Coating Materials Research Articles

Shielding Performance of a New Coating Material Composed of Polyurea Resin and Tungsten Carbide against X‐Rays

Proper shielding measures are essential for protecting individuals from the harm of radiation exposure. In this study, a novel composite of tungsten carbide microparticles and polyurea resin (PUWC), which has the advantage of easy implementation in existing facilities by spraying in addition to low toxicity and high flexibility is investigated as an alternative radiation shielding material against photon radiation. The uniform distribution of tungsten carbide (WC) particles synthesized PUWC sheets is confirmed using the technique of scanning electron microscopy (SEM) coupled with energy dispersive X‐ray spectroscopy (EDX). Macroscopic uniformity is examined using a radiochromic film (Gafchromic EBT3) for X‐rays. The shielding effects of PUWC against X‐rays (160 kV, 6.3 mA) are examined for four sheets with different WC concentrations (15, 20, 30, and 50 wt%), lead, and aluminum. It is found that a PUWC sheet with a higher WC concentration has a better shielding performance; the PUWC sheet with 50 wt% WC shows a performance comparable to that of lead with respect to mass attenuation. These results indicate the potential of PUWC as an alternative shielding material for lead, which is toxic to human health and the environment. Further investigations on the practicality of this novel material are needed.

Research on Modified Thermal Barrier Coatings Against CMAS Corrosion Driven by Mechanism–Data Hybrid Model

With the development of high-efficiency gas turbine engines and increasing inlet temperatures, the performance of thermal barrier coatings (TBCs) for hot-section components has been more severely challenged. The doping of multi-element rare earth elements significantly improves the thermodynamic properties and chemical compatibility of thermal barrier coatings so that the application performance of coatings in high-temperature environments is enhanced considerably. In this work, the doped coatings prepared by REYSZ (RE = La, Sm, Nd) were investigated and characterized in terms of crystal structure, elastic properties, and thermal–mechanical properties based on the first-principles approach, combined with various empirical and semi-empirical formulations, and a predictive model for resistance to CMAS corrosion based on machine learning approaches. The results showed that the tetragonal phase REYSZ material was mechanically stable, had a large strain damage tolerance, and was not easy to fracture under applied loads and thermal shocks. In terms of CMAS corrosion resistance, the NdYSZ interfacial model had a lower surface energy (3.130 J/m2) and Griffith fracture energy (6.934 J/m2) compared with the conventional YSZ model, and Nd2O3 had the potential to improve the CMAS corrosion resistance of zirconia-based material for thermal barrier coatings. By evaluating the machine learning prediction models, the regression coefficients of the two algorithms were 0.9627 and 0.9740, and both these two prediction models showed high prediction accuracy and strong robustness. Ultimately, this work presented a novel mechanism–data hybrid method, which would facilitate the efficient development of TBC new materials for anti-CMAS corrosion.

Thermo-Physical Properties of Hexavalent Tungsten W6+-Doped Ta-Based Ceramics for Thermal/Environmental Barrier Coating Materials

The CaTa0.8WO6 ceramic was fabricated by a solid-state reaction for thermal/environmental barrier coating (Thermal and Environmental Barrier Coating) applications, and the microstructures, mechanical and thermal properties were investigated. The result showed CaTa0.8WO6 has a lower thermal conductivity (1.05 W·m−1·K−1 at 900 °C) than 8 wt.% yttria-stabilized zirconia and the doped Ta-based ceramics with Mg2+, Yb3+, Zr4+ and Nb5+, indicating that hexavalent tungsten element W6+ doping effectively reduces thermal conductivity and improves thermal insulation performance of Ta-based ceramics. The thermal expansion rates curve without inflection points resulting from phase transition indicates that CaTa0.8WO6 has excellent high-temperature phase stability. Since the Young’s modulus and Pugh’s ratio of CaTa0.8WO6 ceramics were lower than those of various valence states doping Ta-based ceramics, which means that CaTa0.8WO6 has better damage tolerance.

