Effect of Surface Reactive Site Density and Reactivity on the Growth of Atomic Layer Deposited WN[sub x]C[sub y] Films

Hoyas, Ana Martin; Whelan, Caroline M.; Schuhmacher, Jörg; Célis, Jean-Pierre; Maex, Karen

doi:10.1149/1.2203239

Cited by 9 publications

(4 citation statements)

References 32 publications

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“…Due to the low concentration of hydroxyl groups on Cu and Al substrates, direct deposition of SOCAL was unsuccessful. Therefore, the SOCAL was coated on top of the sol–gel coating with SiO 2 acting as an intermediate layer between the substrate and SOCAL. ,, The detailed process of SOCAL development is explained elsewhere. , Briefly, we started by making a 100:10:1 wt % mixture of isopropanol: dimethyldimethoxysilane (DMDMS, CAS#: 1112-39-6, Sigma-Aldrich): sulfuric acid (CAS#: 7664-93-9, Sigma-Aldrich). After stirring the solution for 30 s, the mixture was left to rest in a sealed glass container for 20 min at room temperature.…”

Section: Methodsmentioning

confidence: 99%

“…Therefore, the SOCAL was coated on top of the sol−gel coating with SiO 2 acting as an intermediate layer between the substrate and SOCAL. 21,25,26 The detailed process of SOCAL development is explained elsewhere. 21,24 Briefly, we started by making a 100:10:1 wt % mixture of isopropanol: dimethyldimethoxysilane (DMDMS, CAS#: 1112-39-6, Sigma-Aldrich): sulfuric acid (CAS#: 7664-93-9, Sigma-Aldrich).…”

Section: ■ Methodsmentioning

confidence: 99%

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Scalable Corrosion-Resistant Coatings for Thermal Applications

Khodakarami

Zhao

Rabbi

et al. 2021

ACS Appl. Mater. Interfaces

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Corrosion of metallic substrates is a problem for a variety of applications. Corrosion can be mitigated with the use of an electrically insulating coating protecting the substrate. Thick millimetric coatings, such as paints, are generally more corrosion-resistant when compared to nanoscale coatings. However, for thermal systems, thick coatings are undesirable due to the resulting decrease in the overall heat transfer stemming from the added coating thermal resistance. Hence, the development of ultrathin (<10 μm) coatings is of great interest. Ultrathin inorganic silicon dioxide (SiO2) coatings applied by sol–gel chemistries or chemical vapor deposition, as well as organic coatings such as Parylene C, have great anticorrosion performance due to their high dielectric breakdown and low moisture permeability. However, their application to arbitrarily shaped metals is difficult or expensive. Here, we develop a sol–gel solution capable of facile and controllable dip coating on arbitrary metals, resulting in a very smooth (<5 nm roughness), thin (∼3 μm), and conformal coating of dense SiO2. To benchmark our material, we compared the corrosion performance with in-house synthesized superhydrophobic aluminum and copper samples, Parylene C-coated substrates, and smooth hydrophobic surfaces functionalized with a hydrophobic self-assembled monolayer. For comparison with state-of-the-art commercial coatings, copper substrates were coated with an organo-ceramic SiO2 layer created by an elevated temperature and atmospheric pressure metal organic chemical vapor deposition process. To characterize corrosion performance, we electrochemically investigated the corrosion resistance of all samples through potentiodynamic polarization studies and electrochemical impedance spectroscopy. To benchmark the coating durability and to demonstrate scalability, we tested internally coated copper tubes in a custom-built corrosion flow loop to simulate realistic working conditions with shear and particulate saltwater flow. The sol–gel and Parylene C coatings demonstrated a 95% decrease in corrosion rate during electrochemical tests. Copper tube weight loss was reduced by 75% for the sol–gel SiO2-coated tubes when seawater was used as the corrosive fluid in the test loop. This work not only demonstrates scalable coating methodologies for applying ultrathin anticorrosion coatings but also develops mechanistic understanding of corrosion mechanisms on a variety of functional surfaces and substrates.

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Section: Methodsmentioning

confidence: 99%

Section: ■ Methodsmentioning

confidence: 99%

Scalable Corrosion-Resistant Coatings for Thermal Applications

Khodakarami

Zhao

Rabbi

et al. 2021

ACS Appl. Mater. Interfaces

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“…This difference is also responsible for the varying volatile organic compound dynamics that different metal oxides display. , Indeed, the main factors to influence surface modification are the concentration of surface hydroxyl groups, the type of surface hydroxyl groups present at the interface, the hydrolytic stability of the bond formed between the groups and the SOCAL molecules, and geometry and physical dimensions of the substrate . Hydroxyl-containing substrates vary widely in concentration and type of hydroxyl groups present, with glass or silica being two of the best substrate materials for surface modification in comparison to Al. − Given this result, we deposit SiO 2 on Al substrates prior to SOCAL coating. This forms a sandwich structure with three layers (Al–SiO 2 –SOCAL); the SiO 2 layer is deposited by different methods.…”

Section: Methodsmentioning

confidence: 99%

Extreme Antiscaling Performance of Slippery Omniphobic Covalently Attached Liquids

Zhao

Deshpande

et al. 2020

ACS Appl. Mater. Interfaces

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Scale formation presents an enormous cost to the global economy. Classical nucleation theory dictates that to reduce the heterogeneous nucleation of scale, the surface should have low surface energy and be as smooth as possible. Past approaches have focused on lowering surface energy via the use of hydrophobic coatings and have created atomically smooth interfaces to eliminate nucleation sites, or both, via the infusion of lowsurface-energy lubricants into rough superhydrophobic substrates. Although lubricant-based surfaces are promising candidates for antiscaling, lubricant drainage inhibits their utilization. Here, we develop methodologies to deposit slippery omniphobic covalently attached liquids (SOCAL) on arbitrary substrates. Similar to lubricant-based surfaces, SOCAL has ultralow roughness and surface energy, enabling low nucleation rates and eliminating the need to replenish the lubricant. To enable SOCAL coating on metals, we investigated the surface chemistry required to ensure high-quality functionalization as measured by ultralow contact angle hysteresis (<3°). Using a multilayer deposition approach, we first electrophoretically deposit (EPD) silicon dioxide (SiO 2 ) as an intermediate layer between the metallic substrate and SOCAL. The necessity of EPD SiO 2 is to smooth (<10 nm roughness) as well as to enable the proper surface chemistry for SOCAL bonding. To characterize antiscaling performance, we utilized calcium sulfate (CaSO 4 ) scale tests, showing a 20× reduction in scale deposition rate than untreated metallic substrates. Descaling tests revealed that SOCAL dramatically decreases scale adhesion, resulting in rapid removal of scale buildup. Our work not only demonstrates a robust methodology for depositing antiscaling SOCAL coatings on metals but also develops design guidelines for the creation of antifouling coatings for alternate applications such as biofouling and high-temperature coking.

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“…(We see it as slightly ironic that DEZ is used as a source of ethyl groups in organic chemistry, but for zinc in ALD.) In an ALD process, the early stages of film formation, termed the transient regime, may be nonlinear, involving three-dimensional growth that depends on substrate reactivity, i.e., the growth in this regime is highly dependent on the functional groups at the surface [60][61]. In this work, dehydrated, fused silica surfaces with different densities of silanol groups were tagged with Al and Zn.…”

Section: Introductionmentioning

confidence: 99%