Coatings

In this study, the In_0.9Ga_0.1O sensing membrane were deposited by using the RF magnetron sputtering at room temperature and combined with commercial MOSFETs as the extended gate field effect transistor (EGFET) pH sensors. The sensing performance of the In_0.9Ga_0.1O EGFET pH sensors were measured and analyzed in the pH value of range between 2 to 12. In the saturation region, the pH current sensitivity calculated from the linear relationship between the and pH value was approximately 56.64 μA/pH corresponding to the linearity of 97.8%. In the linear region, the pH voltage sensitivity exhibited high sensitivity and linearity of 43.7 mV/pH and 96.3%, respectively. The In_0.9Ga_0.1O EGFET pH sensors were successfully fabricated and exhibited great linearity. The analyzed results indicated that the In_0.9Ga_0.1O was a robust material as a promising sensing membrane and effectively used for pH sensing detection application. Full article

In the present research, the properties of ultraviolet (UV) visible (daylight invisible) fluorescent coatings modified by the addition of SiO₂ and TiO₂ nanoparticles were studied. Structural, surface, and mechanical properties and changes in the coatings caused by accelerated ageing were analyzed. The results showed that the addition of nanoparticles caused the changes in unaged and aged printed coatings. Reflectance measurements of modified coatings showed that addition of TiO₂ nanoparticles improved the visual effect of the unaged coatings. Furthermore, results have shown that the addition of SiO₂ did not diminish the reflectance of the modified coatings after ageing. The results of roughness measurements showed that the addition of SiO₂ decreased roughness after the ageing process, probably due to the degradation process indicated by Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) spectroscopy. The roughness of the coatings with TiO₂ nanoparticles was increased after the ageing on the samples with higher concentrations of TiO₂ due to the agglomerates of plastisol formed on the surface of the coatings, visible in SEM images. Surface analysis of coatings showed that TiO₂ caused an increase in the polarity of the surface coatings. Results of the bending stiffness showed that the addition of the nanoparticles to the coating, especially of SiO₂, significantly improved the bending stiffness of the unaged samples. Full article

Coatings can be used as a preservative method to protect the wood, especially the wood surface. The different component of the coating’s dependence of the purpose of it. The Japanese beech (Fagus crenata Blume) applied by several Japanese commercials coating materials. The coatings application used were spray type and brush type. X-ray microtomography in Fuji, Japan was used for visualized the coating samples. The X-ray target used were Cu, and Mo with Al filter. The X-ray image analysis in 2D and 3D were conducted using image J and VGStudio Max, respectfully. The coating’s containing materials and the concentration of it strongly affected the image result of X-ray microtomography visualization. The different X-ray target shows the different image results. The larger energy of X-ray (Mo with Al filter) is recommended to use for visualization. The X-ray images shows the penetration phenomena, which can be applied to calculate the penetration depth. Full article

Spacers, such as FORMA (Edwards Lifescience) or Mitraspacer, are used to treat mitral regurgitation or tricuspid regurgitations. However, they require external therapeutic liquid filler injection into the spacer device. This should be leak-tight over the time of implantation, which is a major limitation in device design. Here, we propose a self-expandable spacer with a nitinol inner mesh and expanded poly (tetrafluoroethylene) (ePTFE) coating that also functions as a spacer. We designed nitinol 3D mesh templates, coated with a commercially available low and high durometer ePTFE membrane. Finally, we implanted the spacer into a swine pulmonary artery and right atrium (superior vena cava) as an intervention technique. Twenty-four swine were used, except in two cases suspected of procedural infection. The results were analyzed in the remaining 22 cases and all devices were easily delivered and had good function in self-expansion and implantation. After eight weeks, all individuals were examined for gross and pathological analysis to determine the biological safety of the device. There was no evidence of damage or other abnormalities and increased postoperative endothelialization outside of ePTFE coatings. In conclusion, this study suggests using a self-expandable spacer to complement the medical limitations of the existing filling-type spacer devices. Full article

