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Epoxy resin powder coating has been successfully applied on the corrosion protection of magnesium lithium alloys. However, poor wear resistance and microcracks formed during the solidification have limited it extensive application. There are limited approaches to exploit such anti-corrosion and mechanical properties of magnesium lithium alloys. Herein, the epoxy resin powder coating with polydopamine modified molybdenum disulfide (MoS2@PDA-EP powder coating with 0, 0.1, 0.2, 0.5, 1.0 wt.% loading) was well prepared by melt extrusion to investigate its anticorrosion performance and wear resistance. The results revealed that the addition of MoS2@PDA enhanced the adhesion strength between coatings and alloys, wear resistance and corrosion protection of the powder coatings. Among them, the optimum was obtained by 0.2 wt.% MoS2@PDA-EP powder coating which could be attributed to well dispersion and efficient adhesion with coating matrix. To conclude, MoS2@PDA-EP powder coating is meaningfully beneficial for the anticorrosive and wear performance improvement of magnesium lithium alloys.

Especially in the transport sector, lightweight design with fiber reinforced plastics (FRP) is of major relevance due to CO2 reduction through mass saving [1]. In sectors like automotive, FRP are mainly used in secondary structures such as seat shells. In order to be able to operate effective FRP lightweight design in load-bearing structural components, pultruded hybrid profiles are to be established as a new tool for engineers. The profile components are characterized by a FRP base structure and a metallic core that increases the ductility. The manufacturing of the components with pultrusion ensures a large scale production. To guarantee a high covalent bond between the metal cores and the FRP, the inserts are provided by using a newly developed powder coating, which acts like a latent reactive adhesive [2]. Three different profile constructions have been verified, which are identical in the external cross-sectional shape and size, but differing in core structure. A glass-FRP-steel-combination was chosen as material and a pure FRP sample was used as a reference. The mechanical properties were investigated by using a 4-point bending test. Depending on the core structure, various failure behavior and mechanical parameters like energy absorption could be determined.

Powder coating is one of the coating techniques that are widely used today as a substitute for coating using liquid painting. In this research, we report on the effect of the various layers of powder coating on the hardness and corrosion rate of the material. Three different layers of variation were observed with 1, 2, and 4 layers to obtain the best results. The cleaning process was applied before coating the samples. The coating process was performed in a special room/box to avoid contact with air and contamination from the outside environment with a spraying distance of about 20-30 cm. The morphology is compact and bigger grains are seen to be emerging in the 1 layer deposition. Many grains are visible, and uniform grains are distributed in the 2 layers deposited. For the 4 layers, due to higher layer deposition incorporation, the grain size is seen to be enlarged due to the merging of smaller grains with each other ultimately increasing the grain size. The uncoated material has a corrosion rate of 0.505 mm/year which means fair for the relative corrosion resistance. The coated samples have a corrosion rate of 0.353, 0.252, and 0.354 mm/year for the 1 layer, 2 layers, and 4 layers, respectively. Based on the calculation, the average number of the Rockwell hardness of un-coated and coated samples for the 1 layer, 2 layers, and 4 layers, respectively were estimated at about 70, 78, 79, and 58 HRB, respectively. The highest average hardness value is in sample B with 2 layers of 79 HRB. The lowest average hardness value is in sample B with 2 layers of 58 HRB. The lowest performance of sample D with 4 layers confirms the result as shown in the corrosion rate result.

The present study aims to apply an electrostatic dry powder coating process to coat aspirin tablets with polymer blends to produce a single-layer coating film, which potentially allows an advantageous delayed sustained drug release profile. The coating formulations containing polymer blends of enteric polymer (hydroxypropyl methylcellulose phthalate or hydroxypropyl methyl cellulose acetate-succinate) and insoluble polymer (Eudragit® RL) were successfully developed and optimized. Results of scanning electron microscopy and acid resistance test demonstrated that curing conditions had a significant impact on the qualities of the produced film. Drug dissolution experiments revealed that changes in the coating level and the coating formulation with different ratios of the enteric polymer to the insoluble polymer achieved an altered and adjustable drug release profile. All of the results suggested that electrostatic powder coating technology is capable to produce a satisfactory coating film with polymer blends, allowing an advantageous functionality of delayed sustained drug release.

Powder technology has been used to coat fibers with polymeric particles to manufacture composites. The material parameters such as particle size and fiber diameter and process parameters such as the particle charge and the particle velocity will influence the powder coating process. In this work, we present an experimental setup in which we characterize the coating of micron size particles on a fiber and examine the role of process parameters on the coating density. Monodispersed Polystyrene (PS) particles (2.8 ± 0.4 μm in diameter) were used to coat a carbon fiber (CF) 7 μm in diameter. A model setup was designed and fabricated in which the PS particles were charged with an ozone charging system, while the CF was maintained at the grounded state at all times. The setup consisted of two parts namely, a cyclone and a coating chamber. The distance between the PS particles was measured and the density of coating was examined using a microscope as a function of the processing parameters used in the setup. The measured average distance between the PS particles on the CF was used in our developed numerical model to estimate the friction coefficient between the charged PS particle and the grounded CF and the fiber volume fraction. The proposed methodology can be extended to any particle size, particle charge, and fiber diameter to estimate the friction coefficient and the fiber volume fraction at the microscale level.

