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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Low Temperature Tantalum Electrodeposition: Enabling Next Generation Coatings

This project aimed to identify the ligand and solvation conditions necessary for the electrodeposition of refractory metals from low-temperature organic electrolytes. Tantalum (Ta) was chosen as a specific exemplar for programmatic purposes. It was hoped that a deeper understanding of these relationships could facilitate the innovative application of refractory metal coatings on thermally sensitive and geometrically intricate components used in extreme environments related to energy generation and storage, nuclear deterrence, aerospace, defense, and beyond.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Microstructural Assessment of Molybdenum Disulfide Coatings Using Nanoindentation Hardness

MoS 2 coatings are used extensively in aerospace and defense applications due to their ultralow friction and high wear resistance. Burnished and resin-bonded MoS 2 coatings are commonly used in these applications due to simplicity in deposition and history of use, despite issues with consistency in coating properties and performance. Physical vapor deposition (PVD) of MoS 2 thin films has emerged as a process alternative in the past 50 years, promising far greater control over film structure and composition but at a greater cost. Despite PVD’s benefits, hesitance to adoption persists in high-consequence applications, not only due to increased costs but variability in resulting coating properties. These variations in properties and subsequent performance are in part due to the complexity of the PVD process and the sensitive interplay between coating process-structure-property relationships. This work aims to demystify the remaining uncertainties of the process-structure-property relationships in PVD MoS 2 . The microstructure and mechanical and tribological properties of 61 different PVD pure MoS 2 coatings are examined herein. Emphasis has been placed on developing performance-based (i.e., hardness, modulus) metrics that can assess microstructural changes (density, orientation, and crystallinity) and be utilized to accelerate process development and coating optimization. Relationships established within suggest that nanoindentation hardness can be used to infer coating performance (i.e., wear rate) and properties (i.e., density, crystalline texture, and stoichiometry). Furthermore, this work demonstrates that PVD MoS 2 coatings close to the theoretical density of MoS 2 consistently have the best tribological performance and can be reliably identified by their hardness.

MoS2↗
DOE OSTI2026

Application of Machine Learning to Improve Biobased Glucaric Acid Production: Cooperative Research and Development Final Report, CRADA Number CRD-20-17260

The Agile Biofoundry (ABF) is a multi-national lab consortium funded by the DOE Bioenergy Technologies Office that has developed a biofoundry that enables the rapid deployment of bioproducts into the market. Working with four ABF laboratory members (National Laboratory of the Rockies (NLR), Pacific Northwest National Laboratory (PNNL), Lawrence Berkeley National Laboratory (LBNL), and Argonne National Laboratory (ANL)), Kalion will use advanced high throughput techniques, advanced analytics, and machine learning to optimize the production environment for glucaric acid. Low-cost, high-purity glucaric acid enables products in a wide range of fields to improve the chemical properties of products and applications ranging from water treatment, polymers & textiles, coatings, detergents, and pharmaceuticals. With its broad range of applications, glucaric acid has the potential to demonstrate how such bio-based materials offer great benefit to the US economy.

09 BIOMASS FUELS↗
DOE OSTI2024

Distributed strain sensing using Bi-metallic coated fiber optic sensors embedded in stainless steel

Silica fiber optic sensors are resistant to corrosive environments and high temperatures, making them attractive candidates for harsh conditions found in nuclear and aerospace industries. Moreover, fibers can be deployed remotely for continuous measuring of spatially distributed temperatures and strains. Here, this study investigated embedding a Ni/Cu bi-metallic coated fiber in a stainless-steel 316 (SS316) matrix using laser powder bed fusion towards functionalizing metal components for site-specific health monitoring. The embedded fiber was continuously interrogated during controlled heating to 1000°C. The measured fiber strains were similar to the expected differential thermal strains between the fiber and the SS316 matrix, until divergent behavior was observed at temperatures >500°C. No debonding at the matrix–coating–fiber interfaces was observed during microscopy, but significant interactions between the coatings and matrix resulted in diffusion-driven chemistry variations and Kirkendall void formation. Applying the strain-lag theory revealed plastic behavior in the Ni coating at temperatures >500°C, limiting the strain transfer to the fiber at higher temperatures. It was estimated that the elastic modulus in the Ni coating had decreased from ~200 GPa at room temperature to below 40 GPa, starting at 600°C. The low elastic modulus above 600°C is within the margin of what the tangent modulus would be in the case of bilinear isotropic hardening. Regardless of the divergent strain transfer at higher temperatures, the fiber was exposed to the equivalent of 1.9 % engineering strain at 1000°C, but measured only a 0.7 % engineering strain due to the poor strain transfer. Although compensating for the plastic behavior of Ni proved challenging, the bonding of a brittle silica fiber to a metal matrix surviving to 1000°C invites potential iterations on coating material for future application. For example, the embedded fiber is sufficient for acoustic energy transfer, realizing high temperature distributed acoustic sensing.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Crack mitigation and wear performance of high-strength steel coatings deposited by high-speed laser cladding