Carbon powders exhibit electrical conductivity that causes the powders to agglomerate due to the applied electrostatic forces and discharges capacitance when used for surface treatments with plasma sources. To avoid this obstacle, a non-direct method is used with active gas that is generated through plasma. This active gas is in contact with the carbon powder so that the hydrophilic characteristics are formed. It is the carboxyl COO⁻ functional group that causes hydrophilic improvement and it is shown to increase in the carbon surface after soft oxidation. The wettability of carbon powder gradually improves with more plasma treatment time. This is shown through a simple water dispersion test. Eventually, the dispersed aqueous solution gradually separates the powder, which either floats or sinks. The sample treated for 60 min is shown to continuously sustain dispersibility in water over a long period of time. Full article

Traditionally, strain gauge, extensometer, and reflection tracking markers have been used to measure the deformation of materials under loading. However, the anisotropy and inhomogeneity of most biological materials restricted the accessibility of the real strain field. Compared to the video extensometer, digital image correlation has the advantage of providing full-field displacement as well as strain information. In this study, a digital image correlation method (DIC) measurement system was employed for chicken breast bio-tissue deformation measurement. To increase the contrast for better correlation, a mixture of ground black pepper and white sesame was sprayed on the surface of samples. The first step was to correct the distorted image caused by the lens using the inverse distorted calibration method and then the influence of subset size and correlation criteria, sum of squared differences (SSD), and zero-normalized sum of squared differences (ZNSSD) were investigated experimentally for accurate measurement. Test results of the sample was translated along the horizontal direction from 0 mm to 3 mm, with an increment of 0.1 mm and the measurement result was compared, and the displacement set on the translation stage. The result shows that the error is less than 3%, and accurate measurement can be achieved with proper surface preparation, subset size, correlation criterion, and image correction. Detailed examination of the strain values show that the strain ε_x is proportional to the displacement of crosshead, but the strain ε_y indicates the viscoelastic behavior of tested bio-tissue. In addition, the tested bio-tissue’s linear birefringence extracted by a Mueller matrix polarimetry is for comparison and is in good agreement. As noted above, the integration of the optical parameter measurement system and the digital image correlation method is proposed in this paper to analyze the relationship between the strain changes and optical parameters of biological tissue, and thus the relative optic-stress coefficient can be significantly characterized if Young’s modulus of biological tissue is known. Full article

Fe₃Si films are deposited onto the Si(111) wafer using sputtering with parallel facing targets. Surface modification of the deposited Fe₃Si film is conducted by using a microwave plasma treatment under an Ar atmosphere at different powers of 50, 100 and, 150 W. After the Ar plasma treatment, the crystallinity of the coated Fe₃Si films is enhanced, in which the orientation peaks, including (220), (222), (400), and (422) of the Fe₃Si are sharpened. The extinction rule suggests that the B₂–Fe₃Si crystallites are the film’s dominant composition. The stoichiometry of the Fe₃Si surfaces is marginally changed after the treatment. An increase in microwave power damages the surface of the Fe₃Si films, resulting in the generation of small pinholes. The roughness of the Fe₃Si films after being treated at 150 W is insignificantly increased compared to the untreated films. The untreated Fe₃Si films have a hydrophobic surface with an average contact angle of 101.70°. After treatment at 150 W, it turns into a hydrophilic surface with an average contact angle of 67.05° because of the reduction in the hydrophobic carbon group and the increase in the hydrophilic oxide group. The hardness of the untreated Fe₃Si is ~9.39 GPa, which is kept at a similar level throughout each treatment power. Full article

