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Cold plasma coating technology for surface functionalization of pharmaceutical powder particles is a promising approach to introduce new characteristics such as controlled release layers, improved powder flow properties, stability coatings, and binding of active components to the surface. This is typically achieved in a fluidized bed reactor, where a jet containing the chemical precursor and the plasma afterglow is introduced through a nozzle while extra fluidization gas is injected from the bottom plate. However, the process requires proper mixing of the particles and precursor inside the plasma active zone to ensure a homogeneous coating of all particles. Therefore, such coating processes are challenging to optimize, given the complex phenomena involved in fluidization, plasma species reactions, and surface reactions. In this study, we use the CFD-DEM approach as implemented in the CFDEM®coupling package to model the process. The functionalization rate is modeled as mass transfer from the surrounding gas onto the particles, using a plasma coating zone where this transfer may happen. Mass transfer is switched off outside this zone. The DEM contact parameters and drag force are calibrated to our cellulose beads model powder using experimental tests composed by the FT4 rheometer and spouting tests. We show that while the chemistry can make or break the process, the equipment design and process conditions have a non-negligible effect on the coating metrics and thus must be considered. Cases where the fluidization flow is not high enough to produce good mixing have a high coefficient of variation of the coating mass, and therefore, they must be avoided. In addition, we also proposed an extrapolation procedure to provide results at longer coating times, showing that it is possible to predict coating performance even when simulations of the process for more than a minute are not computationally efficient.

Extreme erosion wear from elevated temperature caused by the impact of entrained solid particles in the fluid stream primarily affects aerospace components and marine parts. This work focuses on increasing the base material erosion resistance by applying thermally sprayed carbide-based coatings. A high-temperature Solid particle erosion behavior of WC-Co/NiCr/Mo and Cr3C2-CoNiCrAlY coatings deposited by the HVOF process on a titanium-31 was evaluated using an air-jet erosion tester. The erosion test was conducted utilizing alumina erodent of grit size 35-50 µm. The effects of impact angles (30°, 60°, and 90°) and temperatures (200-800 °C) on the erosion performance of two coatings are compared. The feedstock powder and as-sprayed coatings were characterized for micro-structure phase composition, porosity, density, micro-hardness, and adhesion strength. SEM/EDS and a 3D optical profilometer were used to examine eroded samples further to determine the erosion mode. The Cr3C2-CoNiCrAlY coating shows a brittle mode behavior of erosion at 200-400 °C and ductile mode behavior of erosion at 600-800 °C. In contrast, the WC-Co/NiCr/Mo coating shows brittle mode behavior of erosion at 200-400 °C and 600-800 °C, a mixed mode behavior of erosion. The erosion loss in volume of Cr3C2-CoNiCrAlY is lower than WC-Co/NiCr/Mo for all temperatures and impact angles. The development of carbide and oxide phases on the eroded surfaces demonstrates increasing erosion resistance at high temperatures. The optical profilometer measures the volumetric erosion loss, compares it with the weight loss method, and finds consistency between them. [ABSTRACT FROM AUTHOR]

In this study, satellited CoNiCrAlY/nano-Al2O3 feedstocks with 2 wt.% of oxide nanoparticles and pure CoNiCrAlY powder were deposited by the HVOF and LPPS processes on Inconel738 superalloy substrates. Microstructure and phase composition of powders and coatings were characterized by FESEM and XRD, respectively. The early-stage oxidation test was done at 1050 °C for 10 min. The results showed that the satelliting seems to be a promising method to produce nano-particles dispersed composite powders suitable for thermal spraying. Adding α-Al2O3 nanoparticles increased the porosity of the HVOF and LPPS coatings from 0.6 to 1 and from 2 to 2.45 vol.%, respectively. In the HVOF-sprayed CoNiCrAlY/nano-Al2O3, coating including γ-Co,Ni,Cr, β-(Co,Ni)Al, and α-Al2O3, the growth of non-protective NiO and spinel oxides was significantly limited and a dense α-Al2O3 oxide layer was promoted after the early-stage of oxidation. However, for the LPPS-deposited CoNiCrAlY/nano-Al2O3 coating consisting of γ-Co,Ni,Cr and γ-Al2O3, after oxidation, the presence of Al-rich oxides like θ-Al2O3 whiskers and porous transformed α-Al2O3 were observed on the coating. The correlation between microstructure, phase composition, and early-stage oxidation was discussed in detail. [ABSTRACT FROM AUTHOR]

Coating is a popular technique for the corrosion protection of mild steel (MS) in its various service environments. This work investigated the effectiveness of protecting mild steel from corrosion in sulphuric acid (H2SO4) solutions using calcined cattle bone waste powder coating. A cattle bone (CB) femur was obtained from an abattoir, washed, dried, pulverized, and sieved to obtain powder of 75-micron size. The powder was calcined at 600°C, 750°C, and 900°C using a constant holding time of 3 hrs. The functional groups present in uncalcined and calcined samples were identified using FTIR spectroscopy. The calcined CB powder was dissolved in HNO3 to obtain a 0.5 g/ml concentration that was deposited on the mild steel substrates using the spray deposition method at a set deposition time of 5 minutes. The thickness of the deposits was determined using a thickness gauge, while the surface of coated samples was viewed with a scanning electron microscope (SEM). The corrosion protection of the coating on mild steel samples was ascertained in 1M H2SO4 using the potentiodynamic polarization technique. The results indicated that the corrosion protection efficiency increased with an increase in calcination temperature to attain a maximum value of 91% for the sample coated with CB powder heated to 900°C. The corrosion rate of the uncoated sample, which was 0.02063 g/hr., decreased to 0.000178 g/hr. The FTIR result showed that uncalcined and calcined samples contained OH−, CO32−, and PO43− ions, which impacted their corrosion behaviours. This study proved that CB waste powder coating reduced the corrosion rate of mild steel in H2SO4 solution significantly and added value to this waste material. [ABSTRACT FROM AUTHOR]

