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Coatings, Volume 8, Issue 8 (August 2018)

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Cover Story (view full-size image) Thick stoichiometric hydroxyapatite (HA) coatings have been widely used to improve implants [...] Read more.
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Open AccessArticle High-Temperature Oxidation Resistance of NiAl Intermetallic Formed In Situ by Thermal Spraying
Coatings 2018, 8(8), 292; https://doi.org/10.3390/coatings8080292
Received: 30 June 2018 / Revised: 8 August 2018 / Accepted: 12 August 2018 / Published: 19 August 2018
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Abstract
An Al/Ni composite coating was deposited on the surface of a pure Ti substrate by arc spray technology and plasma spray technology. In order to enable the in-situ reaction between the Al/Ni composite coating and the specimen, they were heated under different conditions.
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An Al/Ni composite coating was deposited on the surface of a pure Ti substrate by arc spray technology and plasma spray technology. In order to enable the in-situ reaction between the Al/Ni composite coating and the specimen, they were heated under different conditions. In addition, oxidation testing was conducted to test the oxidation-resistant property of the coating. The phase transition regulation of the coating after heating, the influence of heating at different temperatures and time on the reaction depth, and the correlated theory of the in-situ formation of the NiAl intermetallic compounds were studied and analyzed. The results showed that after the heat treatment, a ragged wave-like morphology was exhibited in the diffusion front of Al, and a small amount of the Ni in the diffusion region did not participate in the reaction. The growth of the NiAl intermetallic layer in the diffusion region of the Al/Ni/Ti specimen was obviously slower compared with the Al/Ni specimen. Full article
(This article belongs to the Special Issue From Metallic Coatings to Additive Manufacturing)
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Open AccessArticle Preparation and Properties of Sodium Carboxymethyl Cellulose/Sodium Alginate/Chitosan Composite Film
Coatings 2018, 8(8), 291; https://doi.org/10.3390/coatings8080291
Received: 1 July 2018 / Revised: 24 July 2018 / Accepted: 12 August 2018 / Published: 19 August 2018
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Abstract
A sodium alginate/chitosan solution was prepared by dissolving sodium alginate, chitosan, and glycerol in an acetic acid solution. This solution was then combined with a sodium carboxymethyl cellulose solution and the mixture was cast onto a glass plate and dried at a constant
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A sodium alginate/chitosan solution was prepared by dissolving sodium alginate, chitosan, and glycerol in an acetic acid solution. This solution was then combined with a sodium carboxymethyl cellulose solution and the mixture was cast onto a glass plate and dried at a constant temperature of 60 °C. Then, a carboxymethyl cellulose/sodium alginate/chitosan composite film was obtained by immersing the film in a solution of a cross-linking agent, CaCl2, and air-drying the resulting material. First, the most advantageous contents of the three precursors in the casting solution were determined by a completely random design test method. Thereafter, a comprehensive orthogonal experimental design was applied to select the optimal mass ratio of the three precursors. The composite film obtained with sodium alginate, sodium carboxymethyl cellulose, and chitosan contents of 1.5%, 0.5%, and 1.5%, respectively, in the casting solution displayed excellent tensile strength, water vapor transmission rate, and elongation after fracture. Moreover, the presence of chitosan successfully inhibited the growth and reproduction of microorganisms. The composite film exhibited antibacterial rates of 95.7% ± 5.4% and 93.4% ± 4.7% against Escherichia coli and Staphylococcus aureus, respectively. Therefore, the composite film is promising for antibacterial food packaging applications. Full article
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Open AccessArticle Interconnections between Electronic Structure and Optical Properties of Multilayer Nanolaminate TiAlN/Ag and Al2O3/Ag Coatings
Coatings 2018, 8(8), 290; https://doi.org/10.3390/coatings8080290
Received: 27 April 2018 / Revised: 11 August 2018 / Accepted: 11 August 2018 / Published: 18 August 2018
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Abstract
Multilayer nanolaminate TiAlN/Ag and Al2O3/Ag metal-insulator-metal (MIM) coatings with thicknesses of individual layers from a few to several hundreds of nanometers were fabricated by direct current magnetron sputtering. Their optical transmittance and reflectance spectra were measured for photon energies
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Multilayer nanolaminate TiAlN/Ag and Al2O3/Ag metal-insulator-metal (MIM) coatings with thicknesses of individual layers from a few to several hundreds of nanometers were fabricated by direct current magnetron sputtering. Their optical transmittance and reflectance spectra were measured for photon energies 1–5 eV (1240–248 nm). The spectra were non-monotonous as their transmission and reflection bands were strongly dependent on the coating architecture. A set of advanced electron spectroscopy methods was used to analyse the electronic structure of the coatings controlling optical properties. Energies of plasmons peaks and the distribution of their intensities are functions of the Ag layers thickness as well as the composition and thickness of the dielectric nanolayers in the MIM nanocomposite. Statistical analysis established the cross-correlations between geometrical parameters of the coatings, transmissions and reflection bands on the optical spectra and parameters of the electronic structure. Particularly, the blue side of the transmittance band is controlled by plasmons while the dielectric band gap determines the transmittance of the red side. The obtained experimental results allowed us to fulfil the computed architectural design of a multilayer Al2O3/Ag coating with a narrow bandwidth in the visible light region and strong reflection in the infrared and ultraviolet regions. Full article
(This article belongs to the Special Issue Surface Engineering and Nanofilms)
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Open AccessArticle Magnetron Sputtered AlN Layers on LTCC Multilayer and Silicon Substrates
Coatings 2018, 8(8), 289; https://doi.org/10.3390/coatings8080289
Received: 20 June 2018 / Revised: 18 July 2018 / Accepted: 25 July 2018 / Published: 18 August 2018
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Abstract
This work compares the deposition of aluminum nitride by magnetron sputtering on silicon to multilayer ceramic substrates. The variation of sputter parameters in a wide range following a fractional factorial experimental design generates diverse crystallographic properties of the layers. Crystal growth, composition, and
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This work compares the deposition of aluminum nitride by magnetron sputtering on silicon to multilayer ceramic substrates. The variation of sputter parameters in a wide range following a fractional factorial experimental design generates diverse crystallographic properties of the layers. Crystal growth, composition, and stress are distinguished because of substrate morphology and thermal conditions. The best c-axis orientation of aluminum nitride emerges on ceramic substrates at a heater temperature of 150 °C and sputter power of 400 W. Layers deposited on ceramic show stronger c-axis texture than those deposited on silicon due to higher surface temperature. The nucleation differs significantly dependent on the substrate. It is demonstrated that a ceramic substrate material with an adapted coefficient of thermal expansion to aluminum nitride allows reducing the layer stress considerably, independent on process temperature. Layers sputtered on silicon partly peeled off, while they adhere well on ceramic without crack formation. Direct deposition on ceramic enables thus the development of optimized layers, avoiding restrictions by stress compensating needs affecting functional properties. Full article
