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Jin-hyo Boo - One of the best experts on this subject based on the ideXlab platform.
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Enhanced Hardness in two layer a bon nc sic coating prepared by plasma assisted mocvd and thermal mocvd
Surface & Coatings Technology, 2005Co-Authors: Dong-gun Lim, B.-c. Kang, Jeong Seop Moon, O.-m. Moon, Jinny Park, H.-g. Jee, S.-b. Lee, Young-ho Kim, Jeong Yong Lee, Jin-hyo BooAbstract:We have synthesized the simple a-BON and nc-SiC thin films as well as multilayered a-BON/nc-SiC thin film on Si(001) substrates by combining low-frequency RF-derived plasma-assisted MOCVD and thermal MOCVD in the deposition temperature range of 300–900 8C trimethylborate (TMB), and diethylmethylsilane (DEMS) precursors were used to grow a-BON and nc-SiC thin films, respectively. Ar gas was applied as a plasma source and N2 gas was used as a reactive gas as well as additional nitrogen source. To analyze the mechanism of obtaining new materials with high Hardness by combining soft amorphous material with hard crystalline material, in this study, we have mainly investigated the relationship between structure and Hardness enhancement of the coating layers on the effects of different kind of layer and the crystallization of layers. The results show that microstructure of each layer and a new nanocrystalline material that deposited between a-BON thin film and nc-SiC thin film affect the Hardness enhancement in multilayered a-BON/nc-SiC thin films. Hardness obtained from a-BON was about 10 GPa. However, we could obtain strong Hardness enhancement in a multilayered a-BON/nc-SiC thin film up to 36 GPa. D 2004 Elsevier B.V. All rights reserved.
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Enhanced Hardness in two-layer a-BON/nc-SiC coating prepared by plasma-assisted MOCVD and thermal MOCVD
Surface and Coatings Technology, 2005Co-Authors: Dong-gun Lim, B.-c. Kang, Jeong Seop Moon, O.-m. Moon, Jinny Park, H.-g. Jee, S.-b. Lee, Young-ho Kim, Jeong Yong Lee, Jin-hyo BooAbstract:We have synthesized the simple a-BON and nc-SiC thin films as well as multilayered a-BON/nc-SiC thin film on Si(001) substrates by combining low-frequency RF-derived plasma-assisted MOCVD and thermal MOCVD in the deposition temperature range of 300–900 8C trimethylborate (TMB), and diethylmethylsilane (DEMS) precursors were used to grow a-BON and nc-SiC thin films, respectively. Ar gas was applied as a plasma source and N2 gas was used as a reactive gas as well as additional nitrogen source. To analyze the mechanism of obtaining new materials with high Hardness by combining soft amorphous material with hard crystalline material, in this study, we have mainly investigated the relationship between structure and Hardness enhancement of the coating layers on the effects of different kind of layer and the crystallization of layers. The results show that microstructure of each layer and a new nanocrystalline material that deposited between a-BON thin film and nc-SiC thin film affect the Hardness enhancement in multilayered a-BON/nc-SiC thin films. Hardness obtained from a-BON was about 10 GPa. However, we could obtain strong Hardness enhancement in a multilayered a-BON/nc-SiC thin film up to 36 GPa. D 2004 Elsevier B.V. All rights reserved.
Jindřich Musil - One of the best experts on this subject based on the ideXlab platform.
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(Zr,Ti,O) alloy films with Enhanced Hardness and resistance to cracking prepared by magnetron sputtering
Surface and Coatings Technology, 2017Co-Authors: Jindřich Musil, Sergei Zenkin, Radomír Čerstvý, Stanislav Haviar, Zuzana ČiperováAbstract:Abstract The article reports on the effect of (i) the ion bombardment and (ii) the addition of small amount of oxygen into Ar sputtering gas on the structure, microstructure, mechanical properties and macrostress of the (Zr,Ti) alloy films prepared by DC magnetron sputtering. Properties of the (Zr,Ti) alloy films with three different elemental compositions – (1) Zr 95 Ti 5 , (2) Zr 30 Ti 70 and (3) Zr 5 Ti 95 were investigated in detail. It was found that (1) the (Zr,Ti) alloy films sputtered at a low value of the negative substrate bias U s = − 50 V are well crystalline, (2) the (Zr,Ti) alloy films sputtered at high values of the negative substrate bias | U s | ≥ 150 V are nanocrystalline, (3) the (Zr,Ti) alloy films, sputtered at all substrate biases U s used in our experiments and ranging from − 50 to − 250 V, exhibit low Hardness H ⁎ e 10 GPa, high ratio H/E ⁎ ≥ 0.1, high elastic recovery W e ≥ 60% and Enhanced resistance to cracking; here E ⁎ is the effective Young's modulus. The main result of the presented investigation is the demonstration that the incorporation of a small amount of O in a (Zr,Ti) alloy film is a very effective way to increase its Hardness and to form the flexible (Zr,Ti,O) alloy films with Enhanced resistance to cracking.
