Special Issue "Hybrid Surface Coatings & Process (Selected Papers from HyMaP 2017)"

A special issue of Coatings (ISSN 2079-6412).

Deadline for manuscript submissions: closed (30 November 2017)

Special Issue Editors

Guest Editor
Prof. Dr. Kwang Ho Kim

Global Frontier R&D Center for Hybrid Interface Materials, Pusan National University, Busan 609-735, Korea
Website 1 | Website 2 | E-Mail
Interests: hybrid surface and interface materials; structural hard coatings; functional hard coatings; hybrid interface materials for energy application; physical vapor deposition; chemical vapor deposition; atomic layer deposition
Guest Editor
Prof. Dr. Qimin Wang

School of Electromechanical Engineering, Guangdong University of Technology, Guangzhou 510006, China
Website | E-Mail
Interests: hard coatings; high temperature protective coatings; functional hard coatings; physical vapor deposition; high speed machining; oxidation and corrosion

Special Issue Information

Dear Colleagues,

In the past ten years, a new technological paradigm, "Hybrid", has begun to appear in the field of coating science and technology. It creates futuristic coating materials with new functions, prestige features, convergence, and fusion features through design and invention of new surface coating materials, which enable the connection of heterogeneous materials, and scales at an electronic, atomic, and molecular structural level, realizing their new features. Additionally, new coating materials were fabricated by hybrid processes combining different processes, which significantly expanded the ideas and visions of coatings and future industry.

The scope of this Special Issue aims to address applied research of hybrid surface coatings and processes, with a focus on the structral applications. We welcome research papers and topic reviews in this field.

In particular, the topics of interest includes but are not limited to:

  • Hard coatings with hybrid composition/microstructure  for tribological applications;

  • Hard coatings with hybrid functions;

  • Hybrid surface processes and hybrid coating processes;

  • Industrial application of hybrid coatings and processes.

Prof. Dr. Kwang Ho Kim
Prof. Dr. Qimin Wang
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Coatings is an international peer-reviewed open access monthly journal published by MDPI.

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Published Papers (17 papers)