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Open AccessArticle Optimal Patterned Wettability for Microchannel Flow Boiling Using the Lattice Boltzmann Method
Coatings 2018, 8(8), 288; https://doi.org/10.3390/coatings8080288
Received: 22 May 2018 / Revised: 28 July 2018 / Accepted: 5 August 2018 / Published: 17 August 2018
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Abstract
Microchannel flow boiling is a cooling method studied in microscale heat-cooling, which has become an important field of research with the development of high-density integrated circuits. The change in microchannel surface characteristics affects thermal fluid behavior, and existing studies have optimized heat transfer
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Microchannel flow boiling is a cooling method studied in microscale heat-cooling, which has become an important field of research with the development of high-density integrated circuits. The change in microchannel surface characteristics affects thermal fluid behavior, and existing studies have optimized heat transfer by changing surf ace wettability characteristics. However, a surface with heterogeneous wettability also has the potential to improve heat transfer. In this case, heat transfer would be optimized by applying the optimal heterogeneous wettability surface to channel flow boiling. In this study, a change in cooling efficiency was observed, by setting a hydrophobic and hydrophilic wettability pattern on the channel surface under the microchannel flow boiling condition, using a lattice Boltzmann method simulation. In the rectangular microchannel structure, the hydrophobic-hydrophilic patterned wettability was oriented perpendicular to the flow direction. The bubble nucleation and the heat transfer coefficient were observed in each case by varying the length of the pattern and the ratio of the hydrophobic-hydrophilic area. It was found that the minimum pattern length in which individual bubbles can occur, and the wettability pattern in which the bubble nucleation-departure cycle is maintained, are advantageous for increasing the efficiency of heat transfer in channel flow boiling. Full article
(This article belongs to the Special Issue Superhydrophobic Coatings)
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Open AccessArticle The Role of Thin-Film Vacuum-Plasma Coatings and Their Influence on the Efficiency of Ceramic Cutting Inserts
Coatings 2018, 8(8), 287; https://doi.org/10.3390/coatings8080287
Received: 20 June 2018 / Revised: 17 July 2018 / Accepted: 6 August 2018 / Published: 17 August 2018
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Abstract
The main problem with ceramics used in cutting tools is related to the unpredictable failures caused by the brittle fracturing of ceramic inserts, which is critical for the intermittent milling of cyclic loading. A 125-mm-diameter eight-toothed end mill, with a mechanical fastening of
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The main problem with ceramics used in cutting tools is related to the unpredictable failures caused by the brittle fracturing of ceramic inserts, which is critical for the intermittent milling of cyclic loading. A 125-mm-diameter eight-toothed end mill, with a mechanical fastening of ceramic inserts, was used as a cutting tool for milling hardened steel (102Cr6). For the experiments, square inserts of the Al2O3 + SiC ceramic were used and compared with the samples made of Al2O3 + TiC to confirm the obtained results. The samples were coated with diamond-like coating (DLC), TiZrN, and TiCrAlN coatings, and their bending strength and adhesion were investigated. Investigations into the friction coefficient of the samples and operational tests were also carried out. The effect of smoothing the microroughness and surface defects in comparison with uncoated inserts, which are characteristic of the abrasive processing of ceramics, was investigated and analyzed. The process developed by the authors of the coating process allows for the cleaning and activation of the surface of ceramic inserts using high-energy gas atoms. The impact of these particles on the cutting edge of the insert ensures its sharpening and reduces the radius of curvature of its cutting edges. Full article
(This article belongs to the Special Issue Design and Synthesis of Hard Coatings)
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Open AccessArticle Optimization Method for Developing Spectral Controlling Cosmetics: Application for Thermal Barrier Cosmetic
Coatings 2018, 8(8), 286; https://doi.org/10.3390/coatings8080286
Received: 3 July 2018 / Revised: 6 August 2018 / Accepted: 11 August 2018 / Published: 17 August 2018
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Abstract
In this paper, a method of optimizing a thermal barrier cosmetic and spectral selective cosmetic by controlling the particle size and material is proposed as a countermeasure to heatstroke. The radiative properties of single cosmetic particles of a wide range of particle sizes
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In this paper, a method of optimizing a thermal barrier cosmetic and spectral selective cosmetic by controlling the particle size and material is proposed as a countermeasure to heatstroke. The radiative properties of single cosmetic particles of a wide range of particle sizes and wavelengths in non-absorbing air were calculated in this study based on the Mie theory. Al2O3, TiO2, Au, and Ag were used as the material of the cosmetic particle. The radiative property of a particle cloud in dependent scattering was calculated. The radiative transfer in the cosmetic layer was analyzed, and the spectral reflectance of the cosmetic layer on the human skin was calculated. A new parameter was defined to quantitatively evaluate the performance of the thermal barrier cosmetic and spectral selective cosmetic. For the thermal barrier cosmetic, the Al2O3 particle was determined to be suitable, and its size was optimized. For the spectral selective cosmetic, the Au particle was likewise determined to be suitable, and its size was optimized. Our cosmetics satisfied both aesthetic and thermal concerns. Full article
(This article belongs to the Special Issue Binders, Pigments, Dyes and Additives)
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Open AccessArticle The Tribocorrosion and Corrosion Properties of Thermally Oxidized Ti6Al4V Alloy in 0.9 wt.% NaCl Physiological Saline
Coatings 2018, 8(8), 285; https://doi.org/10.3390/coatings8080285
Received: 13 June 2018 / Revised: 9 August 2018 / Accepted: 12 August 2018 / Published: 16 August 2018
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Abstract
Thermal oxidation of Ti6Al4V was carried out at 700 °C for 5 h in air atmosphere. The characteristics of morphology and structure, micro-hardness, and tribocorrosion behavior in 0.9 wt.% NaCl solution of thermally oxidized Ti6Al4V alloys were investigated and compared with those of
