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At least 667 records · Page 37
All sourcesNASA NTRSDOE OSTI
NASA NTRS2024

Wear and Neutron Shielding Resilience of Titanium-Hexagonal Boron Nitride Coatings Against Extreme Lunar Radiation and Thermal Cycles

Ti6Al4V and Al6061 are aerospace alloys used in lunar structural components and rovers owing to their high specific strength. However, they deteriorate rapidly when subjected to demanding conditions of the lunar environment, such as extreme thermal cycles, solar particle radiation, and abrasive regolith. Cryo-milled powders were employed to deposit hBN-reinforced protective titanium coatings through plasma spray (atmospheric APS and vacuum-VPS) with 2 and 10 vol% of hBN on Ti6Al4V and Al6061 substrates. These coatings were evaluated for durability under extreme lunar-like conditions, including thermal cycling, electron radiation, and synergistic (electron radiation-thermal cycle) exposure. The coatings exhibited radiation-induced hardening, resulting in a substantial increase in their microhardness ~20–40% compared to virgin condition. Bright-field transmission electron microscopy (TEM) analysis reveals the presence of high dislocation densities, black dot defects, and dislocation clusters, providing evidence of the severe impact of synergistic environmental stresses. Ball-on-disk tribological tests were conducted in the presence of JSC-1 A lunar regolith simulant to evaluate the wear performance of coatings. Compared to conventional Ti6Al4V substrate, 50%, 90%, and 70% reductions in wear volume were observed in the Ti/2 vol% hBN coatings in thermal-only, radiation-only, and synergistic environments. Neutron shielding tests indicate that the synergistic coatings offer higher neutron shielding performance by up to 28% compared to virgin coatings, attributed to improved neutron capture by 10B isotopes. Upon a comprehensive assessment and ranking of multiple coatings under varying conditions, the VPS Ti/2 vol% hBN coating emerges as the top choice for protection against extreme radiation and thermal cycles for future lunar explorations.

Boron nitride↗
DOE OSTI2016

DIRECT LASER DEPOSITION OF POROUS STRUCTURES AND GRADIENT METAL-CERAMIC COMPOSITE COATINGS

Direct laser deposition is an additive manufacturing technique capable of producing complex geometries, bond different materials, repair broken parts, and add protective coating. In the present study it is used to make micro-porous scaffolds and apply protective vanadium and niobium carbide coatings. Micro-porous metal filters are a difficult thing to make but are required for many applications. In this study it was hypothesized that laser engineering net shaping (LENS) could be used to make porous Ti6Al4V scaffolds with an interconnected micro-porous structure. This proved to be true with cylinders made to have 15.9% porosity, and a pore size less than 100μm. These structures were made by only altering processing parameters, which yielded a scaffold with obstructed random pore interconnectivity. The scaffolds had a compressive strength of 645-556MPa and martensitic like α' grains. Another study was done to apply hard niobium and vanadium carbide surface coatings to stainless steel. The objective was to used LENS to deposit stainless steel coatings with added carbides to eventually make a gradient coating with increased protective qualities. Parts that have suffered material loss from abrasive wear or cavitation could have material added back as well as add a protective coating at the same time. Compositions ranging from 5% to 100% of the carbides were mixed with stainless steel. The coatings were then deposited on a stainless steel 304 substrate individually, as well as in a series to make a gradient structure. These coatings all increased hardness, wear resistance, and 100%VC significantly increased the materials resistance to damage from abrasive water. The carbides integrated into the SS304 matrix on the grain boundaries making a metal ceramic composite. These precipitates left residual stress in the structure which increased the hardness and wear resistance. The study proved that the addition of these carbides did increase the protective qualities and could make a gradient coating with properties tailored to the user’s preference.

13 HYDRO ENERGY↗
DOE OSTI2023

Microstructure geometry for thermal barrier coatings to mitigate CMAS attack

Thermal barrier coatings and methods to make such coatings present improved resistance to CMAS infiltration. The method for forming a thermal barrier coating includes applying a layer of the thermal barrier coating to a component having a surface, forming a plurality of first channels in the thermal barrier coating, and forming a plurality of second channels in the thermal barrier coating. The first channels extend through a thickness of the thermal barrier coating from an interface with the surface of the component to a free surface opposite the interface. The second channels are disposed between the free surface and the interface and extending lengthwise generally parallel to the free surface of the thermal barrier coating, wherein the thermal barrier coating comprises a material comprising yttrium aluminum garnet (YAG) or yttria stabilized zirconia (YSZ).