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Research

Open AccessArticle Improving the Tribological Properties of Spark-Anodized Titanium by Magnetron Sputtered Diamond-Like Carbon
Received: 29 November 2017 / Revised: 8 February 2018 / Accepted: 23 February 2018 / Published: 24 February 2018
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Abstract
Spark-anodization of titanium can produce adherent and wear-resistant TiO2 film on the surface, but the spark-anodized titanium has lots of surface micro-pores, resulting in an unstable and high friction coefficient against many counterparts. In this study, the diamond-like carbon (DLC) was introduced
[...] Read more.
Spark-anodization of titanium can produce adherent and wear-resistant TiO2 film on the surface, but the spark-anodized titanium has lots of surface micro-pores, resulting in an unstable and high friction coefficient against many counterparts. In this study, the diamond-like carbon (DLC) was introduced into the micro-pores of spark-anodized titanium by the magnetron sputtering technique and a TiO2/DLC composite coating was fabricated. The microstructure and tribological properties of TiO2/DLC composite coating were investigated and compared with the anodic TiO2 mono-film and DLC mono-film. Results show that the DLC deposition significantly decreased the surface roughness and porosity of spark-anodized titanium. The fabricated TiO2/DLC composite coating exhibited a more stable and much lower friction coefficient than anodic TiO2 mono-film. Although the friction coefficient of the composite coating and the DLC mono-film was similar under both light load and heavy load conditions, the wear life of the composite coating was about 43% longer than that of DLC mono-film under heavy load condition. The wear rate of titanium with protective composite coating was much lower than that of titanium with DLC mono-film. The superior low friction coefficient and wear rate of the TiO2/DLC composite coating make it a good candidate as protective coating on titanium alloys. Full article
(This article belongs to the Special Issue Hybrid Surface Coatings & Process (Selected Papers from HyMaP 2017))
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Open AccessArticle Influence of a Scanning Radial Magnetic Field on Macroparticle Reduction of Arc Ion-Plated Films
Received: 24 November 2017 / Revised: 14 January 2018 / Accepted: 23 January 2018 / Published: 25 January 2018
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Abstract
Cathode spot motion influences the physical characteristics of arc plasma and the related macroparticles (MPs) in resultant films; these MPs limit the application of arc ion plating (AIP). In this paper, a scanning radial magnetic field (SRMF) was applied to the cathode surface
[...] Read more.
Cathode spot motion influences the physical characteristics of arc plasma and the related macroparticles (MPs) in resultant films; these MPs limit the application of arc ion plating (AIP). In this paper, a scanning radial magnetic field (SRMF) was applied to the cathode surface to control the cathode spot motion and reduce the MP contamination in the deposited films. It was shown that film surface morphologies prepared using SRMF were better than those using a static radial magnetic field (RMF). The improvement was greater with increased scanning range and frequency. Using SRMF, cathode spot motion was confined to a spiral trajectory on the cathode surface and the spots moved over a large area and at a fast-moving velocity. Both the large moving area and the fast velocity decreased the temperature on the cathode surface and thus reduced the emission of the MPs. Full article
(This article belongs to the Special Issue Hybrid Surface Coatings & Process (Selected Papers from HyMaP 2017))
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Open AccessArticle Improved Corrosion Resistance of 5XXX Aluminum Alloy by Homogenization Heat Treatment
Received: 30 November 2017 / Revised: 28 December 2017 / Accepted: 15 January 2018 / Published: 18 January 2018
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Abstract
The corrosion resistance of homogenized Al-Mg (6.5%) alloy—adding Si, Zn, Mn, and Fe (0.2%) to improve various properties—was observed. Differential scanning calorimetry (DSC) and a JMatPro simulation revealed that the optimal homogenization temperature was 450 °C. The homogenization was carried out at 450
[...] Read more.