The surface properties of thermally modified ash wood with a powder coating were investigated, and the results were compared to the unmodified wood. The wood specimens were sanded with 80 grit sandpaper and then pre-heated at 80 °C for 5 min in an infrared oven. The surface of the unmodified and the modified wood specimens were coated with an epoxy/polyester (1 to 1 ratio) hybrid coating using an electrostatic corona spray gun at the pilot plant established in the laboratory. The coatings on the wood specimens were cured at different curing conditions in an infrared oven, i.e., 120 °C/15 min, 140 °C/10 min, and 160 °C/10 min. The results showed that the thermal modification (TM) of the wood caused a slight decrease in the mechanical performance of the surface system (wood substrate and coating film). For example, the scratch and abrasion resistance of the unmodified specimens at the curing temperature of 120 °C were 3.33 N and 135 revolutions but were 3.12 N and 120 revolutions after the TM. However, the average surface roughness (1.26 mu) and contact angle (60.8°) of the distilled water on the cured coatings on the modified wood were lower than those on the unmodified wood (1.86 mu and 80.8°, respectively).

The article examines the hardness of the coating made of PG-CP4 powder. Plasma powder deposition was performed to samples made of 40H13 steel and then the samples treated with a laser beam. A multi-factor model was established that relates the hardness of the protective coating to the radiation power W, the longitudinal feed Spr of the laser beam, and the distance L from the protective casing of the laser head to the treated surface. Depending on the laser treatment modes, coating was in a state of complete, partial reflow or its absence. Full reflow is characterized by the adhesion of the filler material to the substrate, by maximum hardness of HRC 51.2–56.6 and no defects. In the absence of reflow, gas sinks, transverse microcracks, detachments, and other defects were found in the coating material, and the hardness decreased to HB 125–212. An increase in W and a decrease in Spr lead to increases the hardness of the treated coating, which is explained by an increase in the specific heat flux supplied to the coating per unit time, and a high rate of heat removal deep into the surface layer of 40H13 steel. The thickness of the surface layer with increased hardness ranged from 0.1 to 1.5 mm. Based on the multi-factor model, laser processing modes are controlled to ensure the required values of the protective coating hardness. The research results are recommended for use in enterprises that implement laser technologies and develop modern laser systems.

A new UV-curable maleimide-terminated polyimide was prepared and characterized using gel-permeation chromatography, infrared, and nuclear magnetic resonance spectroscopy. The polyimide was formulated with a commercially available UV-curable polyester resin via twin-screw extrusion to prepare a hybrid powder coating system. The hybrid powder coatings were cured by exposing the molten formulation to UV light. The films were studied by dynamic mechanical analysis (DMA), thermomechanical analysis, and differential scanning calorimetry. DMA highlighted the viscoelastic behavior of the films and showed that an increase in Tg was obtained with increasing polyimide content, as determined via the α-transition in the tanδ curve. Thermogravimetric analysis showed an improvement in the thermal stability of the polyester with the addition of the polyimide. Deformation resistance of the UV-cured films was investigated by SAOS and LAOS rheological methods to investigate the relative endurance of these coatings when subjected to different strains. The viscoelastic properties of the hybrid system were most improved when 16% weight percent of polyimide was added into the system.

Application of artificial neural networks for optimization of plasma spraying parameters was considered. Artificial neural networks were used to select realistic parameters of titanium and hydroxyapatite powder coating of titanium products. For titanium coatings, the optimal arc current was found to be 380-450 A; optimal spraying distance, 100-150 mm; optimal titanium powder dispersity, 40-90 μm. Similar optimal ranges were obtained for hydroxyapatite coatings. The goal of the optimization wais to maximize the coating adhesion to the substrate and to improve its porosity.

This study investigated the effects of 3 coating processes, anodizing, electrodeposition, and powder, on the mechanical properties and fatigue life of 6061 aluminum alloys. The coatings were applied at an aluminum extrusion industrial company. All coatings were found to increase the tensile strength and elongation. The anodized coating, prepared via a pickling process, produced a surface vulnerable to pitting attack, which led to fatigue crack nucleation throughout the surface and decreased the fatigue life of the anodized specimens. The powder coating, with a thickness of 100 µm, slightly increased the tensile strength and elongation but did not change the fatigue life of the 6061 aluminum alloy. The electrodeposited coating after anodization recovered the fatigue life so that it was equivalent to that of an uncoated 6061 aluminum alloy. Although the specimens treated by electrodeposition inherited nucleation sites from the prior anodizing process, the electrodeposition increased the endurance limit of the anodized 6061 aluminum alloy from approximately 39% to 50% of the yield tensile strength.

The coating process of tractor cabs is performed in industry by the electrostatic powder coating technique, which is the electrostatic application of powder to metal parts of the cab, requiring a p...

This study presents a comprehensive review of the improved optimization for powder coating process variables in mild steel (SPCC-SD). The effective thickness of the dry film thickness (DFT) keeps a significant influence on the critical protection of mild steel against rust. In the powder coating process, the variable thickness is one of the primary and difficult objectives to accurately control the desired consistency. This empirical study properly uses RAL 7040 epoxy-polyester with the required thickness between 70-100 microns. This empirical study aims to reasonably achieve the optimal value of the effective thickness of the powder layer from specific combinations of specified process criteria. Practical experiments were properly conducted out manipulating an orthogonal Taguchi L16 array of independent variables; program, distance, application method, and the number of layers. This optimization method has been successfully upgraded. The average thickness of the powder coating layers reaches 84.85 microns. For a given limit, the application-method of typically preventing the determined cause correctly examined efficiently provides the most significant effect on effective thickness with an S/N ratio of 0.91. In the future, the relevant research may use our corresponding results to improve the powder coating procedure for other significant impacts.

