key bottleneck in the practical application of proton exchange membrane fuel cells (PEMFCs). Environmental factors inside the PEMFCs significantly accelerate the degradation of electrical conductivity and durability of metallic BPs. In this work, we investigated the corrosion behavior and conductive properties of amorphous carbon coating (a-C) coated SS316L in a simulated PEMFC environment at various operating temperatures. The results showed that the corrosion current density (I corr) of a-C varied in a range of 2.3–8.7 nA/cm2 when subjected to a temperature range of 40–80 °C. Additionally, the interfacial contact resistance increased from 4.36 to 9.56 mΩ/cm2 with a rise in temperature. The reasons could be ascribed to two aspects. First, the a-C maintained the good chemical stability of sp2/sp3 bonds regardless of temperature changes, favoring remarkable anti-corrosion and good conductivity. Second, the higher temperatures intensified the penetration of corrosive species, accelerating the dissolution process of a-C coated SS316L and leading to substantial corrosion failure. [Display omitted] • a-C coatings were fabricated on SS316L by a hybrid magnetron sputtering technique. • a-C coated SS316L enhanced corrosion resistance and interfacial conductive resistance in a simulated PEMFCs condition. • Increasing operating temperature slightly sacrificed the protective capability of a-C due to dissolution of metallic ions. • Strongly chemical stability of a-C favored long-term durability at high running temperature. [ABSTRACT FROM AUTHOR]

The magnetron sputtering deposition of CrN coatings is environmental friendliness and has high surface gloss. Therefore it is a promising alternative to the electroplating deposition of Cr coatings as an effective method to metallize of ABS materials. Nevertheless, the coatings on the polymers suffered from cracks' initiation during temperature alternating processes, resulting in the degradation of decoration and protection function. In this work, we proposed a new application of the HiPIMS CrN coating for as the surface metallization method for ABS, and investigated its properties in comparison with the DCMS method. Based on the electric and spectroscopic characteristics of these two kinds of magnetron sputtering discharge and the resultant coating structures, the corrosion resistance, mechanical properties, as well as the weatherability of the coatings were studied and discussed. Results revealed that the HiPIMS coating had a dense nanocrystalline CrN (200) phase structure, rather than the loose amorphous/nanocrystalline composite structure of the DCMS CrN coating. Consequently, the HiPIMS CrN coating demonstrated superior corrosion resistance, mechanical properties, and meanwhile avoided the crack problem on ABS substrates. Finally, we developed a new CrN coating by HiPIMS as the protective coating for the purpose of replacing the electroplating Cr coating on polymers. • A new application of HiPIMS CrN coating for ABS surface metallization is proposed. • HiPIMS promotes forming dense nanocrystalline CrN by higher target ionization. • HiPIMS CrN presents excellent corrosion resistance and mechanical properties. • Cracking problem of CrN coatings on polymer surface is solved. [ABSTRACT FROM AUTHOR]