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Thermal oxidation of Ti6Al4V was carried out at 700 °C for 5 h in air atmosphere. The characteristics of morphology and structure, micro-hardness, and tribocorrosion behavior in 0.9 wt.% NaCl solution of thermally oxidized Ti6Al4V alloys were investigated and compared with those of the untreated one. The scanning electron microscope (SEM) and glow discharge spectrometer (GDS) results reveal that the oxide layer is completely coated on the substrate, which is a bilayer structure consisted of oxide film and oxygen diffusion zone (ODZ). X-ray diffraction (XRD) and Raman measurements reveal the rutile phase as the dominant phase. The micro-hardness and surface roughness (Ra) increase about 1.63 and 4 times than those of the untreated one. Thermally oxidized sample obtains corrosion and tribocorrosion resistance property in 0.9 wt.% NaCl solution. The corrosion potential has a more than 500 mV anodic shift, the corrosion current density decreases about 80%. The total material loss volume is reduced by almost an order of magnitude under tribocorrosion behavior, which is due to the improvement of the micro-hardness of the oxide layer and ODZ that reduce the corrosion and the synergistic effect of corrosion and wear. Full article
(This article belongs to the Special Issue Nanocomposite Coatings)
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Open AccessFeature PaperArticle Hemin-Modified SnO2/Metglas Electrodes for the Simultaneous Electrochemical and Magnetoelastic Sensing of H2O2
Coatings 2018, 8(8), 284; https://doi.org/10.3390/coatings8080284
Received: 2 July 2018 / Revised: 2 August 2018 / Accepted: 11 August 2018 / Published: 16 August 2018
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Abstract
In this work, we present a simple and efficient method for the preparation of hemin-modified SnO2 films on Metglas ribbon substrates for the development of a sensitive magneto-electrochemical sensor for the determination of H2O2. The SnO2 films
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In this work, we present a simple and efficient method for the preparation of hemin-modified SnO2 films on Metglas ribbon substrates for the development of a sensitive magneto-electrochemical sensor for the determination of H2O2. The SnO2 films were prepared at low temperatures, using a simple hydrothermal method, compatible with the Metglas surface. The SnO2 film layer was fully characterized by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), photoluminescence (PL) and Fourier Transform-Infrared spectroscopy (FT-IR). The properties of the films enable a high hemin loading to be achieved in a stable and functional way. The Hemin/SnO2-Metglas system was simultaneously used as a working electrode (WE) for cyclic voltammetry (CV) measurements and as a magnetoelastic sensor excited by external coils, which drive it to resonance and interrogate it. The CV scans reveal direct reduction and oxidation of the immobilized hemin, as well as good electrocatalytic response for the reduction of H2O2. In addition, the magnetoelastic resonance (MR) technique allows the detection of any mass change during the electroreduction of H2O2 by the immobilized hemin on the Metglas surface. The experimental results revealed a mass increase on the sensor during the redox reaction, which was calculated to be 767 ng/μM. This behavior was not detected during the control experiment, where only the NaH2PO4 solution was present. The following results also showed a sensitive electrochemical sensor response linearly proportional to the concentration of H2O2 in the range 1 × 10−6–72 × 10−6 M, with a correlation coefficient of 0.987 and detection limit of 1.6 × 10−7 M. Moreover, the Hemin/SnO2-Metglas displayed a rapid response (30 s) to H2O2 and exhibits good stability, reproducibility and selectivity. Full article
(This article belongs to the Special Issue Mesoporous Metal Oxide Films)
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Open AccessArticle Waterborne Acrylate-Based Hybrid Coatings with Enhanced Resistance Properties on Stone Surfaces
Coatings 2018, 8(8), 283; https://doi.org/10.3390/coatings8080283
Received: 10 July 2018 / Revised: 2 August 2018 / Accepted: 11 August 2018 / Published: 15 August 2018
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Abstract
The application of coating polymers to building materials is a simple and cheap way to preserve and protect surfaces from weathering phenomena. Due to its environmentally friendly character, waterborne coating is the most popular type of coating, and improving its performance is an
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The application of coating polymers to building materials is a simple and cheap way to preserve and protect surfaces from weathering phenomena. Due to its environmentally friendly character, waterborne coating is the most popular type of coating, and improving its performance is an important key of research. The study presents the results regarding the mechanical and photo-oxidation resistance of some water-based acrylic coatings containing SiO2 nanoparticles obtained by batch miniemulsion polymerization. Coating materials have been characterized in terms of hydrophobic/hydrophilic behavior, mechanical resistance and surface morphology by means of water-contact angle, and scrub resistance and atomic force microscopy (AFM) measurements depending on silica-nanoparticle content. Moreover, accelerated weathering tests were performed to estimate the photo-oxidation resistance of the coatings. The chemical and color changes were assessed by Fourier-transform infrared spectroscopy (FTIR) and colorimetric measurements. Furthermore, the nanofilled coatings were applied on two different calcareous lithotypes (Lecce stone and Carrara Marble). Its properties, such as capillary water absorption and color modification, before and after accelerated aging tests, were assessed. The properties acquired by the addition of silica nanoparticles in the acrylic matrix can ensure good protection against weathering of stone-based materials. Full article
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Open AccessFeature PaperArticle Visually Attractive and High-Power-Retention Solar Modules by Coloring with Automotive Paints
Coatings 2018, 8(8), 282; https://doi.org/10.3390/coatings8080282
Received: 13 June 2018 / Revised: 30 July 2018 / Accepted: 11 August 2018 / Published: 15 August 2018
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Abstract
The automotive painting technique is highly advantageous for coloring solar modules, because it enables the modules to be visually attractive over a large area, numerous colors can be applied, and they are highly durable. Herein, we present a high-performance solar module colored using
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The automotive painting technique is highly advantageous for coloring solar modules, because it enables the modules to be visually attractive over a large area, numerous colors can be applied, and they are highly durable. Herein, we present a high-performance solar module colored using an automotive painting technique. We coated a dilute automotive pigment, the high-transmittance mica pigment, with a clear coat material on a crystalline Si solar module to generate blue color. Our measurements show that a pigment weight concentration of around 10% with the mica pigment is suitable for painting the solar modules, because it enables visual attractiveness while retaining over 80% of the output power, compared to the original solar module. We believe that the technique proposed herein can considerably increase the installable area of solar modules on a car body. Full article
(This article belongs to the Special Issue Thin Film Solar Cells: Fabrication, Characterization and Applications)
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Open AccessArticle Growth of WS2 flakes on Ti3C2Tx Mxene Using Vapor Transportation Routine
Coatings 2018, 8(8), 281; https://doi.org/10.3390/coatings8080281
Received: 1 July 2018 / Revised: 7 August 2018 / Accepted: 11 August 2018 / Published: 14 August 2018
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Abstract
Two-dimensional dichalcogenides (TMDs) and mxene junctions had been predicted to possess distinct tunable electronic properties. However, direct synthesis of WS2 on Ti3C2Tx mxene is still challenging. Herein, we successfully deposited WS2 onto the surface of Ti
[...] Read more.
