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Andre Anders - One of the best experts on this subject based on the ideXlab platform.
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structural optical and electrical properties of indium doped cadmium oxide films prepared by pulsed Filtered Cathodic Arc deposition
Journal of Materials Science, 2013Co-Authors: Rueben J Mendelsberg, Andre AndersAbstract:Indium-doped cadmium oxide (CdO:In) films were prepared on glass and sapphire substrates by pulsed Filtered Cathodic Arc deposition (PFCAD). The effects of substrate temperature, oxygen pressure, and an MgO template layer on film properties were systematically studied. The MgO template layers significantly influence the microstructure and the electrical properties of CdO:In films, but show different effects on glass and sapphire substrates. Under optimized conditions on glass substrates, CdO:In films with thickness of about 125 nm showed low resistivity of 5.9 × 10−5 Ωcm, mobility of 112 cm2/Vs, and transmittance over 80 % (including the glass substrate) from 500 to 1500 nm. The optical bandgap of the films was found to be in the range of 2.7 to 3.2 eV using both the Tauc relation and the derivative of transmittance. The observed widening of the optical bandgap with increasing carrier concentration can be described well only by considering bandgap renormalization effects along with the Burstein–Moss shift for a nonparabolic conduction band.
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transparent and conductive indium doped cadmium oxide thin films prepared by pulsed Filtered Cathodic Arc deposition
Applied Surface Science, 2013Co-Authors: Rueben J Mendelsberg, Andre AndersAbstract:Indium doped cadmium oxide (CdO:In) films with different In concentrations were prepared on low-cost glass substrates by pulsed Filtered Cathodic Arc deposition (PFCAD). It is shown that polycrystalline CdO:In films with smooth surface and dense structure are obtained. In-doping introduces extra electrons leading to remarkable improvements of electron mobility and conductivity, as well as improvement in the optical transmittance due to the Burstein Moss effect. CdO:In films on glass substrates with thickness near 230 nm show low resistivity of 7.23 10-5 cm, high electron mobility of 142 cm2/Vs, and mean transmittance over 80percent from 500-1250 nm (including the glass substrate). These high quality pulsed Arc-grown CdO:In films are potentially suitable for high efficiency multi-junction solar cells that harvest a broad range of the solar spectrum.
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Improved structural and electrical properties of thin ZnO:Al films by dc Filtered Cathodic Arc deposition
Journal of Materials Research, 2012Co-Authors: Rueben J Mendelsberg, Andre AndersAbstract:Submitted to the Journal of Materials ReseArch original version 2011-08-23 revised version of 2011-09-23 accepted 2011-09-26 online 2011-11-07 published in the 2012-03-14 issue of the journal: J. Mater. Res., vol. 27, pp. 857-862, 2012. http://dx.doi.org/10.1557/jmr.2011.342 Improved structural and electrical properties of thin ZnO:Al films by dc Filtered Cathodic Arc deposition Yuankun Zhu, a, b Rueben J. Mendelsberg, b,c Sunnie H.N. Lim, b Jiaqi Zhu, a Jiecai Han, a and Andre Anders b a b Harbin Institute of Technology, Harbin 150080, People’s Republic of China Lawrence Berkeley National Laboratory, Plasma Applications Group, Berkeley, California, 94720 c Lawrence Berkeley National Laboratory, Molecular Foundry, Berkeley, California, 94720 ACKNOWLEDGMENT The authors would like to thank J. Wallig, K.M. Yu, and D.J. Milliron for their contributions to this work. ReseArch was supported by the LDRD Program of Lawrence Berkeley National Laboratory, by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Building Technologies under U.S. Department of Energy Contract No. DE-AC02-05CH11231. Portions of this work were performed as a User Project at the LBNL Molecular Foundry, which is supported by the Office of Science, Office of Basic Energy Sciences, under the same contract. DISCLAIMER This document was prepared as an account of work sponsored by the United States Government. While this document is believed to contain correct information, neither the United States Government nor any agency thereof, nor The Regents of the University of California, nor any of their employees, makes any warranty, express or implied, or assumes any legal responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by its trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof, or The Regents of the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof or The Regents of the University of California. Electronic address: yuan.kun.zhu@gmail.com
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High Rate Deposition of High Quality ZnO:Al by Filtered Cathodic Arc
MRS Proceedings, 2011Co-Authors: Rueben J Mendelsberg, Sunnie H.n. Lim, Delia J. Milliron, Andre AndersAbstract:High quality ZnO:Al (AZO) thin films were prepared on glass substrates by direct current Filtered Cathodic Arc deposition. Substrate temperature was varied from room temperature to 425oC, and samples were grown with and without the assistance of low power oxygen plasma (75W). For each growth condition, at least 3 samples were grown to give a statistical look at the effect of the growth environment on the film properties and to explore the reproducibility of the technique. Growth rate was in the 100-400 nm/min range but was apparently random and could not be easily traced to the growth conditions explored. For optimized growth conditions, 300-600 nm AZO films had resistivities of 3-6 x 10-4 ?Omega cm, carrier concentrations in the range of 2-4 x 1020 cm3, Hall mobility as high as 55 cm2/Vs, and optical transmittance greater than 90percent. These films are also highly oriented with the c-axis perpendicular to the substrate and a surface roughness of 2-4 nm.
