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A comparative analysis of the diffuse reflectance spectra and their changes after irradiation with electrons with an energy of 30 keV of coatings based on polymethylphenylsiloxane resin and pigment powders of two-layer hollow ZnO/SiO2 particles is carried out. The analysis is performed in situ in the range of 250–2500 nm. The samples are irradiated using a Spectrum space-conditions simulator. The radiation resistance of the studied coatings based on two-layer hollow ZnO/SiO2 particles is estimated relative to coatings based on ZnO polycrystals by analyzing the difference diffuse reflectance spectra obtained by subtracting the spectra after irradiation from the spectra of the unirradiated samples. It is found that the intensity of the induced absorption bands in coatings based on hollow ZnO/SiO2 particles is less than in coatings based on ZnO microparticles, and the radiation resistance when estimating changes in the integral absorption coefficient of solar radiation (ΔαS) is twice as high. The increase in the radiation resistance is probably determined by the different nature of defect accumulation: in the case of solid microparticles, defects can accumulate inside grains; in hollow particles, the accumulation of defects can occur only within the thin shell of the sphere. [ABSTRACT FROM AUTHOR]

We presented the results of experimental study of the synthesis of zirconium ceramic coatings partially stabilized with yttrium oxide using the electron-beam method in the forevacuum pressure range (1–100 Pa). The experiments were carried out with a forevacuum plasma-cathode electron source operating in the elevated (forevacuum) pressure range. In a high vacuum, at the initial stage of electron-beam heating and evaporation, the dielectric target can be charged to almost the full accelerating potential. This, in turn, negatively affects the efficiency of energy transfer from the electron beam to the irradiated target. The currently developed forevacuum plasma-cathode electron sources operate at a pressure of several to hundreds of Pascals, which is an order of magnitude higher than the operating pressure of hot-cathode or common plasma electron sources. The beam plasma generated in this range of pressure eliminates the charging effect of the dielectric target. Thereby practically all power of the electron beam is transferred to heating, facilitating evaporation of any refractory dielectric materials. The synthesized coatings with a thickness of over 100 µm were studied, and their mechanical and thermal conductive properties were measured. [ABSTRACT FROM AUTHOR]

Adsorption refrigeration systems were developed as an alternative to traditional vapor compression systems, offering reduced energy consumption and using refrigerants that are less harmful to the environment. Of late, sustainable low-carbon cooling technologies are being widely researched for fulfilling the rapidly expanding cooling requirements. The rate of desorption and adsorption entrust mainly on the thermo-physical properties of the adsorbent and the heat and mass transfer rates of the adsorbent bed. To compete commercially with vapor compression and absorption refrigeration systems, adsorption processes must exhibit efficient mass and heat transfer rates between the adsorbent and adsorbate, also by minimizing manufacturing costs and ensuring the availability of a suitable temperature heat source. This review aims to provide the pathways to enhance the performance of the adsorption cooling system (ACS). It summarizes the current studies and investigations, particularly on the improvement of adsorbent thermal conductivity, increasing heat exchange area and lowering the thermal contact resistance for compact system development and optimization. The most effective approach is the combined effects of the composite adsorbent with surface coatings and suitable bed design modification. It is inferred that the peak performance (COP and SCP) could be attained by optimizing the thermophysical characteristics of a newly developed composite adsorbent. This review emphasizes that the comprehensive approach could led to the development of more efficient and sustainable solutions, by enhancing the effectiveness of the adsorption cooling systems.