Purpose: Epoxy zinc-rich coatings are widely used in harsh environments because of the long-lasting cathodic protection of steel surfaces. The purpose of this paper is to use flake zinc powder instead of the commonly used spherical zinc powder to reduce the zinc powder content. Design/methodology/approach: In this paper, the authors have prepared an anticorrosive zinc-rich coating using a flake zinc powder instead of the conventional spherical zinc powder. The optimal dispersion of scaly zinc powder in zinc-rich coatings has been explored by looking at the surface and cross-sectional morphology and studying the cathodic protection time of the coating. Findings: The final epoxy zinc-rich coating with 35 Wt.% flake zinc powder content was prepared using sand-milling dispersions. It has a similar cathodic protection time and salt spray resistance as the 60 Wt.% spherical zinc-rich coating, with a higher low-frequency impedance modulus value. Originality/value: This study uses flake zinc powder instead of the traditional spherical zinc powder. This reduces the amount of zinc powder in the coating and improves the corrosion resistance of the coating. [ABSTRACT FROM AUTHOR]

It is important to precisely polish the inner surface of medical-grade TA1 pure titanium capillary tubes in order to reduce sample residue and enhance capillary pipetting precision, ultimately improving the accuracy and reliability of in vitro diagnostic equipment. To address the subpar inner surface quality of TA1 capillary tubes and the challenges associated with titanium material polishing, a novel chemically-assisted magnetic compound fluid polishing method was proposed. This method combines oxidation and mechanical removal to efficiently and precisely polish the inner surface of the tubes. Experimental studies were carried out to examine the effects of iron powder mass, hydrogen peroxide concentration and malic acid concentration on both the material removal rate and the inner surface roughness, with the aim of determining the optimal polishing parameters. The study involved the examination of surface morphology and elemental changes on the inner surface of capillary tubes both before and after polishing. This analysis aimed to assess the overall impact of the polishing technique on the inner surface of pure titanium capillary tubes. The results indicated that following a 90-minute polishing process under the specified conditions of 2 mg of iron powder, a hydrogen peroxide concentration of 7.2% and a malic acid concentration of 6%, the surface roughness of the TA1 capillary tube decreased from Ra 675 nm to Ra 75 nm. In the well-polished area devoid of initial dents, the surface roughness reached Ra 19.5 nm, with a material removal depth of up to 28 µm. Furthermore, the original surface scratches were effectively eliminated, both the depth and width of dents were significantly reduced, and no additional elements were introduced during the polishing process. [ABSTRACT FROM AUTHOR]

This research article aims to investigate the impact of various types of powder coatings on the resulting dimensional accuracy in the optical 3D scanning process. The experimental study utilises the GOM ATOS II Triple Scan scanner with measuring volume MV100 to conduct a series of measurements. Different powder coatings, varying in composition and application area, are sequentially applied to the measured etalon. The digitised data is then imported into the GOM Inspect software, enabling necessary measurements and result evaluation. This paper leverages engineering knowledge and proficiency with the GOM Inspect metrology software. The anticipated outcomes of this experiment are expected to offer novel insights into the influence of diverse powder coatings on dimensional accuracy. These findings can have practical implications across industries where measurement accuracy is crucial. Furthermore, this research can serve as a foundation for future advancements in the field and provide valuable guidance for selecting the appropriate scanning powder for specific optical 3D scanning applications. [ABSTRACT FROM AUTHOR]

Copyright of Coatings & Protection / Tuceng yu Fanghu is the property of Coating & Protection Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Titanium coating on a steel substrate by surface technology can improve the corrosion resistance of steel. In this paper, the titanium TA2 coating was deposited on X80 steel by cold spraying equipment with a low-cost irregular powder. The effects of the carrier gas temperature on the microstructure, microhardness, wear resistance, adhesion and corrosion resistance of titanium coatings, especially in a deep sea environment, were studied by methods of porosity analysis, thermal field emission scanning analysis, energy spectrum analysis, Vickers hardness tests, bonding strength tests, friction and wear tests and electrochemical tests. The results showed that as the carrier gas temperature increased from 300 °C to 900 °C, the porosity of the coating decreased to 0.93%, and the hardness and bonding strength of the coating increased to 247 HV0.5 and 46.7 MPa, respectively. With the increase in hydrostatic pressure from 0.1 MPa to 40 MPa, the dimensional blunt current density of the titanium coating with 0.93% porosity was still in the order of 10−7 A·cm−2 with the cast titanium TA2. [ABSTRACT FROM AUTHOR]

Estimating depth from images is a common technique in 3D perception. However, dealing with non-Lambertian materials, e.g., transparent or specular, is still nowadays an open challenge. However, to overcome this challenge with deep stereo matching networks or monocular depth estimation, data sets with non-Lambertian objects are mandatory. Currently, only few real-world data sets are available. This is due to the high effort and time-consuming process of generating these data sets with ground truth. Currently, transparent objects must be prepared, e.g., painted or powdered, or an opaque twin of the non-Lambertian object is needed. This makes data acquisition very time consuming and elaborate. We present a new measurement principle for how to generate a real data set of transparent and specular surfaces without object preparation techniques, which greatly reduces the effort and time required for data collection. For this purpose, we use a thermal 3D sensor as a reference system, which allows the 3D detection of transparent and reflective surfaces without object preparation. In addition, we publish the first-ever real stereo data set, called TranSpec3D, where ground truth disparities without object preparation were generated using this measurement principle. The data set contains 110 objects and consists of 148 scenes, each taken in different lighting environments, which increases the size of the data set and creates different reflections on the surface. We also show the advantages and disadvantages of our measurement principle and data set compared to the Booster data set (generated with object preparation), as well as the current limitations of our novel method. [ABSTRACT FROM AUTHOR]

In order to study the shot peening that occurs during the application of powder coatings, experiments are carried out on glass shot peening of steel test strips using a CCDS2000 detonation device. Experimental dependences of the shot peening depth and the residual stresses in a hardened layer on treatment parameters (particle size, density, and velocity, as well as the strength of the test strip material) are obtained. Engineering equations are proposed for calculating the values of and . [ABSTRACT FROM AUTHOR]