Pectin is a biocompatible polysaccharide with intrinsic biological activity, which may exhibit different structures depending on its source or extraction method. The extraction of pectin from various industrial by-products presents itself as a green option for the valorization of agro-industrial residues by producing a high commercial value product. Pectin is susceptible to physical, chemical, and/or enzymatic changes. The numerous functional groups present in its structure can stimulate different functionalities, and certain modifications can enable pectin for countless applications in food, agriculture, drugs, and biomedicine. It is currently a trend to use pectin to produce edible coating to protect foodstuff, antimicrobial bio-based films, nanoparticles, healing agents, and cancer treatment. Advances in methodology, use of different sources of extraction, and knowledge about structural modification have significantly expanded the properties, yields, and applications of this polysaccharide. Recently, structurally modified pectin has shown better functional properties and bioactivities than the native one. In addition, pectin can be used in conjunction with a wide variety of biopolymers with differentiated properties and specific functionalities. In this context, this review presents the structural characteristics and properties of pectin and information on the modification of this polysaccharide, its respective applications, perspectives, and future challenges. Full article

Thin films of CuGa₂O₄ were deposited using an RF magnetron-sputtering technique for the first time. The sputtered CuGa₂O₄ thin films were post-deposition annealed at temperatures varying from 100 to 900 °C in a constant O₂ ambience for 1.5 h. Structural and morphological studies were performed on the films using X-ray diffraction analysis (XRD) and a Field Emission Scanning Electron Microscope (FESEM). The presence of CuGa₂O₄ phases along with the CuO phases was confirmed from the XRD analysis. The minimum critical temperature required to promote the crystal growth in the films was identified to be 500 °C using XRD analysis. The FESEM images showed an increase in the grain size with an increase in the annealing temperature. The resistivity values of the films were calculated to range between 6.47 × 10³ and 2.5 × 10⁸ Ωcm. Optical studies were performed on all of the films using a UV-Vis spectrophotometer. The optical transmission in the 200–800 nm wavelength region was noted to decrease with an increase in the annealing temperature. The optical bandgap value was recorded to range between 3.59 and 4.5 eV and showed an increasing trend with an increase in the annealing temperature. Full article

A silicon oxycarbide-carbon nanotube coating on steel was synthesized using a novel approach utilizing unmodified carbon nanotubes (CNT), silane surfactant and large monomer-based silsesquioxane sol. This enabled the creation of very stable carbon nanotube dispersion, which in turn resulted in homogenous layers obtained in a simple dip-coating process. The samples were annealed in 800 °C in argon to obtain a uniform glassy silicon oxycarbide-based composite from a silsesquioxane precursor. The layers’ morphology and nanomechanical properties were investigated using a number of methods, including infrared spectroscopy (IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), nanoindentation, Accelerated Property Mapping (XPM) and Quantitative Nanomechanical Mapping—an Atomic Force Microscopy method (QNM-AFM). Full article

In general, the mechanical properties of hard thin coatings are investigated using indentation methods. Material characteristics of hard coatings, such as elastic modulus and hardness, are evaluated by means of nanoindentation and an appropriate evaluation methodology. The most popular method used to obtain the coating properties required using nanoindentation is the evaluation based on the Oliver and Pharr methodology. Adhesion and wear properties can be calculated using these data. In this study, we used a novel method to evaluate the wear and adhesion of coatings. A special measuring device combined with static indentation and acoustic emission signal detection was developed to evaluate the adhesion of coatings. The device consists of a macrohardness instrumental indentation device equipped with an acoustic emission measuring gauge. It was used to investigate crack formation and adhesion of coatings deposited on different substrates using acoustic emissions data. The results using both the existing and novel methods were compared and evaluated. Full article

This paper considers the effect of RF plasma on wood in improving the adhesion of binders to wood by increasing its surface wettability. Our study reveals that radiofrequency (RF) plasma treatment causes a greater than threefold decrease in the marginal wetting angle of wood. The greatest effect is achieved in RF plasma treatment in argon, which is on average 5% greater than that of RF plasma treatment in air or in propane/nitrogen mixture. In addition, the power of the RF plasma torch has the greatest influence, and the main influence comes from the voltage applied to the RF plasma torch; current does not have such a significant effect. To achieve a significant effect, the duration of exposure should be at least 5 min, with a total power of 4.05 kW. Studies have been conducted to determine the adhesive strength of wood. An increase in the strength of laminated beams made from RF-treated bars in relation to control samples was found. The greatest impact on the adhesion strength was revealed when using PVA-based glue, compared with the use of polyurethane-based adhesives and urea-formaldehyde resin. Full article