The corrosion resistance of homogenized Al-Mg (6.5%) alloy—adding Si, Zn, Mn, and Fe (0.2%) to improve various properties—was observed. Differential scanning calorimetry (DSC) and a JMatPro simulation revealed that the optimal homogenization temperature was 450 °C. The homogenization was carried out at 450 °C for 3, 6, 12, 18, 24, and 30 h in order to view the corrosion resistance change. Corrosion resistance was analyzed by a polarization test in 3.5 wt % NaCl solution. The corrosion resistance improved with increasing homogenization time up to 24 h, but there was no change with longer time periods. To observe the reason for the change in corrosion resistance, scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS), X-ray diffraction (XRD), and transmission electron microscopy coupled with energy dispersive X-ray spectroscopy (TEM-EDS) analyses were performed. Precipitates containing Mg, such as Al3Mg2 and Mg32(Al, Zn)49, decreased at the grain boundary. After homogenization, the amount of Mg measured by SEM-EDS at the grain boundary decreased from 36% to 8%, while Si increased. Generally, the potential difference between the grain boundary and the grains leads to intergranular corrosion. Reduction of Mg, whose standard electrode potential is lower than that of Al, and an increase of Si, which is present in higher concentration than Al at the grain boundaries, improved the corrosion resistance of 5XXX Al alloy by reducing the intergranular corrosion. Full article
(This article belongs to the Special Issue Hybrid Surface Coatings & Process (Selected Papers from HyMaP 2017))
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Open AccessArticle Influence of Nitrogen Partial Pressure on Microstructure and Tribological Properties of Mo-Cu-V-N Composite Coatings with High Cu Content
Received: 19 November 2017 / Revised: 25 December 2017 / Accepted: 27 December 2017 / Published: 4 January 2018
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Abstract
In this study, Mo-Cu-V-N composite coatings with high Cu content of ~18 at.% were deposited on 316L stainless steel and YT14 cemented carbide substrates by high power impulse magnetron sputtering in Ar–N2 gas mixtures. The influence of N2 partial pressure was
[...] Read more.
In this study, Mo-Cu-V-N composite coatings with high Cu content of ~18 at.% were deposited on 316L stainless steel and YT14 cemented carbide substrates by high power impulse magnetron sputtering in Ar–N2 gas mixtures. The influence of N2 partial pressure was investigated with respect to the microstructure and tribological properties of the coatings. The results indicated that the Mo-Cu-V-N composite coatings exhibited FCC B1-MoN phase with a strong (200) preferred orientation, and Cu phase was found to exist as metallic species. As the N2 partial pressure increased from 0.11 to 0.35 Pa, the peak intensity of (200) plane decreased gradually and simultaneous peak broadening was observed, which was typical for grain refinement. With increasing the N2 partial pressure, the columnar microstructure became much coarser, which led to the decrease of residual stress and hardness. The Mo-Cu-V-N composite coatings with high Cu content exhibited a relatively low wear rate of 10−8 mm3/N·m at 25 °C, which was believed to be attributed to the mixed lubricious oxides of MoO2, CuO and V2O5 formed during tribo-oxidation, which cannot be formed in the coatings with low Cu content. When the wear temperature was increased up to 400 °C, the wear rate increased sharply up to 10−6 mm3/N·m despite the formation of lubricious oxides of MoO3/CuMoO4 and V2O5. This could be due to the loss of nitrogen and pronounced oxidation at high temperatures, which led the wear mechanism to be transformed from mild oxidation wear to severe oxidation wear. Full article
(This article belongs to the Special Issue Hybrid Surface Coatings & Process (Selected Papers from HyMaP 2017))
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Open AccessArticle Formation of Anticorrosive Film for Suppressing Pitting Corrosion on Al-Mg-Si Alloy by Steam Coating
Received: 28 November 2017 / Revised: 23 December 2017 / Accepted: 29 December 2017 / Published: 4 January 2018
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Abstract
Al alloys offer excellent physical and mechanical properties, such as a low density, high specific strength, and good ductility. However, their low corrosion resistance has restricted their application in corrosive environments. There is a need, therefore, for a novel coating technology that is
[...] Read more.
Al alloys offer excellent physical and mechanical properties, such as a low density, high specific strength, and good ductility. However, their low corrosion resistance has restricted their application in corrosive environments. There is a need, therefore, for a novel coating technology that is capable of improving the corrosion resistance of Al alloys. In the present study, we examined a steam-based method of forming a corrosion-resistant film on Al alloys. Al-Mg-Si alloy was used as the substrate. The cleaned substrates were set in an autoclave with ultrapure water as the steam source and processed using different temperatures and holding times, resulting in the formation of anticorrosive films on the alloy. FE-SEM images of the film surfaces showed that plate-like nanocrystals were densely formed over the entire surface. XRD patterns indicated that the film was composed mainly of AlOOH crystals. The potentiodynamic polarization curves revealed that the corrosion current density of the film-coated substrates significantly decreased, and that the pitting corrosion was completely suppressed, indicating that the corrosion resistance of the Al-Mg-Si alloy was improved by the film formed by means of steam coating. Full article