Thermoset powder coatings exhibit distinctive characteristics such as remarkable hardness and exceptional resistance to corrosion. In contrast to conventional paints, powder coatings are environmentally friendly due to the absence of volatile organic compounds (VOCs). However, their irreversible cross-linking structures limit their chain segment mobility, preventing polymers from autonomously repairing cracks. Dynamic cross-linking networks have garnered attention for their remarkable self-healing capabilities, facilitated by rapid internal bond exchange. Herein, we introduce an innovative method for synthesizing thermoset epoxy containing boronic ester moieties which could prolong the life of the powder coating. The epoxy resin system relies on the incorporation of two curing agents: one featuring small-molecule diamines with boronic bonds and the other a modified polyurethane prepolymer. A state of equilibrium in mechanical properties was achieved via precise manipulation of the proportions of these agents, with the epoxy composite exhibiting a fracture stress of 67.95 MPa while maintaining a stable glass transition temperature (Tg) of 51.39 °C. This imparts remarkable self-healing ability to the coating surface, capable of returning to its original state even after undergoing 1000 cycles of rubbing (using 1200-grit abrasive paper). Furthermore, the introduction of carbon nanotube nanoparticles enabled non-contact sequential self-healing. Subsequently, we introduce this method into powder coatings of different materials. Therefore, this work provides a strategy to develop functional interior decoration and ensure its potential for broad-ranging applications, such as aerospace, transportation, and other fields. [ABSTRACT FROM AUTHOR]

A novel strategy for manufacturing of the main insulation of high‐voltage rotating machines is presented. The developed process is based on established electrostatic powder coating equipment. Using complete automation enables the precise and reproducible application of homogeneous powder coating layers. Individual layers can be stacked by process repetitions to achieve a desired layer thickness. This coating strategy alters the particle deposition process by introducing additional capillary bridges that significantly increase powder adhesion. A systematic parameter study is performed to provide process–structure relations connecting various process parameters with the resultant coating thickness and homogeneity. The parameters of the developed coating process are iteratively improved to maximize coating homogeneity and minimize defect density, the most critical parameters in high‐voltage insulation applications. The obtained powder coatings with a target thickness of 1.5 mm are subjected to electrical testing to examine the partial discharge activity as a key criterion for a functional insulating coating. The measurements reveal no significant partial discharge activity up to an electric field strength of 10 kV mm−1, demonstrating that this novel strategy for the production of the main insulation of high‐voltage rotating equipment surpasses the state‐of‐the‐art process in terms of partial discharge activity. [ABSTRACT FROM AUTHOR]

Nanoclay has proven to be an active anti-corrosive additive due to the self-repairing effect from nanoclay swelling and expansion, except for its passive barrier effect due to the high aspect ratio. But it is still uncertain how these effects of nanoclay are intertwined with the other components in a complex coating system in corrosive environments. In this study, we examined the combined effects of nanoclays of two particle sizes with a commonly used cost-reducing filler, BaSO4. By employing neutral salt spray tests, electrochemical analysis, and surface characterization, we identified the optimal conditions for achieving a strong barrier effect. Surprisingly, a relatively low nanoclay dosage of 2% combined with BaSO4 filler exhibited synergistic behavior. Nanoclay not only compensated for the reduction in the barrier effect owing to the addition of BaSO4 by offering self-repairing and barrier effects, but also overcame the delamination issues observed at higher nanoclay dosages (4% and above). The coating panel with 2% larger nanoclay and BaSO4 showed two orders of magnitude higher pore resistance than the coating without nanoclay, remaining at 107 Ω∙cm2 after 25 days of immersion. As a result, this coating panel demonstrated significantly slower corrosion expansion and reached a lifetime of 2500 h when creepage exceeded 2 mm in salt spray tests. This study contributes to a full understanding and proper utilization of nanoclay for high-performance, smart anti-corrosive coatings. [ABSTRACT FROM AUTHOR]

Magnesium alloys, because of their excellent strength-to-weight ratio, are increasingly used in many industries. When used in external elements, the key factor is to provide adequate anticorrosion protection. High-temperature, cured-powder coatings are widely used to protect most metals, but their use on magnesium alloys is difficult as a result of the instability of the magnesium substrate at elevated temperatures. Another problem is ensuring the proper adhesion of the organic coating to the magnesium substrate. This paper presents the procedure for the synthesis of a duplex coating on AZ91 magnesium alloy. The topcoat was a powder coating based on acrylic resin, the main ingredient of which was glycidyl methacrylate. Because of the presence of epoxy groups, the coating was cured using ultraviolet (UV) radiation (low-temperature technology). The conversion subcoating was produced by plasma electrolytic oxidation (PEO) in an alkaline silicate electrolyte. The synthesized coating system was tested, among others, for microscopic (SEM), adhesive (mesh of cuts), and anticorrosion (EIS). The duplex PEO/UV-curable powder coating showed very good adhesion to the metal and increased the anticorrosion properties of the magnesium substrate, compared to the powder coating produced directly on the magnesium alloy and on an alternative conversion coating (synthesized in the process of chemical zircon phosphating).

The aim of this investigation concerns evaluating the mechanical strength and microhardness values of A356 alloy samples in distinctive heat treatments, including those commonly applied to automotive wheels. It is recognized that A356 and Al-Si-based alloys exhibit considerable versatility across numerous industrial applications. The mechanical behavior obtained is intimately associated with different operational parameters (e.g., cooling rates, solution treatment, quenching, and artificial aging). In this study, a group of samples are quenched at 30, 60 and 80 °C. Another set is quenched and subsequently aged at three different temperatures, i.e., 180, 200, and 220 °C for 5 h, and mechanical responses are compared. Microstructural characterization, X-ray diffraction (XRD) analysis, tensile testing, and microhardness measurements are carried out. Using the Rietveld data and based on the modified Williamson–Hall method, the microstrains, crystallite size, and dislocation densities are calculated. Based on this, the resulting mechanical strengths from distinctive quenching and aging are understood. It was found that there exists a “quasi-optimal range” of operational parameters involving different A356 alloy treatments, which vary depending on the manufacturing route. Considering A356 alloy wheels, the planning of the powder coat treatment before or after T6 treating provides better mechanical properties and ductility.