In order to determine the optimal values of technological factors for electromagnetic hardening process (EMHP), an experimental study of the process of applying ferromagnetic Fe – 2 % V powder coating on 30ХГС (GOST 4543- 71) steel parts was conducted. The process productivity and coating continuity were selected as the target parameters for the EMHP optimization. By applying the experimental design method, based on 5-factor central composite rotatable uniform plan, we have created stochastic models, expressed in regression functions of the second order. It has been determined that the magnetic induction value in the working gap is the most significant technological factor, affecting both target parameters. With the increasing induction magnitude the process productivity and the coating continuity increase non-linearly until the maximum limit value, which was attributed to the forming of current-conductive chains in the working gap, that have varying electrical conductivity and different directions relative to the lines of magnetic field forces. In order to determine the optimal EMHP mode we have solved the problems of finding maximums for greatest productivity and coating continuity within the constraints of the studied factor range. The discovered EMHP-modes, optimal for each separate parameter, coincide only in the value of the magnetic induction and the discharge density. The optimal values for the other control factors belong to different areas of factor range for different optimization parameters. To determine the EMHP modes, balanced against the both parameters, the problem of multicriteria optimization was solved. The obtained solution reveals that the density of discharge currents produces the biggest impact on the process productivity and the coating continuity within the balanced modes. At the same time the high continuity of the coating is achieved by the supplementing increase of peripheral speed of the processed workpiece, which leads to evener distribution of the intensively supplied mass of the ferromagnetic powder on the treated surface. The recommended technological modes of EMHP have been determined, based on the generalized optimality criteria.

The paper presents research on the effect of technological parameters of high-energy processing on the performance properties of powder coatings made of cermet. The use of pulse-plasma treatment is considered as an example of high-energy modification of coatings. As used powder coating materials, various versions of carbide-containing ceramics with the addition of a solid lubricant in an iron-based metal matrix have been selected in the paper. Coatings of carbide-containing ceramics with the addition of a solid lubricant in an iron-based metal matrix on are being developed to replace those of a nickel-based matrix. Such factors as crack resistance, wear resistance, workability, brittleness, as well as economic components often limit the use of powder materials based on carbide ceramics with the addition of solid lubricant in the matrix based on nickel. When only the wear process determines the service life of a part, such powder materials should be replaced with cheaper powder materials based on carbide ceramics with the addition of solid lubricant in an iron-based matrix. The proposed developments increase the wear resistance of the plasma coating due to the introduction of high-chromium steel and molybdenum into the material. Optimum porosity is formed in the initial powder mixture during the synthesis of FeCrMo–MoS 2 –TiC composite materials, there is an improvement in the technological parameters of powder materials, their utilization rate in plasma spraying increases, and the technology of applying wear-resistant plasma coatings becomes cheaper. The addition of the Mo element to the FeCr binder increases the wetting of titanium carbides by the binder melt during self-propagating high-temperature synthesis of the developed composite powder. Subsequent layer-by-layer processing of plasma-sprayed coatings from powders of the developed ceramics using repetitive pulses of plasma flows using different energy levels makes it possible to create strictly defined structures with necessary and controlled porosity, which decreases in a certain sequence from the outer treated layers to the base. Such treatment contributes to a significant increase in the wear resistance of the treated friction surfaces, increases the oil holding capacity, in addition, an increased adhesive and cohesive strength of the formed layers bordering the substrate is formed. Processing distances, the total number of impacts have been varied in accordance with the methodological developments, when changing the applied technological characteristics of pulse-plasma effects. The total number of plasma pulses influences on the created thickness of the plasma coating layers after treatment and contributes to the melting with compaction of the coatings obtained by the plasma treatment and the creation of a structure with hardened characteristics.

The results of domestic and foreign investigations into the laser surfacing of coatings containing a strengthening carbide phase, as well as metallographic and tribological investigations of coatings by alloy powders of the Ni–Cr–B–Si system, including the addition of nanodispersed titanium and tungsten carbide particles, are presented. Values of the wear resistance coefficient (Kw) of coatings during abrasive wear testing according to the Brinell–Haworth scheme are determined. The use of Kw makes it possible to determine coefficient C when performing a scratch test of the coatings, which depends on the coating hardness, treatment modes, and addition of solid particles. It is found that the magnitude of C is affected by a series of factors such as the processing speed, input laser power density, base melting depth, and carbide phase presence and content. The larger the melting depth is, the lower the coating wear resistance is, which is associated with mixing the base material and surfaced coating. Introducing tungsten carbide nanoparticles in an amount from 3 to 7% makes it possible to increase the coating wear resistance by a factor of 1.5–2.0 when compared with the surfaced powder coating made of the PR-HKh15SR2 alloy and by a factor of 4.6–7.1 with respect to the base material—steel 40Kh. Microhardness of the initial powder is 6400–6600 MPa and increases with the introduction of carbides into it. For example, microhardness reaches 7620–9160 MPa with a WC content of 7% in the coating. Positive surfacing results are found with the emission power density up to 50 W s/mm2, but its further increase leads to the burnout of alloying elements and dissociation of carbides.

