Research

227 pages, 13487 KiB

Open AccessArticle

Inkjet-Printed Chemical Solution Y₂O₃ Layers for Planarization of Technical Substrates

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Juan Carlos Fernández

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Coatings 2017, 7(12), 227; https://doi.org/10.3390/coatings7120227 - 11 Dec 2017

Cited by 4 | Viewed by 4568

Abstract

The implementation of the Chemical Solution Deposition (CSD) methodology with the Drop on Demand (DoD) inkjet printing (IJP) technology has been successfully employed to develop a Solution Deposition Planarization (SDP) method. We have used nanocrystalline yttrium oxide (Y₂O₃) to [...] Read more.

The implementation of the Chemical Solution Deposition (CSD) methodology with the Drop on Demand (DoD) inkjet printing (IJP) technology has been successfully employed to develop a Solution Deposition Planarization (SDP) method. We have used nanocrystalline yttrium oxide (Y₂O₃) to decrease the roughness of technical metallic substrates by filling the surface imperfections and thus avoiding costly polishing steps. This alternative process represents an outstanding methodology to reduce the final cost of the second-generation coated conductors manufacturing. Two Y₂O₃ metalorganic precursor ink formulations were successfully developed and tested to obtain surfaces as smooth as possible with adequate mechanical properties to hold the internal stress developed during the growth of the subsequent layers. By using these inks as precursors for IJP and after a proper tuning of the rheological and wetting parameters, we firstly obtained centimeter length uniform 100 nm-thick SDP-Y₂O₃ films on unpolished stainless-steel substrate from Bruker HTS. The scalability of the roll to roll (R2R)-IJP process to 100 m is then demonstrated on metallic substrates as well. A complete characterization of the prepared SDP-Y₂O₃ inkjet-printed layers was carried out using optical microscopy, FIB-SEM (Focus Ion Beam coupled to Scanning Electron Microscopy), XRD (X-ray Diffraction), AFM (Atomic Force Microscopy), reflectometry and nanoindentation techniques. Then, the morphology, thickness, crystallinity and mechanical properties were evaluated, together with the surface roughness in order to assess the resulting layer planarity. The impact of planarity was additionally studied via growth of biaxially textured buffer layers as well as further functional layers. 1.1 µm-thick YSZ layers with in-plane textures better than the stainless steel (SS) polished reference were successfully deposited on top of 100 nm SDP-Y₂O₃ films yielding 50% of I_c in contrast to the standard SS reference. Full article

(This article belongs to the Special Issue Mechanical Behavior of Coatings and Engineered Surfaces)

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216 pages, 11398 KiB

Open AccessArticle

Influence of Power Pulse Parameters on the Microstructure and Properties of the AlCrN Coatings by a Modulated Pulsed Power Magnetron Sputtering

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Coatings 2017, 7(12), 216; https://doi.org/10.3390/coatings7120216 - 30 Nov 2017

Cited by 9 | Viewed by 5095

Abstract

In this study, AlCrN coatings were deposited using modulated pulsed power magnetron sputtering (MPPMS) with different power pulse parameters by varying modulated pulsed power (MPP) charge voltages (350 to 550 V). The influence of power pulse parameters on the microstructure, mechanical properties and [...] Read more.

In this study, AlCrN coatings were deposited using modulated pulsed power magnetron sputtering (MPPMS) with different power pulse parameters by varying modulated pulsed power (MPP) charge voltages (350 to 550 V). The influence of power pulse parameters on the microstructure, mechanical properties and thermal stability of the coatings was investigated. The results indicated that all the AlCrN coatings exhibited a dense columnar microstructure. Higher charge voltage could facilitate a denser coating microstructure. As the charge voltage increased up to 450 V or higher, the microvoids along the column boundaries disappeared and the coatings became fully dense. The main phase in the AlCrN coatings was the c-(Al, Cr)N solid solution phase with NaCl-type phase structure. A diffraction peak of the h-AlN phase was detected at a 2θ of around 33°, when the charge voltage was higher than 500 V. The hardness of the AlCrN coatings varied as a function of charge voltage. The maximum value of the hardness (30.8 GPa) was obtained at 450 V. All the coatings showed good thermal stability and maintained their structure and mechanical properties unchanged up to 800 °C during vacuum annealing. However, further increasing the annealing temperature to 1000 °C resulted in apparent change in the microstructure and decrease in the hardness. The charge voltages also showed a significant influence on the high-temperature tribological behavior of the coatings. The coating deposited at the charge voltage of 550 V exhibited excellent tribological properties with a low friction coefficient. Full article

(This article belongs to the Special Issue Mechanical Behavior of Coatings and Engineered Surfaces)

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128 pages, 4913 KiB

Open AccessArticle

Uncertainty of the X-ray Diffraction (XRD) sin² ψ Technique in Measuring Residual Stresses of Physical Vapor Deposition (PVD) Hard Coatings

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Quanshun Luo

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Shicai Yang

Coatings 2017, 7(8), 128; https://doi.org/10.3390/coatings7080128 - 20 Aug 2017

Cited by 22 | Viewed by 16629

Abstract

Residual stresses of physical vapor deposition (PVD) hard coatings can be measured using X-ray diffraction (XRD) methods under either conventional d-sin² ψ mode or glancing incident (GIXRD) mode, in which substantial uncertainties exist depending on the applied diffraction parameters. This paper [...] Read more.