Copyright of China Plastics / Zhongguo Suliao is the property of Journal Office of CHINA PLASTICS and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This work focuses on different surface treatment processes of the 6061 aluminum alloy profile coatings in the construction industry, mainly including the sand powder film coating, the flat powder coating, the hard anodized film, and the ordinary heat-sealing oxidized coating. The corrosion resistance of the coated aluminum alloy in a 3.5 wt.% NaCl solution (pH 6.5–7.5) and the influence of different surface treatment processes on the corrosion resistance of different samples were studied by scanning electron microscope (SEM) and electrochemical workstation. The result shows that with the increase in corrosion time, the corrosion inhibition performance of the four coated aluminum alloy materials decreased significantly, and the order of decline is: sand powder film coating > hard anodized film > flat powder coating > ordinary heat-sealing oxidized coating. When corroded in a 3.5 wt.% NaCl solution for 2 h, the corrosion inhibition performances of the flat powder coating and ordinary heat-sealing oxidized coating are poor, while the inhibition performances of the sand powder film coating and hard anodized film are good, and the inhibition performance follows the following sequence: the sand powder film coating > hard anodized film> the flat powder coating > ordinary heat-sealing oxidized coating. When corroded in a 3.5 wt.% NaCl solution for 200 h, the corrosion inhibition performances of the sand powder film coating and the flat powder coating are poor, while the inhibition performances of hard anodized film and ordinary heat-sealing oxidized coating are good, and the inhibition performance follows the following sequence: hard anodized film > ordinary heat-sealing oxidized coating > the sand powder film coating > the flat powder coating. [ABSTRACT FROM AUTHOR]

Among non-metal substrate coatings, plastic substrates have certainly asserted themselves as a key market, especially in the automotive industry. The substrates within exterior automotive industries are being diversified and commercialized at a rapid pace. Mainly attributed to the emergence of electric vehicles, environmental regulations, and functional requirements, there is huge scope and many opportunities for advancements and groundbreaking technologies. The above factors have led to the dawn of new and improved coating materials within the revolutionizing new substrate market. At the same time, new product innovations within ultraviolet (UV)-curable technologies, powder coating, nanotechnologies, and several other platforms have brought the possibility of novel coating systems into the picture. This review outlines the inherent challenges, the progress made thus far, and the future opportunities of two significant exterior plastic substrates: thermoplastic polyolefin (TPO) and polycarbonate (PC). While the former serves as the historical choice for plastic bumpers across the globe, the latter has captured the most research attention in recent times as a lightweight option against glass coatings. A meticulous overview of the existing literature was conducted to summarize the recent approaches with a few critical analyses. To surpass the challenges to the equivalent performances, a few of the most promising research studies were also examined, including the sustainability aspect. [ABSTRACT FROM AUTHOR]

The particle size of powder coatings is an important factor affecting flow and fluidization performance, which in turn determines the quality of the coating. Powder coating particles, such as boron nitride, titanium dioxide, barium titanate, niobium oxide, and tungsten oxide, can be seen in SEM images as circular or polygonal shapes, with irregular edges and sizes, as well as aggregation and stacking between them. This paper introduces a novel method of automatic particle identification and size analysis applied in SEM images for the investigation of coating quality. Firstly, a fast gradient segmentation algorithm (Split–Merge) is utilized to automatically generate samples through determining the adhesive particles and particle groups. The samples are then manually checked and corrected to further segment the particles in order to form the dataset. Finally, the YOLOv5, a mature target detection algorithm, is used to train the labeled data in order to produce a multi-target detection recognition model. The model can be applied to identify more pictures of the same substance, and the particles' long and short axes are estimated using the elliptical coverage of the particles within the identified image boundary box. Experiment results from four kinds of powders suggest that this method can provide automatic particle size analysis for industrial SEM particle images. [ABSTRACT FROM AUTHOR]

Based on the alkali resistance of polyester/TGIC, polyester/HAA, polyester/epoxy and polyurethane powder coatings, the hydroxy-terminated polyester resin is modified by means of using some monomer containing steric groups and improving the crosslinking density. The results show that polyester/TGIC and polyester/HAA systems have the worst alkali resistance, polyester/epoxy system is slightly better, and polyurethane system is the best. The modified hydroxy-terminated polyester resin has good mechanical properties, adhesion, boiling water resistance and excellent alkali resistance. At 30 °C, soaked by 50%wt NaOH for 96 h, the gloss retention rate is 77% with no cracking and other defects. At 60 °C, soaked by 50%wt NaOH for 22 h, the gloss retention rate is 60% with no cracking and other defects. [ABSTRACT FROM AUTHOR]

Copyright of China Plastics / Zhongguo Suliao is the property of Journal Office of CHINA PLASTICS and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The present paper is aimed to improve the microhardness and corrosion protection of magnesium (AZ31B) alloy by employing Cu-Zn-Al2O3 coating through cold spray method. A fully dense coating of thickness ~ 877 μm has been achieved due to hammering effect of dense Al2O3 particles. The compositional and microstructural analysis of feedstock powder as well as coatings has been studied and discussed. An enhanced microhardness value of 219 ± 7 HV0.1 (~ 3 times higher) is obtained for Cu-Zn-Al2O3 coating compared to bare Mg alloy substrate (70 ± 10 HV0.1). The corrosion properties of the coatings were examined by potentiodynamic polarization and long-term immersion tests (24, 48, 96 and 336 h) in a 3.5% NaCl solution. Long-term immersed samples showed a positive shift in potential compared to the as-sprayed coated sample. The polarization resistance (Rp) measured is well in accordance with the measured Icorr. Coated samples after immersion for 336 h in 3.5% chloride medium resulted in the formation of a protective passive layer of ZnO and simonkolleite on the surface, which is responsible for corrosion protection of AZ31B alloy. These results are well supported by FESEM, EDAX and XRD data. This study provides an eco-friendly approach for corrosion protection of AZ31B alloy. [ABSTRACT FROM AUTHOR]