Three-dimensional printing of high laser reflectivity metals and metal matrix composites continues to be a challenge because of loss of laser energy and lack of high-quality composite powders. Modifying powders to enhance the interaction between laser and powder and improve the uniformity of reinforcement is a possible solution. However, traditional powder mixing methods such as ball milling destroy the spherical nature of powders. We report here commercial-scale coating of powder by electroless plating for high laser-reflectivity metals and fluidized bed chemical vapor deposition (FBCVD) for composite powders without changing the sphericity. The results indicated that coating high-laser-absorptivity Co and Ni on Al powder enhances the printability leading to good physical and mechanical properties. Similarly, the composite powder made by FBCVD had a good combination of uniformity, sphericity and flowability, which also exhibited improved printability and excellent mechanical properties for the printed bulk composites.

This paper presents fire and explosion hazards during electrostatic powder coating, and describes the course of the process as well as the characteristics of powder coating as a combustible material. Potential sources of ignition that could initiate a fire of a dust layer or an explosion of a dust-air mixture have been identified. The minimum requirements and recommendations raising the level of safety in the area of coating installations are presented.

Nickel-based self-fluxing materials Ni–0.5C–15Cr–3.2Si–2B (PGSR-2) and Ni–1C–17Cr–4.1Si–3.6B (PGSR-4) are studied theoretically and experimentally. These materials are widely used to form wear-resistant coatings on various parts of machines and mechanisms, which are deposited by flame spraying, plasma spraying, and surfacing. To study the relation between the structures and properties and the main technological parameters is of interest to solve applied and theoretical problems. In addition, information on the structure of liquid alloys is necessary for designing and optimizing the deposition of gas-thermal coatings, since heat treatment of a melt can strongly affect the properties of solidified materials. One of the effective ways to solve this problem is the use of computer simulation methods. Thermodynamic simulation of the equilibrium compositions of the self-fluxing materials is carried out. When PGSR-2 and PGSR-4 are uniformly heated, Ni, Cr, C, Ni3B, Ni2B, NiB, Ni2Si, NiSi, CrB, and CrSi are shown to form in a condensed phase. In addition, when PGSR-4 is heated, Cr5B3, CrB2, and Cr3C2 form in a condensed phase along with the above components. The microhardness and microstructure of the coatings deposited by plasma spraying are experimentally studied. The PGSR-2 coating is shown to be characterized by the presence of porosity across the thickness, and pores have an irregular shape and sizes from a few microns to 100 μm, and the PGSR-4 powder coating is characterized by a high density, low porosity, and an even boundary with the substrate. The microhardness of PGSR-4 coating is significantly higher than that of PGSR-2, and the microhardness of both coatings is on average 3.0–4.0 times higher than that of the base.

Nowadays, thermal spray coatings are used to enhance mechanical properties of the material. One of the technologies used to produce thermal spray coating is HVOF spray technology. This is the most advanced and modern technology which has been widely used in the industry due to its flexibility and ability to create coatings with better adhesion in comparison with other thermal spray methods. This article presents some empirical findings from applying the 67Ni18Cr5Si4B alloy powder coating onto C 45 steel shaft by HVOF spray technology. It also analyzes the influence of some technological parameters on the adhesion of the coating. As a result, the parameters of HVOF spray technology are obtained suitable for recovering worn axis-sized workpieces.

The paper presents the results of domestic and foreign studies on laser deposition of coatings using hardening carbide phases, as well as metallographic and tribological studies of coatings with Ni-Cr-B-Si alloy powders and with the addition of nanodispersed particles of titanium and tungsten carbides. Wear resistance coefficients of coatings (K w ) were determined in Brinell-Haworth abrasive wear tests. The K w value was used in coating scratch tests to determine the coefficient С that depends on the coating hardness, treatment modes and addition of solid particles. It was found that the С value is influenced by a number of factors: processing speed, input laser power density, base penetration depth, carbide phase presence and content. The higher the penetration depth, the lower the coating wear resistance due to the mixing of the base material and the deposited coating. The introduction of tungsten carbide nanoparticles in the amount from 3 to 7 % increased the coating wear resistance by 1.5-2.0 times compared to the deposited PR-NiCr15BSi2 coating powder and by 4.6-7.1 times in relation to the base material - 40Cr steel. The microhardness of the initial powder coating was 6400-6600 MPa, and it increases with the introduction of carbides. For example, microhardness reaches 7620-9160 MPa at a WC content of 7 % in the coating. Positive deposition results were obtained at radiation energy density up to 50 W•s/mm 2 , but its further increase leads to the burnout of alloying elements and dissociation of carbides.

Passive cooling materials can emit heat into outer space (approximately 3 K) through an atmospheric window (8–13 μm). Complex photonic crystals and bulk materials for multilayer films are mostly considered as ideal passive cooling materials. However, we have synthesized a novel efficient single passive cooling powder Ca0.5Mg10.5(HPO3)8(OH)3F3 (CFM). The average reflectivity is as high as 0.98 in solar spectrum region (0.2–2.5 μm), while the average emissivity of the atmospheric window (8–13 μm) is 0.91, and explored its reflection and emission mechanism. In order to obtain the cooling effect in the natural environment (without convection shielding), we apply CFM powder coating on commercial wall tiles. Under summer direct sunlight, the surface temperature of CFM coating is 5.1 °C lower than the ambient temperature on average, and at night 2–5.3 °C below the ambient temperature. A CFM coating daytime cooling power up to 84.25 W/m2 was obtained by using the feedback heating method. This simple and cheap, while easy to produce, CFM material can be applied in large scale to urban buildings to reduce the surface temperature, to save energy, and to possibly ameliorate the heat island effect.

