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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.

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).

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 paper presents a study of the effect of adding Mo and MoS2 on the microstructure and properties of a powder coating based on austenitic steels. The coatings have been studied using X-ray diffraction (XRD), optical microscopy, scanning electron microscopy (SEM), a Vickers hardness tester, and abrasion wear resistance has been determined by the Pin on disk method. The results show that a coating that does not contain Mo and MoS2 consists of the phases g(Fe), M7(C, B)3 and (Fe, Cr)2B. The addition of Mo and MoS2 leads to the formation of phases M23(C, B)6, Mo2(B, C) and Fe3Mo3(C, B), where M = Fe, Cr, Mo. The main goal of these studies was to study characteristics of Mo and MoS2 distribution and the effect of their addition on the microstructure, hardness, and abrasion wear resistance of an alloy coating based on austenitic steels. Composite materials based on austenitic steels obtained by diffusion alloying (Aus0Mo), which has a nearly spherical shape with a diameter of 50–100 μm, have been used for deposition. 3–7 wt. % of Mo powder and 1.0–1.5 wt. % of MoS2 powder with a diameter less than 50 μm have been added in the powder of the composite material based on austenitic steels (Aus3Mo, Aus5Mo, Aus7Mo). Surfacing methods, including gas arc welding with a tungsten electrode, arc welding in shielding gas, plasma surfacing (PTA) and laser surfacing are widely used in industry to increase wear resistance of surfaces. The most important differences between these methods are deposition rate, applicability of materials, substrate dilution, microstructure and hardness stability after exposure to high temperatures, as well as manufacturing cost. Among the methods described above, plasma spraying followed by fusion is a good alternative to other surfacing processes. The coating should not be overheated until it is completely melted, since in this case the primary crystals of chromium carbides and borides pass into a liquid solution and upon subsequent crystallization, form a coarser structure, worsening the quality of the coating. This is precisely what does not occur during plasma spraying followed by reflow; in addition, the method is cheap, coatings are of high quality, competitive wear resistance and high stability of properties at high temperature.

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...

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 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.

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.

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.

Although powder coating systems offer many environmental, ecological and energy related benefits over liquid based coatings, in the case of uretdione based polyurethane systems, high curing temperature is still an issue. On the other hand, powder coating systems make it possible to reduce the costs and enhance the process of forming complex 3D structures using the deep drawing method by pre-coated metal substrates. During this processing method, there is a probability of micro crack formation in the coated film due to strain impact on the coating layer. A powder coating with self-healing ability is an ultimate solution to face not only this kind of fraction but also any other possible ones (such as defects caused by any impact on film surface during processing, transporting or even service). Here, a single molecule that is prepared via Diels–Alder cycloaddition reaction and retro Diels–Alder cleavage reaction was utilized as a self-healing additive to achieve self-healing ability in the powder coating system that is based on a commercially available uretdione cross-linker and OH-polyester resin. Coatings were prepared through melt mixing of components in a lab mixer, milling, sieving, and then application on the metal substrate through the electrostatic spraying method. To illustrate the role of self-healing additive, various concentrations (4 and 9% wt.) in combination with different curing temperatures (80 °C to 200 °C) were investigated. Both samples containing HA showed self-healing ability at elevated temperature around 120 °C for about 30 min with acceptable roughness and surface properties. Hardness measurement of cured film as well as thermal investigation indicate the chemical reaction of HA in a cross-linked network of cross-linker and resin. In addition, using HA leads to a 40 K drop in curing temperature of the system without using any catalyst. A 2.58% improvement in hardness values at a lower curing temperature and healing time of around 12.5 min at 120 °C to recover 100% of initial scratch (more than 10 cycles) in the sample containing 9% wt. HA was observed.

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...

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].

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 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.

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.

The efficiency of silver containing antimicrobial coatings depends on the release of the active component (silver ions) embedded in the coated surfaces. Fabrication and analysis of antimicrobial additives to powder coating were investigated in this research. An ion exchange process was used to incorporate the silver and copper ions into the synthetic zeolite LTA. Salts of these active agents in different combinations were tested to optimize the antimicrobial additives by achieving the highest concentration of active components. Yellowing and non-durable problems of this type of coating were studied and solution was proposed and examined. It was found the reduction of silver ions to Ag o during the high temperature curing step causes the coating turns yellower and reduced the durability of the antimicrobial function. The release rate of the active components from the surface to the contaminated environment can be further controlled by using polymeric encapsulation on the additive. Transfer efficiency of the additives in the resin system during the spraying was improved by a PGS treatment. The improved additives from this study showed excellent antimicrobial efficiency and durability. Toxicity produced from the coated surface was proved from LDH analysis.