Titanium (Ti) alloys have been widely used in biomedical applications due to their superior mechanical, physical, and surface properties, while improving their tribological properties is critical to widening their biomedical applications in the current era. The present review examines the recent progress made in enhancing the tribological performance of titanium alloys and titanium matrix composites for biomedical purposes. It specifically focuses on the progress made in biomedical coatings, mechanical surface treatment, and developing titanium matrix composites in terms of their processing, tribological testing conditions, and characterization. Despite thorough investigations, the specific testing procedures for evaluating the friction and wear properties of the alloy and/or biomedical component are still uncertain. The majority of researchers have selected test methods and parameters based on previous studies or their own knowledge, but there is a scarcity of studies that incorporate limb-specific tribological tests that consider the distinct kinematic and biological structure of human limbs. Since advanced microscopy has great potential in this field, a variety of advanced characterization techniques have been used to reveal the relationship between microstructural and tribological properties. Many coating-based strategies have been developed using anodizing, PEO, VD, PVD, nitriding, thermal spray, sol-gel, and laser cladding, however; composition and processing parameters are crucial to improving tribological behaviour. Reinforcing component type, amount, and distribution has dominated Ti matrix composite research. Ti grade 2 and Ti6Al4V alloy has been the most widely used matrix, while various reinforcements, including TiC, Al2O3, TiB, hydroxyapatite, Si3N4, NbC, ZrO2 have been incorporated to enhance tribological performance of Ti matrix. Mechanical surface treatments improve biomedical Ti alloys’ tribological performance, which is advantageous due to their ease of application. The implementation of machine learning methods, such as artificial neural networks, regression, and fuzzy logic, is anticipated to make a substantial contribution to the field due to their ability to provide cost-effective and accurate results. The microstructural and surface features of biomedical Ti alloys directly affect their tribological properties, so image processing strategies using deep learning can help researchers optimize these properties for optimal performance.

Coolant-facing alloys in a tokamak will face harsh environments due to the synergistic effect of flowing coolant, dynamic mechanical loading, ionising radiation, and tritium embrittlement. Reduced activation ferritic/martensitic (RAF/M) EUROFER-97 is the primary candidate as the structural alloy for the breeder blanket to be used in DEMO reactor. Under fusion-like conditions, coatings are required to improve both its corrosion properties and act as a tritium permeation barrier (TPB) layer. In this study, Al-base self-passivating coatings have been investigated as possible solution to provide protection against corrosion and act as TPB layer. The aim of this study was to assess the adhesion properties between different self-passivating Al-base coatings as electroplated and chemical vapour deposited (CVD) coatings on a RAF/M EUROFER-97 under strain. These studies showed the high ductility of pure electroplated Al-coatings, whereas both CVD coatings cracked under the applied strain.

UV curing nail coatings have gained immense popularity for their rapid curing time and enhanced performance. Achieving strong adhesion to natural nails is crucial for these coatings. This study investigates various adhesion promoters used in UV-cured nail coatings. Key composition characteristics such as polymerization temperature (T), post-production viscosity, and viscosity stability over three months at 50°C were evaluated. Adhesion with pull-off testing and physico-mechanical properties of cured coatings were examined. Various adhesion promoters including aliphatic acrylates, silanes, dimethacrylate succinate adduct, dimethacrylate maleate adduct, and acid-based adhesion promoters were tested. Silane compounds exhibited superior adhesion and viscosity stability, making them suitable for long-lasting formulations. Polymerization temperature varied, requiring optimization for each formulation. The choice of adhesion promoter strongly influenced physico-mechanical properties, with dimethacrylate/maleate adduct showing superior durability. The findings offer a comprehensive understanding of the influence of adhesion promoters on coating composition and performance, aiding in the development of high-quality, long-lasting UV curing nail coatings for the cosmetics industry.

In today's automotive, marine and petrochemical industries, the desire for lightweight materials has increased. Hence, necessitating the production of components with low density. In this work, lightweight Zn–Si3N4 coatings were developed by including Si3N4 in the zinc matrix. The optimal coatings were produced on steel samples at 45 °C and varied Si3N4 particles and voltages following ASTM A53/A53M standard. The deterioration (corrosion) property i.e. corrosion rate (CR) and current density (jocorr) of the uncoated (control) and coated samples were examined in 0.5 M of sulphuric acid using a potentiodynamic polarization technique following ASTM G3/G102 standard. The microstructure of the samples was studied via the SEM micrographs and XRD patterns, while the wear performance resistance (following ASTM G99 standard) and electrical conductivity of the samples were examined with a pin-on-disc tribometer and ammeter-voltmeter. The corrosion experiment indicated that the uncoated mild steel specimen possessed a CR of 12.345 mm year−1 and jocorr of 1060 μA/cm2, while the CR and jcorr of the coated samples ranged from 2.6793 to 4.7975 mm year−1 and 231−413 μA/cm2, respectively. The lower CR and jcorr values of the coated specimens, relative to the coated sample showed that the coatings possessed superior passivation ability in the test medium. The SEM micrographs of the samples showed refined morphology, while the XRD patterns revealed high peak intensity crystals such as Zn4SiN, ZnNSi, Zn4N and Zn2NSi, which could be beneficial to the mechanical properties and corrosion resistance of the steel. Moreover, the wear resistance study indicated that the COF of the uncoated sample ranged from 0.1 to 0.5, while those for coated specimens ranged from 0.05 to 0.35. Similarly, the uncoated steel exhibited a wear volume (WV) of 0.00508 mm3, while the WV of the coated specimens ranged from 0.00266 to 0.0028 mm3, indicating the existence of high strengthening mechanisms between the interface of the protecting device and the steel. Also, the electrical conductivity of the mild steel sample reduced from 12.97 Ω−1cm−1 to 0.64 Ω−1cm−1, indicating that the electrical resistivity of the steel was enhanced by the coatings.