Two-dimensional dichalcogenides (TMDs) and mxene junctions had been predicted to possess distinct tunable electronic properties. However, direct synthesis of WS2 on Ti3C2Tx mxene is still challenging. Herein, we successfully deposited WS2 onto the surface of Ti3C2Tx mxene by employing the vapor transportation (VT) routine. By modulating pressure and source-sample distance, multilayer and monolayer (1 L) WS2 flakes were deposited onto the lateral side and top surface of Ti3C2Tx flakes. The 1 L WS2 flakes growing on lateral side of Ti3C2Tx flake have much higher photoluminescence (PL) intensity than 1 L flakes growing on the top surface. Our study has the potential to benefit the design and preparation of novel electronic and electrochemical devices based on TMDs/mxene junctions. Full article
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Open AccessArticle UHMWPE Nanocomposite Coatings Reinforced with Alumina (Al2O3) Nanoparticles for Tribological Applications
Coatings 2018, 8(8), 280; https://doi.org/10.3390/coatings8080280
Received: 28 July 2018 / Revised: 8 August 2018 / Accepted: 12 August 2018 / Published: 14 August 2018
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Abstract
Due to a growing demand for protecting metallic components from wear and tear, polymer coatings are being extensively researched and developed as one of the most effective and efficient solutions to reduce friction and wear in demanding tribological applications. The present study focuses
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Due to a growing demand for protecting metallic components from wear and tear, polymer coatings are being extensively researched and developed as one of the most effective and efficient solutions to reduce friction and wear in demanding tribological applications. The present study focuses on developing a polymer nanocomposite coating of ultra-high molecular polyethylene (UHMWPE) reinforced with different loadings (0.5, 3, 5, and 10 wt %) of alumina to protect steel surfaces. Wear tests were conducted on the coated samples using a tribometer with a ball-on-disk configuration, sliding against a 440C hardened stainless steel ball as a counterface to evaluate the wear life and the load-bearing capacity of the developed coatings. Micro-indentation, energy dispersive X-ray spectroscopy, scanning electron microscopy, and optical profilometry techniques were used to characterize the coatings in terms of hardness, dispersion of the nanofillers, morphology, and wear mechanisms, respectively. Results showed that the UHMWPE nanocomposite coating reinforced with 3 wt % and 5 wt % of alumina did not fail, even until 250,000 cycles at a normal load of 12 N and a linear speed of 0.1 m/s, showing a significant improvement in wear resistance as compared to the pristine UHMWPE coating. Full article
(This article belongs to the Special Issue Nanocomposite Coatings)
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Open AccessArticle Schlieren Visualization of Shaping Air during Operation of an Electrostatic Rotary Bell Sprayer: Impact of Shaping Air on Droplet Atomization and Transport
Coatings 2018, 8(8), 279; https://doi.org/10.3390/coatings8080279
Received: 14 July 2018 / Revised: 1 August 2018 / Accepted: 10 August 2018 / Published: 11 August 2018
PDF Full-text (7683 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Electrostatic rotary bell sprayers (ERBSs) are widely used in the automotive industry. In ERBS, atomization is facilitated using centrifugal forces which disintegrate the paint film inside the cup into droplets at the cup edge. The droplets are then transported by the flow of
[...] Read more.