Low-cost, environmentally friendly and easily applicable coating for Mg alloys, able to resist in real world conditions, are studied. Coatings already used for other metals (aluminum, steel) and never tested on Mg alloy for its different surface and reactivity were deposited on AM60 magnesium alloys to facilitate their technological applications, also in presence of chemically aggressive conditions. A biobased PA11 powder coating was compared to synthetic silicon-based and polyester coatings, producing lab scale samples, probed by drop deposition tests and dipping in increasingly aggressive, salty, basic and acid solutions, at RT and at higher temperatures. Coatings were analyzed by SEM/EDX to assess their morphology and compositions, by optical and IR-ATR microscopy analyses, before and after the drop tests. Migration analyses from the samples were performed by immersion tests using food simulants followed by ICP-OES analysis of the recovered simulant to explore applications also in the food contact field. A 30 μm thick white lacquer and a 120 μm PA11 coating resulted the best solutions. The thinner siliconic and lacquer coatings, appearing brittle and thin in the SEM analysis, failed some drop and/or dipping test, with damages especially at the edges. The larger thickness is thus the unique solution for edgy or pointy samples. Finally, coffee cups in AM60 alloy were produced, as real word prototypes, with the best performing coatings and tested for both migration by dipping, simulating also real world aging (2 h in acetic acid at 70° and 24 h in hot coffee at 60 °C): PA11 resulted stable in all the tests and no migration of toxic metals was observed, resulting a promising candidate for many real world application in chemically aggressive environments and also food and beverage related applications.

Highlights • Nanosilver-incorporated additive increases the antimicrobial durability. • Nanosilver modified by α-lipoic acid is tightly fixed on carrier. • Hydrophilic polymer encapsulation protects Ag+ and promotes nanosilver oxidation. • Complementary effect of Ag+ and nanosilver enhance instant activity and durability. • High silver loading additive with acceptable visual appearance., Applying silver into coatings has become a prevalent method in fabricating antimicrobial surfaces. However, the concerns about durability always exist and limit its applications. Here, a highly inhibitory, active, durable, and easy-to-use silver ions-nanosilver antimicrobial additive for powder coatings was fabricated in this study. Silver nanoparticles were chemically bonded to the Ag, Cu, and Zn-ternary ion-exchanged zeolite by α-lipoic acid, which was then encapsulated by hydrophilic polymers. The fabricated silver ions and silver nanoparticles (Ag+-AgNPs) complementary structure provides a synergistic effect. Ag+ is the main antimicrobial agent, while AgNPs act as a supplementary reservoir of Ag+. As well, the formed thin layer of silver nanoparticles and hydrophilic film prolongs the release of active Ag+ from zeolite, and Ag+ facilitates the activation of AgNPs. The results show that this additive indicates excellent antimicrobial activity to E. coli, S. aureus, P. aeruginosa, and C. albicans, and that the coatings with the additive exhibit over 99.99% reduction rate for the tested bacteria and fungi. The coating film is able to maintain over 99% antimicrobial reduction even after 1200 repeated solution wipings, or over 30 wash cycles of artificial sweat solution, indicating high durability. Furthermore, the yellowness of the coating is not evident (Δb

Surface coating has been used in abundance of engineering applications and components to protect and strengthen the surface of the material from corrosion which damages because of some atmospheric conditions and enhance their span of materials life. Corrosion or abrasion is caused naturally in which the materials destruct gradually using electrochemical or chemical reaction with their environment. This corrosion in metals occurs mainly due to air, water, and other environmental aspects. Steel structures have been used in many years of marine structural applications due to high fatigue strength, higher tensile strength, excellent dimensional stability, and thermal conductivity. The marine structure gets corroded due to the sea water and atmospheric conditions. The marine structures are made up of low carbon steel with various thickness from 6 to 20 mm, depends on the marine applications. The low carbon steel easily corrodes, so that the paint coating on the low carbon steel is in existence. This paint-coated surface directly reacts with marine atmosphere and forms a rust layer between 6 and 12 months. To prevent this rust layer formation, we need to bond coat with excellent corrosive resistive material under marine environment. These structures were partially immersed and floating in sea water. In fishing mechanized boat, the marine hull corrodes quickly due to marine atmosphere and heat lost from the engine room. This work focuses on protecting the marine structure subjected to corrosion and improving the mechanical strength and lifespan of marine structures with microparticle coating on the marine hull surface. The Ni–Cr powder coating was layered on the low carbon steel structure using plasma spray coating techniques with thickness of 100 and 150 µm. These prepared specimens was sized according to ASTM standards to perform the mechanical properties such as tensile, flexural and impact testing, and hardness tests like Rockwell, Brinell, Vickers, etc. The morphological structure also studied using SEM. The results show that the utilization of Ni–Cr micro-particle coating improves the mechanical strength of the mechanized boat hull from the paint coating in existence. The result reveals that coating improves the mechanical strength as well as its lifespan.