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preparation of high transmittance zno al film by pulsed Filtered Cathodic Arc technology and rapid thermal annealing
Applied Surface Science, 2011Co-Authors: K M Yu, Rueben J Mendelsberg, Andre Anders, W WalukiewiczAbstract:Abstract Approximately 200 nm thick ZnO:Al films with high visible and infrared transmittance properties were prepared on glass substrates by the pulsed Filtered Cathodic Arc technique and rapid thermal annealing. The as-deposited and annealed films have a poly-crystalline hexagonal wurtzite type structure. As the annealing temperature increases from 500 °C to 650 °C, the visible transmittance remains nearly constant (∼85%) while the infrared (780–2500 nm) transmittance considerably improves from 22% for the as-deposited film to 58% at 600 °C and 71% at 650 °C at 2500 nm for the annealed films. However, the electrical properties of the films worsen after high-temperature annealing, and resistivity increases from 2.5 × 10−4 Ω cm for the as-deposited film to 3.6 × 10−3 Ω cm and 1.2 × 10−2 Ω cm for the films annealed at 600 and 650 °C, respectively. The high-temperature annealing improved the crystallinity and transmittance of the films. Nevertheless, these improvements may lead to the segregation and oxidation of aluminum atoms, as well as the reduction of oxygen vacancies, thereby degrading the electrical properties of the films.
Antoine Seyeux - One of the best experts on this subject based on the ideXlab platform.
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Interface control of atomic layer deposited oxide coatings by Filtered Cathodic Arc deposited sublayers for improved corrosion protection
Materials Chemistry and Physics, 2014Co-Authors: Emma Härkönen, Belen Diaz, Antoine Seyeux, Vincent Maurice, Philippe Marcus, Sanna Tervakangas, Jukka Kolehmainen, Jolanta Światowska, Martin Fenker, Lajos TóthAbstract:Sublayers grown with Filtered Cathodic Arc deposition (FCAD) were added under atomic layer deposited (ALD) oxide coatings for interface control and improved corrosion protection of low alloy steel. The FCAD sublayer was either Ta:O or Cr:O–Ta:O nanolaminate, and the ALD layer was Al2O3–Ta2O5 nanolaminate, AlxTayOz mixture or graded mixture. The total thicknesses of the FCAD/ALD duplex coatings were between 65 and 120 nm. Thorough analysis of the coatings was conducted to gain insight into the influence of the FCAD sublayer on the overall coating performance. Similar characteristics as with single FCAD and ALD coatings on steel were found in the morphology and composition of the duplex coatings. However, the FCAD process allowed better control of the interface with the steel by reducing the native oxide and preventing its regrowth during the initial stages of the ALD process. Residual hydrocarbon impurities were buried in the interface between the FCAD layer and steel. This enabled growth of ALD layers with improved electrochemical sealing properties, inhibiting the development of localized corrosion by pitting during immersion in acidic NaCl and enhancing durability in neutral salt spray testing.