Impact Resistance of Aluminum Foam Composites with Filler and Coating Materials

The main objective of this study is to analyze the impact resistance of aluminum foam composites containing fillers and coatings and to investigate the effect of different thickness ratios of the composites on this capability. We prepared composites using aluminum foam and polyurea and performed impact tests and numerical simulations. A comparison of the results shows that the Abaqus simulation results are in general agreement with the test results. The results show that the polyurea filler material and polyurea coating can significantly improve the impact resistance of the aluminum foam, and the best impact resistance of the aluminum foam composite with polyurea coating on the back. An extended study of the composites was carried out using a numerical model validated by the test results. For the energy absorption effect of the aluminum foam composites in the impact resistance process, there is an optimum value for the thickness ratio of the aluminum foam/polyurea composite, which is 3:1. The remaining kinetic energy of cylindrical fragments in the 3-1-1-2 composite material decreased by 13.26%, in the 4-1-1-2 composite material decreased by 11.91%, in the 2-1-1-2 composite material decreased by 11.78%, and in the 1-1-1-2 composite material increased by 2.7% when compared to the remaining kinetic energy of cylindrical fragments in the control group. The energy absorption efficiency of the aluminum foam composite increases as the residual kinetic energy of the cylindrical fragments decreases. The 3-1-1-2 composite can significantly improve the energy absorption effect, which can be used as a reference for the design of impact-resistant composites in the future.

Preparation and performance of fluorescent-assisted photocatalytic self-cleaning coatings for enhanced NO degradation

Long afterglow materials have been utilized to reduce the dependence of photocatalytic air purification technology on light sources, but research on the synergistic application of light storage and visible light catalytic materials in self-cleaning coatings is limited. In this work, stable visible light catalytic material, (C3N4/Bi2WO6), was selected as the catalytic material. The afterglow powder mainly composed of strontium aluminate (SA) was used as a light storage material. A ternary composite photocatalytic material SA/C3N4/Bi2WO6 (SCBW) was prepared, which can work in both light and dark environments. Epoxy resin was introduced to construct coatings containing SCBW (CSCB). The high catalytic activity of SCBW is attributed to the heterojunction effect of various semiconductors and the improved interface, resulting in a degradation rate of nitrogen oxides (NO) reaching 75 % and proving the degradation effect on formaldehyde aqueous solution and organic dyes. Additionally, the synergistic effect of fluorescence characteristics and photocatalytic ability endow the material with superior antibacterial properties, while the self-cleaning functionality of CSCB enhances the durability of the coating. Finally, the mechanism of fluorescence-assisted enhanced photocatalytic self-cleaning coating was discussed, providing insights into the design of multifunctional photocatalytic self-cleaning coatings for air purification and pollutant separation.

Polyoxovanadates as Effective Coating Materials for Layered Ni‐Rich Oxide Cathodes in Liquid‐ and Solid‐State Batteries

AbstractAdvanced coatings for improving the electro‐chemo‐mechanical stability of high‐capacity, layered Ni‐rich oxide cathode materials play an important role in modern battery technology. Vanadium‐based protective coatings are particularly promising owing to their ability to provide high ionic conductivity and their intrinsic robustness. In addition, diminishing or eliminating residual lithium through surface coating shows great promise in mitigating capacity loss and addressing associated challenges. Herein, we report on a strategic exploration of a facile coating approach for Ni‐rich LiNixCoyMn1−x−yO2 (NCM851005, 85 % Ni content) utilizing polyoxovanadate. Specifically, TBA3H3[V10O28] was applied due to its solubility in non‐aqueous media, avoiding H2O‐induced side reactions and achieving a more uniform surface coverage. The cycling performance of NCM851005 before and after modification was tested in conventional Li‐ion cells, as well as in all‐solid‐state batteries with a lithium thiophosphate superionic electrolyte. Our findings highlight the potential of polyoxovanadate‐derived protective coatings for improving the cyclability of Ni‐rich cathodes.

High-Entropy Boride HfZrTiTaMoB: Promising Materials for Solar Selective Absorption Coatings in Photothermal Applications.

High-entropy borides (HEBs), as a category of high-entropy materials, exhibit remarkable thermal stability, a broad compositional range, and finely tuned electronic structures, leading to an excellent functional performance. Despite these advantages, their application in photothermal materials has rarely been reported. Herein, we employ a HEB target with multiple transition-metal elements to develop solar selective absorption coatings (SSACs) with simple and scalable bilayer structures for photothermal applications. The performance of these coatings is enhanced by designing different antireflective layers. The designed SSACs, both stainless steel (SS)/HEB/Al2O3 and SS/HEB/Si3N4, exhibit high absorptivity and low thermal emittance (α/ε = 90.0%/8.6% and 91.6%/8.6% at 82 °C). Thermal stability tests show that the absorbers could withstand annealing at 500 °C for 5 h, while maintaining a good optical performance. Long-term thermal stability tests indicate that the coatings retained good spectral selectivity after annealing at 400 °C for 100 h. Notably, the coatings demonstrate advanced photothermal conversion efficiencies of 88.3% and 89.9%, respectively, at 400 °C under 100 sun. In practical simulated solar irradiation experiments, the absorber achieves temperatures of about 85 °C under 1 sun, surpassing the performance of commercial nonselective absorbing coatings. Additionally, the absorbers maintained a stable photothermal performance through six on-off cycle experiments. In summary, the designed SSACs based on HEBs exhibit excellent optical properties and efficient photothermal conversion at moderate temperatures. This study highlights the significant benefits and potential advancements in solar energy collection offered by HEB-based SSACs.