Fumed silica is one of the most commonly used flow additives in the powder coating industry. To investigate the influence of the properties of fumed silica on powder coatings, three different types of fumed silica, Aerosil R812, R972, and R8200, were selected and introduced to an ultra-high-gloss powder paint by the dry-blending method with preset mixing conditions and times. Their effect on the powder flowability, coating application related properties and film properties were carefully studied. The angle of repose (AOR) and bed expansion height data, which represent the semi-dynamic and dynamic flowability of powders respectively, show a strong flowability enhancement for the powders with additives, and R812 exhibits the best performance compared to 8200 and R972, mainly due to its high hydrophobicity and specific surface area. For the ultra-high-gloss powder paint, all the flow additives cause slight gloss reductions, surface roughness increase and a significant effect on the distinctness of image (DOI). The addition of R972 is beneficial to the transfer efficiency of powders compared with the other two, while the additives impose only a minor influence in the Faraday cage effect. The melting and curing dynamics, i.e., gel time, and inclined plate flow, are not affected by the flow additives.

Particle or powder coating with viscous liquids has been essential in industry for surface modification purposes to induce and enhance specific functionalities. This paper evaluates the performance of using foams (of different bubble diameters) versus liquids as a means of coating powder beds based on viscous liquid formulations. Coating with viscous liquids present numerous industrial challenges and therefore preparing foam equivalents can render the liquid component weak enough (through pre shearing to form the foam), to allow it to break up and coat particles under the shear forces exerted in a mixing device. In this study, two shear mixers are used; the first type consists of paddles in different configurations attached to a single rotating shaft, whilst the second type is a commercial twin screw mixer (TSM). The quality of coating achieved on the bulk powder bed using liquids and foams (stained with a dye) is assessed by image analysis to determine the homogeneity of the color distribution. In addition, scanning electron microscopy provides a tool to further investigate the coating quality of individual particles from the bulk product. The results show that large bubble (centimeter size) foams are much more effective at distributing within the fluidized powder bed compared to the starting viscous liquid and small bubble foams (sub-millimeter size). Furthermore, there is a maximum ratio of foam to powder beyond which agglomeration occurs and is insufficient to fully coat the particles. Coating of individual particles is achieved in the case of the TSM, whereas SEM proves that the single shaft paddle mixer crushes the particles and subsequently granulates them together to form granules of a size comparable to the size of coated particles seen after coating with the TSM.

Structural elements in buildings exposed to high temperature may lose their original stability. Application of steel structures has several advantages, however, deflection under exposure to high temperatures may be a potential obstacle. Therefore, the aim of the study was to determine how temperature affects decomposition of protective paints applied in the construction. A dedicated installation for the analysis of the combustion process of protective coating paints in a laboratory scale was prepared. The experimental device consisted of the following parts: top-loading furnace connected to the gas conditioner, the LAT MG-2 gas mixer, and portable gas analyzer GASMET DX-4010. The following type of the protective powder coating paints were analyzed: alkyd and polyurethane. The obtained results indicated that during thermal decomposition of paints, formaldehyde, benzene, heptane, and butanol were released, however in different concentrations. Moreover, decomposition temperature affected the type and amount of released gas mixture components. With increasing temperature, increased release of formaldehyde and benzene was noticed, while the concentration of butanol and heptane decreased. Finally, the product of thermal decomposition emitted in the highest concentration was formaldehyde, which can cause irritation and sensitization in humans.