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tantalum oxide nanocoatings prepared by atomic layer and Filtered Cathodic Arc deposition for corrosion protection of steel comparative surface and electrochemical analysis
Electrochimica Acta, 2013Co-Authors: Belen Diaz, Antoine Seyeux, Vincent Maurice, Emma Härkönen, Mikko Ritala, Sanna Tervakangas, Jukka Kolehmainen, Jolanta światowska, Philippe MarcusAbstract:Abstract A comparative study by Time-of-Flight Secondary Ions Mass Spectrometry and X-ray Photoelectron Spectroscopy, i – E polarization curves and Electrochemical Impedance Spectroscopy of the corrosion protection of low alloy steel by 50 nm thick tantalum oxide coatings prepared by low temperature Atomic Layer Deposition (ALD) and Filtered Cathodic Arc Deposition (FCAD) is reported. The data evidence the presence of a spurious oxide layer mostly consisting of iron grown by transient thermal oxidation at the ALD film/substrate interface in the initial stages of deposition and its suppression by pre-treatment in the FCAD process. Carbonaceous contamination (organic and carbidic) resulting from incomplete removal of the organic precursor is the major cause of the poorer sealing properties of the ALD film. No coating dissolution is demonstrated in neutral or acid 0.2 M NaCl solutions. In acid solution localized corrosion by pitting proceeds faster with the ALD than with the FCAD coating. The roles of the pre-existing channel defects exposing the substrate surface and of the spurious interfacial oxide promoting coating breakdown and/or delamination are emphasized.
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chromium and tantalum oxide nanocoatings prepared by Filtered Cathodic Arc deposition for corrosion protection of carbon steel
Surface & Coatings Technology, 2012Co-Authors: Belen Diaz, Antoine Seyeux, Vincent Maurice, Jolanta światowska, Marcin PisarekAbstract:Abstract Combined analysis by Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS), X-ray Photoelectron Spectroscopy (XPS), polarization curves and Electrochemical Impedance Spectroscopy (EIS) of the relation between chemical Architecture of thin (10 and 50 nm) chromium and tantalum oxide coatings grown by Filtered Cathodic Arc deposition (FCAD) on carbon steel and their corrosion protection properties is reported. Pre-etching in the deposition process allows reducing the substrate native oxide layer to traces of iron oxide. A carbidic interlayer is then formed by reaction between the first deposited metallic particles and the residual carbon surface contamination of the alloy. The bulk coatings mostly consist of Cr 2 O 3 or Ta 2 O 5 with no in-depth variation of the stoichiometry. Surface and bulk of the coatings are contaminated by hydroxyl and organic groups. The 50 nm coating has a relatively large porosity assigned to a columnar growth preventing good sealing at grain boundaries. The duplex structure (Ta/Ta–C) of the carbidic interlayer promotes a less defective growth of tantalum oxide than the single Cr–C interlayer for chromium oxide, thereby improving the sealing properties. The dielectric constants suggest poor insulating properties in line with a defective and porous nanostructure of the coatings. No dissolution was observed for both oxide nanocoatings in neutral 0.2 M NaCl. Penetration of the electrolyte and access to the interface with the carbon steel surface cause the dissolution of the Cr–C interlayer, but not that of the Ta/Ta–C interlayer, and a more rapid initiation of localized corrosion.
Jochen M. Schneider - One of the best experts on this subject based on the ideXlab platform.
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Transmission electron microscopy investigation of the effect of Si alloying on the thermal stability of amorphous alumina thin films deposited by Filtered Cathodic Arc deposition
Surface & Coatings Technology, 2014Co-Authors: Merlin Müller, F. Nahif, Joachim Mayer, Jochen M. SchneiderAbstract:Abstract The effect of thermal annealing treatments on the morphology and structure of amorphous unalloyed and amorphous Si alloyed alumina thin films has been investigated. All amorphous thin films were deposited by Filtered Cathodic Arc deposition at room temperature onto Si 3 N 4 coated Si substrates and subsequently annealed in argon atmosphere at temperatures in the range of 610 °C–1100 °C with a heating rate of 20 °C/min. After each heating sequence the thin film samples were investigated by means of transmission electron microscopy. Upon alloying 2 at.% of Si to alumina, the amorphous to crystalline transition is shifted by ≥ 290 °C to higher temperatures. For the unalloyed thin film crystallization of γ-Al 2 O 3 in an amorphous matrix is observed at 630 °C. Fully crystalline γ-Al 2 O 3 is formed at 750 °C. Evidence for the transition of γ-Al 2 O 3 to α-Al 2 O 3 is obtained after annealing at 900 °C concomitant with substantial crack formation and coating-failure. In contrast, the Si alloyed alumina thin film remains amorphous until 900 °C. At 950 °C first traces of γ-Al 2 O 3 in an amorphous matrix are observed and further annealing at 1100 °C results in the formation of a mullite phase in addition to the γ-Al 2 O 3 -phase. The thermal stability range of amorphous alumina thin films is hence significantly enhanced by alloying with 2 at.% of Si.