Characterization of Palm Kernel Shell Ash Nanoparticles as Coating Material for High Temperature Applications

The kernel shell of oil palm (Elaesis guineensis) was milled, calcinated and synthesized into nanoparticles (np) with a view to analyzing and ascertaining its high temperature strength. The synthesized particles were characterized to reveal their elemental composition and temperature of maximal decomposition/destruction, with the solgel method employed in the nanoparticle synthesis. The morphology of the Palm Kernel Shell Ash nanoparticles (PKSAnp) viewed from Transmission Electron Microscope (TEM) revealed that the nanoparticles were solid in nature but vary in sizes with some spherical particles visible, and an average particle size found to be 39.17nm. The Electron Dispersion Spectroscope (EDS) result shows that only elements such as C, O, Si, Al, Ca, and K are present in the PKSAnp, with silicon (Si) found to be dominant. Oxides of Silicon and Aluminum (SiO2 and Al2O3) were identified as the key chemical compounds in PKSAnp from X-Ray Fluorescence (XRF) investigation whereas K2O, CaO and Na2O were among the other oxides present in traces. The Thermogravimetric analysis (TGA) curve shows a lower proportion of breakdown and a residual weight stability at temperatures above 1000oC, coinciding with the silica content in PKSAnp. This is comparable and consistent with known high temperature coating materials in previous literature.

Effect of laser cladding layers on microstructure and mechanical properties of NiCoCrAlY bond coat

The NiCoCrAlY alloy is usually used as a bonding layer material in thermal barrier coatings (TBCs) system. Owing its excellent high-temperature oxidation resistance and corrosion resistance, it plays a crucial role in maintaining the structural integrity and functionality of TBCs. Laser cladding technology is a flexible and efficient processing technique for the manufacturing of NiCoCrAlY bond coat, with the characteristics of precisely control the layers of the laser cladding and further modulate the quality of the bond coat. Therefore, the investigation on the influence of cladding layers on the microstructure and mechanical properties of the bond coat is of great significance for improving the service performance and lifetime of aircraft engines. To this end, the scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and X-ray diffraction (XRD) were used in this study to explore the influence of cladding layers on the microstructure and mechanical properties of the NiCrAlCoY bond coat. The results indicate that the microstructure of the cladded alloy can be divided into substrate, heat-affected zone, and cladded zone. The hardness of both the heat-affected zone and the cladded zone increases as the number of cladding layers increases, while the hardness of the substrate maintains constant. In addition, as the number of laser cladding layers increases, so does the residual stress of the cladded alloy.

Chitosan Based Edible Coatings: Enhancing Shelf Life and Quality in Fruits and Vegetables

Chitosan-based edible coatings have gained considerable attention as a sustainable solution for harvested fruits and vegetables which are highly prone to post harvest decay and quality deterioration during storage. Chitosan, derived from chitin exhibits biocompatibility, biodegradability and antimicrobial properties making it an ideal material for edible coatings. Edible coating act as effective barriers to moisture loss, gas exchange and microbial contamination thereby enhancing the quality and extending the shelf life of produce. Research has shown that chitosan coatings can significantly reduce respiration rates, inhibit enzymatic browning and preserve the sensory qualities of fruits and vegetables, contributing to a reduction in food waste and improved food security. The effectiveness of chitosan based coating is influenced by factors such as chitosan concentration, the addition of other natural additives and the methods of application. Studies have demonstrated that chitosan coatings alone or in combination with essential oils or plant extracts effectively reduce weight loss, maintain firmness and prevent spoilage in horticultural perishables. Additionally, nano-encapsulated chitosan formulations have been explored for their enhanced protective effects offering more uniform coatings with superior barrier properties. The application of chitosan coatings is expected to evolve with the integration of nanotechnology, the development of functionalized chitosan molecules and the use of biocompatible additives. Chitosan coatings have been successfully applied commercially, such as in the preservation of perishables illustrating their potential as a sustainable solution with practical benefits for both scientific advancement and industrial application These innovations will further improve the efficacy of coatings by enhancing their moisture and gas barrier properties along with antimicrobial and antioxidant properties. Additionally, sustainability concerns are driving research into eco-friendly sources of edible coating and chitosan is a promising alternative to synthetic or chemical ingredients or fungicides. As the technology advances, chitosan based edible coatings are likely to have increased commercial adoption due to its sustainable and biodegradable nature. However, Chitosan-based coatings face challenges with solubility, application consistency, scalability, cost, allergen concerns, and varying regulatory standards.