The present paper deals with the investigation of microstructure and high-temperature hot corrosion behavior of high-velocity oxy fuel (HVOF)-produced coatings. Two powder coating compositions, namely, Ni22Cr10Al1Y alloy powder and Ni22Cr10Al1Y (80wt%; microsized)-silicon carbide (SiC) (20wt%; nano (N)) powder, were deposited on a T-22 boiler tube steel. The hot corrosion behavior of bare and coated steels was tested at 900°C for 50 cycles in Na2SO4-60wt%V2O5 molten-salt environment. The kinetics of corrosion was established with weight change measurements after each cycle. The microporosity and microhardness of the as-coated samples have been reported. The X-ray diffraction, field emission-scanning electron microscopy/energy dispersive spectroscopy, and X-ray mapping characterization techniques have been utilized for structural analysis of the as-coated and hot-corroded samples. The results showed that both coatings were deposited with a porosity less than 2%. Both coated samples revealed the development of harder surfaces than the substrate. During hot corrosion testing, the bare T22 steel showed an accelerated corrosion in comparison with its coated counterparts. The HVOF-sprayed coatings were befitted effectively by maintaining their adherence during testing. The Ni22Cr10Al1Y-20wt%SiC (N) composite coating was more effective than the Ni-22Cr-10Al-1Y coating against corrosion in the high-temperature fluxing process.

Ayrilmis, Nadir/0000-0002-9991-4800 WOS:000511129100105 Use of electrostatic powder coating technology for wood-based panels has considerably increased in the last decade. In this study, oriented strand boards (OSB; OSB/2 and OSB/3 grades) were coated with powder coatings using an electrostatic corona spray gun. Epoxy/polyester (hybrid:1/1) coating that is suitable for indoor applications was applied to the surface of OSB specimens (150 g/m(2)) at three different curing temperatures, 120 degrees C for 15 min, 140 degrees C for 10 min, and 160 degrees C for 10 min using the electrostatic corona gun. The surface properties of the OSB specimens, roughness, wettability, scratch resistance, abrasion resistance, and film thickness were determined. The abrasion resistance and scratch resistance of the coated OSB specimens improved with increasing curing temperature from 120 to 160 degrees C. The highest mechanical surface strength was obtained from the OSB/3 specimens cured in the infrared oven at 160 degrees C for 10 min, while the lowest strength was found in the OSB/2 specimens cured in the infrared oven at 120 degrees C for 15 min. The contact angle values of the coated OSB specimens increased with increasing curing time, while the surface roughness decreased. The curing temperature of the electrostatic powder coating may be a useful indicator to users to obtain better surface quality on the substrate.

Electrostatic powder coating of osmotic pump tablets becomes increasingly attractive in pharmaceutical industry due to its dry coating process. The present study aimed to investigate the influence factors of electrostatic powder coating of osmotic pump tablets with ultrafine powders during the powder adhesion and film formation. The results of the powder adhesion evaluation indicated that the powder adhesion was significantly influenced by the liquid plasticizers and the charging voltage of the electrostatic spray gun. SEM and drug dissolution tests illustrated that coating particle size and curing time and temperature could significantly influenced the film formation process, a finer coating particle size and-/or higher curing temperature and-/or longer curing time led to a more continuous and uniform coating film. Those results indicate that a well-controlled coating film with high qualities could be fabricated by a well-designed electrostatic powder coating, suggesting it is a promising alternative for preparing osmotic drug delivery systems.

In this study, the influence of phosphate surface pretreatment containing a cobalt ion additive on the anti-corrosion features of epoxy coating was investigated. Phosphate conversion coating (PCC) specimens were prepared. Then the epoxy coating was electrostatically sprayed on the phosphated substrate. The surface morphology and the composition of a zinc phosphate conversion coating with a cobalt ion additive were studied by scanning electron microscopy and X-ray diffraction, respectively. Also, the corrosion protection properties of specimens were studied by the polarization potentiodynamic test in 3.5% NaCl solution. Protective performance of double-layer coatings was studied using electrochemical impedance spectroscopy during 30 days in the mentioned solution. In addition, the impact of phosphate chemical treatment on increasing the adhesion strength of the powder coating was studied using the pull-off adhesion test and cathodic disbodnment test in the same solution. As a result, it was found that the corrosion resistance of PCC containing a cobalt additive enhanced significantly and that the PCC containing 3 g/L Co is less porous than other coatings. Also, the protection properties, adhesion strength, and cathodic disbondment resistance of the double-layer coatings with phosphate pretreatment containing 3 g/L Co increased significantly.

