Article Dans Une Revue Surface and Coatings Technology Année : 2025

Chemical and mechanical performances of CVD‑silicon oxycarbonitride films for corrosion protection applications: Towards inert coatings in aggressive aqueous media

Résumé

This study investigates the alteration behaviour of three CVD amorphous silica thin films deposited at three different deposition temperatures, exhibiting thus different network qualities. The hydrolysis of the networks was elucidated through ERDA hydrogen depth profiles acquired throughout the alteration process. It is worth noting that this hydrolysis is insignificant since a maximum of hydrogen atomic concentration of 10% was recorded during all the study. It was also evinced that the concentration and distribution of hydrogen throughout the depth are influenced by two competing phenomena: hydrolysis and ionic exchange of protons with K + ions coming from the solution. This competition is particularly noticeable in the film deposited at the lowest investigated temperature, where the presence of sufficiently large voids facilitates this exchange. Thickness loss rates were successfully calculated showing remarkably low initial rates ranging from 2.5 to 4.8 nm/day, directly correlated with the initial network quality. A residual rate as low as 0.5 nm/day was recorded, indicating limited hydration and hydrolysis mechanisms leading to the release of H4SiO4, given the higher dissociation energy required for such polymerized networks. These findings represent the first available dataset on dissolution rates of CVD-deposited silica films. It was demonstrated that network dissolution occurs evenly across the entire surface since the measured RMS values post-alteration remain quite low with a maximum of 2 nm. Finally, our study was supported by nanoindentation tests to assess hardness and elasticity, revealing a decrease of 38% and 13%, respectively, which was attributed to the high sensitivity of these two properties to physicochemical changes, particularly on the surface, during alteration. This comprehensive investigation has facilitated the accurate correlation of CVD deposition conditions and, consequently, the network quality of silica films to the chemical and mechanical response to aqueous alteration.
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Dates et versions

hal-04887921 , version 1 (17-01-2025)

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Farah Inoubli, Babacar Diallo, Konstantina Christina Topka, Raphael Laloo, Brigitte Caussat, et al.. Chemical and mechanical performances of CVD‑silicon oxycarbonitride films for corrosion protection applications: Towards inert coatings in aggressive aqueous media. Surface and Coatings Technology, 2025, 497, pp.131756. ⟨10.1016/j.surfcoat.2025.131756⟩. ⟨hal-04887921⟩
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