Corrigendum to “Investigation of the corrosion behaviour of steel coated with amorphous silicon carbon alloys” [Surf. Coat. Technol. 206 (2012) 3626–3631, (S0257897212001582), (10.1016/j.surfcoat.2012.02.056)]

The authors regret that, in the original version of this article, Fig. 1A contains a discrepancy in the C1s XPS signature of the carbonated silicon, a-Si_1−xC_x:H before and after sputtering, due to an accidental mixing among the data. This is corrected herewith. We, in addition, performed again the quantitative analysis of the XPS spectra and updated Table 1. This correction does not alter the conclusion of this work, but some values of Table 1 cited in the discussion have been somewhat modified. Therefore, for the legibility of the discussion, we reproduce hereafter the first paragraph of Section 3.1 where Table 1 is introduced and commented. An additional conclusion which can be drawn for this slightly modified picture is that adventitious carbon and oxygen contamination are less easily removed by the sputtering treatment, which reinforces the interest of a-Si:H coatings highlighted in the conclusion of the article (Section 4). The authors would like to apologise for any inconvenience caused. [Figure presented] 3.1 Coating of stainless steel interfaces with amorphous silicon carbon films Amorphous silicon carbon films of 100 nm in thickness with a carbon concentration varying between 0 and 0.37 at.% were deposited onto steel using PECVD in a “low-power” regime [15]. The carbon content in the film has been found to be governed by the methane ratio in the gas mixture only, as long as the deposition is performed in the low-power regime. The correspondence between the carbon content x in the a-Si_1−xC_x:H film and the methane ratio has been determined using X-ray photoelectron spectroscopy (XPS). XPS survey spectra of steel interfaces coated with a-Si_1−xC_x:H (x = 0, 0.1, 0.2, 0.37 at.%) display bands at 101, 151, 285 and 533 eV due to Si2p, Si2s, C1s and O1s, respectively (data not shown). The intensities of the C1s and O1s bands increase with increasing the carbon content of the a-Si_1−xC_x:H, while the Si2p, Si2s components decrease. Table 1A summarizes the atomic percentage of the different components. The carbon content found on the initial unsputtered a-Si:H surface is ≈16 at.% and increased up to ≈70 at.% with increasing the carbon content in the deposited thin film. This amount of carbon is several times higher than expected from the stoichiometry of the deposited films and is most likely due to adsorbed carbon impurities on the surface. Deconvolution of high resolution C1s XPS spectra revealed that the carbon impurities were mainly in the form of C–C/C–H and C-O bonds (Fig. 1A). A sputtering step was thus performed on the a-Si_1−xC_x:H interfaces to remove the organic contaminants prior to XPS analysis and to gain a better picture on the real composition of the deposited films (Fig. 1A). As seen in Table 1, sputtering decreases significantly the carbon content measured by XPS. For the a-Si:H surface no C1s is detected. In addition, deconvolution of the Si2p high resolution core level XPS spectra indicate that after 20 s sputtering≈12 at.% of Si in form of SiO₂ was removed from the surface (Table 1B). The thin silicon oxide (native oxide) film was formed during exposure of the a-Si:H to ambient. Sputtering of the carbonated samples for 20 s, decreased as well the overall carbon content (Table 1A) and surface confined SiO₂ (Table 1B). The amount of Si-O-C bonds in the a-Si_1−xC_x:H film increased with increasing the carbon content, while the amount of Si-Si bonds decreased (Table 1B). However, the stoichiometric amount as expected from the deposition parameters was not achieved neither for carbon nor silicon. For an a-Si_0.9C_0.1:H film, a carbon content (Si-C form) of ≈14 at.% and a total silicon concentration of ≈75 at.% was determined, being not too far from the expected C/Si ratio. In the case of an a-Si_0.8 C_0.2:H film, a carbon content of 26 at.%, being close to the stoichiometry of the film, is determined, while the Si total concentration is only 52 at.% instead of 80 at.%. The ratio of Si/C is again lower for an a-Si_0.63C_0.37:H film for which the carbon and Si contents did not exceed 29 at.% and 30 at.%, respectively. It is to be noted that the a-Si_1−xC_x:H interfaces used for corrosion studies did not experience any sputtering step (the organic contaminants and the native SiO₂ were not removed from the surface prior to corrosion studies).