Hydration of epoxy coatings reduces adhesion performance and causes degradation of the material, such as microstructural failures. Quantification of water vapor transport at elevated temperatures is fundamental to understanding polymer coating performance, especially when the coating is exposed to extreme operating conditions. As the water activity increases, the permeability/selectivity of polymers against other permeants changes. In this study, we examined the water permeation kinetics of two common epoxy-based powder coating systems for pipelines (fusion-bonded epoxy, FBE, and high-performance powder coating, HPPC) across a range of industrially-relevant temperatures (from room temperature to 80°C). Specifically, we utilized vapor permeation features of FBE and HPPC films with quantification of equilibrium flux as a function of temperature and pressure. In addition, we analyzed the nonlinear dependency of water transport on the vapor concentration at 65°C. The vapor transport analysis demonstrated that although data for FBE were indicative of a decrease in permeability around 65°C, perhaps due to self-association of water molecules, the coating was likely to experience a plasticization pressure around this temperature. We also examined microstructural changes of the epoxy network due to water transport. Our results revealed evidence of irreversible damage to epoxy coatings under wet-state conditions above 65°C. It appears that the combination of thermal exposure and internal stresses in the glassy epoxy lead to a phase separation of filler particles from the epoxy matrix, as well as to a distinctive cavity formation in the coating membrane. Yet, despite formation of percolating paths for water transport, our results indicate that vapor permeation is primarily restrained due to self-association of water molecules. The vapor transport flux and its permeance are lowered by one order of magnitude in the multilayered HPPC thanks to the moisture-resistant polyethylene topcoat, thus reducing the extent of damage to the underlying substrate. Since barrier protection against gas phase diffusion is controlled by the FBE primer, however, consequences of coating hydration are more pronounced in the overall selectivity toward gaseous transport. Hydrothermal exposure is likely to increase aggregate porosity of the coating and a conservative implementation of standard coating requirements is therefore reasonable to avoid early degradation issues.

This study aims to improve polyurethane-based coating by modified zirconium oxide and aluminum oxide nanoparticles for preparing thin polymeric heat insulation coatings. In the first step, the nanoparticles were chemically modified with the silane coupling agent. Then, three different weight percent of modified nanoparticles (1, 3, and 5% w/w) were mixed with polyurethane, to prepare the nanocomposites, which were coated on metallic plate samples. Then, these plates are used to measure the radiation heat transfer coefficients, absorption coefficient in a region of short wavelengths (UV/VIS/NIR), the emissivity coefficient, and thermography of the samples in a region of long wavelengths (IR). Results showed that by adding the modified nanoparticles to the polyurethane matrix, absorption was decreased and the emissivity coefficient was increased. According to the thermography results, it was observed that the surface temperature of both samples with 3% w/w of nanoparticles had the minimum temperature compare to others. Minimum heat surface observed for 3% w/w of modified nano zirconium oxide.

There is an increasing interest to enhance resistance to pathogens on the powder-coated surface. Traditional silver antimicrobial agents are hard to endure high curing temperature and lead to the yellowness of the surface appearance. Commercial sources usually cut down silver loading (less than 2.5w%) to avoid the color change and this will result in low inhibitory effect and poor durability. To improve the antimicrobial performance and maintain the appearance, Ag+, Cu2+, Zn2+ ternary inorganic antimicrobial agents on Linde A zeolite supports were prepared in this study. The silver content of this agent is increased to 8-10w% and the coated surface exhibits high antimicrobial efficiency. The coating appearance shows little adverse color change (∆E=1.47) when adding 2w% amount of agent. The reduction rate of this agent was over 99.99% after 6hrs for E. coli, S. aureus and C. albicans according to ASTM E2180-07 standard, and the paint film can maintain over 99% reduction rate even for 11 cleaning cycles. XP...

Sands are naturally hydrophilic granular materials, yet, rendering them hydrophobic could lend them to a wide range of geotechnical applications. This study describes a powder-coating procedure per...

The influence of the direction and magnitude of direct (DC) stray current on the disbonding performance of epoxy powder coating was studied by using electrochemical impedance spectroscopy and scanning electron microscopy technology. The results show that the application of DC stray current could accelerate the anodic dissolution. The peeling degree of the coating increases as the magnitude of positive DC stray current interference increases in the range of 2–8 V. With 16 V positive stray current disturbance, the degree of coating disbonding decreases. With the application of negative stray current, the coating peeling becomes more serious, and the degree of peeling increases as the DC stray current increases.

Highly surface-roughened zirconia substrates were obtained from additive zirconia powder coating by room temperature spray processing. Homogeneous and dense zirconia coatings were deposited on sintered zirconia substrates with strong bonding by a powder spray coating method. The thickness and surface roughness of the coating layers on zirconia substrates increased with increasing coating cycles, which was confirmed from atomic force microscopy (AFM) and roughness analyses. The tetragonal phase and chemical composition of the zirconia coating layers were similar to those of the raw 3Y-TZP powder used as a raw material, indicating that no phase or composition changes occurred during the spray process.

The results of investigation of phase and elemental compositions, defect substructure states, mechanical and tribological properties of the modified surface of Steel Gr1 are presented. The process of modification consists in plasma spraying of a Ni–Cr–B–Si-based powder coating followed by its irradiation with a high-intensity pulsed electron beam. It is shown that the coating surface formed by plasma spraying contains micro- and macro-pores and is characterized by high relief. A subsequent processing of the modified surface with a highintensity pulsed electron beam of a submillisecond duration in the mode of surface layer melting is accompanied by smoothing of the coating surface, saturation of the surface layer crystal lattice with Ni, Cr, B and Si atoms, formation of submicron cells of dendritic recrystallization, precipitation of nanosized particles of the second phase, and formation of quench structure. When combined, these treatments result in the formation of a hardened layer up to 1500 μm in thickness, whose microhardness and wear resistance by 4.6–6.5 and 4 factors exceed the respective characteristics of the initial steel.

The open porosity of wear-resistant modified coatings is investigated, and their macrostructure is analyzed. A statistical method is proposed for describing the formation of porosity in the laminar structure of a powder coating. The matrix of transition probabilities is determined for a uniform Markov chain. The porosity of a coating on a smooth substrate is calculated.