Flaky FeSiCr@SiO 2 composites with broadband and intense absorption were successfully synthesized by modified Stöber method. The phase, microstructure and morphology of flaky FeSiCr@SiO 2 composites were investigated by XRD, FT-IR, SEM and TEM, confirming the successful preparation of SiO 2 coating. The thermal behavior of flaky FeSiCr@SiO 2 composites was analyzed by TGA/DSC. The results showed that the oxidation resistance of the coated FeSiCr powder was promoted. The electromagnetic wave absorption properties of samples with different contents of tetraethyl orthosilicate (TEOS) were systematically investigated. The sample synthetized with 10 ml TEOS possesses the optimal absorption performance, which is attributed to the synergistic effect of magnetic loss and dielectric loss. The minimum reflection loss is −65.3 dB at 4.4 GHz. And the maximum effective absorption bandwidth is 6.0 GHz with only a 1.5 mm thickness. In particular, by controlling the thickness of the absorber, the effective absorption bandwidth can reach 13.3 GHz (2.9–16.2 GHz), covering the entire C and X bands. Thus, the flaky FeSiCr@SiO 2 composites can be used as high-performance microwave absorption materials. [ABSTRACT FROM AUTHOR]

The results of studying the density of powder coatings obtained by the electrocontact method are presented. The functional performance of coatings presents the two problems: density and strength of adhesion to the base. Review and analysis of theoretical and practical aspects of producing powder coatings resulted in deciding the prime lines of research on their density, which are related to the mechanics of their compaction on formation, establishment of basic density against pressure relations, micromechanics of the contact interaction of powder particles and surface to be hardened. The three stages of powder coating formation by the electrocontact method are recognized: powder precompaction, second compaction and preheating, sintering. The dominant processes are cold molding (pressing), hot pressing (sintering) or rolling. Cold molding is governed by the density-pressure relation, which was viewed in the context of the discrete powder nature concept, based on the analysis of contact interaction and deformation conditions of single powder particles. Phenomenologically, molding of powder materials under pressure at high temperatures (hot pressing or rolling) results in the change of linear dimensions of a porous powder body, which is appropriate for consideration as a rheological process, i.e., change of the form and volume of the dispersed system with time. The kinetics for powder particles in contact and their interfacial (base) contact is presented. In the coating formation, powder particles are bonded to the base as a result of their deformation, mechanical cohesion, adhesion, and welding in between and with the base. The interpolation equation that describes the powder layer compaction on its formation by the electrocontact method (coating density against pressure whereby the tool electrode compacts the powder layer) is proposed. Theoretical and experimental results for the powder coating density related to the pressure of their formation by the electrocontact method were obtained. [ABSTRACT FROM AUTHOR]

Aerogels, the lowest-density solids in the world, have very effective thermal insulation properties with their extremely high surface area and porous structure. Recently, there has been an increasing interest in using aerogels in the textile industry, especially to obtain functional and technical textiles. In this study, thermal and solar properties of polyester fabrics coated at different concentrations (1 %, 2 %, and 4 %) of aerogels with different particle sizes (~ 8 µm, 0 - 80 µm, 0 - 0.5 mm) were investigated. It was observed that the aerogel particle size and concentration had a significant effect on the thermal and solar properties, and the lowest thermal conductivity coefficient and thermal resistance values (0.036 W/mK and 14.33 m2 K/W, respectively) appeared at the largest particle size and maximum concentration. In contrast, the solar reflectance values of the coated samples decrease up to 62 % with increasing aerogel particle size. In a conclusion, the coating method with aerogel powders could be applied to improve the thermal insulation and solar protection properties of mainly curtains, tents, tarpaulins, and sportswear fabrics. [ABSTRACT FROM AUTHOR]

This research aims to develop bitter taste-masking microcapsules containing azithromycin (AZI) by a simpler and familiar method, fluid-bed coating technology, in comparison with Zithromax®. Cores of microcapsules, AZI microparticles, were prepared by fluid-bed granulation, then taste-masking polymer was covered on by fluid-bed coating technique. Eudragit L100, Eudragit RL100, and ethyl cellulose in single and combined with Eudragit L100 and Eudragit E100 were used as taste-masking polymers. The obtained microcapsules were characterised by taste-masking ability, in vitro release, SEM, coating thickness, and coating efficiency. Combination of ethyl cellulose and Eudragit E100 (3:1) in coating thickness of 45.13 ± 2.12% w/w prevents AZI release from microcapsules below bitter taste threshold (1.78 ± 1.17 µg/ml). Bioavailability of powders containing AZI microcapsules and pH modulators (50 mg Na3PO4 and 35 mg Mg(OH)2) was not significantly different from the reference product (Zithromax®, Pfizer, New York, NY) in the rabbit model (p > 0.05). These results support the possibility of developing a generic product containing AZI. [ABSTRACT FROM AUTHOR]

The coating of aluminum nitride powder has a great importance industrially and environmentally. AlN can be rapidly hydrolyzed to aluminum hydroxide and ammonia in the atmosphere or water media. To prevent the hydrolysis of AlN, the inorganic or organic based coatings are used frequently. For the first time, this study describes the phosphate esters as organophosphate coating used for the inhibition of hydrolysis reaction of AlN in its water suspension. Phenyl phosphate showed the best inhibition against AlN hydrolysis with an easy application technique and at low concentration of 0.005 M. AlN coating efficiency was proved by spectroscopic and imaging methods. It was concluded that the coating acquired the protective properties of phenyl phosphate through its water repellence. [ABSTRACT FROM AUTHOR]