Jordan, Eric↗
DOE OSTI2018

Radiation Tolerance Studies of Commercial Strippable Coatings and Fixatives used for Decontamination - 18642

A number of commercially available products, designed for use as strippable coating and fixatives for decontamination purposes, were tested to determine their tolerability to high radiation fields and how they potentially degrade. Each product was cured and exposed to γ-radiation from a Co-60 source, up to a total dose of 500 kGy. Obvious physical colour changes and deformities were detected by visual inspection, and images captured by scanning electron microscope (SEM) showed major differences post-irradiation in some coatings. Other physical changes to the coatings were measured using Fourier-transform infrared spectroscopy (FT-IR), Raman spectroscopy, and energy-dispersive X-ray spectroscopy (EDS); both pre- and post-irradiation. FT-IR suggested that some chemical changes were taking place in the coatings, in particular the C-H bonds and the fingerprint region appeared to be drastically altered in some coatings. EDS data indicated an increase in surface oxygen content as a result of irradiation in the majority of the samples. Additionally, coating samples were subjected to analysis by gas chromatography mass spectrometry (GCMS) in order to determine the evolved gases. The GC-MS results show that short chain hydrocarbons are produced to some degree in all the coatings during irradiation. Finally, three of the best performing coatings were selected and were irradiated using an ion beam, mimicking Pu alpha particles (with energy of around 5.25 MeV). Using the Dalton Cumbrian Facility's 5 MV tandem accelerator, coating samples were irradiated by ∼5.25 MeV He{sup 2+} particles to total dose of approximately 500 kGy. Samples were analysed using SEM, FT-IR, Raman and EDS, as was done for the gamma irradiated samples, allowing a comparison to be made between α-particle and γ-ray damage. Results from the alpha and gamma irradiations showed many similarities for the comparable assessments. A number of spectral changes observed in the FT-IR analysis were consistent across both γ-ray and α-particle irradiated samples. While there were some differences, these may be attributed to the conditions under which the irradiations were carried out. The observed similarities may allow for the inference of alpha degradation by Co-60 gamma irradiation as a more easily accessible method for determining the extent of radiolytic damage. Furthermore, gamma irradiation allows for additional analysis that is currently otherwise not possible to achieve with ion-beam exposure. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2017

Fabrication of Superhydrophobic Calcium Phosphate Coating on Mg-Zn-Ca alloy and Its Corrosion Resistance

A novel superhydrophobic calcium phosphate coating was prepared on a magnesium alloy substrate by a highly effective chemical conversion process and subsequent chemical modification. Different methods were employed to characterize the surface morphology and chemical composition as well as measure the wettability of the coating. It was demonstrated that the as-prepared superhydrophobic calcium phosphate coating has a typical three-level hierarchical structure consisted of micro-protrusions, submicro-lumps and nano-grains, conferring excellent superhydrophobicity with a water contact angle of 159°. The electrochemical measurements and appropriate equivalent circuit revealed that the corrosion-resistant performance of the superhydrophobic calcium phosphate coating was significantly improved as compared with that of the substrate, the corrosion potential of the superhydrophobic coating increases from −1.56 to −1.36 V, and its corrosion current density decreases from 1.29 × 10{sup −4} to 1.3 × 10{sup −6} A/cm{sup 2}. The anti-corrosion mechanism of the superhydrophobic coating was also discussed. It can be indicated that the corrosion inhibitive properties of the coating are in accordance with its hydrophobicity, which is owing to the presence of a protective layer of air trapped in the grooves of the coating surface to isolate the underlying materials from the external environment.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Structural and Mechanical Properties of Zr-Si-N Coatings Deposited by Arc Evaporation at Different Substrate Bias Voltages