Cold spray (CS) is a new kind of coating that has many potential uses, including functionalizing surfaces, doing localized repairs, and mass production. Its fast deposition rate and diverse feedstocks have led to its growing popularity as an additive manufacturing method, which has been driven by improvements in lateral resolution. CS materials have several uses in the transportation industry, and some of the most frequent ones include nickel super-alloys, titanium alloys, copper, aluminum and metal-ceramic composites. Nevertheless, the mechanical properties depend upon number of parameters involved during spraying process. Therefore, there is an immediate need for researchers and businesses to understand the various parameters affecting the adhesion strength of CS deposits. The current research presents an analysis of the adhesion behavior of coatings that have been deposited by CS methodology.

In high-temperature boiler operations, conventional steels and alloys grapple with the formidable challenges posed by oxidation and corrosion. Prolonged exposure to extreme thermal conditions exacerbates these issues, progressively diminishing operational efficiency. Surface treatment emerges as a pivotal strategy for safeguarding materials against deterioration while optimizing component performance cost-effectively. Recent attention has honed on surface coatings as a means to combat hot corrosion in boiler steels. Thermal coating, electroplating, and other metallurgical techniques are widely embraced for surface modification, with composite coatings gaining traction for bolstering metallurgical, mechanical, and corrosion resistance properties. This review, unlike any other, takes a comprehensive approach to exploring various thermal spraying methods and their applications, ensuring a robust understanding of the subject matter. Beyond a mere compilation of existing literature, this review identifies emerging trends and technologies, offering fresh insights and interpretations. In this work, 84 articles were critically evaluated for current research, discerning strengths, weaknesses, and avenues for future research on thermal spray coatings on high-temperature oxidation and corrosion. This incisive approach promises to enrich the knowledge base of researchers, scholars, and professionals in materials science, metallurgy, and industrial engineering, facilitating advancements in the field. By pinpointing research gaps in thermal spray coating, this study directs attention toward areas ripe for further investigation, fostering continued innovation and progress.

This review summarized the characteristics and preparation technology of metallic BPPs of fuel cells. Metal bipolar plates have many properties required for fuel cells, such as mechanical properties, thermal and electrical conductivity, and versatility. The main shortcoming of metal is its vulnerability to corrosion in the fuel cell operating environment. During this process, the formation of the passivation layer causes an unavoidable increase in the interfacial contact resistance. With an appropriate deposition method, a suitable coating system can effectively deal with this shortcoming. In this review, we summarize the classification and preparation methods of metallic BPPs coatings that are currently being studied by scholars around the world and compare the differences between the different coatings through various types of tests. It also provides relevant experience on performance test methods for fuel cell bipolar plates and the factors affecting performance and test parameters.

Abstract Integration of bioelectronic devices in clinical practice is expanding rapidly, focusing on conditions ranging from sensory to neurological and mental health disorders. While platinum (Pt) electrodes in neuromodulation devices such as cochlear implants and deep brain stimulators have shown promising results, challenges still affect their long‐term performance. Key among these are electrode and device longevity in vivo, and formation of encapsulating fibrous tissue. To overcome these challenges, organic conductors with unique chemical and physical properties are being explored. They hold great promise as coatings for neural interfaces, offering more rapid regulatory pathways and clinical implementation than standalone bioelectronics. This study provides a comprehensive review of the potential benefits of organic coatings in neuromodulation electrodes and the challenges that limit their effective integration into existing devices. It discusses issues related to metallic electrode use and introduces physical, electrical, and biological properties of organic coatings applied in neuromodulation. Furthermore, previously reported challenges related to organic coating stability, durability, manufacturing, and biocompatibility are thoroughly reviewed and proposed coating adhesion mechanisms are summarized. Understanding organic coating properties, modifications, and current challenges of organic coatings in clinical and industrial settings is expected to provide valuable insights for their future development and integration into organic bioelectronics.