The potential of wastewaters from the galvanic industry treated to remove toxic heavy-metal contaminants for the manufacture of commercial products lies in the development of processes for their reuse. This research addresses the feasibility of employing galvanic waste in the production of powder coatings. Powder waste generated through the resource-saving ferritic method and electroerosion dispersion method is significantly safer for the environment than that generated through reagent methods. Coatings resulting from wastewater treatment exhibit mechanical properties that meet current industry standards. The introduction of 15 wt.% spent polyvalent iron oxide sorbent into paint coatings enhances their mechanical performances. Specifically, the rebound strength increases from 20 to 40 cm/kg and tensile strength from 5 to 7.4 mm, the bending strength decreases from 8 to 5 mm, and the corrosion resistance of the coatings improves by 1.5 times compared to the standard samples. These improvements are attributed to the introduction of chemically and thermally stable crystalline phases possessing ferromagnetic properties into the coatings. As a result, these coatings increase shielding against electromagnetic radiation in the megahertz range by three times compared to the standard coatings. A significant research finding is the potential for reusing ferromagnetic waste from the galvanic industry in specialized materials. [ABSTRACT FROM AUTHOR]

Brake lining, a friction lining material has over the years been produced mainly from asbestos. Asbestos health hazards have necessitated the need to source friction lining materials from other safer directions. A novel composite from local materials was developed. The brake lining production was a dispersion hardening process by the techniques of powder metallurgy of finely divided particles of the raw material powder mix. The raw materials included sawdust, resin, rubber latex, clay, carbon black, brass chips, zinc oxide and sulphur. The friction lining material thus produced, with its friction coefficient was analysed relative to its responses to increasing temperatures and pressures. The environment of increasing temperatures and pressures is its operating condition, in situ. Temperature range studied was from 300C-3000C, while pressure range was from 50KPa-250KPa. Results of the analysis showed the fiction coefficient not adversely affected, with minimum value at 0.31 and maximum value at 0.56. [ABSTRACT FROM AUTHOR]

Copyright of Coatings & Protection / Tuceng yu Fanghu is the property of Coating & Protection Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Powder coatings are a promising, solvent-free alternative to traditional liquid coatings due to the superior corrosion protection they provide. This study investigates the effects of incorporating montmorillonite-based nanoclay additives with different particle sizes into polyester/triglycidyl isocyanurate (polyester/TGIC) powder coatings. The objective is to enhance the corrosion-protective function of the coatings while addressing the limitations of commonly employed epoxy-based coating systems that exhibit inferior UV resistance. The anti-corrosive and surface qualities of the coatings were evaluated via neutral salt spray tests, electrochemical measurements, and surface analytical techniques. Results show that the nanoclay with a larger particle size of 18.38 µm (D50, V) exhibits a better barrier effect at a lower dosage of 4%, while a high dosage leads to severe defects in the coating film. Interestingly, the coating capacitance is found, via electrochemical impedance spectroscopy, to decrease during the immersion test, indicating a self-repairing capability of the nanoclay, arising from its swelling and expansion. Neutral salt spray tests suggest an optimal nanoclay dosage of 2%, with the smaller particle size (8.64 µm, D50, V) nanoclay providing protection for 1.5 times as many salt spray hours as the nanoclay with a larger particle size. Overall, incorporating montmorillonite-based nanoclay additives is suggested to be a cost-effective approach for significantly enhancing the anti-corrosive function of powder coatings, expanding their application to outdoor environments. [ABSTRACT FROM AUTHOR]

Massive production of tiny droplets is critical for industrial processes and biomedical applications. Such droplets are formed by splitting the bulk liquid (top-down) or condensation to grow the droplet (bottom-up). Various generation methods have been reported; however, the generated droplets stick to the contacting substrate and/or coalesce into a larger droplet, limiting handling flexibility and/or size uniformity. Herein, tiny powder-stabilized droplets were massively generated by applying pulse pressure to a "powdered" superhydrophobic mesh on a water pool. The generated droplets were stabilized by a fine hydrophobic powder, namely, liquid marble, which does not coalesce or stick to the contact materials. The effects of mesh size, wettability, powdering, and applied pressure on the droplet formation dynamics were investigated. The generated droplet size depended on the mesh size and droplets were not formed on the hydrophilic mesh. When the superhydrophobic mesh gradually sank into the water pool to apply quasi-static hydro-pressure, the penetrated water did not split, and a continuous large water droplet was formed. However, tapping the superhydrophobic mesh to apply pulsed hydro-pressure induced multiple droplets to split through the mesh penetration. Without powder, the formed droplets coalesced to form large droplets. However, when the superhydrophobic mesh was powdered, the formed droplets were coated with the hydrophobic powder to form a liquid marble, preventing their coalescence. [ABSTRACT FROM AUTHOR]