This article discloses a rare and outstanding type of Mn-rich black-blue patina found on mural painting and granite ashlars located in the church of Sta. Marinha, north of Portugal, and conjectures the phenomenon associated to the appearance of such patinas in different surface materials. This Mn-patina reported on mural painting and their origin is probably assigned to manganese leaching from building materials (i.e., granite and phyllites). Stained mural painting and granite examined by XPS and SEM have showed patinas enriched with manganese (IV) oxide, potentially catalysed by a microbiota, like fungi, observed in SEM micrographs. The pigments used to depict mural painting and groundwater were also analysed by micro-Raman and ICP-MS, respectively, indicating that they are unlikely manganese sources. Unstained building materials, such as granite ashlars, historic joints, mortars and phyllite rocks, were also analysed by ICP-MS showing that historic joints and mortars present significant concentrations of manganese, possibly associated to their absorbing feature. The main materials with potential to impart manganese to Mn-rich patinas are granite ashlars and phyllites. The aim of this investigation is to reveal and ascertain the hypothetical sources and the phenomenon responsible for the Mn-rich black-blue patina appearance, both on mural painting and granite ashlars. Full article

Metal acetylacetonates are coordination complexes of metal ions and the acetylacetonate anion with diverse uses including catalysts, cross-linking agents and adhesion promotors. Some metal acetylacetonates can photostabilize polymers whereas others are photocatalysts. We hypothesize that the ability of metal acetylacetonates to photostabilize wood will vary depending on the metal in the coordination complex. We test this hypothesis by treating yellow cedar veneers with different acetylacetonates (Co, Cr, Fe, Mn, Ni, and Ti), exposing veneers to natural weathering in Australia, and measuring changes in properties of treated veneers. The most effective treatments were also tested on yellow cedar panels exposed to the weather in Vancouver, Canada. Nickel, manganese, and titanium acetylacetonates were able to restrict weight and tensile strength losses and delignification of wood veneers during natural weathering. Titanium acetylacetonate was as effective as a reactive UV absorber at reducing the greying of panels exposed to 6 months of natural weathering, and both titanium and manganese acetylacetonates reduced the photo-discoloration of panels finished with a polyurethane coating. We conclude that the effectiveness of metal acetylacetonates at photostabilizing wood varies depending on the metal in the coordination complex, and titanium and manganese acetylacetonate show promise as photoprotective primers for wood. Full article

In order to enhance wear properties of Al-Zn-Mg-Cu alloy parts, Al₂O₃-MoO₂-SiO₂ composite ceramic coatings are formed on Al-Zn-Mg-Cu alloy by the DC micro-arc oxidation (MAO) method in the silicate electrolyte with sodium molybdate. Effects of sodium molybdate concentration on the structure characteristics and wear resistance of the composite ceramic coatings are analyzed by scanning electron microscopy, X-ray diffraction and the wear test, respectively. Analyses indicate that the composite coating consists of different states of Al₂O₃, MoO₂ and mullite phase. With the addition of molybdate in the electrolyte, the morphology and structure are changed. The tribological behavior is greatly affected by the surface characteristics and hardness of the coatings. The composite coatings formed by adding 3 g/L of sodium molybdate electrolyte have the best wear resistance. Full article