Influence of FeSiAl Content on the Morphological Evolution and Electromagnetic Properties of FeSiAl/CaO–B2O3–SiO2 Microwave-Absorbing Coatings

CaO–B2O3–SiO2 (CBS) is a promising lightweight, low-dielectric matrix material for high-temperature microwave-absorbing coatings. However, the comprehensive study of absorbent morphology evolution within such coatings and its influence on electromagnetic (EM) performance has not been conducted. In this work, a series of FeSiAl (FSA)/CBS composite coatings with various FSA contents were fabricated using atmospheric plasma spraying. The morphological evolution of the FSA phase and the resulting EM properties of the coatings were systematically analyzed. Experimental findings show that during the spraying process, when the size of FSA clusters in the composite powder exceeds the thickness of CBS splats, FSA clusters form a rigid contact with the underlying solidified coating, leading to the development of a lamellar structure. This lamellar FSA phase creates local conductive networks, which significantly increase the complex permittivity of the coating. These results provide valuable guidance for controlling absorbent morphology and optimizing the EM properties of CBS-based coatings.

Isothermal oxidation behavior of EB-PVD TBCs based on (Yb0.1Gd0.9)2Zr2O7 ceramic coat and Cr modified (Ni, Pt)Al bond coat

Rare earth oxide doping zirconate ceramics are a new kind of thermal barrier coatings (TBCs) materials that can be suitable for higher service temperature. Single layer (Yb0.1Gd0.9)2Zr2O7 ceramic coatings were fabricated onto both of (Ni, Pt)Al and Cr-modified (Ni, Pt)Al bond coat surfaces. The microstructure, interface elemental diffusion, residual stress as well as isothermal oxidation behavior of two TBCs specimens were evaluated. The compact and uniform Cr-modified layer can act as a diffusion barrier, effectively preventing Al element from diffusing to the bond coat surface. The thickness of pre-oxidation layer grown at the interface between Cr-modified (Ni, Pt)Al and (Yb0.1Gd0.9)2Zr2O7 is relatively thin, which is measured to be only ∼140 nm. With the prolonging of oxidation durations, the surface microcracks' width and sintering morphology of Cr-modified (Ni, Pt)Al TBCs are obviously less severe than that of (Ni, Pt)Al TBCs. The modification effect of Cr onto (Ni, Pt)Al surface is also reflected in the decrease of the thickening rate of thermally grown oxide (TGO) and the improvement durability of β phase within bond coat. Although the residual stress in TGO layer of Cr-modified (Ni, Pt)Al TBCs increases continuously during thermal exposure from 200 h to 700 h, no serious microcracks' propagation occurs on the surface of (Yb0.1Gd0.9)2Zr2O7 coating. The ceramic coat of (Ni, Pt)Al TBCs spalls extensively and further the TGO exhibits a double-layer structure when the isothermal oxidation is carried out up to 700 h. In that TGO morphology, the columnar crystals are observed near the bond coat, while the fine equiaxed grains are detected approach to the ceramic coat. In comparison, the bond coat of Cr-modified (Ni, Pt)Al with (Yb0.1Gd0.9)2Zr2O7 ceramic topcoat has better interlayer matching, and such TBCs shall have the potential to provide thermal protection for the superalloy substrate even after 700 h of isothermal oxidation.

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.

