Evaluation of corrosion performance of ultra-thin Si-DLC overcoats with electrochemical impedance spectroscopy

P Papakonstantinou, JF Zhao, A Richardot, ET McAdams, JAD McLaughlin

Research output: Contribution to journalArticle

36 Citations (Scopus)

Abstract

Diamond-like carbon (DLC) incorporating 3.6 at.% Si and with thickness ranging from 2 to 100 run were deposited on conducting Al2O3-TiC substrate by means of the PECVD technique. Electrochemical behaviour has been studied in 2 M HCl solution using AC impedance and polarisation measurements. The electrochemical impedance (EI) spectra were analysed in the context of an equivalent circuit model, which incorporated two times constants representing the Si-DLC coating and the corrosion reaction occurring at electrolyte Al2O3-TiC interface. However, 5 and 10 nm thick films displayed three phase constants suggesting the existence of interlayers, density gradients and inhomogeneities in the films. Results indicate that ultrathin films in the range 2-10 nm provide barrier properties, evidenced by increases of one order of magnitude relative to the substrate in the charge transfer resistance, which is a measure of the rate of electrochemical reactionsoccurring at the electrolyte/substrate interface. After the potentiodynamic scan, films thicker than 20 nm remained intact while their thinner counterparts exhibited a severely pitted surface. Pitting occurred preferentially in the TiC sites. The corrosion resistance of the ultrathin films increased substantially with immersion time in the electrolyte solution due to the filling of pores with a passivating material, thus stopping access of the electrolyte to the substrate. (C) 2002 Elsevier Science B.V. All rights reserved.
LanguageEnglish
Pages1124-1129
JournalDiamond and Related Materials
Volume11
Issue number3-6, S
DOIs
Publication statusPublished - Mar 2002

Fingerprint

Diamond
Electrochemical impedance spectroscopy
Electrolytes
Diamonds
Carbon
Corrosion
Ultrathin films
Substrates
Thick films
Plasma enhanced chemical vapor deposition
Pitting
Equivalent circuits
Corrosion resistance
Charge transfer
Polarization
Coatings

Keywords

  • electrochemical impedance
  • pinholes
  • potentiodynamic curves
  • corrosion
  • Si doped DLC

Cite this

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title = "Evaluation of corrosion performance of ultra-thin Si-DLC overcoats with electrochemical impedance spectroscopy",
abstract = "Diamond-like carbon (DLC) incorporating 3.6 at.{\%} Si and with thickness ranging from 2 to 100 run were deposited on conducting Al2O3-TiC substrate by means of the PECVD technique. Electrochemical behaviour has been studied in 2 M HCl solution using AC impedance and polarisation measurements. The electrochemical impedance (EI) spectra were analysed in the context of an equivalent circuit model, which incorporated two times constants representing the Si-DLC coating and the corrosion reaction occurring at electrolyte Al2O3-TiC interface. However, 5 and 10 nm thick films displayed three phase constants suggesting the existence of interlayers, density gradients and inhomogeneities in the films. Results indicate that ultrathin films in the range 2-10 nm provide barrier properties, evidenced by increases of one order of magnitude relative to the substrate in the charge transfer resistance, which is a measure of the rate of electrochemical reactionsoccurring at the electrolyte/substrate interface. After the potentiodynamic scan, films thicker than 20 nm remained intact while their thinner counterparts exhibited a severely pitted surface. Pitting occurred preferentially in the TiC sites. The corrosion resistance of the ultrathin films increased substantially with immersion time in the electrolyte solution due to the filling of pores with a passivating material, thus stopping access of the electrolyte to the substrate. (C) 2002 Elsevier Science B.V. All rights reserved.",
keywords = "electrochemical impedance, pinholes, potentiodynamic curves, corrosion, Si doped DLC",
author = "P Papakonstantinou and JF Zhao and A Richardot and ET McAdams and JAD McLaughlin",
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Evaluation of corrosion performance of ultra-thin Si-DLC overcoats with electrochemical impedance spectroscopy. / Papakonstantinou, P; Zhao, JF; Richardot, A; McAdams, ET; McLaughlin, JAD.

In: Diamond and Related Materials, Vol. 11, No. 3-6, S, 03.2002, p. 1124-1129.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Evaluation of corrosion performance of ultra-thin Si-DLC overcoats with electrochemical impedance spectroscopy

AU - Papakonstantinou, P

AU - Zhao, JF

AU - Richardot, A

AU - McAdams, ET

AU - McLaughlin, JAD

N1 - 12th European Conference on Diamond Diamond-Like Materials Carbon Nanotubes Nitrides and Silicon Carbide (Diamond 2001), BUDAPEST, HUNGARY, SEP 02-07, 2001

PY - 2002/3

Y1 - 2002/3

N2 - Diamond-like carbon (DLC) incorporating 3.6 at.% Si and with thickness ranging from 2 to 100 run were deposited on conducting Al2O3-TiC substrate by means of the PECVD technique. Electrochemical behaviour has been studied in 2 M HCl solution using AC impedance and polarisation measurements. The electrochemical impedance (EI) spectra were analysed in the context of an equivalent circuit model, which incorporated two times constants representing the Si-DLC coating and the corrosion reaction occurring at electrolyte Al2O3-TiC interface. However, 5 and 10 nm thick films displayed three phase constants suggesting the existence of interlayers, density gradients and inhomogeneities in the films. Results indicate that ultrathin films in the range 2-10 nm provide barrier properties, evidenced by increases of one order of magnitude relative to the substrate in the charge transfer resistance, which is a measure of the rate of electrochemical reactionsoccurring at the electrolyte/substrate interface. After the potentiodynamic scan, films thicker than 20 nm remained intact while their thinner counterparts exhibited a severely pitted surface. Pitting occurred preferentially in the TiC sites. The corrosion resistance of the ultrathin films increased substantially with immersion time in the electrolyte solution due to the filling of pores with a passivating material, thus stopping access of the electrolyte to the substrate. (C) 2002 Elsevier Science B.V. All rights reserved.

AB - Diamond-like carbon (DLC) incorporating 3.6 at.% Si and with thickness ranging from 2 to 100 run were deposited on conducting Al2O3-TiC substrate by means of the PECVD technique. Electrochemical behaviour has been studied in 2 M HCl solution using AC impedance and polarisation measurements. The electrochemical impedance (EI) spectra were analysed in the context of an equivalent circuit model, which incorporated two times constants representing the Si-DLC coating and the corrosion reaction occurring at electrolyte Al2O3-TiC interface. However, 5 and 10 nm thick films displayed three phase constants suggesting the existence of interlayers, density gradients and inhomogeneities in the films. Results indicate that ultrathin films in the range 2-10 nm provide barrier properties, evidenced by increases of one order of magnitude relative to the substrate in the charge transfer resistance, which is a measure of the rate of electrochemical reactionsoccurring at the electrolyte/substrate interface. After the potentiodynamic scan, films thicker than 20 nm remained intact while their thinner counterparts exhibited a severely pitted surface. Pitting occurred preferentially in the TiC sites. The corrosion resistance of the ultrathin films increased substantially with immersion time in the electrolyte solution due to the filling of pores with a passivating material, thus stopping access of the electrolyte to the substrate. (C) 2002 Elsevier Science B.V. All rights reserved.

KW - electrochemical impedance

KW - pinholes

KW - potentiodynamic curves

KW - corrosion

KW - Si doped DLC

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DO - 10.1016/S0925-9635(01)00688-4

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T2 - Diamond and Related Materials

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SN - 0925-9635

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ER -