With chitosan, nano-TiO₂ and nano-Ag as raw materials, nano-TiO₂ and nano-TiO₂-Ag were modified by a surface modifier-sodium laurate. Chitosan (CTS), chitosan-nano-TiO₂ (CTS-TiO₂), and chitosan-nano-TiO₂-nano-Ag (CTS-TiO₂-Ag) composite materials and corresponding films were prepared by a solution co-blending method. Then, the antibacterial performances of the above three types of materials against Escherichia coli, Staphylococcus aureus, and Bacillus subtilis were compared. Moreover, potato and strawberry weight loss rates, peroxidase activity, and vitamin C contents after different film coating treatments were measured. Compared with CTS films, the CTS-TiO₂-Ag and CTS-TiO₂ composite films both showed better physical properties, and both demonstrated higher antibacterial effects, especially for E. coli. Measurement of physiological indices in fruits and vegetables showed that the freshness-preserving effect of CTS-TiO₂-Ag coating films was the most significant. In all, the CTS-TiO₂-Ag coating films can actively contribute to the storage of fruits and vegetables at room temperature, and better ensure product quality. Thus, such films are meaningful for research and development of new fruit freshness-keeping techniques and materials. Full article

Recent years have witnessed an increase in the use of composite coatings for numerous applications, including aerospace, aircraft, and maritime vessels. These materials owe this popularity surge to the superior strength, weight, stiffness, and electrical insulation they exhibit over conventional substances, such as metals. The growing demand for such materials is accompanied by the inevitable need for fast, accurate, and affordable nondestructive testing techniques to reveal any possible defects within the coatings or any defects under coating. However, typical nondestructive testing (NDT) techniques such as ultrasonic testing (UT), infrared thermography (IRT), eddy current testing (ECT), and laser shearography (LS) have failed to provide successful results when inspecting composite coatings. Consequently, microwave NDT techniques have emerged to compensate for the shortcomings of traditional NDT approaches. Numerous microwave NDT methods have been reported for composite coatings inspection. Although existing microwave NDT methods have shown successful inspection of composite coatings, they often face several challenges, such as low spatial image quality and extensive data interpretation. Nevertheless, many of these limitations can be addressed by utilizing microwave NDT techniques with modern technologies such as soft computing. Artificially intelligent techniques have greatly enhanced the reliability and accuracy of microwave NDT techniques. This paper reviews various traditional NDT techniques and their limitations in inspecting composite coatings. In addition, the article includes a detailed review of several microwave NDT techniques and their benefits in evaluating composite coatings. The paper also highlights the advantages of using the recently reported microwave NDT approaches employing artificial intelligence approaches. This review demonstrates that microwave NDT techniques in conjunction with artificial intelligence approaches have excellent prospects for further enhancing composite coatings inspection and assessment efficiency. The review aimed to provide the reader with a comprehensive overview of most NDT techniques used for composite materials alongside their most salient features. Full article

The bond coat of a NiCrAlY thermal barrier coating plays an important role in solving the thermal expansion mismatch between a metal matrix and a ceramic layer and in improving the oxidation resistance of the whole thermal barrier coating. However, the NiCrAlY bond coat prepared by low-pressure plasma spraying is not conducive to its oxidation resistance because its lamellar structure is loose, porous and the surface is rough. To improve the oxidation resistance of the bond coat, the NiCrAlY bond coat prepared by plasma spraying was modified by high-current pulsed electron beam with different energy densities. Under the electron beam irradiation, the surface of the coating became smooth, and there was a 3–5 μm thick remelting layer on the surface. Under the irradiation, the thickness of the thermal growth oxide layer decreased, and the oxidation resistance was significantly improved, the oxidation product being mainly Al₂O₃. Full article

TaN_x coatings were deposited by RF magnetron sputtering with different bias voltages. The growth morphology, crystalline structure, chemical bond structure, hardness and elastic modulus, adhesion strength and tribological performance of the coatings were studied as a function of the bias voltage. The results showed that an increasing bias voltage refines the coating grains and facilitates structure densification. Simultaneously, the structure of the TaN_x coatings transfers from a composite structure consisting of TaN and Ta₂N crystals, through a single composite mainly composed of the Ta₂N crystal, to an amorphous structure as the bias voltage increases from low to high, indicating that the phase composition of the TaN_x coatings can be varied by the bias voltage. The coating composed of Ta₂N crystal showed a good overall performance including enhanced hardness, enhanced adhesive strength, and good tribological performance with enhanced wear resistance and a low friction coefficient of 0.18. Full article