The present work is concerned with studying surface parameters of coatings deposited to titanium alloy Ti6Al4V by electrospark deposition (ESD) with hard alloy depositing electrodes based on WC, TiC and TiCN. The variation of roughness parameters, composition, structure and tribological characteristics of coatings as a function of ESD mode parameters was investigated. The influence of the mode parameters on the main coating roughness parameters (Ra, Rz, Rmax, Rpk, Rk, Rs, Rsk, Rku (ISO 21920-2:2021) was analysed, the values of which can be used to determine the load bearing capacity and wear resistance. The results of the tribological tests showed that within the test range, the roughness of the coatings has a controversial influence on their frictional wear performance. As the roughness parameters increase to Ra=3÷3.5 µm, the relative wear resistance of the coated surfaces also increases, reaching values up to 4÷5 µm for the electrodes used and no significant changes in the wear mechanism were observed. However, increasing coating roughness above Ra=3.5 to 5 µm results in a monotonic decrease in relative wear resistance to 2.5÷3 times. Possible ways to reduce the surface roughness and increase the wear resistance of coatings were presented.

Abstract Fruit coatings serve a dual purpose in preserving the quality of fruits. Not only do they act as a barrier against water evaporation and fungal infiltration, but they also enhance the fruit’s visual appeal in the market. Yet, their influence on the fruit’s quality components, which play a crucial role in determining its nutritional value, taste, and overall flavor, has remained relatively unexplored. This study aimed to evaluate the effects of carnauba wax coating on the quality of Moro oranges during storage. The selected fruits were meticulously chosen for uniformity in size. The experiment involved applying carnauba wax, a commonly used type among local producers, at four different concentrations: 0%, 0.5%, 1%, and 1.5%. These treatments were applied during various storage periods, including immediately after fruits were harvested and after 40 and 80 days. Following the application of these treatments, the oranges were stored in a controlled environment (morgue) at a temperature of 4 ± 1 °C. Subsequently, several physicochemical parameters of both the fruit flesh and skin were examined. The results unveiled a decline in the overall ascorbic acid content of the fruits. In terms of phenol content, a general decreasing trend was observed after harvesting. At each sampling interval during storage, the phenol content in uncoated fruits consistently exceeded that of their waxed counterparts. Significant reduction in fruit weight was observed throughout the storage period. Both vitamin C and total acidity levels in the fruit exhibited decreases during the storage period. As time passed, fruit firmness gradually declined, while fruit decay increased during the 40- and 80-day storage periods for untreated Moro oranges. The anthocyanin content showed an increasing trend. The study also unveiled a decline in the antioxidant capacity of citrus fruits during storage. Strong significant positive correlations were observed between total phenol content and key parameters, such as antioxidant activity (0.941**), MDA (0.364*), vitamin C content, and total carbohydrate content (0.475**). Skin radiance showed a perfect correlation with chroma and hue (1.000**). Principal component analysis revealed that the first principal component accounted for 34.27% of the total variance, out of a total of five principal components that explained 77.14% of the variance. Through cluster analysis, the variables were categorized into three distinct groups; one associated with weight loss and another with ion leakage. Considering these findings, carnauba wax-based coating emerges as a promising solution for preserving Moro oranges. It effectively mitigates fruit weight loss and helps maintain fruit firmness during storage, making it a valuable tool for fruit preservation.

Abstract Co3O4 nanoparticles (Co3O4-NPs) are synthesized using the facile solvothermal method. FT-IR and XRD spectroscopic analyses verify the creation of cobalt oxide nanoparticles with an average size of 13.20 nm. Furthermore, Zeta potential assessments were carried out to identify the electrical charge of the surface of the produced Co3O4-NPs, which was found to be -20.5 mV. In addition, the average pore size of Co3O4-NPs is 19.8 nm, and their BET surface area is 92.4 m/g. The study also concerned the effect of Co3O4-NPs on epoxy's improvement of mechanical and corrosion protection for carbon steel in salt solution. By including Co3O4-NPs in an epoxy (EP) coating, corrosion is effectively prevented by non-permeable protective coatings that effectively reduce the transfer of corrosion ions and oxygen.