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Ab initio and experimental study on the effect of Y additions on the phase formation and thermal stability of Al2O3 thin films deposited by Filtered Cathodic Arc evaporation
Surface and Coatings Technology, 2014Co-Authors: F. Nahif, Denis Music, Stanislav Mráz, Philipp Keuter, Jochen M. SchneiderAbstract:Abstract The effect of 0.6 to 7.5 at.% Y addition on the phase formation and thermal stability of Al2O3 has been investigated using density functional theory and post-annealing of Y containing alumina thin films deposited by Filtered Cathodic Arc evaporation. The calculations indicate the decomposition of the Y containing γ- and α-Al2O3 solid solutions into Y2O3 and the corresponding alumina phase. This prediction is consistent with experiments: The lattice parameters of the γ-Al2O3 thin films with and without Y are comparable and are hence inconsistent with the predicted expansion in equilibrium volume as Y is incorporated into the γ-(Al,Y)2O3 solid solution. The predicted metastable character of γ-(Al,Y)2O3 is also consistent with the formation of γ-Al2O3, Y2O3, and Y3Al5O12 in the as-deposited state as identified by X-ray diffraction. While the phase transition from γ-Al2O3 to α-Al2O3 phase takes place at T ≤ 1100 °C, the formation of traces of α-Al2O3 is restrained to T ≤ 1200 °C for alumina thin films containing Y and additionally the formation of Y3Al5O12 is observed. The restrained transition of the metastable γ-Al2O3 polymorph to α-Al2O3 may be explained by the segregation of Y at the metastable Al2O3 grain boundaries impeding mass transport and hence retard both formation and grain growth of α-Al2O3.
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The effect of Si alloying on the thermal stability of Al2O3 films deposited by Filtered Cathodic Arc
Surface and Coatings Technology, 2013Co-Authors: F. Nahif, Denis Music, Stanislav Mráz, Hamid Bolvardi, L. Conrads, Jochen M. SchneiderAbstract:Abstract The effect of Si alloying on the phase transformation sequence and phase formation temperatures of Al2O3 thin films deposited by Filtered Cathodic Arc was investigated by annealing experiments in air. By addition of Si the transformation of γ- to δ- and θ-Al2O3 is restrained by 100 °C. The thermal stability range of the δ- and θ-phase is also increased by ≥ 200 °C with respect to the unalloyed Al2O3 thin film and the formation of α-Al2O3 is restrained by 200 °C upon addition of Si. Based on the observed Si addition induced changes in phase formation, crystallite size and bonding it appears reasonable that the presence of SiO2 at the grain boundaries impeding mass transport governs the Si induced stability enhancement of the metastable γ-/δ- and θ-Al2O3 phases and the restrained α-Al2O3 formation. The competing proposal assuming a random substitution of Al by Si on the lattice sites is not consistent with the XPS data.
