Film Coatings Research Articles

COMPARISON OF NITROGEN-DOPED PHOTOCATALYTIC SURFACES SYNTHESIZED BY PVD AND SOL-GEL METHODS

The aim of this study was to produce photocatalytic TiO2–xNx coatings that can be active in visible light using different methods. Physical vapour deposition (PVD) and sol-gel methods were preferred for these coatings. Thin films were synthesized by dip coating on a glass substrate using the sol-gel method. In addition, thin glass film coatings were obtained by applying an arc for one minute to the glass films using the PVD method. Since the coating phase is important in terms of photoactivity, a phase analysis was performed using XRD. The obtained surfaces will be used in antibacterial applications. Therefore, the thickness of the coatings was determined with the X-Ray refraction method, and their optical band gap was measured. Based on these values, it was observed that nitrogen has a reducing effect on the optical band gap in titanium oxide-based coatings. The aim of nitrogen doping was to enhance photoactivity by adding an additional band between the valence band and conduction band of a photocatalytic surface. After these experiments using rhodamine-B and methylene blue solutions, specimens’ photocatalytic effects under fluorescent, sun and UV light were tested. It was determined that nitrogen’s decreasing effect on the optical band gap results in increased photoactivity with both PVD and sol-gel techniques. In addition, it was found that the coatings made with PVD exhibited a more controlled structure in a shorter time, while the production of sol-gel coatings was a much cheaper method, with low investment costs.

Advancements in nanocarbon-based catalysts for enhanced fuel cell performance: a comprehensive review

AbstractFuel cells hold great promise as a clean energy technology, yet challenges such as material compatibility, manufacturing costs, and durability issues, particularly with noble metal-based electrocatalysts like platinum (Pt), hinder their widespread adoption. This review explores strategies to enhance fuel cell performance while minimizing costs, focusing on developing efficient and cost-effective catalysts supported by nanocarbon materials, such as carbon nanotubes, graphene, carbon films, and their composites. The investigation delves into how these catalysts supports improve activity and stability, leading to superior fuel cell performance characterized by higher current density and enhanced durability compared to conventional Pt/C catalysts, with a specific focus on proton-exchange membrane fuel cells. Key topics covered include the role of nanocarbon in fuel cells, various nanocarbon-based catalyst supports, Pt-containing alloys, non-Pt catalysts, and nanocarbon composites for electrolyte membranes and corrosion protection. Notable findings include the importance of heteroatom doping in enhancing reactivity, the effectiveness of organic–inorganic composite proton exchange membranes in improving proton conductivity, and the potential of amorphous carbon film coatings and conductive polymer-nanocarbon composites in enhancing corrosion resistance. These advancements underscore the potential of nanocarbon-based catalysts and coatings in ensuring the reliability and longevity of fuel cell components, thus contributing to the widespread commercialization of fuel cell technology.

A comparative analysis of different surface tribological and electrochemical properties of TiAlN, TiAlSiN, and CrAlN thin film coatings in seawater

Abstract To reveal the wear mechanisms of TiAlN, TiAlSiN, and CrAlN coatings in a seawater environment, the changes in frictional surfaces and the electrochemical characteristics of these coatings were compared and analyzed in this paper. The coatings were deposited on 316L stainless steel surfaces. Tribological tests were investigated using a ball-on-disk tribometer with Si3N4 ceramic balls as the counter material. Although the friction coefficient of 316L stainless steel was the lowest at 0.34, the order of wear rates was 316L stainless steel (7.38×10-5)>TiAlN(5.31×10-6)>TiAlSiN(4.23×10-6)>CrAlN(1.10×10-6) and the electrochemical protective efficiencies of TiAlSiN and CrAlN were both greater than 97%. Seawater penetrated through the grain boundaries of the TiAlN coating, which led to corrosion and delamination failure. Conversely, the grain refinement in TiAlSiN and CrAlN coatings can significantly slow down the penetration of seawater into the coating under frictional pressure, and the oxide lubricating layer formed during the friction process can become an effective barrier to isolate seawater. Therefore, mechanical wear was the main wear form of these two coatings. Additionally, among the oxides formed in the friction, Cr2O3 showed the strongest corrosion resistance, making the CrAlN coating exhibit superior wear resistance and the lowest wear rate in seawater.