Preparation and performances of conductive, wear-resistant, and anti-corrosion coatings based on low content monodisperse SWCNTs

Single-walled carbon nanotubes (SWCNTs) are considered an ideal candidate material for multifunctional coatings because of their excellent electrical, thermal and mechanical properties. However, achieving uniform dispersion of SWCNTs while maintaining their structure and performance remains a significant challenge. The monodisperse SWCNTs (m-SWCNTs) can be obtained using a non-covalent PVP dispersant under the graded homogenization method. PVP acted as steric hindrance due to the π-π conjugate, thereby hindering the agglomeration and preventing the damage of SWCNTs. We incorporate low amounts of m-SWCNTs into fluorocarbon (FC) coatings to fabricate m-SWCNTs/FC composite coatings. We also investigate the effect of m-SWCNTs content on the electrical conductivity, corrosion resistance and wear resistance of the composite coating. Our results indicate that when the content of m-SWCNTs reaches at 0.25 wt%, the electrical resistivity of the m-SWCNTs/FC composite coating is 1.67 × 10−2 Ωm, significantly decreased by 9 orders of magnitude compared to FC coating. The conductive network would be formed by the high aspect ratio and non-damaged of m-SWCNTs to improve the conductivity. Additionally, the wear rate containing 0.15 wt% m-SWCNTs decreased by 50.1 % due to the improved strength and heat conduction to inhibit the adhesive wear. Furthermore, in comparison to bare steel, the corrosion current density of 0.15 wt% m-SWCNTs/FC composite coating is reduced by two orders of magnitude due to zigzag the corrosive path. Our studies suggest that the m-SWCNTs/FC composite coatings have a broad prospect in preparing large-scale, high-performance, and low-cost functional coatings.

Synergism of h-BN and La2O3 in improving the tribological performance of Al2O3 coatings

Wear is a significant cause of material loss, contributing to surface degradation of crucial components, notably within engineering sectors. This article is dedicated to enhancing tribological properties through the implementation of Al2O3-based ceramic coatings, specifically targeting situations where reciprocating sliding wear predominates. This study introduces lanthanum oxide (La2O3), a rare earth oxide, as a reinforcing material in Al2O3 coatings in varying weight percentages of 1.2%, 1.6%, and 1.8% respectively along with 3% hexagonal boron nitride (h-BN). The coatings were developed by the high-velocity oxy-fuel (HVOF) surface modification technique, with SS304 serving as the substrate. The porosity, hardness, and chemical composition of the developed coatings were examined. Additionally, reciprocating tribological testing of the coatings was conducted at two loads (5 N and 15 N) under dry sliding conditions. Results indicated that coating containing 95.4% Al2O3–3% h-BN–1.6% La2O3 reduced the porosity up to 50% and improved hardness by 46% compared to the 97% Al2O3–3% h-BN coating. The formation of the α-Al2O3 phase leads to an increase in coating hardness and a reduction in porosity. Notably, the coating comprising 97% Al2O3–3% h-BN exhibited the lowest coefficient of friction among all developed coatings under both loads. Furthermore, an increase in load led to a decrease in the coefficient of friction for all developed coatings. Furthermore, the addition of La2O3 (1.6 wt%) to the coating with 3 wt% h-BN exhibited the lowest wear at both loads. The findings also revealed increased wear at high loads for all developed coatings. SEM, EDS, and XRD analysis of the worn surfaces revealed the contribution of h-BN and La2O3 in enhancing friction behavior through the formation of oxides such as α-Al2O3, B2O3, Al8B2O15, and Al11La0.497O17, along with alterations in wear mechanism and the size of wear debris. The composite coatings developed in this study shall be helpful in advanced engineering applications.

Pentadecanoic Acid-Releasing PDMS: Towards a New Material to Prevent S. epidermidis Biofilm Formation

Microbial biofilm formation on medical devices paves the way for device-associated infections. Staphylococcus epidermidis is one of the most common strains involved in such infections as it is able to colonize numerous devices, such as intravenous catheters, prosthetic joints, and heart valves. We previously reported the antibiofilm activity against S. epidermidis of pentadecanoic acid (PDA) deposited by drop-casting on the silicon-based polymer poly(dimethyl)siloxane (PDMS). This material exerted an antibiofilm activity by releasing PDA; however, a toxic effect on bacterial cells was observed, which could potentially favor the emergence of resistant strains. To develop a PDA-functionalized material for medical use and overcome the problem of toxicity, we produced PDA-doped PDMS by either spray-coating or PDA incorporation during PDMS polymerization. Furthermore, we created a strategy to assess the kinetics of PDA release using ADIFAB, a very sensitive free fatty acids fluorescent probe. Spray-coating resulted in the most promising strategy as the concentration of released PDA was in the range 0.8–1.5 μM over 21 days, ensuring long-term effectiveness of the antibiofilm molecule. Moreover, the new coated material resulted biocompatible when tested on immortalized human keratinocytes. Our results indicate that PDA spray-coated PDMS is a promising material for the production of medical devices endowed with antibiofilm activity.