ZrN and Zr-Si-N coatings were formed using vacuum-arc plasma fluxes deposition system at the substrate bias voltage (U{sub B}) ranged from − 50 to − 220 V on HS6-5-2 steel substrates. The structural, mechanical and tribological properties were characterized using x-ray diffraction, atomic force microscopy, scanning electron microscopy, optical microscopy, nanoindentation and ball-on-disk test. The surface roughness parameter Ra of ZrN coatings is lower than Zr-Si-N coatings. Both roughness Ra of Zr-Si-N coatings and the number of surface defects with mainly small dimensions to 1 µm decrease with increasing negative substrate bias voltage. The addition of silicon to ZrN significantly reduces the crystallite size, from about 18.3 nm for ZrN coating to 6.4 nm for Zr-Si-N coating both deposited at the same U{sub B} = − 100 V and 7.8 nm for U{sub B} = − 150 V. The hardness of Zr-Si-N coatings increases to about 30 GPa with the increase in negative substrate bias voltage (U{sub B} = − 220 V). Adhesion of the coatings tested is high, and critical load is above 80 N and reduces with U{sub B} increase. Coefficient of friction determined using AFM shows similar trend as surface roughness in microscale.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Robust silane self-assembled monolayer coatings on plasma-engineered copper surfaces promoting dropwise condensation

Dropwise condensation is well known to result in better heat transfer performance owing to efficient condensate/droplet removal, which can be harnessed in various industrial heat/mass transfer applications such as power generation and conversion, water harvesting/desalination, and electronics thermal management. The key to enhancing condensation via the dropwise mode is thin low surface energy coatings (<100 nm) with low contact angle hysteresis. Ultrathin (<5 nm) silane self-assembled monolayers (or SAMs) have been widely studied to promote dropwise condensation due to their minimal thermal resistance and scalable integration processes. Such thin coatings typically degrade within an hour during condensation of water vapor. After coating failure, water vapor condensation transitions to the inefficient filmwise mode with poor heat transfer performance. We enhance silane SAM quality and durability during water vapor condensation on copper compared to state-of-the-art silane coatings on metal surfaces. We achieve this via (i) surface polishing to sub-10 nm levels, (ii) pure oxygen plasma surface treatment, and (iii) silane coating integration with the copper substrate in an anhydrous/moisture-free environment. The resulting silane SAM has low contact angle hysteresis (≈20°) and promotes efficient dropwise condensation of water for >360 hours without any visible sign of coating failure/degradation in the absence of non-condensable gases. We further demonstrate enhanced heat transfer performance (≈5-7× increase over filmwise condensation) over an extended period of time. Surface characterization data post-condensation leads us to propose that in the absence of non-condensable gases in the vapor environment, the silane SAM degrades due to reduction and subsequent dissolution of copper oxide at the oligomer-substrate interface. The experiments also indicate that the magnitude of surface subcooling (or condensation rate) affects the rate of coating degradation. Finally, this work identifies a pathway to durable dropwise promoter coatings that will enable efficient heat transfer in industrial applications.

42 ENGINEERING↗
DOE OSTI2026

Using Artificial Soiling to Rank Anti-Soiling Coatings for Arid Climates

A simple method to evaluate (e.g., screen and rank) the performance of coatings that are fully or partially anti-soiling (AS) is lacking within the PV industry. Artificial soiling may be used as a rapid and economical assessment approach, offering an efficient alternative to time-intensive, site-specific field testing. In this study, we present an artificial soiling method to replicate the anti-soiling performance rankings of two groups of coated glass samples supplied by two manufacturers (group C with CA, CP, and CS coatings; group A with AC coating). These are compared to field aging in two climates: semi-arid Lemoore, California over 4 months, and the hot desert in Mesa, Arizona over 7 months. Both field and indoor performance ranking utilize the transmittance ratio, defined as the optical transmittance between a coated sample and an uncoated reference in each group, as an evaluation metric to assess the effectiveness of the artificial soiling approach in replicating field soiling. It is critical to mimic the dominant field meteorological conditions associated with soiling-prone days and vulnerable times of day during the soiling season. Our results reveal that the use of artificial soiling for field performance ranking among coatings strongly depends on the soil type (composition and particle distribution), dust surface density, and prevalent environmental factors (wetting saturation by humidity, dew condensation extent, and prior weathering history of the coating). The similar rank order relative to the field suggests that the artificial soiling approach presented may be used for down-selecting anti-soiling coatings prior to prolonged field validation.

