Effect of N+ Implantation on Surface Characteristics of 316L Stainless Steels for Bipolar Plate in PEMFC

Yu-Sung Kim,Byung-Chul Cha,In-Sik Lee,Dae-Wook Kim,Shinhee Jun,Daeil Kim,Sungook Yoon

doi:10.3390/coatings10070604

Yu-Sung Kim, Byung-Chul Cha + Show 5 more

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https://doi.org/10.3390/coatings10070604

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Abstract

Nitrogen was implanted into 316L stainless steel by plasma immersion ion implantation (PIII) for surface modification. Due to nitrogen implantation, the corrosion resistance and interfacial contact resistance (ICR) were improved compared to the bare 316L stainless steel. The improved corrosion resistance was attributed to the formation of the expanded austenite phase (γN). The phase formation was found to be closely related to the evolution of the (111) plane texture. The formation of γN is strongly related to applied bias voltages. When bias voltages were increased to 15 kV, the γN phase was partially decomposed due to the formation of excessive nitride, including the CrN phase. For the ICR, increased crystallite size is effective in reducing contact resistance, which might arise from a reduced number of the grain boundary with electron scattering. In particular, the applied bias voltage of 10 kV was the most effective to both corrosion resistance and ICR, and its performance satisfies the demand for a bipolar plate in the Polymer Electrolyte Membrane Fuel Cells (PEMFC).

Highlights

Polymer Electrolyte Membrane Fuel Cells (PEMFC) possess various advantages compared to other fuel cells
It acts as an electrical connector that transfers electrons in close contact with the electrode, and as a separator that separates between unit cells to prevent the binding of fuel and oxidizer
The bipolar plate acts as a supporter to maintain the position of the Membrane Electrode Assembly (MEA)

Summary

Introduction

Polymer Electrolyte Membrane Fuel Cells (PEMFC) possess various advantages compared to other fuel cells. They can possibly be applied to a wide range of fields such as automobiles and ultra-small mobile power generation devices. The bipolar plate, one of the main parts of the stack, accounts for about 45% of the stack cost and 80% of stack weight. The technology for lowering the price and the weight of the bipolar plate should be established [1]. The bipolar plate acts as a supporter to maintain the position of the Membrane Electrode Assembly (MEA). The bipolar plate should possess excellent electrical conductivity, corrosion resistance, low gas permeability, high mechanical properties, and workability [1,2].

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