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On the high temperature stability of γ-Al2O3/Ti0.33Al0.67N coated WC–Co cutting inserts
International Journal of Materials Research, 2012Co-Authors: Kaiyun Jiang, Joachim Mayer, Kostas Sarakinos, Adil Atiser, A. Reinholdt, Jochen M. SchneiderAbstract:The high temperature stability of gamma-Al2O3 films deposited using Filtered Cathodic Arc and plasma assisted chemical vapor deposition on Ti0.33Al0.67N coated WC-Co cutting inserts is investigated. X-ray diffractometry reveals that Filtered Cathodic Arc deposited films transform partially into the thermodynamically stable alpha-Al2O3 phase at a temperature of 1000 degrees C. The gamma to alpha-Al2O3 transformation for plasma assisted chemical vapor deposition grown films is observed at 900 degrees C. These results are in qualitative agreement with differential scanning calorimetry measurements. Transmission electron microscopy on Filtered Cathodic Arc and plasma assisted chemical vapor deposition films annealed at 900 degrees C reveals the existence of hexagonal AlN in the Ti0.33Al0.67N interlayer, as well as Al depletion at the Al2O3/Ti0.33Al0.67N interface. After annealing the plasma assisted chemical vapor deposition sample at 900 degrees C, alpha-Al2O3 grains with a size of 100 nm are observed inside the gamma-Al2O3 matrix, while for Filtered Cathodic Arc samples only the gamma-phase is identified. Transmission electron microscopy analysis on both Filtered Cathodic Arc and plasma assisted chemical vapor deposition samples annealed at 1000 degrees C shows that the original Al2O3/Ti0.33Al0.67N/WC-Co layer Architecture is no longer intact. The formation of TiO2 is detected along the growth direction of the Al2O3 films. The present study suggests that not only the morphology and the impurities incorporated into gamma-Al2O3 but also stability of the Ti0.33Al0.67N interlayer determine the high temperature stability of gamma-Al2O3/Ti0.33Al0.67N coated hard-metal.
Chao Sun - One of the best experts on this subject based on the ideXlab platform.
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tialn cu nanocomposite coatings deposited by Filtered Cathodic Arc ion plating
Journal of Materials Science & Technology, 2017Co-Authors: Lei Chen, Z.l. Pei, Jinquan Xiao, Jun Gong, Chao SunAbstract:TiAlN/Cu nanocomposite coatings with Cu concentration of 0–1.4 at.% were deposited on the high-speed steel (HSS) substrates by Filtered Cathodic Arc ion plating technique. The chemical composition, microstructure, morphology, adhesion strength, mechanical and tribological properties of the TiAlN/Cu coatings were characterized and analyzed. The results reveal that the coating structure and properties depend on not only the Cu concentration, but also the deposition condition. The addition of Cu significantly decreases the grain size and weakens the texture in the TiAlN/Cu coatings. With increasing the Cu concentration, the coating hardness decreases slightly from 30.7 GPa of the pure TiAlN coating to 28.5 GPa of the TiAlN/Cu coating with 1.4 at.% Cu. All the TiAlN/Cu coatings present sufficient adhesion strength. In addition, the existing state of additive Cu in the TiAlN/Cu coatings is also investigated.
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TiAlN/Cu Nanocomposite Coatings Deposited by Filtered Cathodic Arc Ion Plating
Journal of Materials Science & Technology, 2017Co-Authors: Lei Chen, Z.l. Pei, Jinquan Xiao, Jun Gong, Chao SunAbstract:TiAlN/Cu nanocomposite coatings with Cu concentration of 0–1.4 at.% were deposited on the high-speed steel (HSS) substrates by Filtered Cathodic Arc ion plating technique. The chemical composition, microstructure, morphology, adhesion strength, mechanical and tribological properties of the TiAlN/Cu coatings were characterized and analyzed. The results reveal that the coating structure and properties depend on not only the Cu concentration, but also the deposition condition. The addition of Cu significantly decreases the grain size and weakens the texture in the TiAlN/Cu coatings. With increasing the Cu concentration, the coating hardness decreases slightly from 30.7 GPa of the pure TiAlN coating to 28.5 GPa of the TiAlN/Cu coating with 1.4 at.% Cu. All the TiAlN/Cu coatings present sufficient adhesion strength. In addition, the existing state of additive Cu in the TiAlN/Cu coatings is also investigated.
Belen Diaz - One of the best experts on this subject based on the ideXlab platform.