14 SOLAR ENERGY↗
DOE OSTI2020

Porous architecture and thermal properties of thermal barrier coatings deposited by suspension plasma spray

Besides the intrinsic low heat transfer capability of material, the thermal insulation property of thermal barrier coatings (TBCs) also relies on their microstructures. For better understanding the relationship between process parameters, porous architecture, and thermal properties of coatings, YSZ coatings were firstly manufactured by suspension plasma spray (SPS). Afterwards their total porosities were characterized by using the technique of X-ray transmission, the nano/submicro pores in those coatings were detected with Ultra-Small Angle X-ray Scattering (USAXS), and the thermal properties of coatings were measured using the laser flash method. The results indicated that: i) the porous architecture of SPS coatings can be tailored by adapting process parameters. ii) increasing total porosity is an effective means for reducing the heat transfer capability of SPS coatings. iii) nano/submicro pores have higher influence sensitivity on thermal properties than that of larger pores. Increasing the content of nano-submicro pores is therefore more effective for improving the thermal insulation property of SPS coatings. The potential of SPS technique for fabricating TBCs was discussed as well.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Evaluation of Amorphous Oxide Coatings for High-Voltage Li-Ion Battery Applications Using a First-Principles Framework

Cathode surface coatings are widely used industrially as a means to suppress degradation and improve electrochemical performance of lithium-ion batteries. However, developing an optimal coating is challenging, as different coating materials may enhance one aspect of performance while hindering another. Furthermore, to elucidate the fundamental thermodynamic and transport properties of amorphous cathode coating materials, here, we present a framework for calculating and analyzing the Li + and O 2- transport and the stability against delithiation in such materials. Our framework includes systematic workflows of ab-initio molecular dynamics calculations to obtain amorphous structures and diffusion trajectories coupled with an analysis of critical changes of the active-ion local environment during diffusion. Based on these data, we provide an estimate of room-temperature diffusivities, including statistical error bars, and the evaluation of the coating suitability in terms of its ability to facilitate Li + transport while blocking O 2- transport. Finally, we add the thermodynamic stability analysis of the coating chemistry within the operating voltage of common Li-ion cathodes. We apply this framework to two commonly used amorphous coating materials, Al 2 O 3 and ZnO. We find that (1) in general, a higher Li + content increases both Li + and O 2- diffusivities in both Al 2 O 3 and ZnO. Also, Li + and O 2- diffuse much faster in ZnO than in Al 2 O 3 . (2) However, neither Al 2 O 3 nor ZnO is expected to retain a significant concentration of Li + at high charge. (3) ZnO performs much more poorly in terms of O 2- blocking, and hence, Al 2 O 3 is preferred for high-voltage cathode applications. These results will help to quantitatively evaluate amorphous materials, such as metal oxides and fluorides, for different performance metrics and facilitate the development of optimal cathode coatings.

25 ENERGY STORAGE↗
DOE OSTI2022

Thermally Grown Oxide Stress in PS-PVD and EB-PVD Thermal Barrier Coatings Observed at Various Lifetimes Via Synchrotron X-ray Diffraction

The current standard application method for thermal barrier coatings (TBCs) on turbine blades for jet engines is electron-beam physical vapor deposition (EB-PVD) due to its high strain tolerance and low thermal conductivity. An emerging deposition method, plasma-spray physical vapor deposition (PS-PVD), presents an opportunity for a tailorable microstructure, and non-line-of-sight deposition that is faster and less expensive. To compare the lifetime behavior of both PS-PVD and EB-PVD coatings, samples subjected to 300 and 600 thermal cycles were measured during a 1 h thermal cycle to determine the strains, which were converted to stress, in the thermally grown oxide (TGO) layer of the TBCs using synchrotron X-ray diffraction (XRD). Room temperature XRD measurements indicated among samples that PS-PVD coatings experienced greater variation in in-plane room temperature strain in the TGO after cycling than the EB-PVD coatings. In-situ XRD measurements indicated similar high-temperature strain and no spallation after 600 thermal cycles for both coatings. Further, microscopy imaging after cycling showed greater rumpling in PS-PVD coatings that led to different failure modes between the two coatings’ TGO layers. The tailorability of PS-PVD coatings allows for adjustments in the processing parameters to improve their overall performance after aging and bridge the differences between the two deposition methods.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Low thermal inertia thermal barrier coatings for spark ignition engines: An experimental study

Application of thermal barrier coatings in spark ignition engines have historically been avoided due to the knock penalty associated with higher surface temperatures induced by the ceramic layer. However, advances in low thermal inertia coatings (i.e. temperature swing coatings) that combine low thermal conductivity with low volumetric heat capacity can prevent excessively high surface temperatures during the intake stroke and reduce or avoid knock while improving performance and efficiency. In this study, a novel coating material was tested in a low compression ratio spark ignition engine to evaluate the performance of an advanced low thermal inertia coating during steady and cold-start conditions. A total of four pistons with this novel material was tested, with an additional piston coated with gadolinium zirconate. Spark timing sweeps demonstrated a maximum 0.8% relative thermal efficiency gain with a thin coating of the novel material. Here, the novel material coated above 200-microns showed a deterioration in performance and efficiency due to charge heating increasing knock propensity. Cold-start tests demonstrated that charge heating is beneficial for reducing unburned hydrocarbons and particle matter emissions.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2013