This article investigates the fabrication of defect-free Rockit® 606, a high‑carbon, vanadium- and chromium-enriched precipitation-hardening martensitic steel coating, using high-speed laser cladding (HSLC). Compared to conventional laser cladding, HSLC offers higher deposition efficiency, improved coating quality, minimal thermal distortion, and a reduced heat-affected zone. Various HSLC parameters—including laser power, travel speed, powder feed rate, and overlap distance—were optimized to achieve superior coating properties. Microstructural analysis revealed solidification cracks in coatings deposited on carburized steel, regardless of processing parameters. However, preheating the substrate to 250 °C effectively eliminated cracking by reducing thermal gradients. The coatings exhibited a columnar dendritic microstructure, with coarser dendrites near the substrate and finer dendrites towards the surface. Hardness measurements confirmed that all coatings significantly exceeded the industry-specified threshold of 60 HRC, with preheating having minimal effect on overall hardness distribution. Reciprocating sliding wear tests demonstrated a substantial improvement in wear resistance for the defect-free HSLC coatings compared to baseline carburized steel. These findings underscore the potential of HSLC for producing high-performance, wear-resistant coatings suitable for industrial applications.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Effects of Concentration, Salinity and Temperature on the Conformations of Zwitterionic Poly(2-Vinylpyridine- N -Oxide) Chains in Semidilute Solutions Probed by Small-Angle X-Ray and Neutron Scattering

Polyzwitterions, composed of repeating units with equal numbers of anionic and cationic groups, have drawn considerable interest for applications ranging from antimicrobial coatings and antifouling membranes to low-friction interfaces, energy storage media, and actuators. A characteristic feature of many polyzwitterions is the anti-polyelectrolyte effect salt-induced chain expansion in aqueous solution a phenomenon often implicated in their functional behavior. In this study, we investigated the conformational behavior of poly(2-vinylpyridine-N-oxide) (P2VPNO) using smallangle X-ray and neutron scattering (SAXS and SANS). Small-angle X-ray scattering (SAXS) revealed that, in salt-free aqueous solution, P2VPNO adopts an expanded wormlike conformation stabilized by hydration. With increasing concentration, the chains contract due to screening of intrachain excluded-volume interactions, qualitatively consistent with de Gennes’ scaling predictions for neutral polymers. Small-angle neutron scattering (SANS) further demonstrated that P2VPNO exhibits the characteristic anti-polyelectrolyte response to added salt, as observed in many other polyzwitterions. At elevated temperatures, chain flexibility increases, leading to a shorter Kuhn length and reduced radius of gyration. Notably, however, salt-induced chain expansion persists, indicating that the anti-polyelectrolyte effect remains operative under elevated thermal conditions. These findings provide the first experimental evidence of scaling behavior in polyzwitterions, as well as the first observation of their altered antipolyelectrolyte response at elevated temperatures, offering new insights into the solution physics of this important class of polymers.