Electrostatic rotary bell sprayers (ERBSs) are widely used in the automotive industry. In ERBS, atomization is facilitated using centrifugal forces which disintegrate the paint film inside the cup into droplets at the cup edge. The droplets are then transported by the flow of a shaping air (SA) and electrostatic forces to a target surface; the characteristics of these droplets dramatically influence the quality of a painted surface and the painting transfer efficiency. In the current paper, a novel Schlieren-based visualization of the shaping air in the absence of paint droplets was performed during a qualitative investigation to delineate shaping air flow behavior and its interaction with droplets and droplet transport. An infrared thermographic flow visualization (IRFV) method and droplet size measurement were used to complement the Schlieren data for providing insight into shaping air-droplet interactions. The results demonstrated the impact of different operating conditions on the SA flow pattern, and the influence SA has on the secondary atomization and transport of droplets. Hence, these experimental methods combine with a useful tool for optimizing SA configurations that improve spray quality, droplet transport, and the efficiency of ERBS operations. Full article
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Open AccessReview A Review of Conductive Metal Nanomaterials as Conductive, Transparent, and Flexible Coatings, Thin Films, and Conductive Fillers: Different Deposition Methods and Applications
Coatings 2018, 8(8), 278; https://doi.org/10.3390/coatings8080278
Received: 9 July 2018 / Revised: 1 August 2018 / Accepted: 5 August 2018 / Published: 9 August 2018
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Abstract
With ever-increasing demand for lightweight, small, and portable devices, the rate of production of electronic and optoelectronic devices is constantly increasing, and alternatives to the current heavy, voluminous, fragile, conductive and transparent materials will inevitably be needed in the future. Conductive metal nanomaterials
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With ever-increasing demand for lightweight, small, and portable devices, the rate of production of electronic and optoelectronic devices is constantly increasing, and alternatives to the current heavy, voluminous, fragile, conductive and transparent materials will inevitably be needed in the future. Conductive metal nanomaterials (such as silver, gold, copper, zinc oxide, aluminum, and tin) and carbon-based conductive materials (carbon nanotubes and graphene) exhibit great promise as alternatives to conventional conductive materials. Successfully incorporating conductive nanomaterials into thin films would combine their excellent electrical and optical properties with versatile mechanical characteristics superior to those of conventional conductive materials. In this review, the different conductive metal nanomaterials are introduced, and the challenges facing methods of thin film deposition and applications of thin films as conductive coatings are investigated. Full article
(This article belongs to the Special Issue Nanostructured Functional Coatings)
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Open AccessReview Metal Fluorides as Lithium-Ion Battery Materials: An Atomic Layer Deposition Perspective
Coatings 2018, 8(8), 277; https://doi.org/10.3390/coatings8080277
Received: 9 June 2018 / Revised: 25 July 2018 / Accepted: 6 August 2018 / Published: 8 August 2018
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Abstract
Lithium-ion batteries are the enabling technology for a variety of modern day devices, including cell phones, laptops and electric vehicles. To answer the energy and voltage demands of future applications, further materials engineering of the battery components is necessary. To that end, metal
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Lithium-ion batteries are the enabling technology for a variety of modern day devices, including cell phones, laptops and electric vehicles. To answer the energy and voltage demands of future applications, further materials engineering of the battery components is necessary. To that end, metal fluorides could provide interesting new conversion cathode and solid electrolyte materials for future batteries. To be applicable in thin film batteries, metal fluorides should be deposited with a method providing a high level of control over uniformity and conformality on various substrate materials and geometries. Atomic layer deposition (ALD), a method widely used in microelectronics, offers unrivalled film uniformity and conformality, in conjunction with strict control of film composition. In this review, the basics of lithium-ion batteries are shortly introduced, followed by a discussion of metal fluorides as potential lithium-ion battery materials. The basics of ALD are then covered, followed by a review of some conventional lithium-ion battery materials that have been deposited by ALD. Finally, metal fluoride ALD processes reported in the literature are comprehensively reviewed. It is clear that more research on the ALD of fluorides is needed, especially transition metal fluorides, to expand the number of potential battery materials available. Full article
(This article belongs to the Special Issue Atomic Layer Deposition)
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Open AccessArticle Bioceramic Layers with Antifungal Properties
Coatings 2018, 8(8), 276; https://doi.org/10.3390/coatings8080276
Received: 11 July 2018 / Revised: 30 July 2018 / Accepted: 3 August 2018 / Published: 8 August 2018
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Abstract
The sol-gel method was used to synthesize the silver doped hydroxyapatite (Ag:HAp) gels in order to produce the antifungal composite layers. The pure Ti disks were used as the substrate for the composite layers. Important information about suspensions used to make Ag:HAp composite
[...] Read more.
The sol-gel method was used to synthesize the silver doped hydroxyapatite (Ag:HAp) gels in order to produce the antifungal composite layers. The pure Ti disks were used as the substrate for the composite layers. Important information about suspensions used to make Ag:HAp composite layers were obtained from an ultrasonic technique. The identification of the phase composition of the Ag:HAp composite layers was accomplished X-ray diffraction (XRD). The morphology and the thickness of the layers was evaluated using scanning electron microscopy (SEM). The uniform distribution of the constituent elements (Ag, Ca, P, and O) in both analyzed samples was observed. The antifungal activity of the samples against Candida albicans ATCC 10231 microbial strain were investigated immediately after their preparation and six months later. SEM and confocal laser scanning microscopy (CLSM) images showed that the composite layers at the two time intervals exhibited a strong antifungal activity against Candida albicans ATCC 10231 and completely inhibited the biofilm formation. Full article
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Open AccessArticle Shellac Thin Films Obtained by Matrix-Assisted Pulsed Laser Evaporation (MAPLE)
Coatings 2018, 8(8), 275; https://doi.org/10.3390/coatings8080275
Received: 14 June 2018 / Revised: 27 July 2018 / Accepted: 3 August 2018 / Published: 7 August 2018
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Abstract
We report on the fabrication of shellac thin films on silicon substrates by matrix-assisted pulsed laser evaporation (MAPLE) using methanol as matrix. Very adherent, dense, and smooth films were obtained by MAPLE with optimized deposition parameters, such as laser wavelength and laser fluence.