We report a scalable two-step plasma mediated process for the synthesis of sillimanite and mullite spray grade powders and their coatings on stainless steel (SS) substrate. In the first step, spray grade sillimanite and mullite powders were prepared by thermal plasma processing followed by second step of plasma spray coating on SS. X-ray diffraction has been used to study the phase formation and structural changes of powders before and after coating on SS. Grown-up stress and defects on the surface of the achieved coatings before and after mechanical tests was visualised by scanning electron microscopy. Mechanical hardness and wear tests were performed to compare the mechanical strength and applicability of these coatings in comparison to commercial powder coating. Further, electrochemical corrosion behaviour of these coatings in-comparison with commercial powder coating confirmed the potential of this two-step process and product for industrial scale-up.

Sanhuang tablets (SHT) had a broad antibiotic spectrum with high efficiency and low toxicity. However, the clinical application was seriously limited by extremely bitter taste. A novel powder coating technology was established to mask the bitter taste of Sanhuang powder (SHP). Initially, the type and particle size of coating material, coating time and the ratio of coating material were investigated. The microstructure of composites was characterized by scanning electron microscopy (SEM), contact angles (CAs), infrared ray spectrogram (IR) and surface elemental analysis. Furthermore, chemical measurement and electronic tongue test were applied to evaluate the masking effect. As a result, starch was chosen as the best coating material, and the optimal ratio of SHP and starch was 6.5:3.5 with grinding together for 2 min in vibromill. The composites and starch shared the same characteristics of infrared spectroscopy and surface properties. The microstructure demonstrated that small particles of starch was successfully coated on the surface of the SHP. The experimental results revealed that powder coating technology can be used to taste masking without coating the surface of the tablets. In addition, it provides a new strategy for taste masking of national medicine.

Mineral fertilisers such as nitrous, phosphorous and potassium (NPK –usually called macro elements) are one of the most significant products in agricultural industry. By providing nutrients to the plants, they play an important role in the process of regulating the acidity (pH) and the fertility of the soil and all it leads to increase the crops growth [6].

There are shown studies on influence of film-forming components on the corrosion resistance of powder coating. Protective and decorative powder coatings - one of the most promising types of paints and varnishes for industrial use. Their main advantages are: absence of solvents, practically waste-free coating technology (the degree of powder utilization during application is close to 100 relative simplicity and cost-effectiveness of the production process of coating. The study of protective properties of powder coatings is associated with the detection of high performance properties and high corrosion resistance of the material. Although corrosion resistance of powder coating performance continues to improve via the design of more effective film-forming components the nomenclature of which is wide enough.

Laser cladding was used to distribute a CeO2-modified 316L powder coating onto a 316L stainless steel surface. The cladding layer phase composition was evaluated through x-ray diffraction. An analysis of the microstructure was conducted using an optical microscope and scanning electron microscope, while the micro-hardness was measured using a tester. The coating corrosion behavior in response to 3.5% NaCl solution was analyzed by polarization curves and electrochemical impedance spectroscopy. Finally, the overall performance of coatings with different CeO2 concentrations, 1, 2, and 3%, was compared. Results showed that adding CeO2 significantly refined the grains, reduced the coating porosity, and effectively limited the appearance of local corrosion. Also, additive CeO2 shifted the coating’s electrode potential in a positive direction, minimizing the current density of corrosion, creating a stable passivation film, and improving the coating’s corrosion resistance. The coating performance (hardness and corrosion behavior) was optimal when 2% CeO2 was employed as the powder mass.

A geopolymer-based drying powder decorative coating was successfully prepared from metakaolin and solid type water glass by using simple powder mixing process, and the coating was successfully applied in engineering. The compressive strength and rheological performances of coating were studied. To improve the coating anti-cracking performance, the quartz sand and polycondensed aluminum phosphate (PAP) were applied and studied. The experiment results showed that water glass and water content significantly influenced the viscosity and compressive strength of drying powder coating, 3 wt% PAP improved the 3 d compressive strength from 23 to 29 MPa and prolonged surface drying time from 0.6 to 3 h, no crack in 500 μm thickness coating including quartz sand. The coating performances, including surface drying time, hardness, water resistance, and scrub resistance, were systematically tested based on the Chinese construction coating standards. The optimal coating formula (WG/MK = 0.8, W/P = 0.5, PAP = 3 wt%) was obtained for a coating that has excellent properties of high strength, artificial aging resistance, high temperature resistance, good workability, etc. The coating has good prospects of development and application due to its outstanding advantages, low manufacturing cost, simple manufacturing technology, environment friendly, etc.

In this article, a newly developed method for forming metal sheets together with long fiber-reinforced thermoplastics (LFT) to hybrid parts is presented. The idea of combining two different materials in one part is nothing new, but most of the existing processes use at least separate production techniques for each material and an additional joining operation. The special characteristic of this new process is realized by a combined forming tool for both sheet metal and LFT to create a hybrid part with only one necessary and simultaneously executed process step. Besides contact to the punch, the metal sheet is also formed by the molten LFT material, which behaves like a hydraulic fluid in hydroforming processes. With this method, it is possible to reduce the thickness of sheet metal components by adding a LFT reinforcement structure. The interface connection between the metal sheet and LFT is realized by using a bonding agent, which is previously applied to the metal sheet via coil or powder coating. To achieve this hybrid forming process, new tool and sealing concepts have been developed and the corresponding process parameters were identified and optimized. As a result, the innovative process offers a cost- and time-efficient solution for multi-material lightweight design.