Residual stresses of physical vapor deposition (PVD) hard coatings can be measured using X-ray diffraction (XRD) methods under either conventional d-sin² ψ mode or glancing incident (GIXRD) mode, in which substantial uncertainties exist depending on the applied diffraction parameters. This paper reports systematic research on the effect of the two analytical modes, as well as the anisotropic elastic modulus, on the measured residual stress values. A magnetron sputtered TiN grown on hardened tool steel was employed as the sample coating, to measure its residual stress using various diffraction peaks from {111} to {422} acquired at a range of incident glancing angles from 2° to 35°. The results were interpreted in terms of the effective X-ray penetration depth, which has been found to be determined predominantly by the incident glancing angle. In the d-sin² ψ mode, the results present an approximate residual stress over a depth of effective X-ray penetration, and it is recommended to use a diffraction peak of high-index lattice plane from {311} to {422}. The GIXRD mode helps determine a depth profile of residual stress, since the measured residual stress depends strongly on the X-ray penetration. In addition, the anisotropy of elastic modulus shows limited influence on the calculated residual stress value. Full article

(This article belongs to the Special Issue Mechanical Behavior of Coatings and Engineered Surfaces)

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125 pages, 9545 KiB

Open AccessArticle

Process Parameter Settings and Their Effect on Residual Stresses in WC/W₂C Reinforced Iron-Based Arc Sprayed Coatings

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Wolfgang Tillmann

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Leif Hagen

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Weifeng Luo

Coatings 2017, 7(8), 125; https://doi.org/10.3390/coatings7080125 - 15 Aug 2017

Cited by 11 | Viewed by 5076

Abstract

Residual stresses have been a major source of concern, as they are an inevitable consequence of manufacturing and fabrication processes. The magnitude of these stresses is often as high as, or at least, comparable to the yield strength of the material. In terms [...] Read more.

Residual stresses have been a major source of concern, as they are an inevitable consequence of manufacturing and fabrication processes. The magnitude of these stresses is often as high as, or at least, comparable to the yield strength of the material. In terms of arc sprayed coatings, the utilization of bore hole drilling methods presents some practical disadvantages as mechanical parameters (Poisson’s ratio, Young’s modulus) need to be identified in order to determine the residual stress distribution. Curvature techniques using Almen strips are cost- and time-effective methods that can be used for analytical quality assurance. Within the scope of this work, a quantitative study of the amount of residual stresses induced in a twin wire arc spraying (TWAS) process for a given combination of process parameters was conducted using the incremental bore hole drilling method, as well as the curvature method including Almen strips. Therefore, the effect of the primary gas pressure, substrate preheating temperature, and handling parameters, such as the spray angle and gun velocity, which influence the coating deposition as well as the heat input into the substrate, are examined. The experiments were carried out by using an iron-based cored wire with cast tungsten carbides as filling. The results of both methods are in an acceptable accordance with each other. Different stress fields were observed depending on the parameter settings. Full article

(This article belongs to the Special Issue Mechanical Behavior of Coatings and Engineered Surfaces)

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119 pages, 10671 KiB

Open AccessArticle

Microstructure, Mechanical, Oxidation and Corrosion Properties of the Cr-Al-Si-N Coatings Deposited by a Hybrid Sputtering System

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Coatings 2017, 7(8), 119; https://doi.org/10.3390/coatings7080119 - 09 Aug 2017

Cited by 22 | Viewed by 6130

Abstract

CrN and Cr-Al-Si-N coatings were deposited on SUS304 and Si-wafers by a hybrid coating system. The Cr and Al-Si target were connected to the cathode arc ion plating (AIP) and high power impulse magnetron sputtering (HiPIMS), respectively. Various Al and Si contents in [...] Read more.

CrN and Cr-Al-Si-N coatings were deposited on SUS304 and Si-wafers by a hybrid coating system. The Cr and Al-Si target were connected to the cathode arc ion plating (AIP) and high power impulse magnetron sputtering (HiPIMS), respectively. Various Al and Si contents in the coatings were obtained by changing the power of Al-Si target from 0 to 1 kW. The results demonstrated a face-centered cubic structure in all of the coatings. With increasing Al-Si target power, both the density and mean diameter of the macroparticles on the coating surface declined. As Al and Si contents increased, the microstructure of the Cr-Al-Si-N coatings evolved from a dense column structure, to a finer grain column structure, and then to a compact granular-like structure. The hardness of the coatings increased from 21.5 GPa for the pure CrN coating, to a maximum value of ~27 GPa for the Cr-Al-Si-N coating deposited at 0.4 kW, which was mainly attributed to the solid solution strengthening and increased residual stress. The addition of Al and Si contents led to enhanced wear resistance against alumina balls at both room and elevated temperatures. Meanwhile, the Cr-Al-Si-N coatings also exhibited an excellent resistance to high-temperature oxidation at 800 and 1000 °C, and improved corrosion resistance, as compared with CrN coatings. Full article