Bioactive thermal spray coatings produced via high-velocity oxygen fuel spray (HVOF) from hydroxyapatite (HAp) and bioactive glasses (BG) have the potential to be employed on temporary implants due to the ability of both HAp and BG to dissolve and promote osseointegration, considering that both phases have different reaction and dissolution rates under in-vitro conditions. In the present work, 75% wt. HAp - 25% wt. S53P4 bioactive glass powders were HVOF-sprayed to obtain HAp/S53P4 BG composite coatings on a bioresorbable AZ31 alloy. The study is focused on exploring the effect of the stand-off distance and fuel/oxygen ratio variation as HVOF parameters to obtain stable structural coatings and to establish their effect on the phases and microstructure produced in those coatings. Different characterization techniques, such as scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy, were employed to characterize relevant structural and microstructural properties of the composite coatings. The results showed that thermal gradients during coating deposition must be managed to avoid delamination due to the high temperature achieved (max 550 °C) and the differences in coefficients of thermal expansion. It was also found that both spraying distance and oxygen/fuel ratio allowed to keep the hydroxyapatite as the main phase in the coatings. In addition, in-vitro electrochemical studies were performed on the obtained HAp/S53P4 BG composite coatings and compared against the uncoated AZ31 alloy. The results showed a significant decrease in hydrogen evolution (at least 98%) when the bioactive coating was applied on the Mg alloy during evaluation in simulated body fluid (SBF).

The wear resistance of the part surface has become an important factor affecting its own service life. Laser cladding (LC), as a surface modification technology, can prepare a coating with good metallurgical bonding with the substrate, which can significantly improve the wear resistance of the material surface. High entropy alloys (HEAs) are an emerging coating material with excellent wear resistance. Therefore, this paper reviews the latest development status in wear resistance of laser cladding-high-entropy alloy coatings (LC-HEACs) in terms of the HEAs material system, LC process parameters, strengthening phase, amorphous phase strengthening, assisted cladding, and post-treatment. At the same time, this paper also expounds on the mechanism of LC-HEACs enhancing the surface wear resistance of materials, and the current research status of LC-HEACs in different engineering materials and application environments. Finally, the current research deficiencies, challenges, and future development trends of LC-HEACs in the field of wear resistance are also elaborated, and it is expected to provide some references for their future development and applications.

Press hardenable steels (PHS) coated with Al–Si alloy are widely used in the automotive industry owing to their good mechanical properties (Yield Strength >1200 MPa and Tensile Strength >1500 MPa). The presence of Al–Si coating prevents oxidation and decarburization of steel during austenitization. However, aluminized PHS are sensitive to hydrogen absorption during austenitization, while Al–Si coating prevents hydrogen degassing from the specimen at room temperature so that diffusible hydrogen could lead to hydrogen embrittlement in specific conditions.In this study, H trapping in aluminized steels was critically assessed using deuterium sources instead of hydrogen sources during austenitization and thermal desorption analysis (TDA). 22MnB5 steel coated with Al and Al–Si alloys were studied. D is mainly trapped in the dislocations strain field in the steel substrate of aluminized steels and it is responsible for the three main D2 desorption peaks in Al and Al–Si coated steels. Multiple peaks observed on D2 desorption profiles of Al and Al–Si coated steels are explained by the preferential desorption path of D depending on the sample temperature.

The coating materials, thickness and number of layers directly influence the reflectance and absorptance properties of the thin films. However, while selecting the materials for single and coatings, the substrate’s refractive index; bond layer, functional layer and protective layer have to be carefully chosen to obtain the desired reflectance and absorptance values. Hence, modelling and simulating the thin film coatings is essential before conducting the experiments to get meaningful results. The simulation results of single coatings have been discussed. Generally, glass is one of the widely used substrate materials for solar reflectors, aluminum is the optimal functional material, with a reflection of 93 % of light. Nickel would be a preferable functional layer with a reflection of 64 % and absorptance of 36 %, Si3N4 being the acceptable bond layers and protective layers with a reflection of 68 % some solar thermal receiver tube applications however research effort is being made to find alternate lightweight materials for this application. Polycarbonate has been chosen as an alternate material for the substrate because it is light in weight with a reflection of 93 %, which is durable and not fragile.