Conformation↗
DOE OSTI2026

Molecular Dynamics Investigation of Oil Wetting on Synthetic Polymer Substrates

Understanding the interaction of polymer surfaces with nonpolar, low surface tension liquids, or whether a substrate is oleophobic versus oleophilic, is critical for applications ranging from antifingerprint coatings to oil–water separation membranes and oil spill remediation. Despite its technological importance, the molecular mechanisms underpinning polymer–oil wetting are not well characterized. Here, we employ molecular dynamics simulations to investigate the behavior of n-hexadecane in contact with chemically distinct polymer surfaces, spanning eight constitutional unit chemistries as well as amorphous and crystalline morphologies. This permits a critical examination of both thermodynamic and dynamic descriptors of oleophobicity, including oil contact angle, dewetting free energy, interfacial diffusivity, and a proposed “ghost probe energy,” which does not require explicit simulation of oil–polymer interactions. We find that the oil contact angle does not reliably distinguish oleophobic behavior across polymer chemistries, whereas other metrics provide clearer and more consistent differentiation. Analysis of the results reveals that polymer–oil wetting behavior is primarily governed by interfacial van der Waals interactions and modulated by surface flexibility and morphology. Collectively, this work establishes a computational framework for characterizing oil wetting and provides additional insight into what molecular-level factors dictate trends in oleophobicity.

lipids↗
DOE OSTI2026

Upcycling plastic waste into polyhydroxyalkanoates with high carbon conversion via CO 2 plasma-enabled deconstruction

Plastic deconstruction into fermentable intermediates is a key step for microbial bio-upcycling into value-added products. In this study, CO 2 plasma deconstruction was used as an electrified route to convert polyethylene into oxygenated intermediates and liquid (OIL). The resulting OIL was rich in fatty acids, fatty alcohols, and hydrocarbons, making it a suitable feedstock for medium-chain-length polyhydroxyalkanoate (mcl-PHA) production by Pseudomonas putida NRRL B-14688 and Pseudomonas resinovorans NRRL B-2649. Compared with batch fermentation and monocultures, fed-batch co-cultivation markedly improved biomass formation and PHA accumulation, likely due to complementary substrate utilization, particularly hydrocarbon conversion by P. resinovorans. Using virgin polyethylene-derived OIL (Vir-OIL), the co-culture achieved 40.11% mcl-PHA content and about 18% PHA yield based on total OIL fed. More importantly, OIL produced from post-consumer single-use plastic films (PCR-OIL) was directly fermented and well supported the cell growth and PHA accumulation, achieving 38.11% PHA content and about 14.7% PHA yield. Based on emulsified OIL fractions, PHA yields for Vir-OIL and PCR-OIL were comparable (∼28%). PHA granules were extracted from PCR-OIL-grown cells with high recovery (88.25%) and purity (94.8%). Five monomers were identified in the polymer, including 3-hydroxyhexanoate (3HHx), 3-hydroxyoctanoate (3HO), 3-hydroxydecanoate (3HD), 3-hydroxydodecanoate (3HDD), and 3-hydroxytetradecanoate (3HTD), with 3HO (44.28%) and 3HD (40.60%) as the dominant units. The polymer exhibited moderate molecular weight and narrow dispersity (M n = 65.4 kDa, M w = 92.1 kDa, Đ = 1.40) and low crystallinity (T m ≈ 76.6 °C, X c ≈ 15.5%). These characteristics indicate elastomer-like behavior, making the material suitable for flexible applications such as films, coatings, adhesives, and blend modifiers. Overall, this study establishes a CO 2 plasma-assisted route for generating fermentable polyethylene-derived intermediates and demonstrates that fed-batch co-culture fermentation can effectively funnel plastic-derived carbon into mcl-PHA.

42 ENGINEERING↗
DOE OSTI2025

TEAMER Technical Support on Biofouling and Corrosion for E-Wave Technologies LLC Novel (Abstract)

National Technology & Engineering Solutions of Sandia (NTESS) in collaboration with the Pacific Northwest National Laboratory (PNNL), and with guidance from E-Wave, will assess corrosion and biofouling challenges specific to E-Wave’s innovative WEC designed to retrofit into and power existing aquaculture farm infrastructure from ocean waves. The teams will examine coatings via a static raw seawater test and determine the efficacy of coatings for E-Wave’s applications. Samples will include panels of materials provided by E-Wave and coated with three different paint treatments. Fouling will be determined using a staining technique followed by photographic analysis to evaluate fouling intensity on the surface. Materials will also be weighed before and after submersion to facilitate weight change analysis resulting from fouling organisms aggregating on the materials.