Impact of Edible Coating Films on some Physiological, Physicochemical and Microbiological Properties of some Vegetable and Fruits

Impact of Edible Coating Films on some Physiological, Physicochemical and Microbiological Properties of some Vegetable and Fruits

A High-Sensitivity Fiber Optic Soil Moisture Sensor Based on D-Shaped Fiber and Tin Oxide Thin Film Coatings

We present a high-sensitivity fiber optic soil moisture sensor based on side-polished multimode fibers and lossy mode resonance (LMR). The multimode fibers (MMFs), after side-polishing to form a D-shaped structure, are coated with a single-layer SnO2 thin film by electron beam evaporation with ion-assisted deposition technology. The LMR effect can be obtained when the refractive index of the thin film is positive and greater than its extinction coefficient and the real part of the external medium permittivity. The D-shaped fiber optic soil moisture sensor was placed in soil, allowing moisture to penetrate into the thin film microstructure, and it observed the resonance wavelength shift in LMR spectra to measure the relative humidity change in soil. Meanwhile, an Arduino electronic soil moisture sensing module was used as the experimental control group, with soil relative humidity ranging from 10%RH to 90%RH. We found that the D-shaped fiber with a residual thickness of 93 μm and SnO2 thin film thickness of 450 nm had a maximum sensitivity of 2.29 nm/%RH, with relative humidity varying from 10%RH to 90%RH. The D-shaped fiber also demonstrates a fast response time and good reproducibility.

Development and analysis of silver-iron nitroprusside nanoparticles incorporated into starch-xanthan gum films for extending blueberry shelf life

Given the increasing health risks and environmental pollution caused by non-degradable petroleum-based packaging materials, developing environmentally friendly packaging materials is crucial. This study investigated the use of silver‑iron nitroprusside nanoparticles (Ag-FeNNPs) incorporated starch-xanthan gum (ST-XG) films for food coatings with antibacterial properties. Ag-FeNNPs were cubic, polydisperse with a uniform size of 126.06 ± 3.11 nm and a metallic composition of silver and iron. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyses confirmed the crystalline properties and functional groups of ST, XG, and Ag-FeNNPs. The Ag-FeNNPs/ST-XG films exhibited excellent UV-blocking properties, with a transmittance of only 0.5 % at 400 nm. Ag-FeNNPs/ST-XG films exhibited significant inhibition on Staphylococcus aureus, Listeria monocytogenes, Salmonella enterica, and Escherichia coli. Furthermore, the Ag-FeNNPs/ST-XG coating effectively reduced nutrient loss, bacterial contamination, and extended shelf life compared to ST-XG-coatings and uncoated blueberries, suggesting promising applications in food coating.

Reversible Demountable Coating Films Composed of Trifunctional Liquid Anthracene Compounds and Evaluation of Their Adhesive Properties

AbstractTechnologies that facilitate recycling are attracting considerable interest from the perspective of resource constraints. In the present study, degradable primer films are to facilitate the removal of strongly bonded joints. This film consists of a light‐cured trifunctional anthracene compound that thermally decomposes to its original liquid state. To demonstrate its function as a degradable primer film and verify its range of applications, various substrates, such as aluminum alloys, stainless steel, carbon fiber‐reinforced plastics, carbon fiber‐reinforced thermoplastics, and polyetheretherketone, are bonded through the primer film using a two‐component epoxy adhesive. All the single‐lap specimens exhibit strengths above 10 MPa, which is sufficient, or base material fracture. When adhesive bonding specimens prepared using the same procedure are heated at 180 °C to transform the coating film to a liquid state, the bond strength is significantly reduced. The primer film is expected to exhibit long‐term stability of more than one year at ≈60 °C.