Oxidation of Slurry Aluminide Coatings on Cast Stainless Steel Alloy CF8C-Plus at 800oC in Water Vapor

A new, cast austenitic stainless steel, CF8C-Plus, has been developed for a wide range of high temperature applications, including diesel exhaust components, turbine casings and turbocharger housings. CF8C-Plus offers significant improvements in creep rupture life and creep rupture strength over standard CF8C steel. However, at higher temperatures and in more aggressive environments, such as those containing significant water vapor, an oxidation-resistant protective coating will be necessary. The oxidation behavior of alloys CF8C and CF8C-Plus with various aluminide coatings were compared at 800oC in air plus 10 vol% water vapor. Due to their affordability, slurry aluminides were the primary coating system of interest, although chemical vapor deposition (CVD) and pack cementation coatings were also compared. Additionally, a preliminary study of the low cycle fatigue behavior of aluminized CF8C-Plus was conducted at 800oC. Each type of coating provided substantial improvements in oxidation behavior, with simple slurry aluminides showing very good oxidation resistance after 4,000 h testing in water vapor. Preliminary low cycle fatigue results indicated that thicker aluminide coatings degraded high temperature fatigue properties of CF8C-Plus, whereas thinner coatings did not. Results suggest that appropriately designed slurry aluminide coatings are a viable option for economical, long-term oxidation protection of austenitic stainless steels in water vapor.

Coating↗
DOE OSTI2018

Effects of Disodium Phosphate Concentration (Na{sub 2}HPO{sub 4}·2H{sub 2}O) on Microstructure and Corrosion Resistance of Plasma Electrolytic Oxidation (PEO) Coatings on 2024 Al Alloy

Since the electrolyte composition plays a pivotal role in the microstructure and corrosion behavior of plasma electrolytic oxidation (PEO) coatings, the effects of disodium phosphate (Na{sub 2}HPO{sub 4}·2H{sub 2}O) concentration on the microstructure and corrosion resistance of PEO coatings fabricated on 2024 Al alloy were studied in this investigation. Accordingly, electrolyte with four different concentrations of phosphate ion (5, 10, 15 and 20 g/L) was used. All PEO processes were conducted at constant current density of 15 A/dm{sup 2} for 15 min. The surface and cross-sectional morphologies of the coatings indicated that the coating formed in the electrolyte with 10 g/L Na{sub 2}HPO{sub 4}·2H{sub 2}O (with 9.14 µm thickness) had the most compact and uniform structure with the lowest and smallest micropores. Furthermore, studying the corrosion behavior of samples in 3.5 wt.% NaCl solutions by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests revealed that the sample coated in the electrolyte with 10 g/L Na{sub 2}HPO{sub 4}·2H{sub 2}O had the highest corrosion potential, the lowest corrosion current density and, accordingly, the best corrosion resistance. The corrosion resistance of this coating was 4.574 × 10{sup 5} Ω cm{sup 2}, which could increase the corrosion resistance of uncoated 2024 Al alloy substrate 48 times. The x-ray diffraction pattern of this coating proved that the coating was composed of α-Al{sub 2}O{sub 3} and γ-Al{sub 2}O{sub 3} phases.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Effect of Sputtering Current on the Comprehensive Properties of (Ti,Al)N Coating and High-Speed Steel Substrate

To improve the practical property of (Ti,Al)N coating on a high-speed steel (HSS) substrate, a series of sputtering currents were used to obtain several (Ti,Al)N coatings using a magnetron sputtering equipment. The phase structure, morphology, and components of (Ti,Al)N coatings were characterized by x-ray diffraction, scanning electron microscopy, energy-dispersive x-ray spectroscopy, and x-ray photoelectron spectroscopy, respectively. The performance of (Ti,Al)N coatings, adhesion, hardness, and wear resistance was tested using a scratch tester, micro/nanohardness tester, and tribometer, respectively. Based on the structure–property relationships of (Ti,Al)N coatings, the results show that both the Al content and deposition temperature of (Ti,Al)N coatings increased with sputtering current. A high Al content helped to improve the performance of (Ti,Al)N coatings. However, the HSS substrate was softened during the high sputtering current treatment. Therefore, the optimum sputtering current was determined as 2.5 A that effectively increased the hardness and wear resistance of (Ti,Al)N coating.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Tribological and Corrosion Properties of Coatings Produced by Plasma Electrolytic Oxidation on the ZA27 Alloy