16 TIDAL AND WAVE POWER↗
DOE OSTI2025

Tunable Semiconducting Behavior and Linear-Nonlinear Optical Properties of Ag–Sn Dual-Doped Nanocrystalline CdO Thin Films for Optoelectronics

Semiconductor-based thin films have a great impact on determining the anticipated optoelectronic device construction and the advancement of cutting-edge applications. Herein, Ag and Sn dual-doped nanocrystalline transparent conducting CdO thin films were prepared on glass substrates using a cost-effective spray coating method, and their structural, morphological, optical, and semiconducting behaviors were investigated. The successful incorporation of Ag and Sn resulted in the polycrystalline nature of the deposited films without the additional peaks, as verified by X-ray diffraction (XRD) analysis. The XRD report also revealed the enhanced crystallinity (65%) at the higher doping level (3 wt % Ag and Sn-doped CdO film). All the deposited CdO films exhibited homogeneous, spherical, or round-shaped grains, with agglomeration revealed by scanning electron microscopy analysis. UV–visible spectroscopy was utilized to determine the linear and nonlinear optical properties of the deposited CdO thin films, and a reduction in the band gap from 3.891 to 3.772 eV was observed. A significant enhancement in the first- and third-order nonlinear susceptibility and nonlinear refractive index of the doped CdO films was also observed with increasing doping concentration. Hall effect data were collected at room temperature to investigate the electrical properties of all of the CdO films. The charge carrier concentration of CdO thin films was increased from 142.08 × 10 18 to 169.10 × 10 18 cm –3 , and the highest conductivity was found to be 192 s/cm on doping 3 wt % Ag–Sn. All the CdO thin films exhibited n-type conductivity, while an incredible n-type to p-type charge carrier transition was noticed at a higher doping level (3 wt % Ag–Sn). The findings of the current work are expected to advance the synthesis of semiconductor thin films through cost-effective spray coating methods for optoelectronic device applications.

deposition↗
DOE OSTI2025

Boron‐Doped Nano‐Crystalline Coated Carbon Fibers for Phasic Dopamine Sensing

Real time, chronic electrochemical detection of neurotransmitters will provide a positive step in the treatment and understanding of neurological disease. However, current electrodes using carbon fibers (CF) fail to perform chronically. While diamond-based coatings show promise in improving their longevity, achieving a uniform layer of such coatings on CFs is challenging, and the electrodes often lose sensitivity after coating. In this work, a complete and uniform boron-doped nanocrystalline material grown in a diamond reactor (B-NCD) was developed to coat CF microelectrodes for neurochemical sensing. The coating was characterized electrically, optically, mechanically, and chemically. The B-NCD coated CF electrodes were able to detect phasic dopamine at a sensitivity comparable to the most widely used alternatives (uncoated and PEDOT:Nafion coated CFs). During biofouling testing, the B-NCD coated CF electrodes demonstrated better stability than uncoated CFs and comparable performance to PEDOT:Nafion coated CFs. Moreover, B-NCD exhibited no signs of degradation during consecutive FSCV applications, while uncoated and PEDOT:Nafion coated CF electrodes degraded significantly over time. Furthermore, the B-NCD coating supported the survival and development of neurons and astrocytes in vitro, exhibited excellent adhesion and durability during mechanical bending testing, and enabled successful in vivo recording of phasic dopamine release in the rat brain. Overall, B-NCD coated CFs present as an ideal candidate for chronic, flexible neural implantable electrodes for long-term neurochemical monitoring.

carbon fiber↗
DOE OSTI2025

Rapid Screening of Liquid Metal Wetting for a Materials Compatibility Library

Wetting behavior of molten metals on solid substrates is a critical phenomenon influencing numerous industrial applications, including welding, anti-corrosion coatings, and metal additive manufacturing (AM). In particular, molten metal jetting (MMJ), an emerging AM technology, requires that the molten metal remain pinned at the nozzle exit. Thus, each new metal requires a specific nozzle material to ensure consistent droplet ejection and deposition, making it important to rapidly identify the appropriate wetting combinations. However, traditional measurements of wetting angles require expensive equipment and only allow one combination of materials to be investigated at a time which can be time consuming. This work introduces a rapid screening method based on sessile droplet experiments to evaluate wetting profiles across multiple metal–substrate combinations simultaneously. This study investigates the wetting interactions of molten Al alloy (Al4008), Cu, and Sn on various ceramic and metal substrates to identify optimal material combinations for MMJ nozzle designs. Results demonstrate that Al4008 achieves wetting on ceramic substrates such as AlN, TiO 2 , and SiC, with varying mechanisms including chemical reactions and weak surface interactions. Additionally, theoretical predictions regarding miscibility gaps and melting point differences were verified for Cu and Sn on refractory metals like Mo and W. Findings from this study contribute to the establishment of a materials compatibility library, enabling the selection of wetting/non-wetting combinations for stable MMJ operation. This resource not only advances MMJ technologies but also provides valuable insights for broader applications such as welding, coating, and printed electronics.