(This article belongs to the Special Issue Mechanical Behavior of Coatings and Engineered Surfaces)

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81 pages, 3135 KiB

Open AccessArticle

Maximum Deformation Ratio of Droplets of Water-Based Paint Impact on a Flat Surface

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Coatings 2017, 7(6), 81; https://doi.org/10.3390/coatings7060081 - 19 Jun 2017

Cited by 7 | Viewed by 4404

Abstract

In this research, the maximum deformation ratio of water-based paint droplets impacting and spreading onto a flat solid surface was investigated numerically based on the Navier–Stokes equation coupled with the level set method. The effects of droplet size, impact velocity, and equilibrium contact [...] Read more.

In this research, the maximum deformation ratio of water-based paint droplets impacting and spreading onto a flat solid surface was investigated numerically based on the Navier–Stokes equation coupled with the level set method. The effects of droplet size, impact velocity, and equilibrium contact angle are taken into account. The maximum deformation ratio increases as droplet size and impact velocity increase, and can scale as We^1/4, where We is the Weber number, for the case of the effect of the droplet size. Finally, the effect of equilibrium contact angle is investigated, and the result shows that spreading radius decreases with the increase in equilibrium contact angle, whereas the height increases. When the dimensionless time t* < 0.3, there is a linear relationship between the dimensionless spreading radius and the dimensionless time to the 1/2 power. For the case of 80° ≤ θ_e ≤ 120°, where θ_e is the equilibrium contact angle, the simulation result of the maximum deformation ratio follows the fitting result. The research on the maximum deformation ratio of water-based paint is useful for water-based paint applications in the automobile industry, as well as in the biomedical industry and the real estate industry. Please check all the part in the whole passage that highlighted in blue whether retains meaning before. Full article

(This article belongs to the Special Issue Mechanical Behavior of Coatings and Engineered Surfaces)

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57 pages, 2282 KiB

Open AccessArticle

Theoretical Studies of the Adsorption and Migration Behavior of Boron Atoms on Hydrogen-Terminated Diamond (001) Surface

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Coatings 2017, 7(5), 57; https://doi.org/10.3390/coatings7050057 - 27 Apr 2017

Cited by 9 | Viewed by 4916

Abstract

The adsorption and migration activation energies of boron atoms on a hydrogen-terminated diamond (001) surface were calculated using first principles methods based on density functional theory. The values were then used to investigate the behavior of boron atoms in the deposition process of [...] Read more.

The adsorption and migration activation energies of boron atoms on a hydrogen-terminated diamond (001) surface were calculated using first principles methods based on density functional theory. The values were then used to investigate the behavior of boron atoms in the deposition process of B-doped diamond film. On the fully hydrogen-terminated surface, the adsorption energy of a boron atom is relatively low and the maximum value is 1.387 eV. However, on the hydrogen-terminated surface with one open radical site or two open radical sites, the adsorption energy of a boron atom increases to 4.37 eV, and even up to 5.94 eV, thereby forming a stable configuration. When a boron atom deposits nearby a radical site, it can abstract a hydrogen atom from a surface carbon atom, and then form a BH radical and create a new radical site. This study showed that the number and distribution of open radical sites, namely, the adsorption of hydrogen atoms and the abstraction of surface hydrogen atoms, can influence the adsorption and migration of boron atoms on hydrogen-terminated diamond surfaces. Full article

(This article belongs to the Special Issue Mechanical Behavior of Coatings and Engineered Surfaces)

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32 pages, 3291 KiB

Open AccessArticle

Damping Optimization of Hard-Coating Thin Plate by the Modified Modal Strain Energy Method

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Wei Sun

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Rong Liu

Coatings 2017, 7(2), 32; https://doi.org/10.3390/coatings7020032 - 17 Feb 2017

Cited by 9 | Viewed by 5347

Abstract

Due to the medium and small damping characteristics of the hard coating compared with viscoelastic materials, the classical modal strain energy (CMSE) method cannot be applied to the prediction of damping characteristics of hard-coating composite structure directly. In this study, the CMSE method [...] Read more.

Due to the medium and small damping characteristics of the hard coating compared with viscoelastic materials, the classical modal strain energy (CMSE) method cannot be applied to the prediction of damping characteristics of hard-coating composite structure directly. In this study, the CMSE method was modified in order to be suitable for this calculation, and then the damping optimization of the hard-coating thin plate was carried out. First, the solution formula of modified modal strain energy (MMSE) method was derived and the relevant calculation procedure was proposed. Then, based on the principle that depositing the hard coating on the locations where modal strain energy is higher, the damping optimization method and procedure were presented. Next, a cantilever thin plate coated with Mg-Al hard coating was taken as an example to demonstrate the solution of the modal damping parameters for the composite plate. Finally, the optimization of coating location was studied according to the proposed method for the cantilever thin plate, and the effect of the coating area on the damping characteristics of hard-coating plate was also discussed. Full article

(This article belongs to the Special Issue Mechanical Behavior of Coatings and Engineered Surfaces)

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