Advances in Coating Materials for Silicon-Based Lithium-Ion Battery Anodes

Silicon anodes, which exhibit high theoretical capacity and very low operating potential, are promising as anode candidates that can satisfy the conditions currently required for secondary batteries. However, the low conductivity of silicon and the alloying/dealloying phenomena that occur during charging and discharging cause sizeable volume expansion with side reactions; moreover, various electrochemical issues result in inferior cycling performance. Therefore, many strategies have been proposed to mitigate these problems, with the most commonly used method being the use of nanosized silicon. However, this approach leads to another electrochemical limitation—that is, an increase in side reactions due to the large surface area. These problems can effectively be resolved using coating strategies. Therefore, to address the issues faced by silicon anodes in lithium-ion batteries, this review comprehensively discusses various coating materials and the related synthesis methods. In this review, the electrochemical properties of silicon-based anodes are outlined according to the application of various coating materials such as carbon, inorganic (including metal-, metal oxide-, and nitride-based) materials, and polymer. Additionally, double shells introduced using two materials for double coatings exhibit more complementary electrochemical properties than those of their single-layer counterparts. The strategy involving the application of a coating is expected to have a positive effect on the commercialization of silicon-based anodes.

Effect of Different Coating Materials on Black Périgord Truffle (Tuber melanosporum) Aroma Profile and Its Shelf Life

AbstractBlack Périgord truffles (Tuber melanosporum) are the highest-priced edible fungus in the world due to their unique flavour, rarity, short growing season, difficulty in mass cultivating, and short shelf-life. The current industrial practices have not been effective in extending truffle shelf-life while preserving its aroma profiles. This study aimed to determine the effectiveness of several preservation methods on Australian-grown black Périgord truffles, which include assessing the changes in the volatile organic compounds (VOCs) of truffles treated with edible coatings, antimicrobial agents, or antioxidants such as chitosan, gum Arabic, kafirin, natamycin, tocopherol, vitamin C, and citric acid at the interval of 0, 7, and 14 days of storage. The study also aimed to assess the capability of gamma-cyclodextrin (γ-CD) in encapsulating truffle VOCs at the intervals of 0, 14, and 28 days of storage. Among all the edible coatings, chitosan-treated truffles had the least change in VOCs, especially the black truffle aroma volatile markers, 2-methyl-1-butanal, 2,4-dithiapentane, and dimethyl sulphide. Chitosan also resulted in no significant changes (P < 0.05) in the carbon dioxide emissions of truffle. The PCA plots showed that chitosan-coated samples displayed the least changes. The sole application of antimicrobial agents or antioxidants was ineffective in delaying the deterioration process. On the other hand, the results show that γ-CD was able to encapsulate 30 truffle’s VOCs, which included 3-methyl-1-butanal, 2-methyl-1-butanol, dimethyl sulphide, and 2,4-dithiapentane with no significant changes over the storage period.

Mechanical and Tribological Properties of Fe- and Ni-based Coating Material under Laser Cladding Process

Mechanical and Tribological Properties of Fe- and Ni-based Coating Material under Laser Cladding Process

Low-loss and low-temperature Al2O3 thin films for integrated photonics and optical coatings

Amorphous aluminum oxide (Al2O3) is a key material in optical coatings due to its notable properties, including a broad transparency window (ultraviolet to mid-infrared) and excellent durability. Moreover, its higher refractive index contrast relative to silica cladding layers and high solubility of rare-earth ions make it well suited for optical waveguides and the development of various functionalities in integrated photonics. In many coatings and integrated photonics applications, the substrates are temperature and stress sensitive, while relatively thick (∼1 μm) alumina layers are required; thus, it is crucial to fabricate low optical loss alumina thin films at low deposition temperatures, while maintaining high deposition rates. In this study, plasma-assisted reactive magnetron sputtering, operated in an alternating current mode, is investigated as a reliable, straightforward, and wafer-scale compatible technique for the deposition of high optical quality and uniform Al2O3 thin films at low temperature. One-micrometer-thick amorphous Al2O3 planar waveguides, deposited at 150 °C and a rate of 23.3 nm/min, exhibit optical losses below 1 dB/cm at 638 nm and as low as 0.1 dB/cm in the conventional optical communication band.