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Enhanced Hardness in sputtered Zr–Ni–N films
Surface & Coatings Technology, 2006Co-Authors: Jindřich Musil, Václav OndokAbstract:Abstract Recently, it was found that the reactive magnetron sputtering of TiN films with the addition of small (≤ 10 at.%) amount of Fe makes it possible to change the preferred crystallographic orientation of grains in the film when the partial pressure of nitrogen p N 2 in the sputtering gas is continuously increased. Between the films with different preferred crystallographic orientations there is a transition region (TR). The films produced inside TR are characterized by an X-ray amorphous structure. In spite of the fact that the films produced inside TR and outside of it strongly differ in their structure, both kinds of films exhibit an Enhanced Hardness [J. Musil, H. Polakova, J. Suna, J. Vlcek, Surf. Coat. Technol. 177–178 (2004) 289]. It was found that the Enhanced Hardness arises in two cases: (1) in the materials composed of a mixture of small grains of different crystallographic orientations, i.e. in the films produced inside TR, and (2) in the materials composed of nanocolumns perpendicular to the film/substrate interface, i.e. in the films produced outside TR. These findings are in an agreement with a new concept of nanocomposite phases with Enhanced Hardness based on the size of grains and the shape of crystallites [J. Musil, in: A. Cavaleiro, J.T.M. De Hosson (Eds.), Nanostructured Hard Coatings, Kluwer Academic/Plenum Publishers, New York, 2005, Chapter 10]. A development of mechanical properties of the Zr–Ni–N films with increasing p N 2 is also discussed in detail.
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Control of macrostress σ in reactively sputtered Mo–Al–N films by total gas pressure
Vacuum, 2006Co-Authors: J. Šůna, Jindřich Musil, P. DohnalAbstract:Abstract This article reports on the effect of the energy delivered to a growing film by bombarding ions and fast neutrals on the macrostress σ and the structure of sputtered films. To demonstrate this effect, we selected Mo–Al–N films with a low (⩽20 at.%) Al content reactively sputtered using an unbalanced dc magnetron with a target of 100 mm diameter at a high total pressure p T = 3 Pa , low substrate bias U s = - 20 V and a high substrate ion current density i s = 1 mA / cm 2 . The main goal of this study was to show the reduction of σ in films sputtered at high pressures of several Pa. Under the conditions given above approximately 4 μm thick Mo–Al–N films with Enhanced Hardness H≈35 GPa and a very low (⩽−0.5 GPa) macrostress σ were successfully prepared. This result demonstrates that the Enhanced Hardness H of Mo–Al–N films is not caused by σ but is due to its nanostructure as shown in the XRD patterns of these films. The Mo–Al–N films with Enhanced Hardness are composed of a mixture of grains of different crystallographic orientations.
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NANOCOMPOSITE COATINGS WITH Enhanced Hardness
2005Co-Authors: Jindřich MusilAbstract:The article reviews the present state of the art in the magnetron sputtering of hart and superhard nanocomposite coatings. It is shown that there are (1) two groups of hard and superhard nanocomposites: (i) nc-MN/hard phase and (ii) nc-MN/soft phase, (2) three possible origins of the Enhanced Hardness: (i) dislocation-dominated plastic deformation, (ii) cohesive forces between atoms and (iii) nanostructure of materials, and (3) huge differences in the microstructure of single- and two-phase films. A main attention is devoted to the formation of nanocrystalline and/or X-ray amorphous films. Such films are created in a vicinity of transitions between (i)crystalline and amorphous phases, (ii) two crystalline phases of different chemical composition or (iii) two different preferred orientations of grains of the sane material from which the coating is composed. The existence of the last transition makes it possible to explain the Enhanced Hardness in single-phase films. The thermal stability and oxidation resistance of hard nanocomposite films is also shortly discussed.