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We report on the fabrication of shellac thin films on silicon substrates by matrix-assisted pulsed laser evaporation (MAPLE) using methanol as matrix. Very adherent, dense, and smooth films were obtained by MAPLE with optimized deposition parameters, such as laser wavelength and laser fluence. Films with a root mean square (RMS) roughness of 11 nm measured on 40 × 40 µm2 were obtained for a 2000-nm-thick shellac film deposited with 0.6 J/cm2 fluence at a laser wavelength of 266 nm. The MAPLE films were tested in simulated gastric fluid in order to assess their capabilities as an enteric coating. The chemical, morphological, and optical properties of shellac samples were investigated by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and atomic force microscopy (AFM). Full article
(This article belongs to the Special Issue Current Research in Pulsed Laser Deposition)
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Open AccessArticle Poly(Phenylene Methylene): A Multifunctional Material for Thermally Stable, Hydrophobic, Fluorescent, Corrosion-Protective Coatings
Coatings 2018, 8(8), 274; https://doi.org/10.3390/coatings8080274
Received: 29 June 2018 / Revised: 20 July 2018 / Accepted: 25 July 2018 / Published: 7 August 2018
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Abstract
Poly(phenylene methylene) (PPM) is a thermally stable, hydrophobic, fluorescent hydrocarbon polymer. PPM has been proposed earlier to be useful as a coating material but this polymer was isolated in relevant molar masses only recently, and in large quantities. Accordingly, the preparation of coatings
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Poly(phenylene methylene) (PPM) is a thermally stable, hydrophobic, fluorescent hydrocarbon polymer. PPM has been proposed earlier to be useful as a coating material but this polymer was isolated in relevant molar masses only recently, and in large quantities. Accordingly, the preparation of coatings based on PPM and their behavior was explored in this study, with the example of the metal alloy AA2024 as a common substrate for corrosion tests. Coatings free of bubbles and cracks were obtained by hot pressing and application of the following steps: Coating on AA2024 with a layer of polybenzylsiloxane to improve the adhesion between PPM and the metal surface, the addition of polybenzylsiloxane to PPM in order to enhance the viscosity of the molten PPM, and the addition of benzyl butyl phthalate as a plasticizer. Electrochemical corrosion tests showed good protection of the metal surface towards a NaCl solution, thanks to a passive-like behavior in a wide potential window and a very low current density. Remarkably, the PPM coating also exhibited self-healing towards localized attacks, which inhibits the propagation of corrosion. Full article
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Open AccessArticle Composition versus Wear Behaviour of Air Plasma Sprayed NiCr–TiB2–ZrB2 Composite Coating
Coatings 2018, 8(8), 273; https://doi.org/10.3390/coatings8080273
Received: 13 June 2018 / Revised: 23 July 2018 / Accepted: 5 August 2018 / Published: 6 August 2018
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Abstract
The NiCr–TiB2–ZrB2 composite coating was deposited on the surface of blades made of steel (SUS304) using high-energy ball milling technology and air plasma spraying technology, which aimed to relieve the wear of the blades during operation. The influence of titanium
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The NiCr–TiB2–ZrB2 composite coating was deposited on the surface of blades made of steel (SUS304) using high-energy ball milling technology and air plasma spraying technology, which aimed to relieve the wear of the blades during operation. The influence of titanium diboride (TiB2) and zirconium diboride (ZrB2) on the microstructure and wear resistance of the coatings was investigated by X-ray diffraction, scanning electron microscopy, Vickers microhardness tester, and a wear tester. The results showed that the TiB2 and ZrB2 particles were unevenly distributed in the coatings and significantly increased the hardness and anti-wear, which contributed to their ultra-high hardness and extremely strong ability to resist deformation. The performance of the coatings was improved with the increase of the number of ceramic phases, while the hardness and wear resistance of the coating could reach their highest value when the TiB2 and ZrB2 respectively took up 15 wt.% of the total mass of the powder. Full article
(This article belongs to the Special Issue Coatings Tribology)
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Open AccessArticle Automated Control of Plasma Ion-Assisted Electron Beam-Deposited TiO2 Optical Thin Films
Coatings 2018, 8(8), 272; https://doi.org/10.3390/coatings8080272
Received: 4 July 2018 / Revised: 20 July 2018 / Accepted: 3 August 2018 / Published: 5 August 2018
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Abstract
A hollow cathode plasma source has been operated automatically, demonstrating independent control of plasma ion energy and ion current density for plasma ion-assisted electron beam-deposited titania (TiO2). The lanthanum hexaboride hollow cathode design described in this work utilizes both the interior
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A hollow cathode plasma source has been operated automatically, demonstrating independent control of plasma ion energy and ion current density for plasma ion-assisted electron beam-deposited titania (TiO2). The lanthanum hexaboride hollow cathode design described in this work utilizes both the interior and exterior cathode surfaces, with the additional electrons generated removing the need for a separate neutralizing source. Automatic feedback control of plasma source cathode-to-anode accelerator voltage (AV—via argon gas flow to the anode and/or cathode plasma source areas) and accelerator current (AC—via an external high-current power supply) provides independent control of the ion energy distribution function and ion current density, respectively. Automated run-to-run reproducibility (over six separate deposition runs) in TiO2 refractive index (550 nm) was demonstrated as 2.416 ± 0.008 (spread quoted as one standard deviation), which is well within the required refractive index control for optical coating applications. Variation in refractive index is achievable through control of AV (ion energy) and/or AC (ion current density), directly influencing deposited TiO2 structural phase. Measured dependencies of TiO2 refractive index and extinction coefficient on AV and AC are described. Optimum plasma source parameters for assisted electron beam deposition of TiO2 optical thin-film applications are highlighted. Full article
(This article belongs to the Special Issue Applications of Optical Thin Film Coatings)
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Open AccessArticle IRI Sensitivity to the Influence of Surface Distress on Flexible Pavements
Coatings 2018, 8(8), 271; https://doi.org/10.3390/coatings8080271
Received: 23 June 2018 / Revised: 19 July 2018 / Accepted: 28 July 2018 / Published: 2 August 2018
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Abstract
Today, authorities responsible for the operation of highways aim to provide comfort to road users as well as safety while driving. While driving, the most important component that determines comfort for road users is the pavement. The relative effects of various surface distress