(This article belongs to the Special Issue Hybrid Surface Coatings & Process (Selected Papers from HyMaP 2017))
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Open AccessArticle Influence of Oxygen Contents on the Microstructure, High Temperature Oxidation and Corrosion Resistance Properties of Cr–Si–O–N Coatings
Received: 8 November 2017 / Revised: 19 December 2017 / Accepted: 25 December 2017 / Published: 3 January 2018
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Abstract
Cr–Si–O–N coatings with different oxygen contents were deposited by multi-arc ion plating, where various O2/(N2 + O2) reactive gas rates were adopted. The XRD and XPS results showed that the CrN crystals disappeared with the increasing of the
[...] Read more.
Cr–Si–O–N coatings with different oxygen contents were deposited by multi-arc ion plating, where various O2/(N2 + O2) reactive gas rates were adopted. The XRD and XPS results showed that the CrN crystals disappeared with the increasing of the oxygen flux ratio to 10 at.%. The microhardness of all the Cr–Si–O–N coatings was approximately 2000 Hv0.05, which were dramatically plummeted compared to that of the Cr–Si–N coatings (≈3300 Hv0.05). The Cr–Si–O–N coatings were annealed under 800 °C and 1200 °C in the air atmosphere for 2 h to study the high-temperature oxidation resistance of the coatings. Meanwhile, Cr–Si–O–N coatings with different O2/(N2 + O2) rates were also used to carry out the corrosion resistance testing using the electrochemical working station in 3.5% NaCl solution under free air condition at room temperature. The results indicated that the coatings containing oxygen were more vulnerable to the high-temperature destruction and more easily corroded in the NaCl electrolyte. Full article
(This article belongs to the Special Issue Hybrid Surface Coatings & Process (Selected Papers from HyMaP 2017))
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Open AccessArticle Computer Simulation of Temperature Parameter for Diamond Formation by Using Hot-Filament Chemical Vapor Deposition
Received: 15 November 2017 / Revised: 12 December 2017 / Accepted: 28 December 2017 / Published: 29 December 2017
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Abstract
To optimize the deposition parameters of diamond films, the temperature, pressure, and distance between the filament and the susceptor need to be considered. However, it is difficult to precisely measure and predict the filament and susceptor temperature in relation to the applied power
[...] Read more.
To optimize the deposition parameters of diamond films, the temperature, pressure, and distance between the filament and the susceptor need to be considered. However, it is difficult to precisely measure and predict the filament and susceptor temperature in relation to the applied power in a hot filament chemical vapor deposition (HF-CVD) system. In this study, the temperature distribution inside the system was numerically calculated for the applied powers of 12, 14, 16, and 18 kW. The applied power needed to achieve the appropriate temperature at a constant pressure and other conditions was deduced, and applied to actual experimental depositions. The numerical simulation was conducted using the commercial computational fluent dynamics software ANSYS-FLUENT. To account for radiative heat-transfer in the HF-CVD reactor, the discrete ordinate (DO) model was used. The temperatures of the filament surface and the susceptor at different power levels were predicted to be 2512–2802 K and 1076–1198 K, respectively. Based on the numerical calculations, experiments were performed. The simulated temperatures for the filament surface were in good agreement with the experimental temperatures measured using a two-color pyrometer. The results showed that the highest deposition rate and the lowest deposition of non-diamond was obtained at a power of 16 kW. Full article
(This article belongs to the Special Issue Hybrid Surface Coatings & Process (Selected Papers from HyMaP 2017))
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Open AccessArticle Dicalcium Phosphate Coated with Graphene Synergistically Increases Osteogenic Differentiation In Vitro
Received: 8 November 2017 / Revised: 16 December 2017 / Accepted: 26 December 2017 / Published: 28 December 2017
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Abstract
In recent years, graphene and its derivatives have attracted much interest in various fields, including biomedical applications. In particular, increasing attention has been paid to the effects of reduced graphene oxide (rGO) on cellular behaviors. On the other hand, dicalcium phosphate (DCP) has
[...] Read more.
