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10 pages, 4294 KiB

Open AccessFeature PaperArticle

Fracture Properties of α– and ĸ–Al₂O₃ Hard Coatings Deposited by Chemical Vapor Deposition

by Fabian Konstantiniuk, Michael Tkadletz, Christoph Czettl and Nina Schalk

Coatings 2021, 11(11), 1359; https://doi.org/10.3390/coatings11111359 - 4 Nov 2021

Cited by 6 | Viewed by 3171

Although α– and κ–Al₂O₃ hard coatings deposited by chemical vapor deposition are well established in the metal-cutting industry for their ability to increase the performance and lifetime of cutting tools, the literature on their fracture properties is scarce. Thus, within [...] Read more.

Although α– and κ–Al₂O₃ hard coatings deposited by chemical vapor deposition are well established in the metal-cutting industry for their ability to increase the performance and lifetime of cutting tools, the literature on their fracture properties is scarce. Thus, within this study, the microstructure and mechanical properties of α– and κ–Al₂O₃ coatings were investigated and compared to each other. X-ray diffraction and scanning electron microscopy combined with electron backscatter diffraction showed that both coatings exhibited a fiber texture, where the α-Al₂O₃ coating displayed a (0001) texture and the κ–Al₂O₃ coating a (001) texture with a certain (013) contribution. Higher hardness and Young’s modulus values of 31.0 ± 0.9 GPa and 474.6 ± 12.5 GPa, respectively, were obtained for the α–Al₂O₃ coating, compared to 24.2 ± 0.8 GPa and 356.8 ± 7.9 GPa for κ–Al₂O₃. While the α–Al₂O₃ coating exhibited a higher fracture stress of 8.1 ± 0.3 GPa (compared to 6.4 ± 0.6 GPa for κ–Al₂O₃), the κ–Al₂O₃ coating showed a higher fracture toughness of 4.4 ± 0.3 MPa*m^1/2 (compared to 3.2 ± 0.3 MPa*m^1/2 for alpha). Full article

(This article belongs to the Special Issue Chemical Vapor Deposition (CVD) Coatings)

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9 pages, 6858 KiB

Open AccessArticle

Powder Diffraction Data of Aluminum-Rich FCC-Ti_1−xAl_xN Prepared by CVD

by Ingolf Endler, Mandy Höhn, Björn Matthey, Jakub Zálešák, Jozef Keckes and Reinhard Pitonak

Coatings 2021, 11(6), 683; https://doi.org/10.3390/coatings11060683 - 5 Jun 2021

Cited by 2 | Viewed by 3380

Abstract

Fcc-Ti_1−xAl_xN-based coatings obtained by Physical Vapor Deposition (PVD) or Chemical Vapor Deposition (CVD) are widely used as wear-resistant coatings. However, there exists no JCPDF card of fcc-Ti_1−xAl_xN for the XRD analysis of such [...] Read more.

Fcc-Ti_1−xAl_xN-based coatings obtained by Physical Vapor Deposition (PVD) or Chemical Vapor Deposition (CVD) are widely used as wear-resistant coatings. However, there exists no JCPDF card of fcc-Ti_1−xAl_xN for the XRD analysis of such coatings based on experimental data. In this work, an aluminum-rich fcc-Ti_1−xAl_xN powder was prepared and, for the first time, a powder diffraction file of fcc-Ti_1−xAl_xN was determined experimentally. In the first step, a 10 µm thick Ti_1−xAl_xN coating was deposited on steel foil and on cemented carbide inserts by CVD. The steel foil was etched and flakes of a free-standing Ti_1−xAl_xN layer were obtained of which a part consisted of a pure fcc phase. A powder was produced using the major part of the flakes of the free-standing Ti_1−xAl_xN layer. Following the Ti_1−xAl_xN coating, a flake of the free-standing layer and the powder were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), selected area electron diffraction and high-resolution transmission electron microscopy (SAED–HRTEM), wavelength dispersive X-ray spectroscopy (WDS) and energy dispersive X-ray spectroscopy (EDS). The powder consisted of 88% fcc-Ti_1−xAl_xN. The stoichiometric coefficient of fcc-Ti_1−xAl_xN was measured on a flake containing only the fcc phase. A value of x = 0.87 was obtained. Based on the powder sample, the XRD data of the pure fcc-Ti_1−xAl_xN phase were measured and the lattice constant of the fcc-Ti_1−xAl_xN phase in the powder was determined to be a = 0.407168 nm. Finally, a complete dataset comprising relative XRD intensities and lattice parameters for an fcc-Ti_0.13Al_0.87N phase was provided. Full article