Impact of submicron Nb3Sn stoichiometric surface defects on high-field superconducting radiofrequency cavity performance

Nb3Sn film coatings have the potential to drastically improve the accelerating performance of Nb superconducting radiofrequency (SRF) cavities in next-generation linear particle accelerators. Unfortunately, persistent Nb3Sn stoichiometric material defects formed during fabrication limit the cryogenic operating temperature and accelerating gradient by nucleating magnetic vortices that lead to premature cavity quenching. The SRF community currently lacks a predictive model that can explain the impact of chemical and morphological properties of Nb3Sn defects on vortex nucleation and maximum accelerating gradients. Both experimental and theoretical studies of the material and superconducting properties of the first 100 nm of Nb3Sn surfaces are complicated by significant variations in the volume distribution and topography of stoichiometric defects. This work contains a coordinated experimental study with supporting simulations to identify how the observed chemical composition and morphology of certain Sn-rich and Sn-deficient surface defects can impact the SRF performance. Nb3Sn films were prepared with varying degrees of stoichiometric defects, and the film surface morphologies were characterized. Both Sn-rich and Sn-deficient regions were identified in these samples. For Sn-rich defects, we focus on elemental Sn islands that are partially embedded into the Nb3Sn film. Using finite element simulations of the time-dependent Ginzburg-Landau equations, we estimate vortex nucleation field thresholds at Sn islands of varying size, geometry, and embedment. We find that these islands can lead to significant SRF performance degradation that could not have been predicted from the ensemble stoichiometry alone. For Sn-deficient Nb3Sn surfaces, we experimentally identify a periodic nanoscale surface corrugation that likely forms because of extensive Sn loss from the surface. Simulation results show that the surface corrugations contribute to the already substantial drop in the vortex nucleation field of Sn-deficient Nb3Sn surfaces. This work provides a systematic approach for future studies to further detail the relationship between experimental Nb3Sn growth conditions, stoichiometric defects, geometry, and vortex nucleation. These findings have technical implications that will help guide improvements to Nb3Sn fabrication procedures. Our outlined experiment-informed theoretical methods can assist future studies in making additional key insights about Nb3Sn stoichiometric defects that will help build the next generation of SRF cavities and support related superconducting materials development efforts. Published by the American Physical Society 2024

Structural, Mechanical, and Optical Properties of Laminate-Type Thin Film SWCNT/SiOxNy Composites.

The development of new encapsulating coatings for flexible solar cells (SCs) can help address the complex problem of the short lifespan of these devices, as well as optimize the technological process of their production. In this study, new laminate-type protective composite coatings were prepared using a silicon oxynitride thin-film matrix obtained by curing the pre-ceramic polymer perhydropolysilazane (PHPS) through two low-temperature methods: (i) thermal annealing at 180 °C and (ii) exposure to UV radiation at wavelengths of 185 and 254 nm. Single-walled carbon nanotubes (SWCNTs) were used as fillers via dry transfer, facilitating their horizontal orientation within the matrix. The optical, adhesive, and structural properties of the matrix films and SiOxNy/SWCNT composite coatings, along with their long-term stability, were studied using Fourier transform infrared spectroscopy (FTIR), UV-Vis spectroscopy, HR-SEM, spectral ellipsometry, and a progressive-load scratch test. In this work, the optical constants of PHPS-derived films were systematically studied for the first time. An antireflection effect was observed in the composites revealing their two-component nature associated with (i) the refractive index of the SiOxNy matrix film and (ii) the embedding of a SWCNT filler into the SiOxNy matrix. The curing method of PHPS was shown to significantly affect the resulting properties of the films. In addition to being used as protective multifunctional coatings for SCs, both SiOxNy/SWCNT composites and SiOxNy matrix films also function as broadband optical antireflective coatings. Furthermore, due to the very low friction coefficients observed in the mechanical tests, they show potential as scratch resistant coatings for mechanical applications.