In recent years, graphene and its derivatives have attracted much interest in various fields, including biomedical applications. In particular, increasing attention has been paid to the effects of reduced graphene oxide (rGO) on cellular behaviors. On the other hand, dicalcium phosphate (DCP) has been widely used in dental and pharmaceutical fields. In this study, DCP composites coated with rGO (DCP-rGO composites) were prepared at various concentration ratios (DCP to rGO concentration ratios of 5:2.5, 5:5, and 5:10 μg/mL, respectively), and their physicochemical properties were characterized. In addition, the effects of DCP-rGO hybrid composites on MC3T3-E1 preosteoblasts were investigated. It was found that the DCP-rGO composites had an irregular granule-like structure with a diameter in the range order of the micrometer, and were found to be partially covered and interconnected with a network of rGO. The zeta potential analysis showed that although both DCP microparticles and rGO sheets had negative surface charge, the DCP-rGO composites could be successfully formed by the unique structural properties of rGO. In addition, it was demonstrated that the DCP-rGO composites significantly increased alkaline phosphatase activity and extracellular calcium deposition, indicating that the DCP-rGO hybrid composites can accelerate the osteogenic differentiation by the synergistic effects of rGO and DCP. Therefore, in conclusion, it is suggested that the DCP-rGO hybrid composites can be potent factors in accelerating the bone tissue regeneration. Full article
(This article belongs to the Special Issue Hybrid Surface Coatings & Process (Selected Papers from HyMaP 2017))
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Open AccessArticle Plastic Deformation Induced by Nanoindentation Test Applied on ZrN/Si3N4 Multilayer Coatings
Received: 20 November 2017 / Revised: 22 December 2017 / Accepted: 25 December 2017 / Published: 27 December 2017
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Abstract
ZrN/Si3N4 multilayer coating that alternates with either nanocrystalline ZrN or amorphous Si3N4 interlayers was fabricated by reactively magnetron sputtering in an Ar-N2 mixture atmosphere. The thicknesses of the nanocrystalline ZrN and the amorphous Si3N
[...] Read more.
ZrN/Si3N4 multilayer coating that alternates with either nanocrystalline ZrN or amorphous Si3N4 interlayers was fabricated by reactively magnetron sputtering in an Ar-N2 mixture atmosphere. The thicknesses of the nanocrystalline ZrN and the amorphous Si3N4 interlayers are ~12.5 and 2.5 nm, respectively. The ZrN/Si3N4 coating exhibits a promoted hardness of 28.6 ± 1.2 GPa when compared to the binary ZrN. Microstructure evolution just underneath the nanoindentation impression of the ZrN/Si3N4 multilayer coating has been investigated. The result indicates that both ZrN nanograin rotations and plastic flow of the Si3N4 interlayers contribute to the permanent deformation of the multilayer coating induced by the nanoindentation. In addition, the introduction of the a-Si3N4 interlayers hinders both the initiation and propagation of microcracks when the multilayer coating was applied to the scratch test. The propagation deflection of the microcracks was observed attributed to the heterogenous interface, which produces the hardness promotion of the multilayer coating eventually. Full article
(This article belongs to the Special Issue Hybrid Surface Coatings & Process (Selected Papers from HyMaP 2017))
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Open AccessArticle Effects of Negative Bias Voltage and Ratio of Nitrogen and Argon on the Structure and Properties of NbN Coatings Deposited by HiPIMS Deposition System
Received: 9 November 2017 / Revised: 18 December 2017 / Accepted: 22 December 2017 / Published: 24 December 2017
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Abstract
The NbNx>1 coatings were deposited on Si wafer and SUS 304 stainless steel substrates by a high power impulse magnetron sputtering (HiPIMS) system at various bias voltages and the ratios of nitrogen and argon (N2/Ar). By virtue of electron
[...] Read more.
The NbNx>1 coatings were deposited on Si wafer and SUS 304 stainless steel substrates by a high power impulse magnetron sputtering (HiPIMS) system at various bias voltages and the ratios of nitrogen and argon (N2/Ar). By virtue of electron probe microanalysis (EPMA), X-ray diffraction pattern (XRD), scanning electron microscope (SEM), atomic force microscope (AFM) and nano indentation test, the relationships between deposition parameters and coatings properties were examined in detail. These coatings show a strong preferred orientation of (200) plane at free bias voltage. With increasing bias voltage, the intensity of (200) plane peak became weaker and the full width at half maximum of peaks ((200) and (111) peaks) became broader, implying the crystalline grain size were decreased. The (200) plane almost is disappeared at −150 V bias voltage and the phase transition maintains the same change tendency with the increase of N2/Ar gas ratio. The coating microstructure gradually evolved from coarse columnar to dense columnar, and then to compact featureless structure with increase of the bias voltage, corresponding to the decreased surface roughness. The columnar structure of coatings is unrelated to N2/Ar gas ratio and the thickness is minimum at high N2/Ar ratio, which is attributed to the poor sputtering capability of nitrogen compared with argon instead of target poisonous effect. The higher hardness (H) and elastic recovery value are obtained for NbNx>1 (H = 31.3 GPa and We = 69.2%) at −150 V bias voltage, suggesting considerable influence of bias voltage on hardness than that of the N2/Ar gas ratio. Full article