Apple pomace, which makes up 20–30% of all processed apples, is an accessible source of bioactive ingredients that could be used in the food industry. A research of the impact of drying techniques on the quality characteristics of apple pomace powder was carried out to efficiently utilize this waste. The pomace was dried at 50 °C and 60 °C in a vacuum-assisted microwave dryer and an oven dryer, respectively. The different temperatures chosen for the drying of apple pomace were selected based on preliminary tests. Microwave drying resulted in reducing the drying time and improving the physicochemical, functional and morphological properties of the powder. The TPC (Total phenolic content) and AA (antioxidant activity) of pomace powder were found to be considerably influenced by the drying technique. Maximum TPC, DPPH and FRAP values observed for the apple pomace powder dried in the microwave were 5.21 ± 0.09 mg GAE/g, 93 ± 1% and 3.22 ± 0.04 µg/mg, respectively while as in oven drying, the values were 3.14 ± 0.06 mg GAE/g, 89 ± 1% and 2.22 ± 0.02 µg/mg. Microwave drying led to increasing bulk density (0.55 ± 0.01 g/cc), water hydration capacity (3.35 ± 0.09 mL/g), oil binding capacity (0.95 ± 0.04 g/g), solubility index (14.0 ± 0.9%), and emulsion capacity (60.0 ± 1.0%) of the powder. Lower values for bulk density (0.50 ± 0.01 g/cc), water hydration capacity (3.04 ± 0.08 mL/g), oil binding capacity (0.70 ± 0.03 g/g), solubility index (10.0 ± 0.8%), and emulsion capacity (48.0 ± 0.9%) were observed in oven-dried powder. Microwave drying resulted in a more disordered, crystalline and porous structure of apple pomace powder as compared to oven-dried powder as confirmed by SEM (Scanning electron microscopy) and XRD (X-ray diffraction). Microwave-dried powder also had a higher vitamin C content (20.00 ± 0.12 mg/100 mg) than oven-dried powder (12.53 ± 0.08 mg/100 mg). This study may be helpful in the preprocessing of apple pomace for bioconversion processes and extraction of valuable components from apple pomace. Highlights: ✔ Vacuum-assisted microwave dryer reduced the drying time of apple pomace by 87% as compared to conventional oven drying ✔ Microwave drying improved the physicochemical, morphological and functional properties of apple pomace powder ✔ The overall quality of the apple pomace was improved by microwave drying than conventional oven drying [ABSTRACT FROM AUTHOR]

To demonstrate the difference in moisture adsorption properties of fibers and the influence on the moisture adsorption properties of the five plant fibers ( conifer, broadleaf, flax, grass and bamboo) and one regenerated fiber ( Tencel), as well as the adaptability between moisture adsorption properties of fibers and coating performance of reconstituted tobacco for heated tobacco products, were studied. The results showed that the moisture adsorption properties of the six fibers were different. Tencel fiber performed the best, followed by bamboo fiber, and flax fiber performed the worst. The maximum adsorption rate and desorption rate of the fibers increased significantly with the increase of relative humidity during moisture migration. The parallel exponential dynamic model (PEK) was used to fit the moisture migration, it indicated that the progress consisted of a fast and a slow sorption procedure which occurred simultaneously. The fast procedure dominated the water migration behaviour in the sheet. As the relative humidity increased, the equilibrium moisture absorption content of the fast procedure increased and its characteristic time decreased. Meanwhile, the characteristic parameters of the slow procedure had no obvious rule with relative humidity. The micro-structure morphology, environmental conditions and other factors strongly influenced the moisture adsorption properties of fibers, the hygroscopic properties of fibers were positively correlated with the relative humidity ( RH), negatively correlated with the crystallization of cellulose, while the temperature showed a weak effect on it. It was found that the reconstituted tobacco sheet showed outstanding coating performance including water and coating liquid with the application of excellent hygroscopic fibers under the condition of adding the same amount ratio during application. [ABSTRACT FROM AUTHOR]

The aim of this study was to optimize the formulation of coating of bulked corn products using maltodextrin, corn and spinach in order to improve the nutritional characteristics of puffed snacks. oil (55 -65%) and powder materials (35 -45%) as fixed components (80%) including milk powder, whey powder and salt (25, 50 and 5%, respectively) – and variable components (20%) including cheese powder, maltodextrin and corn starch were used to prepare the coating. Optimization was done with cross statistical design. After the physicochemical and sensory tests and selecting the optimal sample, spinach powder was added to the optimal formulation at 4, 6, and 8%, and sensory tests and uniformity evaluation were performed. The results showed that the oil absorption, hardness, redness, colloidal stability and sensory characteristics of the sample was increased by use of corn starch in the coating formulation, but overall acceptance was reduced, while redness and sensory characteristics increased by use of maltodextrin and oil absorption and hardness was reduced. The oil absorption, hardness, colloidal stability and flavor increased by use of cheese powder in the coating and redness and sensory characteristics reduced. Increasing the percentage of oil to 63% increased oil absorption and decreased the redness index (p<0.05). Increasing the percentage of oil to 60% significantly increased texture hardness, colloidal stability and color factor (p<0.05). The best optimal coating containing 10% each maltodextrin and cheese powder and 55% oil was obtained. The scores of sensory factors in the formulation containing 8% spinach powder were significantly higher than the others (p<0.05) and adding 8% of spinach powder to the optimal coating was recognized as the best sample. The results showed that in order to improve the uniformity and stability of the coating emulsion, maltodextrin and corn starch can be used and its nutritional value can be increased by using spinach. [ABSTRACT FROM AUTHOR]

CoCrFeNiTi high entropy alloy (HEA) has been extensively studied to serve as coating materials on complexly shaped parts of equipment used in industries such as oil, gas, and mining due to its high hardness, excellent wear resistance, and good high-temperature stability. Laser-directed energy deposition has potential to fabricated HEA caotings due to its advantages of excellent metallurgical bonding, high coating density, suppressed element segregation, and the capability of thick coating deposition. However, limited investigations have been conducted on the effects of input parameters (such as powder geometry and laser power) on the mechanical properties of laser DED fabricated CoCrFeNiTi high-entropy alloy coatings. In this study, CoCrFeNiTi HEA coatings have been fabricated on Ti substrates from spherical-shaped and irregular-shaped powders under different levels of laser power. The effects of powder geometry and laser power on molten pool thermal characteristics (including temperature, cooling rate, and solidification time), phase constitution, microstructure, and mechanical properties of hardness and wear resistance have been investigated. Under the same laser power, the utilization of irregular-shaped powders resulted in uniform microstructures and higher hardness. For the coatings fabricated from spherical-shaped powders, the increase of laser power could improve the microhardness and wear resistance. For the coatings fabricated from spherical-shaped powders, the increase of laser power could increase the microhardness. However, the wear resistance is increased and then decreased due to the increase in friction of coefficient. [ABSTRACT FROM AUTHOR]