In this paper, a continuous and dense coating was deposited on samples of the ZA27 alloy through the plasma electrolytic oxidation (PEO) process to improve its wear and corrosion performance. A nontoxic and environmentally friendly inorganic salt, Na{sub 2}SiO{sub 3}, is chosen as electrolytes with different concentrations. The effect of the concentration of Na{sub 2}SiO{sub 3} aqueous solutions on the coating performances was investigated. The coatings with 3Al{sub 2}O{sub 3}·2SiO{sub 2} (mullite), Zn{sub 2}SiO{sub 4} and Al{sub 2}O{sub 3} (either crystal phase or with some amorphous SiO{sub 2} phases) were formed by the PEO processes. It was found that the coating thickness increased with the increase in electrolyte concentration. However, the wear and corrosion resistance performance of the coatings did not improve as the coating’s thickness increased. This was due to the fact that the coating produced with electrolytes of 10 g/L has a porous structure with large pore size. Among all the samples, coating produced by 15 g/L Na{sub 2}SiO{sub 3} has the best wear and corrosion resistance, which is attributed to its continuous and dense structure with thickness of about 47 μm.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Structural and Mechanical Properties of the ZrC/Ni-Nanodiamond Coating Synthesized by the PVD and Electroplating Processes for the Cutting Knifes

In this work, combined gradient ZrC/Ni-nanodiamond ultradispersed diamonds (UDD) coatings were synthesized on the surface of knife blades made of hard alloy WC-2 wt.% Co by electroplating and cathode arc evaporation PVD techniques to increase the durability period of a wood-cutting milling tool. The microstructure, phase and elemental composition, microhardness, and adhesion strength of the coatings were investigated. Ni-UDD layer is not mixed with the ZrC coating and hard alloy substrate. Cobalt is present in Ni-UDD layer after deposition of ZrC. The ZrC/Ni-nanodiamond coating consists of separate phases of zirconium carbide (ZrC), α-Ni, and Ni-UDD. The maximum value of microhardness of the Ni-nanodiamond coating is 5.9 GPa. The microhardness value of the ZrC/Ni-nanodiamond coatings is 25 ± 6 GPa, which corresponds to the microhardness of the hard alloy substrate and ZrC coating. The obtained high values of the critical loads on the scratch track of the ZrC/Ni-nanodiamond coating in 24 N prove a sufficiently high value of the adhesion strength of the bottom Ni-UDD layer with WC-Co substrate. Pilot testing of ZrC/Ni-nanodiamond-coated cutting tools proved their increasing durability period to be 1.5-1.6 times higher than that of bare tools, when milling laminated chipboard.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Antifouling Properties and Release of Dissolved Copper of Cold Spray Cu/Cu{sub 2}O Coatings for Ships and Steel Structures in Marine Environment

At the submarine screen doors of ships, the flow of water was fast and organic coatings were easy to peel off. To solve the problems of biofouling, the Cu/Cu{sub 2}O coatings were prepared by cold spray technology. In this paper, the release mechanism of effective antifouling components of the coatings was studied by micro-domain electrochemical potential scanning technique. Cuprous oxide in the coatings and the surrounding copper constituted micro-cells which accelerated the local electrochemical dissolution of copper. Cuprous oxide acted as the cathode, and the surrounding copper acted as the anode. Meanwhile, under the action of current, chloride ions were transferred from cathode to the anode and promoted local electrochemical dissolution of copper. Experiments show that the higher the Cu{sub 2}O content in the coatings, the greater the release rate of dissolved copper and inhibitory effect on diatoms. In the environments varied in dissolved oxygen, salinity, temperature and flow rate, the coatings maintained sufficient release rate of dissolved copper, unless the salinity was very low. Most of the dissolved copper was provided by the electrochemical dissolution process of copper. Whether in the indoor test or marine environment experiments, 30% Cu{sub 2}O coatings show the best performance. After insulating layer was sprayed, the effect of antifouling was improved evidently and the coatings were applied to the submarine screen doors of ships.

36 MATERIALS SCIENCE↗