(This article belongs to the Special Issue Chemical Vapor Deposition (CVD) Coatings)

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12 pages, 12145 KiB

Open AccessArticle

Enhanced Growth Rate of Chemical Vapor Deposition Diamond Coating Motivated by Graphene Oxide

by Fan Zhou, Naichao Chen and Fasong Ju

Coatings 2021, 11(5), 559; https://doi.org/10.3390/coatings11050559 - 10 May 2021

Cited by 3 | Viewed by 2919

Abstract

To improve the growth rate of chemical vapor deposition (CVD) diamond coating, increasing the chemical reaction rate is essential. A novel method of dispersing graphene oxide (GO) particles as adsorbent on the substrate prior to deposition was proposed, with which the diamond coating [...] Read more.

To improve the growth rate of chemical vapor deposition (CVD) diamond coating, increasing the chemical reaction rate is essential. A novel method of dispersing graphene oxide (GO) particles as adsorbent on the substrate prior to deposition was proposed, with which the diamond coating with large grain size and high thickness was deposited on the silicon nitride under the normal CVD environment. The as-deposited diamond coating was characterized by scanning electron microscopy (SEM), surface profilometer, atomic force microscope (AFM), Raman spectrum, and indentation. The surface morphologies showed that the GO particles were covered by a layer of diamond coating. The diamond coating without and with GO particles had growth rates of 1.10–1.38 and 1.50–2.94 μm h⁻¹, respectively. No differences in the Raman spectra of the microcrystalline diamond (MCD) coatings without and with GO particles were found. Indentation tests suggested that GO particles could enhance the adhesive strength and the crack resistance of diamond coating, which may result from the large thickness and the strong adsorbed capacity of destructive energy. Hence, dispersing particles on the substrate can be regarded as a potential and alternative technique by accelerating the CVD chemical reaction to obtain desired diamond coating. Full article

(This article belongs to the Special Issue Chemical Vapor Deposition (CVD) Coatings)

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13 pages, 6885 KiB

Open AccessArticle

Microstructure and Mechanical Properties of ZrN, ZrCN and ZrC Coatings Grown by Chemical Vapor Deposition

by Florian Frank, Michael Tkadletz, Christoph Czettl and Nina Schalk

Coatings 2021, 11(5), 491; https://doi.org/10.3390/coatings11050491 - 22 Apr 2021

Cited by 15 | Viewed by 7333

Abstract

As the demands for wear-resistant coatings in the cutting industry are constantly rising, new materials that have the potential to exhibit enhanced coating properties are continuously explored. Chemical vapor deposited (CVD) Zr(N,C) is a promising alternative to the well-established and thoroughly investigated Ti(C,N) [...] Read more.

As the demands for wear-resistant coatings in the cutting industry are constantly rising, new materials that have the potential to exhibit enhanced coating properties are continuously explored. Chemical vapor deposited (CVD) Zr(N,C) is a promising alternative to the well-established and thoroughly investigated Ti(C,N) coating system, owing to its advantageous mechanical and thermal properties. Thus, within this work, CVD ZrN, ZrCN and ZrC coatings were deposited at 1000 °C, and subsequently their microstructure and mechanical properties were investigated in detail. Scanning electron microscopy, electron backscatter diffraction and X-ray diffraction experiments revealed that all coatings exhibited a columnar structure and a fiber texture, where ZrN and ZrCN displayed a <100> preferred orientation in growth direction and ZrC showed a <110> texture. Tensile residual stresses that arise due to a mismatch in the coefficient of thermal expansion between the cemented carbide substrate and the coating material decreased with the addition of C to the coatings. No stress relaxation through thermal crack formation was observed in the coatings. The highest hardness was determined for the ZrC coating with 28.1 ± 1.0 GPa and the lowest for the ZrN coating with 22.1 ± 0.9 GPa. Addition of C to the ZrN coating increased the hardness to 26.1 ± 1.6 GPa, which can be explained by a more covalent bonding character, as well as by solid solution strengthening. The ZrCN coating exhibited the highest Young’s modulus, followed by the ZrC and ZrN coatings, which can be attributed to differences in their electronic band structure. Full article