In this work, polyester/TiO2 coatings on wood surfaces were prepared in one step via two deposition methods by using an atmospheric pressure plasma jet technique with the aim to further enhance the stabilization of the wood surfaces against UV-radiation and moisture. The first method, based on the combination of plasma spray powder (PSP) coating and liquid precursor plasma spraying (LPPS) coating techniques, used polyester powder and titanium tetraisopropoxide (TTIP) liquid precursor as feedstock. In the second method, the polyester/TiO2 coatings were prepared by using a mixed powder of polyester micro-particles and TiO2 nano-particles as feedstock and applied via plasma spray powder coating technique. The surface topology and morphology of the wood samples were observed by scanning electron microscopy (SEM). The SEM results showed the presence of a rough structure after coating with polyester/TiO2. The surface chemical compositions of the samples were characterized by X-ray photoelectron spectroscopy and by Fourier transform infrared spectroscopy. The wetting behaviour of the coated wood surfaces was studied by measuring the water contact angle. After coating a hydrophilic wood surface with polyester/TiO2 prepared via (PSP + LPPS), it showed excellent water repellency, the wood surfaces were transformed from hydrophilic to superhydrophobic, while the polyester/TiO2 coating prepared via (PSP) was hydrophilic. Protection against UV radiation-induced colour changes was determined by UV tests and photo-assisted analysis using the CIELab colour system. The abrasion test results indicated that the polyester-containing films had good abrasion resistance and good adhesion to the wood substrates.

Highly roughened surfaces on dental implants enhance the bone-bonding ability and in vivo cell adhesion on the implant surface. In this study, zirconia substrates were coated by powder coating using room temperature spray processing to improve their surface properties. Processing factors (particle size of the starting powder, number of repetitions of the deposition cycle, and spraying distance) were controlled to form a dense coating layer with high surface roughness on the zirconia substrate. Starting zirconia powders for coating were heat-treated at high temperature to control the particle size and kinetic energy. The coating layer fabricated from starting powder with a particle size of about 1.52 μm shows a homogeneous and dense microstructure, and it has a maximum surface roughness about 0.37 μm. The surface roughness of the film coatings increased with the number of times that the deposition cycle was repeated. No phase changes between the starting powder and the coating layer were observed, and all of the materials show identical tetragonal phases.

A novel phenomenon known as Industry X.0 is becoming extremely popular for digitizing and reinventing business organizations through the adaption of rapid and dynamic technological, innovational, and organizational changes for attaining the profitable revenue. This work investigates the die-casted commercially pure aluminum alloyed with 9% silicon and 3% copper (AlSi9Cu3) that is produced through the gravity die casting process. Further, the degradation of surface coating on die-casted AlSi9Cu3 alloy was explored. The acrylic paint electrodeposition (ED) coat, 2-coat polyester without primer and 3-coat polyester with epoxy primer powder coatings were used in this study. Moreover, the 3.5 wt.% of sodium chloride (3.5 wt.% of NaCl) test solution was used for electrochemical and salt spray test and the tools used to assess electrochemical properties were electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, and neutral salt spray test (NSS). The microstructure of AlSi9Cu3 after corrosion exposure was investigated, also, the microstructure of coated and uncoated AlSi9Cu3 samples was analyzed by SEM microscopy after corrosion exposure. Besides, the electrochemical studies were also carried out on the Al alloy die casting. It was found that acrylic paint ED coatings exhibited higher corrosion resistance than 2-coat polyester without primer &amp, 3-coat polyester with epoxy primer powder coatings. Acrylic paint ED coating showed higher corrosion resistance in AC and a lower value in DC and 3-coat polyester with epoxy primer powder coating displayed higher corrosion resistance in DC and a lower value in AC.

Synthesis of diamond films on carbide insert is a recent area of research in surface engineering. This research is carryout to know the effect of different seeding powders on diamond coating of WC tool by Hot Filament Chemical Vapor Deposition (HFCVD) method. Here, the formation of microcrystalline diamond (MCD) on SPUN tungsten carbide (WC-Co) cutting tool insert is carried out. Basically, before coating in HFCVD method, the substrate cobalt content should minimize by ultra-sonic etching. The uncoated tools are seeded ultrasonically by Diamond, Iridium, Platinum and Tungsten powder at the same coating condition to observe the growth of diamond crystals. X- ray diffraction gives clear results of diamond plane and adhesion of coating. The purity of diamond crystal after coating can be clear by observing the Raman shift in Raman spectroscopy (RS). The tool is seeded with diamond powder gives more nucleation density due to the presence of more sp3 bond as compared with sp2. Use of diamond and platinum powder as a seeding material gives fully developed crystal and uniform coating during diamond film deposition by HFCVD technique, rather in case of other powder coating the discrete crystals were formed.

