Investigation of pitting corrosion of diamond-like carbon films using synchrotron-based spectromicroscopy

Abstract

Corrosion behavior of diamond-like carbon (DLC) films was evaluated via potentiodynamic polarization in a 3.5 wt. % NaCl solution with pH 2 at room temperature. The polarization results elucidated that the corrosion resistance of the films was enhanced with the variation of the chemical compositions and film thicknesses. The use of the spectromicroscopy method in the investigation of the pitting corrosion was a success in this study. Formation of orbital mapping, bonding state, and composition of the DLC films at non-corrosion and corrosion areas indicate the different structures between DLC and graphite oxide. Also, the π* (C=C) and π* (C=O) bonding states were found to increase in the corrosion areas. This finding not only exhibited the increase of sp2 content but also promoted the rise of oxygen atoms in corrosion zones. Consequently, the present results indicate that the synchrotron–based spectromicroscopy plays an important role in the characterization of the corrosion on DLC films.

Structural analysis of amorphous carbon films by spectroscopic ellipsometry, RBS/ERDA, and NEXAFS

“…Since the pioneer work of Aisenberg and Chabot in 1971, 1 the research on amorphous carbon films has been spreading from their theoretical basis to industrial applications because of their outstanding properties in chemical, biological, mechanical, and optical fields. [2][3][4][5] With the continuous expansion of the research, the effective classification of amorphous carbon films has become necessary because their properties depend strongly on the conditions and methods of synthesis. 6,7 In order to classify the amorphous carbon films systematically, many attempts have been made so far.…”

“…6,7 In order to classify the amorphous carbon films systematically, many attempts have been made so far. 2,[8][9][10] In these classification schemes, the amorphous carbon films can be categorized into six types: tetrahedral amorphous carbon (ta-C), hydrogenated tetrahedral amorphous carbon, amorphous carbon, hydrogenated amorphous carbon (a-C:H), graphite-like carbon, and polymer-like carbon (PLC) films. 2,7 The hydrogen content and sp 2 /(sp 2 þ sp 3 ) ratio play crucial roles in these schemes.…”

“…2,[8][9][10] In these classification schemes, the amorphous carbon films can be categorized into six types: tetrahedral amorphous carbon (ta-C), hydrogenated tetrahedral amorphous carbon, amorphous carbon, hydrogenated amorphous carbon (a-C:H), graphite-like carbon, and polymer-like carbon (PLC) films. 2,7 The hydrogen content and sp 2 /(sp 2 þ sp 3 ) ratio play crucial roles in these schemes. The former can be measured by the Rutherford backscattering/elastic recoil detection analysis (RBS/ERDA) using an electrostatic accelerator, 11,12 and the latter can be measured by the near-edge X-ray absorption fine-structure (NEXAFS) based on synchrotron radiation.…”

Spectroscopic Ellipsometry - Application on the Classification of Diamond-Like Carbon Films

“…In order to classify the DLC films systematically, various experimental methods have been used for structural analysis of DLC films. Raman spectroscopy, X-ray photoelectron spectroscopy, electron energy loss spectroscopy, near-edge X-ray absorption fine-structure (NEXAFS), solid-state nuclear magnetic resonance techniques, and Rutherford backscattering and elastic recoil detection analysis (RBS/ERDA) have been used to obtain the sp 3 /(sp 3 + sp 2 ) ratios or hydrogen contents of DLC films [3,7,8]. Based on these studies, the researchers in Germany and Japan have proposed a classification standard of DLC films in 2005 [9] and 2012 [10], successively.…”

“…It was proposed in 2013 [11], for which a lot of considerable discussion in the past ISO/TC-107 meetings in 2016 (BSI, UK) and 2017 (Tokyo, Japan) has been made [12]. Since this method needs to use only an SE without the largescale equipment (the hydrogen content was measured by the RBS/ERDA using an electrostatic accelerator [13], and the sp 2 /(sp 2 + sp 3 ) ratio was obtained by NEXAFS based on synchrotron radiation [2,7,14]), it is more conducive to simplify the classification of DLC films. However, it is necessary to discuss the consistency between the structural analyses made with SE and NEXAFS.…”