Pinwen Zhu - One of the best experts on this subject based on the ideXlab platform.
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Enhanced Hardness in tungsten substituted molybdenum diboride solid solutions by local symmetry reduction
Materials Chemistry and Physics, 2020Co-Authors: Feng Zhao, Qiang Tao, Cun You, Xin Wang, Tian Cui, Yang Han, Shushan Dong, Pinwen ZhuAbstract:Abstract MoB2, with a layered structure, is a potential functional material that is expected to be used as catalysts and conductors. However, the lower Hardness limits its application in extreme environment. Solid-solution hardening is a suitable way to enhance Hardness and keep structure, but it is complicated in transition metal borides (TMBs) solid solutions. Up to now, uncovering the intrinsic factors of solid-solution hardening is still a challenge. In this work, the structural, electronic and Hardness properties of Mo1-xWxB2 (x = 0.01~0.20) is studied to explore the potential factors. It is found that sharp increase in Hardness of Mo1-xWxB2 at low W doping level (≤5 at%), and highest Vickers Hardness of 26.7 ± 1.2 GPa (applied 0.49 N load) was obtained by Mo0.95W0.05B2. The high Hardness reason is ascribed to the lattice distortions lead to internal stress at the nanoscale, which created local symmetry reduction by affected local electron distribution of B–B bond and the lattice position of Mo atoms. Moreover, at higher W doping level, TM-B bond is strengthened by increasing electron transfer from the tungsten atoms to the boron atoms, which resulting in the Hardness increasing of Mo1-xWxB2. This provides guidance for designing TMBs solid solutions with better mechanical properties.
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Enhanced Hardness in tungsten–substituted molybdenum diboride solid solutions by local symmetry reduction
Materials Chemistry and Physics, 2020Co-Authors: Feng Zhao, Qiang Tao, Cun You, Han Yang, Dong Shushan, Xin Wang, Tian Cui, Pinwen ZhuAbstract:Abstract MoB2, with a layered structure, is a potential functional material that is expected to be used as catalysts and conductors. However, the lower Hardness limits its application in extreme environment. Solid-solution hardening is a suitable way to enhance Hardness and keep structure, but it is complicated in transition metal borides (TMBs) solid solutions. Up to now, uncovering the intrinsic factors of solid-solution hardening is still a challenge. In this work, the structural, electronic and Hardness properties of Mo1-xWxB2 (x = 0.01~0.20) is studied to explore the potential factors. It is found that sharp increase in Hardness of Mo1-xWxB2 at low W doping level (≤5 at%), and highest Vickers Hardness of 26.7 ± 1.2 GPa (applied 0.49 N load) was obtained by Mo0.95W0.05B2. The high Hardness reason is ascribed to the lattice distortions lead to internal stress at the nanoscale, which created local symmetry reduction by affected local electron distribution of B–B bond and the lattice position of Mo atoms. Moreover, at higher W doping level, TM-B bond is strengthened by increasing electron transfer from the tungsten atoms to the boron atoms, which resulting in the Hardness increasing of Mo1-xWxB2. This provides guidance for designing TMBs solid solutions with better mechanical properties.
A. Mestra - One of the best experts on this subject based on the ideXlab platform.
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Processing of alumina–zirconia composites by surface modification route with Enhanced Hardness and wear resistance
Ceramics International, 2015Co-Authors: Frank Kern, Paola Palmero, Fernando García Marro, A. MestraAbstract:Abstract Zirconia toughened alumina (ZTA) materials are frequently used in mechanical engineering and biomedical applications due to their Enhanced toughness, strength and wear resistance compared to monolithic alumina. In this study, a submicron size alumina powder was modified via wet chemical route: the alumina particles surface was coated with zirconium chloride, to yield 10 vol% zirconia by subsequent thermal treatment. From this powder, several ZTA materials were produced by slip casting, sintered at different temperatures from 1475 to 1575 °C. In all materials, a full characterization of their mechanical properties, microstructure and phase composition was carried out, together with wear tests carried out in a linear-reciprocating mode using a Y-TZP ball counterpart under environmental conditions. The results show low wear at sintering temperatures below 1525 °C and high wear at higher sintering temperatures, which can be well correlated to the Hardness, microstructure and phase evolution. The microstructure of the materials is initially extremely homogeneous and fine grained. The grain size increases moderately both for the zirconia and alumina components with the sintering temperatures considered. The grain shape of alumina gradually changes from isometric to elongated. Up to 1525 °C, the size of zirconia grains stays below 400 nm. The zirconia transformability was evaluated and it was observed that the zirconia dispersion remains vastly untransformable up to that sintering temperature. In this condition, the alumina matrix is under compressive hydrostatic stress and fracture resistance is moderate. At higher sintering temperatures, grain growth induces higher zirconia transformability and fracture resistance but at the expense of Hardness and wear resistance. The simultaneous evolution of tabular morphology in matrix grains also contributes to toughness but facilitates grain breakout and disruption of the surface during final machining and under tribological load.