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Interface control of atomic layer deposited oxide coatings by Filtered Cathodic Arc deposited sublayers for improved corrosion protection
Materials Chemistry and Physics, 2014Co-Authors: Emma Härkönen, Belen Diaz, Antoine Seyeux, Vincent Maurice, Philippe Marcus, Sanna Tervakangas, Jukka Kolehmainen, Jolanta Światowska, Martin Fenker, Lajos TóthAbstract:Sublayers grown with Filtered Cathodic Arc deposition (FCAD) were added under atomic layer deposited (ALD) oxide coatings for interface control and improved corrosion protection of low alloy steel. The FCAD sublayer was either Ta:O or Cr:O–Ta:O nanolaminate, and the ALD layer was Al2O3–Ta2O5 nanolaminate, AlxTayOz mixture or graded mixture. The total thicknesses of the FCAD/ALD duplex coatings were between 65 and 120 nm. Thorough analysis of the coatings was conducted to gain insight into the influence of the FCAD sublayer on the overall coating performance. Similar characteristics as with single FCAD and ALD coatings on steel were found in the morphology and composition of the duplex coatings. However, the FCAD process allowed better control of the interface with the steel by reducing the native oxide and preventing its regrowth during the initial stages of the ALD process. Residual hydrocarbon impurities were buried in the interface between the FCAD layer and steel. This enabled growth of ALD layers with improved electrochemical sealing properties, inhibiting the development of localized corrosion by pitting during immersion in acidic NaCl and enhancing durability in neutral salt spray testing.
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tantalum oxide nanocoatings prepared by atomic layer and Filtered Cathodic Arc deposition for corrosion protection of steel comparative surface and electrochemical analysis
Electrochimica Acta, 2013Co-Authors: Belen Diaz, Antoine Seyeux, Vincent Maurice, Emma Härkönen, Mikko Ritala, Sanna Tervakangas, Jukka Kolehmainen, Jolanta światowska, Philippe MarcusAbstract:Abstract A comparative study by Time-of-Flight Secondary Ions Mass Spectrometry and X-ray Photoelectron Spectroscopy, i – E polarization curves and Electrochemical Impedance Spectroscopy of the corrosion protection of low alloy steel by 50 nm thick tantalum oxide coatings prepared by low temperature Atomic Layer Deposition (ALD) and Filtered Cathodic Arc Deposition (FCAD) is reported. The data evidence the presence of a spurious oxide layer mostly consisting of iron grown by transient thermal oxidation at the ALD film/substrate interface in the initial stages of deposition and its suppression by pre-treatment in the FCAD process. Carbonaceous contamination (organic and carbidic) resulting from incomplete removal of the organic precursor is the major cause of the poorer sealing properties of the ALD film. No coating dissolution is demonstrated in neutral or acid 0.2 M NaCl solutions. In acid solution localized corrosion by pitting proceeds faster with the ALD than with the FCAD coating. The roles of the pre-existing channel defects exposing the substrate surface and of the spurious interfacial oxide promoting coating breakdown and/or delamination are emphasized.
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chromium and tantalum oxide nanocoatings prepared by Filtered Cathodic Arc deposition for corrosion protection of carbon steel
Surface & Coatings Technology, 2012Co-Authors: Belen Diaz, Antoine Seyeux, Vincent Maurice, Jolanta światowska, Marcin PisarekAbstract:Abstract Combined analysis by Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS), X-ray Photoelectron Spectroscopy (XPS), polarization curves and Electrochemical Impedance Spectroscopy (EIS) of the relation between chemical Architecture of thin (10 and 50 nm) chromium and tantalum oxide coatings grown by Filtered Cathodic Arc deposition (FCAD) on carbon steel and their corrosion protection properties is reported. Pre-etching in the deposition process allows reducing the substrate native oxide layer to traces of iron oxide. A carbidic interlayer is then formed by reaction between the first deposited metallic particles and the residual carbon surface contamination of the alloy. The bulk coatings mostly consist of Cr 2 O 3 or Ta 2 O 5 with no in-depth variation of the stoichiometry. Surface and bulk of the coatings are contaminated by hydroxyl and organic groups. The 50 nm coating has a relatively large porosity assigned to a columnar growth preventing good sealing at grain boundaries. The duplex structure (Ta/Ta–C) of the carbidic interlayer promotes a less defective growth of tantalum oxide than the single Cr–C interlayer for chromium oxide, thereby improving the sealing properties. The dielectric constants suggest poor insulating properties in line with a defective and porous nanostructure of the coatings. No dissolution was observed for both oxide nanocoatings in neutral 0.2 M NaCl. Penetration of the electrolyte and access to the interface with the carbon steel surface cause the dissolution of the Cr–C interlayer, but not that of the Ta/Ta–C interlayer, and a more rapid initiation of localized corrosion.