Enhancing the anti-tarnish and mechanical properties of gold-coated silver sheets for decorative applications using TiO2 film protection

This study explores an innovative method to enhance the anti-tarnish and mechanical properties of gold-coated silver sheets, targeting decorative applications through the TiO2 film coatings. The research focuses on gold films with a thickness of approximately 100 nm, and TiO2 films ranging from 10 to 31 nm. It was observed that the color of the multilayer coatings exhibited significant sensitivity to variations in thickness, indicating that a TiO2 coating with a thickness around 20 nm could be optimally applied to the gold film, maintaining an acceptable ΔE value. X-ray photoelectron spectroscopy analysis demonstrated the TiO2 film’s potential to inhibit the formation of Ag2S on the surface, thereby enhancing tarnish resistance. Furthermore, the application of a 20 nm TiO2 layer reduced the friction coefficient from 0.28 to 0.24 for gold-coated silver. Durability tests involving 1,000 abrasion cycles revealed that the gold film without TiO2 protection experienced delamination, with only about 57 % of the coated area remaining intact. In contrast, the samples protected with a TiO2 layer retained approximately 90 % of the coating, underscoring the effectiveness of TiO2 in preserving the structural integrity and appearance of the gold-coated silver sheets.

Understanding the effect of plasticizers in film coat materials on the physical stability of amorphous solid dispersions

Amorphous solid dispersions (ASDs) have been extensively utilized to improve the bioavailability of drugs that have low aqueous solubility. The influence of different excipients on the conversion of amorphous drugs into their crystalline forms in ASDs has been extensively researched. However, there is limited knowledge examining the impact of film coating materials on the physical stability of oral tablet formulations containing ASDs. In this study, we demonstrate that plasticizers present in film coats can have a detrimental impact on the physical stability of ASDs. We systematically compared two frequently used plasticizers in film coats: triacetin and polyethylene glycol 3350 (PEG 3350). To gain mechanistic insights into the detrimental effects of plasticizers on the physical stability of ASDs, plasticizer leaching studies and physical stability studies of solvent-evaporated and spray-dried intermediates (SDI) using two BCS class II drugs were conducted. Triacetin was found to leach into the tablet core within one week when stressed at 40°C/75% RH, whereas no leaching was observed for PEG 3350, as discerned from spectroscopic studies. We also found that triacetin-containing ASDs exhibited greater amorphous to crystalline form conversion of the drug compared to PEG 3350-containing ASDs after stability testing. Moreover, the incorporation of triacetin into polymers was found to cause a significant depression of glass transition temperature and upon equilibration with moisture, a drop below room temperature. Overall, these observations underscore the importance of carefully selecting plasticizers to be present in film coatings when developing ASD pharmaceutical products.

Influences of Whey protein concentrate based-antimicrobial edible film coatings on soft cheese properties

Influences of Whey protein concentrate based-antimicrobial edible film coatings on soft cheese properties

Biobased Self-Healing Thin Film Coatings Based on Poly (Itaconic Acid Esters).

Paper used for packaging applications is often coated with thin polymer coatings to improve the properties, like printability and barrier properties, respectively. Today, these coatings are still often based on petroleum-based polymers. In this study, the fabrication of biobased thin film coatings is described. Poly(itaconic acid ester)s, which are prepared by emulsion polymerization, are used as water-based coatings for paper. The thermal properties of the polymers are tuned by the side chain of the monomers (diethyl itaconate vs. dibutyl itaconate). Different formulations based on the polymer emulsion and additives, like rheology modifiers, are prepared and their film formation is studied. The usage of a rheology modifier results in excellent film formation. These polymer coatings feature an additional function - they are capable of self-healing. The healing ability is studied in scratch healing tests, in which almost complete recovery can be observed after healing at 100 °C. Moreover, the restoration of optical properties/aesthetics is studied. In gloss measurements before and after damage as well as after a healing time the complete recovery of the gloss can be observed. Furthermore, the barrier properties against fat are studied.