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Today, authorities responsible for the operation of highways aim to provide comfort to road users as well as safety while driving. While driving, the most important component that determines comfort for road users is the pavement. The relative effects of various surface distress types in bituminous, hot mixed asphalt pavements on the International Roughness Index (IRI) component—used to evaluate the present performance, and hence the comfort, of pavements—are determined in this study. The presence of only one type of surface distress is very difficult to achieve in practice, especially in regards to pavements where a high degree of deterioration is observed. The presence of different types of surface distress in road pavements, due to similar problems in very close positions and even in nested forms, makes it difficult to assess this issue. The relationships between surface distress and IRI have been modelled to overcome this challenge. To this end, the Multivariate Adaptive Regression Splines (MARS) modelling approach, which is very successful in investigating the relationships between a large number of independent variables and dependent variables, has been used. The sensitivities of the surface distress inputs are evaluated singularly by means of a model with 29 input variables calibrated using the pavement distress data collected in 3295 highway pavement sections. As a result of this analysis, the sensitivity of surface distress inputs collected, as an area, has been determined to have an effect on the increase in IRI. The results are interpreted with the help of figures and tables. Full article
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Open AccessFeature PaperArticle Investigation of TiO2 Thin Film Deposited by Microwave Plasma Assisted Sputtering and Its Application in 3D Glasses
Coatings 2018, 8(8), 270; https://doi.org/10.3390/coatings8080270
Received: 2 July 2018 / Revised: 23 July 2018 / Accepted: 31 July 2018 / Published: 2 August 2018
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Abstract
TiO2 deposition using separate regions for sputtering and oxidation is not well investigated. We optimized process parameter for such as oxygen flow and microwave power to produce high quality TiO2 filters for Stereo/3D imaging applications. This deposition technique was chosen for
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TiO2 deposition using separate regions for sputtering and oxidation is not well investigated. We optimized process parameter for such as oxygen flow and microwave power to produce high quality TiO2 filters for Stereo/3D imaging applications. This deposition technique was chosen for its unique advantages: high deposition rates while increasing the probability of obtaining stoichiometric oxides, reduces possibility of target poisoning and provides better stability of process. Various characterization methods, such as scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman, X-ray diffraction (XRD), transmission spectroscopy, were used in compliment to simulations for detailed analysis of deposited TiO2 thin films. Process parameters were optimized to achieve TiO2 films with low surface scattering and absorption for fabricating multi-passbands interference filter for 3D glasses. From observations and quantitative analysis of surfaces, it was seen that surface roughness increases while oxygen flow or microwave power increases. As the content of anatase phase also increases with higher microwave power and higher oxygen flow, the formation of anatase grains can cause higher surface roughness. Optical analysis of samples validates these trends and provided additional information for absorption trends. Optimized parameters for deposition process are then obtained and the final fabricated 3D glasses filters showed high match to design, within 0.5% range for thickness error. Full article
(This article belongs to the Special Issue Applications of Optical Thin Film Coatings)
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Open AccessFeature PaperReview A Review on Ionic Substitutions in Hydroxyapatite Thin Films: Towards Complete Biomimetism
Coatings 2018, 8(8), 269; https://doi.org/10.3390/coatings8080269
Received: 19 June 2018 / Revised: 23 July 2018 / Accepted: 28 July 2018 / Published: 31 July 2018
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Abstract
Plasma sprayed coatings composed of stoichiometric hydroxyapatite have been extensively used to improve integration of metallic implants in the host bone, as hydroxyapatite (HA) is normally regarded as similar to the mineralized phase of bone. However, these coatings exhibited several drawbacks that limited
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Plasma sprayed coatings composed of stoichiometric hydroxyapatite have been extensively used to improve integration of metallic implants in the host bone, as hydroxyapatite (HA) is normally regarded as similar to the mineralized phase of bone. However, these coatings exhibited several drawbacks that limited their success. On the one hand biological apatite is a carbonated-HA, containing significant amounts of foreign ions, having low crystallinity and a small crystals size. This means that it differs from stoichiometric HA in terms of composition, stoichiometry, crystallinity degree, crystal size/morphology and, as a direct consequence, solubility, and ions release in the peri-implant environment. On the other hand, thick plasma sprayed coatings can undergo cracking and delamination and are scarcely uniform. For these reasons, research is pushing into two directions: (i) Increasing the similarity of apatite coatings to real bone, and (ii) exploring deposition by alternative plasma assisted techniques, allowing to achieve thin films, and having superior adhesion and a better control over the coating composition. In this article, we review the latest advances in the field of plasma-assisted deposition of ion-substituted hydroxyapatite thin films, highlighting the state of the art, the limitations, potentialities, open challenges, and the future scenarios for their application. Full article
(This article belongs to the Special Issue Ion-Substituted Calcium Phosphates Coatings)
Open AccessArticle Sliding Wear Behavior of Fe-Al Coatings at High Temperatures
Coatings 2018, 8(8), 268; https://doi.org/10.3390/coatings8080268
Received: 23 June 2018 / Revised: 17 July 2018 / Accepted: 26 July 2018 / Published: 31 July 2018
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Abstract
The medium and high temperature tribological behavior of different iron aluminide thermal spray coatings was investigated. Several powders synthesized through different routes (ball milling, self-decomposition, and self-propagating high-temperature sintering (SHS)) were evaluated. High heterogeneity of conventional High Velocity Oxygen Fuel (HVOF) coatings plays
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The medium and high temperature tribological behavior of different iron aluminide thermal spray coatings was investigated. Several powders synthesized through different routes (ball milling, self-decomposition, and self-propagating high-temperature sintering (SHS)) were evaluated. High heterogeneity of conventional High Velocity Oxygen Fuel (HVOF) coatings plays a vital role in their sliding performance, but as long as their integrity is preserved under high temperature oxidizing conditions, the wear rates are found to be acceptable, as it occurs in the case of ball milled Fe-40Al (at.%) powder. The friction phenomenon and wear mechanisms were analyzed in detail through the wear track morphology, contact surface, and friction coefficients. The occurrence of brittle phases in the sprayed coatings, which are also present when tested at high temperatures, appeared to be crucial in accelerating the coating failure. Full article
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Open AccessArticle The Potential of Tribological Application of DLC/MoS2 Coated Sealing Materials
Coatings 2018, 8(8), 267; https://doi.org/10.3390/coatings8080267
Received: 13 June 2018 / Revised: 19 July 2018 / Accepted: 29 July 2018 / Published: 31 July 2018
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Abstract
The potential of the combination of hard and soft coating on elastomers was investigated. Diamond-like carbon (DLC), molybdenum disulfide (MoS2) and composite coatings of these two materials with various DLC/MoS2 ratios were deposited on four elastomeric substrates by means of