(This article belongs to the Special Issue Chemical Vapor Deposition (CVD) Coatings)

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15 pages, 6650 KiB

Open AccessArticle

Effect of Pressure and Temperature on Microstructure of Self-Assembled Gradient Al_xTi_1−xN Coatings

by Jakub Zalesak, Juraj Todt, Jan Michalička, Bernhard Sartory, Igor Matko, Mario Lessiak, Margarethe Traxler, Ronald Weißenbacher, Reinhard Pitonak, Christoph Gammer and Jozef Keckes

Coatings 2021, 11(4), 416; https://doi.org/10.3390/coatings11040416 - 3 Apr 2021

Cited by 5 | Viewed by 2459

Abstract

The correlation between structural properties of Al-rich self-assembled nano-lamellar Al_xTi_1−xN coatings and process parameters used during their chemical vapor deposition (CVD) remains unexplored. For this article, two gradient Al_xTi_1−xN coatings were prepared by [...] Read more.

The correlation between structural properties of Al-rich self-assembled nano-lamellar Al_xTi_1−xN coatings and process parameters used during their chemical vapor deposition (CVD) remains unexplored. For this article, two gradient Al_xTi_1−xN coatings were prepared by a stepwise increase in temperature and pressure in the ranges of 750–860 °C and 1.56 to 4.5 kPa during the depositions at a constant composition of the process gas mixture. The cross-sectional properties of the coatings were analyzed using X-ray nanodiffraction (CSnanoXRD) and electron microscopy. Experimental results indicate that the variation of the process parameters results in changes in microstructure, grain morphology, elastic strain, nanolamellae’s chemistry and bi-layer period. At temperatures of ~750–800 °C and pressures of 2.5–4.5 kPa, preferably cubic nanolamellar grains are formed, whose microstructure correlates with the build-up of tensile stresses, which become relaxed in coating regions filled with nanocrystalline grains. CSnanoXRD superlattice satellite reflections indicate the period of the cubic Al(Ti)N-Ti(Al)N bilayers, which changes from 6.7 to 9 nm due to the temperature increase from 750 to ~810 °C, while it remains nearly unaffected by the pressure variation. In summary, our study documents that CVD process parameters can be used to tune microstructural properties of self-assembled Al_xTi_1−xN nanolamellae as well as the coatings’ grain morphology. Full article

(This article belongs to the Special Issue Chemical Vapor Deposition (CVD) Coatings)

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16 pages, 4491 KiB

Open AccessArticle

In-Situ Investigation of the Oxidation Behaviour of Chemical Vapour Deposited Zr(C,N) Hard Coatings Using Synchrotron X-ray Diffraction

by Florian Frank, Michael Tkadletz, Christian Saringer, Andreas Stark, Norbert Schell, Marco Deluca, Christoph Czettl and Nina Schalk

Coatings 2021, 11(3), 264; https://doi.org/10.3390/coatings11030264 - 24 Feb 2021

Cited by 6 | Viewed by 2800

Abstract

The oxidation behaviour of chemical vapour deposited ZrN, ZrC and ZrCN coatings was investigated using in-situ synchrotron X-ray diffraction (XRD). To obtain a precise analysis of the temperature–dependent phase evolution during oxidation, coating powders were annealed in air between 100 °C and 1000 [...] Read more.

The oxidation behaviour of chemical vapour deposited ZrN, ZrC and ZrCN coatings was investigated using in-situ synchrotron X-ray diffraction (XRD). To obtain a precise analysis of the temperature–dependent phase evolution during oxidation, coating powders were annealed in air between 100 °C and 1000 °C. Simultaneously, 2D XRD patterns were recorded in ~2 °C increments, which were subsequently evaluated using parametric Rietveld refinement. The results were correlated with differential scanning calorimetry and thermogravimetric analysis measurements, to further illuminate the oxidation mechanism of each coating system. ZrCN exhibited the highest oxidation onset temperature, followed by ZrC and ZrN. Furthermore, ZrCN was completely oxidised at a temperature of ~720 °C, which was ~50–70 °C higher than for ZrN and ZrC. The in-situ experiments revealed a similar oxidation sequence for all three samples: first, tetragonal and/or cubic (c/t)–ZrO₂ is formed, which subsequently transforms into the more stable monoclinic (m)–ZrO₂ phase. ZrCN and ZrC showed a higher c/t–ZrO₂ fraction than the ZrN sample at 1000 °C. Furthermore, ex-situ Raman and XRD investigations of the oxidised samples revealed the ongoing c/t–ZrO₂ → m–ZrO₂ phase transformation during cooling. Full article