Multiphysics simulation software has been developed to predict the key performance attributes of industrial powder coating applications based on applied process-parameter settings. The software is a Eulerian-Lagrangian finite-volume Multiphysics solver based on OpenFOAM, capable of modelling mass transfer effects between powder-coating pistols and electrically grounded metallic substrates. It considers various factors such as fluid dynamics of process airflow, coating-particle dynamics, particlesubstrate interactions, and particle charging mechanisms within the corona. The software is fully compatible with Massive Simultaneous Cloud Computing technology, allowing hundreds of simulated coating scenarios to be computed simultaneously. Experimental validation efforts have been conducted, indicating a high degree of practical relevance of the technology. The current simulation study aims to demonstrate the potential of the simulation software for adjusting coating lines and optimizing powder coating of U-profiles. Specifically, the study focuses on optimizing the keyperformance-attributes of the powder coating application with respect to varying material parameters of the applied powder, namely mean particle diameter, standard deviation of Gaussian particle size distribution, and powder particle density. The software predicts and visualizes coating patterns, coating efficiencies, and the batch-based standard deviation of coating thickness on a U-shaped metallic substrate, resulting in concrete and optimized powder settings. The presented results and the applied software are highly relevant for powder material suppliers. [ABSTRACT FROM AUTHOR]

Upgraded plasma source based on atmospheric pressure glow discharge device and features of its operation are presented. The main purpose of the upgraded device is the generation of metal-contained plasma flows. A brief review of the state-of-the-art methods for generating metal-containing plasma at atmospheric pressure is given. The possibilities of the application of the described discharge system in research on the production of ultrafine powders and functional coatings are indicated. [ABSTRACT FROM AUTHOR]

In this study, the effect of different concentrations of calcium hydroxide (Ca(OH)2) was evaluated as a pre-treatment for accelerated carbonation and its influence on the fibrillation of cellulosic pulps to obtain nanofibrils, and its application as a coating agent for papers. Eucalyptus (EUC) and Pine (PIN) unbleached cellulosic fibers were submitted to pre-treatment with Ca(OH)2 at concentrations of 5 and 10% and subjected to accelerated carbonation, being subsequently mechanically fibrillated to produce cellulose nanofibrils (CNF). Pretreatment with calcium hydroxide followed by accelerated carbonation provided a 35% reduction in energy consumption. Cellulosic pulps EUC and PIN pretreated with calcium hydroxide showed higher fibrillation efficiency. There was a reduction in the cobb test values for papers coated with CNF in PIN. The WVP was lower for papers coated with CNF of EUC and control PIN. The CNF coating of EUC and PIN provided an oil barrier for the kit 11 solution. The CNF coating improved the dispersion of PVA and PVOH. The papers coated in this work have the potential to be used as packaging for fatty and oily foods or as a spreading agent for other industrial coatings. [ABSTRACT FROM AUTHOR]

In this experiment, we explored how to control the penetration of palmitoyl chloride in the gas grafting of PVOH-coated paper. When calcium carbonate was pre-coated, the gas grafting reaction of the PVOH-coated paper tended to be inhibited. It is believed that palmitoyl chloride is additionally consumed by moisture generated when calcium carbonate neutralizes hydrochloric acid gas, a by-product of the graft reaction, thereby inhibiting the graft reaction and reducing the hydrophobization efficiency by generating unreacted residual free fatty acids. Unlike calcium carbonate, the clay coating layer blocks the penetration of vaporized palmitoyl chloride and improves the gas grafting density of PVOH without moisture generation. The PVOH coating layer, where vaporized palmitoyl chloride penetrates, is thinly processed to avoid unnecessary graft reactions in the thickness direction, and the propagation of palmitoyl chloride in the gas phase is blocked by the clay-coating layer. In previous studies, an excess of 1400 mg/m2 of palmitoyl chloride was required to secure strong hydrophobicity of less than 10 g/m2 of Cobb hot water absorption. However, by pre-coating the clay, only 650 mg/m2 of palmitoyl chloride, which was about a 53% reduction compared to previous studies, was sufficient to perform a strong hydrophobic treatment. [ABSTRACT FROM AUTHOR]

Via micro- and nano-structure design of a coating layer on the bottom of ceramic pots with copper powders and low melting point glass powders, a simple and low-cost solution for fabricating high-efficiency induction heating ceramic pots without changing the induction cookers has been provided. The influences of sintering temperature and glass content on the heating efficiency of the copper layer were studied. The hysteresis loop, resistivity, and microstructure of the copper layer were investigated using a vibrating sample magnetometer, a field-emission scanning electron microscope, and a high-resolution transmission electron microscope, respectively. Microstructure observation revealed that an insulating glass film with 1.06 nm width was formed between the adjacent copper particles in the sintered copper layer. The experimental results showed that the sintered layer made with copper powder slurry had a resistivity of 22.67 × 10–8 Ωm, which is 12.95 times that of a pure copper plate. The saturation magnetization of the sintered layer under the static magnetic field was about 3.55 × 10–2 emu/g, which is 3.38 times that of a copper plate. A ceramic pot with a sintered copper layer takes about 510 s to heat 500 mL of water from room temperature to 100°C under the power of 500 W. Its heating efficiency is comparable to that of a ferromagnetic stainless-steel pot. [ABSTRACT FROM AUTHOR]

The paper is focused on steel surface processing to ensure an improved adhesion of applied powder layer. Mechanical pre-treatment, chemical pre-treatment and their combination were used to compare their results with each other and to find out the pre-treatment that affected the final outcome the most. The final score was determined by the grid method. The outcome displayed a huge mutual dependency between the result and a kind of various surface treatments. The method with no pre-treatment was by far the worst, followed by the mechanical pre-treatment only, followed by the chemical pre-treatment only, and finally by their combination. The time of blasting affects the final outcome. Through the grid method, coating thickness, and aesthetic test it was confirmed that an optimal blasting time of 5 min provides the best outcome. [ABSTRACT FROM AUTHOR]

Copyright of Coatings & Protection / Tuceng yu Fanghu is the property of Coating & Protection Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)