Materials science↗
DOE OSTI2025

Pulse duration dependent effects of ultrafast laser induced damage on a 1030 nm multi-layer dielectric mirror for high repetition rate, high average power laser systems

High repetition rate, high peak, and average power laser systems are crucial for next-generation particle accelerators, inertial confinement fusion, and secondary particle sources. These applications demand durable laser optics, particularly interference coatings on optics lasting millions of shots at high fluence. This study focuses on designing, testing, and simulating multi-layer dielectric (MLD) mirrors for pulse durations of 260 fs, 77 fs, and 25 fs at 1030 nm wavelength and 45-degree incidence angle with p -polarization. S-on-1 laser-induced damage thresholds (LIDT) for varying pulse numbers were determined, with single-shot LIDT values of 0.98 Jcm -2 , 1.63 Jcm -2 , and 2.3 Jcm -2 for 25 fs, 77 fs, and 260 fs respectively. A strong correlation between blister shape and local fluence was observed, implying that the layer expansion in a blister depends on local fluence. We have also examined mechanisms responsible for laser-induced stress generation and energy release rates in blister formation. Damage mechanisms are further explored by finite-difference time-domain (FDTD) simulations, incorporating Keldysh strong field ionization, whose predictions were in excellent agreement with the onset of damage determined experimentally. These findings offer insights for enhancing MLD coating technology, promising more efficient and resilient laser systems for diverse scientific and industrial applications.

Noor, Mohamed Yaseen (ORCID:000000021036644X)↗
DOE OSTI2026

Toward Lithium Recovery Using Modular (and Membraneless) Phase Separation and Extraction (MPSE) Technology with Ionic Liquid (IL) Solvents: Effect of Coatings

In this work, a single-channel slope-plate Modular and Membrane-less Phase Separation and Extraction (MPSE) device was fabricated using 3D printing. The slope-plate was designed with an insertable glass slide to enable surface modification with coatings. Self-assembled monolayers (SAMs) and perfluoropolyether (Zdol) coatings were applied to tailor surface wettability and enhance phase separation. Using a model biphasic system of water and hexadecane, both coatings significantly improved the separation efficiency compared to the uncoated device by promoting selective wetting. Building on these results, lithium extraction from a simulated saline solution was investigated using 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][NTf₂]) as the ionic liquid (IL) extractant. The IL effectively extracted Li⁺ from the aqueous phase in bulk extraction, demonstrating its potential for lithium recovery. However, the low interfacial tension between the IL and aqueous phases posed challenges for phase separation. The application of SAM and Zdol coatings effectively mitigated this issue. Overall, integrating tailored surface chemistry with the slope-plate MPSE design shows great promise as an efficient and scalable platform for studying liquid–liquid separation and optimizing ionic liquid–based extraction processes for lithium recovery from saline sources.

3D printing↗
DOE OSTI2024

Surface Modified Fly Ash for Value Added Products (SuMo Fly Ash)

The objective of this project is to develop a technology to encapsulate coal fly ash particles in sulfurized vegetable oil, enhancing physical and mechanical properties of the fly ash as a filler material when applied in commercial products. This project significantly advances the knowledge base and technology for synthesizing coated fly ash particles for application in different polymer matrices to increase cross-linking, compatibility, air-entrainment and to decrease the leaching potential of metals of concern. Specifically, the project focuses on (a) collection, and characterization of fly ash material from coal power plants; (b) development of Sulfurized Vegetable Oil (SVO) modified (SuMo) fly ash and their detailed characterization; (c) evaluation of the mechanical properties of the SuMo fly ash incorporated plastic and rubber composites for potential replacement of CaCO 3 or carbon black as filler materials with SuMo fly ash in plastic and rubber composites; (d) leaching potential of SuMo fly ash and SuMo fly ash-incorporated plastic and rubber composites to determine the rate of release of trace metals. The major findings of this project are: i) Sulfurized Vegetable Oil coated fly ash (SuMo fly ash) was successfully prepared with a particle size of ≤ 45 micron which exhibited hydrophobicity of contact angle > 90°; ii) the coating reduces leaching of metals (e.g., B, Cr) from fly ash when exposed to water; iii) incorporation of SuMo fly ash increases thermal stability and yield strength of plastics; iv) SuMo coating helps disperse fly ash particles into cured rubbers, natural rubber; (v) SuMo fly ash-incorporated plastic/cured rubbers compounds protects against leaching of toxic elements.