(This article belongs to the Special Issue Hybrid Surface Coatings & Process (Selected Papers from HyMaP 2017))
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Open AccessArticle Electrodeposition of Copper/Carbonous Nanomaterial Composite Coatings for Heat-Dissipation Materials
Received: 24 November 2017 / Revised: 8 December 2017 / Accepted: 19 December 2017 / Published: 21 December 2017
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Abstract
Carbonous nanomaterials are promising additives for composite coatings for heat-dissipation materials because of their excellent thermal conductivity. Here, copper/carbonous nanomaterial composite coatings were prepared using nanodiamond (ND) as the carbonous nanomaterial. The copper/ND composite coatings were electrically deposited onto copper substrates from a
[...] Read more.
Carbonous nanomaterials are promising additives for composite coatings for heat-dissipation materials because of their excellent thermal conductivity. Here, copper/carbonous nanomaterial composite coatings were prepared using nanodiamond (ND) as the carbonous nanomaterial. The copper/ND composite coatings were electrically deposited onto copper substrates from a continuously stirred copper sulfate coating bath containing NDs. NDs were dispersed by ultrasonic treatment, and the initial bath pH was adjusted by adding sodium hydroxide solution or sulfuric acid solution before electrodeposition. The effects of various coating conditions—the initial ND concentration, initial bath pH, stirring speed, electrical current density, and the amount of electricity—on the ND content of the coatings were investigated. Furthermore, the surface of the NDs was modified by hydrothermal treatment to improve ND incorporation. A higher initial ND concentration and a higher stirring speed increased the ND content of the coatings, whereas a higher initial bath pH and a greater amount of electricity decreased it. The electrical current density showed a minimum ND content at approximately 5 A/dm2. Hydrothermal treatment, which introduced carboxyl groups onto the ND surface, improved the ND content of the coatings. A copper/ND composite coating with a maximum of 3.85 wt % ND was obtained. Full article
(This article belongs to the Special Issue Hybrid Surface Coatings & Process (Selected Papers from HyMaP 2017))
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Open AccessArticle Influence of N2/Ar Flow Ratio on Microstructure and Properties of the AlCrSiN Coatings Deposited by High-Power Impulse Magnetron Sputtering
Received: 9 November 2017 / Revised: 12 December 2017 / Accepted: 18 December 2017 / Published: 21 December 2017
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Abstract
The cutting properties of tools can be greatly improved by AlCrSiN coatings. The AlCrSiN coatings with nitrogen content in the range of 28.2–56.3 at.% were prepared by varying the N2/Ar flow ratio from 1/4 to 1/1. The influence of N2
[...] Read more.
The cutting properties of tools can be greatly improved by AlCrSiN coatings. The AlCrSiN coatings with nitrogen content in the range of 28.2–56.3 at.% were prepared by varying the N2/Ar flow ratio from 1/4 to 1/1. The influence of N2/Ar flow ratio on composition, microstructure, and mechanical properties, as well as the tribological properties, of the coatings was investigated. With increasing N content, the coating microstructure gradually evolved from single fcc-(Cr,Al)N (200) phase to the mixture of fcc-(Cr,Al)N and hcp-(Cr,Al)N phase, which corresponds to an increased crystallinity within the coatings. The coating presents the highest hardness and best wear resistance for an N2/Ar flow ratio of 1/1, but the film adhesive strength and inner stress decreased obviously with increasing N2/Ar flow ratio, which was attributed to the rapid reduction of particle kinetic energy induced by the obstruction of neutral nitride particles between target and substrates. The highest H3/E*2 value exhibited the lowest wear rate, at 0.81 × 10−14 m3/(N·m), indicating that it had the best resistance to plastic deformation. The main wear mechanisms of the as-deposited coatings were abrasive wear and adhesive wear. The increasing crystallinity of the interior coatings resulted in higher hardness and better tribological behavior with an increase in N2/Ar flow ratio. Full article
(This article belongs to the Special Issue Hybrid Surface Coatings & Process (Selected Papers from HyMaP 2017))