Waterborne cellulose acetate pickering emulsion generation mediated by cellulose nanocrystals for paper coating applications

There is a continually increasing demand for alternatives to single-use, non-degradable, and synthetic plastic packaging. Environmentally friendly paper products offer a potential solution, but typically do not meet stringent demands for barrier and other physical property performance unless coated with polymeric films, usually polyolefins. Replacing conventional plastic film coatings with bio-based polymer alternatives, such as cellulose acetate, can provide competitive barrier property performance while also providing sustainability benefits. Furthermore, water can be used as a coating medium for added environmental and coatability advantages. In this study, 10 wt% Pickering emulsions of cellulose acetate dispersed in water and stabilized via cellulose nanocrystals (CNC) were generated. Rheological behavior, particle size, stability, and particle morphology were analyzed, as was the effect of modifying the CNCs using (2-Dodecen-1-yl)succinic anhydride over several weeks. Unbleached kraft paper was coated and compared to polyolefin coated and uncoated paper. Water vapor permeability, grease resistance, water absorption, and wet mechanical properties were all investigated, displaying promising properties for barrier paper coating. The grease kit test yielded a result of 10/12 for the coated paper versus 0/12 for uncoated, and water Cobb value showed a 60 % improvement. Lastly, the performance of the coated paper as a food takeout container coating was explored, with convincing results demonstrating a strong avenue of applicability. Overall, the waterborne cellulose acetate Pickering emulsion formation and its paper coating application yielded promising results for sustainable packaging development.

Special issue on thin-films for sustainable manufacturing

Sustainable manufacturing is the creation of products using technologies capable of decoupling the factors that may adversely affect the environment. One such technology is thin film coating, extensively used for various commercial applications. Achieving energy and resource efficiency, cost reduction, short process chain of manufacturing and long life for tools and products are some of the benefits of using thin film coatings. This technology significantly contributes to strengthening all three pillars, that is, environment, economy and society of sustainability. This special issue aims to highlight some of the critical application areas of thin film coatings under sustainable manufacturing, focusing on machining.

Coating Tablets, Compositions, Recent Advancement and Current Status: A Comprehensive Review

Conventional Tablets are solid oral dosage forms that contain an active pharmaceutical ingredient (API) along with excipients. These tablets are typically prepared through direct compression, wet granulation, or dry granulation. They are designed to disintegrate and release the API in a controlled or immediate manner, depending on the formulation. Tablet coating is a vital process in pharmaceutical technology, designed to improve the therapeutic efficacy, patient compliance, and stability of oral dosage forms. This comprehensive review explores the key aspects of tablet coating, including the types, compositions, and recent advancements. Coating materials such as polymers, plasticizers, and pigments are discussed in detail, along with their roles in controlling drug release, masking taste, and enhancing aesthetic appeal. The recent advancements focus on innovative coating techniques like film coatings, enteric coatings, and the application of nanotechnology to improve precision and functionality. Additionally, the current status of tablet coating is analyzed in terms of regulatory compliance and industry trends. The review highlights the future potential of personalized coatings, smart coatings, and environmentally friendly approaches, showcasing the evolving landscape of tablet coating technologies/pans in modern pharmaceutical manufacturing and development. Keywords: Table coating; dosage form; enteric; coating pans; formulation; advancement; polymers

Evolution of TiAlSi thin film coatings under varying target power in DC magnetron sputtering