(This article belongs to the Special Issue Chemical Vapor Deposition (CVD) Coatings)

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16 pages, 9988 KiB

Open AccessArticle

Numerical Analysis of an Inline Metal-Organic Chemical Vapour Deposition Process Based on Sliding-Mesh Modelling

by Xiaosong Zhou, Yiyi Wu, Xiaogang Yang and Chaowen Huang

Coatings 2020, 10(12), 1198; https://doi.org/10.3390/coatings10121198 - 9 Dec 2020

Cited by 4 | Viewed by 2859

Abstract

The flow behaviour under the influence of susceptor moving speed is a key factor for the fabrication of high-quality cadmium telluride (CdTe) thin films during the inline metal-organic chemical vapour deposition (MOCVD) process. The main purpose of this paper is to find a [...] Read more.

The flow behaviour under the influence of susceptor moving speed is a key factor for the fabrication of high-quality cadmium telluride (CdTe) thin films during the inline metal-organic chemical vapour deposition (MOCVD) process. The main purpose of this paper is to find a method to study the real-time dynamics of transport phenomena inside the reactor. The sliding mesh method is thus proposed and its feasibility is evaluated using computational fluid dynamics (CFD) modelling. A computational grid with 173,400 hexahedral cells is adopted through a grid sensitivity test validation. The simulations show that comparing to 2D modelling, the results of 3D modelling are found to be in good agreement with the experimental data for the temperature range of 628–728 K. Based on the velocity field, the temperature field and distribution of species concentration under different sampling time intervals of 60, 180 and 300 s, the thin film uniformity on both edges of the substrate is found to be influenced by the side effect of the baffle plate. The mass deposited on the substrate is further investigated under different susceptor moving speeds from 0.75 to 2.25 cm/min, and a moving speed between 0.75 to 1.13 cm/min is found to be effectively beneficial to the deposition process. Full article

(This article belongs to the Special Issue Chemical Vapor Deposition (CVD) Coatings)

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10 pages, 4101 KiB

Open AccessArticle

Effect of Substrate Holder Design on Stress and Uniformity of Large-Area Polycrystalline Diamond Films Grown by Microwave Plasma-Assisted CVD

by Vadim Sedov, Artem Martyanov, Alexandr Altakhov, Alexey Popovich, Mikhail Shevchenko, Sergey Savin, Evgeny Zavedeev, Maxim Zanaveskin, Andrey Sinogeykin, Victor Ralchenko and Vitaly Konov

Coatings 2020, 10(10), 939; https://doi.org/10.3390/coatings10100939 - 30 Sep 2020

Cited by 31 | Viewed by 5093

Abstract

In this work, the substrate holders of three principal geometries (flat, pocket, and pedestal) were designed based on E-field simulations. They were fabricated and then tested in microwave plasma-assisted chemical vapor deposition process with the purpose of the homogeneous growth of 100-μm-thick, low-stress [...] Read more.

In this work, the substrate holders of three principal geometries (flat, pocket, and pedestal) were designed based on E-field simulations. They were fabricated and then tested in microwave plasma-assisted chemical vapor deposition process with the purpose of the homogeneous growth of 100-μm-thick, low-stress polycrystalline diamond film over 2-inch Si substrates with a thickness of 0.35 mm. The effectiveness of each holder design was estimated by the criteria of the PCD film quality, its homogeneity, stress, and the curvature of the resulting “diamond-on-Si” plates. The structure and phase composition of the synthesized samples were studied with scanning electron microscopy and Raman spectroscopy, the curvature was measured using white light interferometry, and the thermal conductivity was measured using the laser flash technique. The proposed pedestal design of the substrate holder could reduce the stress of the thick PCD film down to 1.1–1.4 GPa, which resulted in an extremely low value of displacement for the resulting “diamond-on-Si” plate of Δh = 50 μm. The obtained results may be used for the improvement of already existing, and the design of the novel-type, MPCVD reactors aimed at the growth of large-area thick homogeneous PCD layers and plates for electronic applications. Full article

(This article belongs to the Special Issue Chemical Vapor Deposition (CVD) Coatings)

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