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Open AccessArticle Preparation and Isothermal Oxidation Behavior of Zr-Doped, Pt-Modified Aluminide Coating Prepared by a Hybrid Process
Received: 16 November 2017 / Revised: 17 December 2017 / Accepted: 18 December 2017 / Published: 21 December 2017
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Abstract
To take advantage of the synergistic effects of Pt and Zr, a kind of Zr-doped, Pt-modified aluminide coating has been prepared by a hybrid process, first electroplating a Pt layer and then co-depositing Zr and Al elements by an above-the-pack process. The microstructure
[...] Read more.
To take advantage of the synergistic effects of Pt and Zr, a kind of Zr-doped, Pt-modified aluminide coating has been prepared by a hybrid process, first electroplating a Pt layer and then co-depositing Zr and Al elements by an above-the-pack process. The microstructure and isothermal oxidation behavior of the coating has been studied, using a Pt-modified aluminide coating as a reference. Results showed that the Zr-doped, Pt-modified aluminide coating was primarily composed of β-(Ni,Pt)Al phase, with small amounts of PtAl2- and Zr-rich phases dispersed in it. The addition of Zr diminished voids on the coating surface since Zr could hinder the growth of β-NiAl grains. It also helped to increase the spalling resistance of the oxide scale and reduce the oxidation rate, which made the Zr-doped, Pt-modified aluminide coating possess better oxidation resistance than the reference Pt-modified aluminide coating at the temperature of 1100 °C. Full article
(This article belongs to the Special Issue Hybrid Surface Coatings & Process (Selected Papers from HyMaP 2017))
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Open AccessArticle Effect of the Addition of Molybdenum on the Structure and Corrosion Resistance of Zinc–Iron Plating
Coatings 2017, 7(12), 235; https://doi.org/10.3390/coatings7120235
Received: 24 November 2017 / Revised: 11 December 2017 / Accepted: 14 December 2017 / Published: 16 December 2017
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Abstract
Zn–Ni plating is indispensable in various industries because of its high corrosion resistance. However, Ni has been reported to trigger allergies; thus, an alternative Ni-free plating is desired. Zn–Fe plating is considered to be a promising candidate, albeit its corrosion resistance still needs
[...] Read more.
Zn–Ni plating is indispensable in various industries because of its high corrosion resistance. However, Ni has been reported to trigger allergies; thus, an alternative Ni-free plating is desired. Zn–Fe plating is considered to be a promising candidate, albeit its corrosion resistance still needs to be improved. The corrosion resistance of Zn–Fe plating is expected to increase by the addition of Mo as the third alloying element as it is more noble than Zn and Fe. In this study, Zn–Fe–Mo plating with a corrosion resistance nearly equivalent to that of the Zn–Ni plating was fabricated. Zn–Fe–Mo plating was electrically deposited from continuously-agitated plating baths prepared by mixing ZnSO4, FeSO4, Na2MoO4, Na3C6H5O7, and Na2SO4 using Fe or Ni plates as the substrate. The surface morphology, composition, crystal phase, and electronic state of Mo of the platings were investigated by scanning electron microscopy equipped with energy-dispersive spectroscopy (SEM-EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The anti-corrosion performance was evaluated by Tafel extrapolation method. Formation of plating comprising a Mo containing alloy phase was found to be crucial for improving corrosion resistance. The Zn–Fe–Mo plating demonstrates promise for replacing anti-corrosion Zn–Ni platings. Full article
(This article belongs to the Special Issue Hybrid Surface Coatings & Process (Selected Papers from HyMaP 2017))
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Open AccessArticle Mechanical and Thermal Properties of Epoxy Composites Containing Zirconium Oxide Impregnated Halloysite Nanotubes
Coatings 2017, 7(12), 231; https://doi.org/10.3390/coatings7120231
Received: 9 November 2017 / Revised: 8 December 2017 / Accepted: 8 December 2017 / Published: 15 December 2017
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Abstract
Liquid epoxy resins have received much attention from both academia and the chemical industry as eco-friendly volatile organic compound (VOC)-free alternatives for applications in coatings and adhesives, especially in those used in households. Epoxy resins show high chemical resistance and high creep resistance.
[...] Read more.