An investigation into the flexural properties of unidirectional composites (UDC) produced from blending of carbon fiber and polypropylene (PP) matrix in varying forms of fiber, powder and film are reported. Dr. Ernst Fehrer (DREF) friction spun hybrid yarns were manufactured from PP fibers and carbon tows, and were consolidated to yield UDC-D. PP powder was layered on carbon tows by electrostatic spray coating and were consolidated to form UDC-P. A third laminate, UDC-F was manufactured by the consolidation of PP films stacked between carbon tows. The fiber volume fraction was ∼50% in all the three UDCs. Better mechanical properties of UDC-P were observed in 3-point bending and short beam tests. Analysis by micro-computed tomography, and scanning electron microscopy indicate better impregnation of PP powder in UDC-P despite higher viscosity of PP powder than PP fiber, and thereby higher interlaminar strength. This is the first work reported on comparison of laminates from powder coating versus DREF and film stacking.

In 3D printing, the highest degree of freedom in design is achieved using powder bed techniques such as selective laser melting (SLM). The current disadvantage of this technique is that it allows only for the production of single material parts using standard setups. However, advanced designs and local requirements are met best by a tailored arrangement of different materials. A key challenge for multi-material powder bed SLM is the selective deposition of the materials in each layer. In this paper, a hybrid-material powder coating system for SLM machines was developed and installed in a SLM125 Realizer machine. First, the generic classification for the material arrangements in additive manufactured parts is reviewed and extended. Furthermore, existing principles and procedures used for multi-material coating, especially focusing on contamination-free processes are examined. Based on this, an advanced coating mechanism is developed and proof of principle is provided.

A statistical approach is proposed based on the Markovian chain theory to describe the coordinate distribution for the profile of powder coatings under sliding friction. Transitional probability matrices are constructed for homogeneous Markovian chains corresponding to a stage of steady-state-state wear of powder coatings. Calculated and experimental data concerning the friction surface profiles of wear-resistant coatings are analyzed. It is shown that the proposed approach simplifies the calculations upon processing a large amount of profilometric data to predict the wear and microgeometry of the friction surfaces of powder coatings.

Hot rolled steel (HRS) has long been a major product to the motor industry for bodywork, as galvanised steel (zinc coatings), and it is widely used in building and as tinplate (including tin and ch...

The aim of this study is to determine the effect of cataphoretic and powder coatings and also the method of application the primer on the adherends surface on the strength and failure modes of EN AW-5754 aluminium alloy adhesive joints. The study is performed on lap joints made of EN AW-5754 aluminium alloy, subjected to three different types of surface treatment; namely a) polyurethane cataphoretic coating, b) powder coating based on black mat RAL 9005 UL polyester resin and c) no coating. The tested adhesive joints were made using a one-component polyurethane adhesive Terostat 8596, which was dedicated for automotive and cured under a constant load of 0.018 MPa at 20 ± 2 °C. In addition, this study investigates the effect of the application of Terostat 8519P adhesion promoter which is a liquid polyurethane-based primer containing solvents and which is corresponding to Terostat 8596 polyurethane adhesive. Terostat 8519P adhesion promoter was applied in two different ways: a) to one substrate and b) to both substrates. The produced adhesive joints were subjected to strength tests using the Zwick/Roell Z150 testing machine. The examination of fracture in the tested adhesive joints was performed in accordance with the EN ISO 10365 standard. The shear strength results have demonstrated that both the method of application of the adhesion promoter (Terostat 8519 P) and the presence of cataphoretic coating had an influence on adhesive joints strength. The use of the adhesion promoter significantly affects the strength of both uncoated EN AW-5754 aluminium alloy adhesive joints and the adhesive joints subjected to powder coating. The use of the adhesion promoter has a less significant effect on the cataphoretic-coated samples.

WOS: 000464889400011 EPS solutions (derived from Lactobacillus brevis E25) with varying concentrations (0, 20 and 40%) were used to understand their adhesive properties on food surfaces. Selected model powders (glass powder and salt powder) and food powders were applied on wood veneer and corn chip surfaces prior to adhesion tests. The data obtained depicted that smaller particles (below 100 mu m) showed similar or better adhesion than other fractions for almost all runs. Increasing centrifugal speed from 1000 to 4000 rpm resulted in more particles detached from the surfaces for most of the runs. Sunflower oil exhibited better adhesive properties when glass powder used. However, EPS solutions improved salt powder adhesion especially after drying the surfaces after powder coating when compared to oil. For cocoa, starch, xanthan gum and red pepper powders, EPS solutions were ineffective due to differences in hydrophobicity and interparticle bonding/solid bridging behavior. Scientific and Technological Research Council of Turkey (TUBITAK) [TOVAG 2150307] The authors would like to thank Assoc. Prof. Dr. Enes Dertli (Food Engineering Department, Bayburt University, Turkey) for providing LAB strain used, Ms. Asena Kurnaz and Ms. Ecem Poyraz (Food Engineering Department, Yildiz Technical University, Turkey) for production of EPS powder and Prof. Dr. Mustafa Tahsin Yilmaz for valuable discussions. This work was supported by The Scientific and Technological Research Council of Turkey (TUBITAK) (Project No: TOVAG 2150307).