20 FOSSIL-FUELED POWER PLANTS↗
DOE OSTI2025

Multilayer Architecture Barriers for High Temperature Nuclear Applications

Innovative thin film multilayer metal/ceramic barrier coatings have been developed by Argonne National Laboratory to protect fuel cladding against different phenomena that can be encountered under the harsh operating conditions of advanced nuclear reactors. One phenomenon is Fuel-Cladding Chemical Interaction (FCCI), which can represent a challenge to the performance of steel-clad metallic fuels in sodium-cooled fast reactors (SFRs), especially when operating to high burnups at elevated cladding temperatures, and long fuel residence time. Another phenomenon is the corrosion of zirconium-based cladding under prototypic boiling water reactor (BWR) conditions and associated cladding during off normal conditions, including loss of coolant accidents (LOCA). This work provides details of the development and testing of a thin film (few microns) multilayer metal/ceramic (CrY/Y 2 O 3 ) coatings on steel cladding and its performance against FCCI. The coating architecture evolved through systematic mechanical testing, radiation tolerance assessments, and high-temperature diffusion studies from a preliminary multilayer concept to an optimized high-performance design. The optimized structure leverages stoichiometric Y 2 O 3 for its exceptional radiation stability, chemical inertness, and ultra-low fission product diffusivity (e.g., Ce diffusivity ~10 -20 m 2 /s in irradiated Y 2 O 3 at 650 °C). This is paired with ductile chromium-rich interlayers (Cr 95 Y 5 ), which significantly enhance fracture toughness and mechanical resilience. Design refinements, including increased ceramic layer thickness and optimized Cr–Y interlayer composition, eliminated fracture propagation and preserved coating integrity under extreme mechanical stress (>10× typical reactor conditions) and prolonged radiation exposure (~300 dpa). Those conditions are well beyond expected conditions during normal operations in SFR, and cover some of the transient conditions as well. In addition, the coating deposition was demonstrated to be applied uniformly to the inner surface of steel tubes representing prototypic SFR cladding. Another phenomenon under consideration in this work is the corrosion of zirconium-based cladding under prototypic boiling water reactor (BWR) conditions and associated off normal conditions including loss of coolant accident (LOCA). Another multilayer thin film coating is considered for mitigation of this phenomenon, where a coating of yttrium aluminum and yttrium aluminum ceramic/metal thin film coating. Preliminary results on the coating performance during high temperature thermal cycling (up to 1000 C) have shown promising performance of the coating. On-going optimization of the coating will continue in FY26.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2024

Chromium-Free Coating for Al Alloy Corrosion Protection Based on a Novel Ti/Mg Oxyfluoride

Chromium-free corrosion protection of aluminum alloys comparable to that of chromates (Cr(VI)) is demonstrated using a TiF 6 2– fluoro-anion-based coating recipe containing boric acid and a Mg salt. Boric acid drove TiF 6 2– hydrolysis enabling up to micrometer-scale thick coatings. The Mg salt led to deposition of a novel crystalline phase Ti/Mg oxyfluoride coating with an approximate composition of Ti 5 MgO 7 F 8 . Corrosion protection performance was characterized by polarization resistance measurements during immersion in 5% aqueous NaCl solution and neutral salt fog exposure following ASTM B.117. The performance is discussed in terms of the presence of fluoride in the coating enabling active behavior during its gradual depletion (in corrosion environments) toward a final composition approaching TiO 2 . This active corrosion protection mechanism may be more generally applicable for transition metal-based coatings that do not have high oxidation state oxo-anions, but do have stable fluoro-anions.

36 MATERIALS SCIENCE↗