Liquid epoxy resins have received much attention from both academia and the chemical industry as eco-friendly volatile organic compound (VOC)-free alternatives for applications in coatings and adhesives, especially in those used in households. Epoxy resins show high chemical resistance and high creep resistance. However, due to their brittleness and lack of thermal stability, additional fillers are needed for improving the mechanical and thermal properties. Halloysite nanotubes (HNTs) are naturally abundant, inexpensive, and eco-friendly clay minerals that are known to improve the mechanical and thermal properties of epoxy composites after suitable surface modification. Zirconium is well known for its high resistance to heat and wear. In this work, zirconium oxide-impregnated HNTs (Zr/HNTs) were added to epoxy resins to obtain epoxy composites with improved mechanical and thermal properties. Zr/HNTs were characterized by field-emission transmission electron microscopy, transmission electron microscopy with energy-dispersive X-ray spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. Changes in the thermal properties of the epoxy composites were characterized by thermo mechanical analysis and differential scanning calorimetry. Furthermore, flexural properties of the composites were analyzed using a universal testing machine. Full article
(This article belongs to the Special Issue Hybrid Surface Coatings & Process (Selected Papers from HyMaP 2017))
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Open AccessArticle In-Situ Heat Treatment Study on the Nanocrystalline Cr2O3 Film Using an Environmental Scanning Electron Microscope
Coatings 2017, 7(12), 225; https://doi.org/10.3390/coatings7120225
Received: 9 November 2017 / Revised: 5 December 2017 / Accepted: 7 December 2017 / Published: 8 December 2017
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Abstract
In this work, the surface morphology changes of nanocrystalline Cr2O3 film deposited on Si wafer during the heating process were observed in-situ by means of an environmental scanning electron microscope (ESEM). The Cr2O3 film cracked at high
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In this work, the surface morphology changes of nanocrystalline Cr2O3 film deposited on Si wafer during the heating process were observed in-situ by means of an environmental scanning electron microscope (ESEM). The Cr2O3 film cracked at high temperature due to the cause of thermal stress; the corresponding crack area percentages on the film surface were real-time evaluated using image analysis software (SISC IAS V8.0) based on the principle of gray value analysis. In the meantime, the effects of the heating temperature on the crack area percentage, phase constituents, and grain size of the Cr2O3 film were also studied in detail. The results showed that the percentage of crack area on film surface first increased with the heating temperature rise, and reached the maximum value at around 980 °C, and then gradually declined again. The above trend is closely related to the changes of thermal stress and grain growth in film. In addition, the heat treatment also had a strong influence on the grain size of the Cr2O3 film. Full article
(This article belongs to the Special Issue Hybrid Surface Coatings & Process (Selected Papers from HyMaP 2017))
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Open AccessArticle Identification of Intermetallic Compounds and Its Formation Mechanism in Boron Steel Hot-Dipped in Al-7 wt.% Mn Alloy
Coatings 2017, 7(12), 222; https://doi.org/10.3390/coatings7120222
Received: 10 November 2017 / Revised: 27 November 2017 / Accepted: 1 December 2017 / Published: 6 December 2017
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Abstract
In laser welding and hot stamping Al-Si-coated boron steel, there is a problem that the strength of the joint is lowered due to ferrite formation in the fusion zone. The purpose of this study is to develop an Al-7 wt.% Mn hot-dip coating
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In laser welding and hot stamping Al-Si-coated boron steel, there is a problem that the strength of the joint is lowered due to ferrite formation in the fusion zone. The purpose of this study is to develop an Al-7 wt.% Mn hot-dip coating in which Mn, an austenite stabilizing element, replaces the ferrite stabilizing element Si. The nucleation and formation mechanism of the reaction layer was studied in detail by varying the dipping time between 0 and 120 s at 773 °C. The microstructure and phase constitution of the reaction layer were investigated by various observational methods. Phase formation is discussed using a phase diagram calculated by Thermo-CalcTM. Under a 30 s hot-dipping process, no reaction occurred due to the formation of a Fe3O4 layer on the steel surface. The Fe3O4 layer decomposed by a reduction reaction with Al-Mn molten alloy, constituent elements of steel dissolved into a liquid, and the reaction-layer nucleus was formed toward the liquid phase. A coated layer consists of a solidified layer of Al and Al6Mn and a reactive layer formed beneath it. The reaction layer is formed mainly by inter-diffusion of Al and Fe in the solid state, which is arranged on the steel in the order of Al11Mn4 → FeAl3 (θ) → Fe2Al5 (η) phases, and the Fe3AlC (κ) in several nm bands formed at the interface between the η-phase and steel. Full article
(This article belongs to the Special Issue Hybrid Surface Coatings & Process (Selected Papers from HyMaP 2017))
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