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The potential of the combination of hard and soft coating on elastomers was investigated. Diamond-like carbon (DLC), molybdenum disulfide (MoS2) and composite coatings of these two materials with various DLC/MoS2 ratios were deposited on four elastomeric substrates by means of the magnetron sputtering method. The microstructures, surface energy of the coatings, and substrates were characterized by scanning electron microscopy (SEM) and contact angle, respectively. The chemical composition was identified by X-ray Photoelectron Spectroscopy (XPS). A ball on disc configuration was used as the model test, which was performed under dry and lubricated conditions. Based on the results from the model tests, the best coating was selected for each substrate and subsequently verified in component-like test. There is not one coating that is optimal for all substrates. Many factors can affect the coatings performance. The topography and the rigidity of the substrates are the key factors. However, the adhesion between coatings and substrates, and also the coating processes, can impact significantly on the coatings performance. Full article
(This article belongs to the Special Issue Coatings Tribology)
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Open AccessArticle Surface Analysis and Optical Properties of Cu-Doped ZnO Thin Films Deposited by Radio Frequency Magnetron Sputtering
Coatings 2018, 8(8), 266; https://doi.org/10.3390/coatings8080266
Received: 19 June 2018 / Revised: 16 July 2018 / Accepted: 29 July 2018 / Published: 31 July 2018
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Abstract
In this study, Cu-doped ZnO (CZO) thin films were grown on glass substrates by using the radio frequency magnetron sputtering technique. The effects of Cu doping on the structural, surface morphological, optical properties, and wettability behaviors of CZO thin films were investigated by
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In this study, Cu-doped ZnO (CZO) thin films were grown on glass substrates by using the radio frequency magnetron sputtering technique. The effects of Cu doping on the structural, surface morphological, optical properties, and wettability behaviors of CZO thin films were investigated by X-ray diffraction (XRD), atomic force microscopy (AFM), UV-Visible spectroscopy, and contact angle measurement, respectively. The XRD results indicated that all CZO thin films were textured, having a preferential crystallographic orientation along the hexagonal wurtzite (002) axis. The average transmittance in the visible wavelength region was above 80% for all CZO thin films. The optical band gap of the CZO films decreased from 3.18 to 2.85 eV when the Cu-doping was increased from 2% to 10%. In addition, the water contact angle measurements were carried out to delineate the Cu-doping effects on the changes in the surface energy and wettability of the films. Full article
(This article belongs to the Special Issue Advanced Thin Films Deposited by Magnetron Sputtering)
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Open AccessArticle Effect of Adding UV Absorbers Embedded in Carbonate Calcium Templates Covered with Light Responsive Polymer into a Clear Wood Coating
Coatings 2018, 8(8), 265; https://doi.org/10.3390/coatings8080265
Received: 24 June 2018 / Revised: 19 July 2018 / Accepted: 28 July 2018 / Published: 28 July 2018
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Abstract
The limited durability of clear coatings is a major issue for the coating and wood industry. The addition of organic UV absorbers improves coating resistance by the absorption and the conversion of the UV radiation into harmless heat. Organic UVAs are prone to
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The limited durability of clear coatings is a major issue for the coating and wood industry. The addition of organic UV absorbers improves coating resistance by the absorption and the conversion of the UV radiation into harmless heat. Organic UVAs are prone to degradation and can migrate in the binder of coatings. In this study, commercial UVAs and HALS have been entrapped into CaCO3 templates coated with stimuli responsive polymers. Microspheres were incorporated into a clear acrylic water-based coating formulation. The formulation was applied on glass and wood panels and was placed into an artificial UV chamber. This study presents a comparison between the aesthetic behavior of coating formulations with free and encapsulated commercial UVAs and HALS during the accelerated ageing test. Encapsulation of UVAs was confirmed by XPS and TGA analysis. Results have shown that the coating’s aesthetic was slightly improved when using the encapsulated products. Full article
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Open AccessArticle Microstructure and Oxidation Resistance of a Si Doped Platinum Modified Aluminide Coating Deposited on a Single Crystal Superalloy
Coatings 2018, 8(8), 264; https://doi.org/10.3390/coatings8080264
Received: 12 June 2018 / Revised: 14 July 2018 / Accepted: 25 July 2018 / Published: 27 July 2018
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Abstract
A Si doped Pt modified aluminide coating was prepared by electroplating and the chemical vapour deposition method. The microstructure and oxidation resistance of the coating were studied, with a single Pt modified aluminide coating as a reference. The results showed that the Si
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A Si doped Pt modified aluminide coating was prepared by electroplating and the chemical vapour deposition method. The microstructure and oxidation resistance of the coating were studied, with a single Pt modified aluminide coating as a reference. The results showed that the Si doped Pt modified aluminide coating consisted of singular β-(Ni, Pt)Al phase, and no PtAl2 phase was detected, which might be due to the fact that the addition of Si retarded the formation of PtAl2 phase in the outer layer. Si was dissolved in the β-(Ni, Pt)Al phase in the outer layer and might form silicide with refractory elements in the inter-diffusion zone. The Si doped Pt modified aluminide coating possesses a better oxidation resistance than the Pt modified aluminide coating since Si could promote the formation of α-Al2O3 and inhibit the diffusion of the refractory elements, reducing the formation of detrimental volatile phase. Full article
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Open AccessArticle Mechanical Properties of Zr–Si–N Films Fabricated through HiPIMS/RFMS Co-Sputtering
Coatings 2018, 8(8), 263; https://doi.org/10.3390/coatings8080263
Received: 1 July 2018 / Revised: 21 July 2018 / Accepted: 26 July 2018 / Published: 27 July 2018
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Abstract
Zr–Si–N films were fabricated through the co-deposition of high-power impulse magnetron sputtering (HiPIMS) and radio-frequency magnetron sputtering (RFMS). The mechanical properties of the films fabricated using various nitrogen flow rates and radio-frequency powers were investigated. The HiPIMS/RFMS co-sputtered Zr–Si–N films were under-stoichiometric. These
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Zr–Si–N films were fabricated through the co-deposition of high-power impulse magnetron sputtering (HiPIMS) and radio-frequency magnetron sputtering (RFMS). The mechanical properties of the films fabricated using various nitrogen flow rates and radio-frequency powers were investigated. The HiPIMS/RFMS co-sputtered Zr–Si–N films were under-stoichiometric. These films with Si content of less than 9 at.%, and N content of less than 43 at.% displayed a face-centered cubic structure. The films’ hardness and Young’s modulus exhibited an evident relationship to their compressive residual stresses. The films with 2–6 at.% Si exhibited high hardness of 33–34 GPa and high Young’s moduli of 346–373 GPa, which was accompanied with compressive residual stresses from −4.4 to −5.0 GPa. Full article
(This article belongs to the Special Issue Design and Synthesis of Hard Coatings)
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