In this study, the wear resistance of an epoxy powder coating was improved by SiO2 nanoparticles and their possible effect on curing kinetics of the coating was also evaluated. The epoxy powder coating was prepared with different percentages of nanoparticles (1-3 by wt.%) using a hot mixer, a method that can be more economic than other ones. The particle size distribution and Fourier-transform infrared spectroscopy (FT-IR) of epoxy powder were evaluated to examine the effect of mixing on the powder. The effect of SiO2 on the curing of epoxy powder was studied by differential scanning calorimetry (DSC). The Kissinger and model free kinetics (MFK) methods were used to calculate the activation energy (Ea) of the curing process of powders. The coating spraying process was carried out in an industrial installation on carbon steel substrates. The glass transition temperature (Tg) of the coatings was also studied using DSC. The morphology of the cured organic coatings was observed by scanning electron microscopy (SEM). Stiffness and hardness Vickers (HV) were evaluated. A test based on ASTM D969 was developed to perform erosion measurements. The results obtained by both the Kissinger and MKF methods showed that nanoparticles do not influence significantly the Ea of curing of the coatings. The addition of 1% SiO2 improves the erosion wear at 45 and 60°, due to the increase in stiffness and hardness provided by the nanoparticles, though, when particles collide at 60° with the samples, the lowest thickness loss was found for the epoxy with 3% nanoreinforcements. This research was funded by Interreg SUDOE, through the KrEaTive Habitat project [grant number SOE1/P1/E0307]. Publicado

The present study investigates the individual effects of three different thermosetting waste materials, used as fillers, on the mechanical, thermal and flow properties of acetal copolymers (POM). Different amounts ranging from 5% to 30% by weight of hydrolyzed powder coating recyclates were mixed as filler material in POM. The matrix and the fillers were first dry-mixed and then compounds were prepared through melt extrusion. The resulting compounds were cooled, granulated, and then standard tensile test bars were produced through use of an injection-molding machine. We investigated the mechanical and thermal properties of test specimens, and tensile strength, bending strength and impact strength were evaluated as a function of type and amount of filler material in the POM matrix. In addition, the change in melt flow index of POM/filler mixtures was determined, before and after extrusion. Furthermore, the morphology of the specimens was examined via electron microscopy. The results of this investigation are encouraging and present an innovative approach to reutilize hydrolyzed electrostatic powder coating wastes with thermoset structures as fillers in acetal copolymers.

Magnesium alloys are used in the motorsport and aerospace fields because of their high specific strength. However, due to their low corrosion resistance, protective surface treatments, such as conversion coating or electroless plating, are necessary when they are used in humid or corrosive environments. The present study aimed at evaluating the effect of plasma electrolytic oxidation (PEO), followed by the deposition of a polymeric layer by powder coating, on the rotating bending fatigue behaviour of the wrought magnesium alloy ZK60A-T5. The specimens were extracted from forged wheels of racing motorbikes and were PEO treated and powder coated. Microstructural characterization was carried out by optical (OM) and scanning electron microscopy (SEM) to analyse both the bulk material and the multilayer, consisting of the anodic oxide interlayer with the powder coating top layer (about 40 &micro, m total thickness). Rotating bending fatigue tests were carried out to obtain the S&ndash, N curve of PEO-treated specimens. The results of the rotating bending tests evidenced fatigue strength equal to 104 MPa at 106 cycles and 90 MPa at 107 cycles. The results of the investigation pointed out that PEO led to a reduction in fatigue strength between 14% and 17% in comparison to the untreated alloy. Fracture surface analyses of the fatigue specimens, carried out by SEM and by 3D digital microscopy, highlighted multiple crack initiation sites at the interface between the PEO layer and substrate, induced by the concurrent effects of coating defects, local tensile stresses in the substrate, and increased roughness at the substrate&ndash, coating interface.

A coating is a material that is applied to the surface of an object to form a continuous film that is firmly attached. It is usually based on vegetable oil or resin, with or without pigmentation, with an organic solvent or water to prepare a viscous liquid, or a solvent-free liquid coating or solid powder coating without solvent. Coatings are a companion engineering material. It relies on the coated object to exert its protective and decorative effects.