This study, for the first time, presents the growth, nucleation, and characteristics of TiAlSi thin films sputtered from a partially sintered Ti30Al16Si10 (at. %) composite target under controlled conditions of target power. The TiAlSi thin films were grown on soda-lime glass substrates through Direct Current (DC) sputtering at varying levels of the target power: 73.2 W, 151.2 W, and 269.5 W. The other deposition parameters: the deposition temperature, time, argon mass flow rate, substrate rotation, and deposition pressure, were kept constant at 23 °C, 150 min, 25 sccm, 5 rpm, and 10−3 mbar, respectively. The pre-sputter power, argon flow rate, and time were also kept constant at 73.2 W, 20 sccm, and 5 min, respectively. The physical properties, microstructure, crystal structure, topography, and mechanical properties of the thin film coatings were analysed. The thickness and rate of deposition of the TiAlSi thin films increased with an increase in the target power (73.2 W – 269.5 W) from 414.6 nm and 0.046 nm/s to 1358.8 nm and 0.151 nm/s, respectively. The chemical composition of all the thin films remained constant, with the formation of a uniform TiAlSi alloy with no segregation of elements. However, a thin (wetting) interlayer consisting of Si and O elements was observed between the TiAlSi layer and the glass substrate. Further, the structure sizes and roughness values of the TiAlSi thin films increased with an increase in the target power, with a maximum of 75.4 nm for the size and 4.78 nm for the RMS roughness of thin films deposited at the maximum target power (269.5 W). Lastly, mechanical analysis of the TiAlSi thin films depicted an increase in the hardness as the target power increased, with the highest hardness at maximum power (269.5 W) obtained as 4.76 GPa. Despite having the lowest elastic modulus (50.5 GPa), the coating deposited at the highest power exhibited the highest plasticity index (H/E) and plastic deformation factor (H3/E2) of 0.094 and 0.042 GPa, respectively, which indicated the high resistance to abrasive wear, cracking, and deformation, compared to thin films deposited at the lowest target power (H/E = 0.066 and H3/E2 = 0.015 GPa). This study demonstrates that target power is a significant factor in determining the growth of TiAlSi thin films during the sputtering process and can be used for better control of their physical, structural, and mechanical properties.

Development of Pericarp-Based Coatings from Corn Nixtamalization Residue for Stone Fruits: Applications for Peach and Tejocote

This study investigated corn pericarp, a by-product of the nixtamalization process, in developing sustainable films for fruit coatings. These films were evaluated for their optical, structural, barrier, and mechanical properties. The results showed that the pericarp films were transparent, had heterogeneous surfaces, and exhibited favorable mechanical and barrier properties, suggesting their potential as fruit coatings. The pericarp films significantly extended shelf life when applied to peaches and tejocotes postharvest. The films slowed the maturation process, as evidenced by minimal changes in peel and mesocarp color for up to five days for tejocotes and even longer for peaches. Additionally, coated fruits showed slower rates of weight loss, firmness reduction, and decreases in titratable acidity, total soluble solids, and total sugar content compared to control samples. These findings demonstrate the potential of corn pericarp films as effective coatings for extending the shelf life of stone fruits.

Transforming Agro-Industrial Waste into Bioplastic Coating Films.

Addressing the environmental impact of agro-industrial waste, this study explores the transformation of banana, potato, and orange peels into bioplastics suitable for thin coating films. We prepared six extracts at 100 g/L, encompassing individual (banana peel, BP; orange peel, OP; and potato peel, PP) and combined [BP/OP, BP/PP, and BP/OP/PP] formulations, with yeast mold (YM) medium serving as the control. Utilizing the spin-coating method, we applied 1 mL of each sample at 1000 rpm for 1 min to create the films. Notably, the OP extract demonstrated a twofold increase in bioplastic yield (860.33 mg/L) compared to the yields of BP (391.43 mg/L), PP (357.67 mg/L), BP/OP (469.40 mg/L), BP/PP (382.50 mg/L), BP/OP/PP (272.67 mg/L), and YM (416.33 mg/L) extracts. Atomic force microscopy analysis of the film surfaces revealed a roughness under 8 nm, with the OP extract recording the highest at 7.0275 nm, whereas the BP/OP mixture exhibited the lowest roughness at 0.2067 nm and also formed the thinnest film at 6.5 nm. With R2 trend values exceeding 0.9950, the films exhibited water vapor permeability values ranging from 3.05 × 10-3 to 4.44 × 10-3, with the OP film being the least permeable and the BP/PP films the most permeable. The OP film demonstrated the lowest solubility in both water and ethanol with values of 64.71 and 1.05%, respectively. The solubilities of all films were above 60% in water and below 4% in ethanol. Furthermore, the films exhibited antimicrobial efficacy against both Gram-positive and Gram-negative bacteria. Our findings confirm the potential of utilizing banana, orange, and potato peels as viable substrates for eco-friendly bioplastics in thin-film applications.

Fungicide Film Coating—A New Approach to Potato Tubers Health

Fungicide Film Coating—A New Approach to Potato Tubers Health