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processing of alumina zirconia composites by surface modification route with Enhanced Hardness and wear resistance
Ceramics International, 2015Co-Authors: Frank Kern, Paola Palmero, Fernando García Marro, A. MestraAbstract:Abstract Zirconia toughened alumina (ZTA) materials are frequently used in mechanical engineering and biomedical applications due to their Enhanced toughness, strength and wear resistance compared to monolithic alumina. In this study, a submicron size alumina powder was modified via wet chemical route: the alumina particles surface was coated with zirconium chloride, to yield 10 vol% zirconia by subsequent thermal treatment. From this powder, several ZTA materials were produced by slip casting, sintered at different temperatures from 1475 to 1575 °C. In all materials, a full characterization of their mechanical properties, microstructure and phase composition was carried out, together with wear tests carried out in a linear-reciprocating mode using a Y-TZP ball counterpart under environmental conditions. The results show low wear at sintering temperatures below 1525 °C and high wear at higher sintering temperatures, which can be well correlated to the Hardness, microstructure and phase evolution. The microstructure of the materials is initially extremely homogeneous and fine grained. The grain size increases moderately both for the zirconia and alumina components with the sintering temperatures considered. The grain shape of alumina gradually changes from isometric to elongated. Up to 1525 °C, the size of zirconia grains stays below 400 nm. The zirconia transformability was evaluated and it was observed that the zirconia dispersion remains vastly untransformable up to that sintering temperature. In this condition, the alumina matrix is under compressive hydrostatic stress and fracture resistance is moderate. At higher sintering temperatures, grain growth induces higher zirconia transformability and fracture resistance but at the expense of Hardness and wear resistance. The simultaneous evolution of tabular morphology in matrix grains also contributes to toughness but facilitates grain breakout and disruption of the surface during final machining and under tribological load.
Dong-gun Lim - One of the best experts on this subject based on the ideXlab platform.
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Enhanced Hardness in two layer a bon nc sic coating prepared by plasma assisted mocvd and thermal mocvd
Surface & Coatings Technology, 2005Co-Authors: Dong-gun Lim, B.-c. Kang, Jeong Seop Moon, O.-m. Moon, Jinny Park, H.-g. Jee, S.-b. Lee, Young-ho Kim, Jeong Yong Lee, Jin-hyo BooAbstract:We have synthesized the simple a-BON and nc-SiC thin films as well as multilayered a-BON/nc-SiC thin film on Si(001) substrates by combining low-frequency RF-derived plasma-assisted MOCVD and thermal MOCVD in the deposition temperature range of 300–900 8C trimethylborate (TMB), and diethylmethylsilane (DEMS) precursors were used to grow a-BON and nc-SiC thin films, respectively. Ar gas was applied as a plasma source and N2 gas was used as a reactive gas as well as additional nitrogen source. To analyze the mechanism of obtaining new materials with high Hardness by combining soft amorphous material with hard crystalline material, in this study, we have mainly investigated the relationship between structure and Hardness enhancement of the coating layers on the effects of different kind of layer and the crystallization of layers. The results show that microstructure of each layer and a new nanocrystalline material that deposited between a-BON thin film and nc-SiC thin film affect the Hardness enhancement in multilayered a-BON/nc-SiC thin films. Hardness obtained from a-BON was about 10 GPa. However, we could obtain strong Hardness enhancement in a multilayered a-BON/nc-SiC thin film up to 36 GPa. D 2004 Elsevier B.V. All rights reserved.
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Enhanced Hardness in two-layer a-BON/nc-SiC coating prepared by plasma-assisted MOCVD and thermal MOCVD
Surface and Coatings Technology, 2005Co-Authors: Dong-gun Lim, B.-c. Kang, Jeong Seop Moon, O.-m. Moon, Jinny Park, H.-g. Jee, S.-b. Lee, Young-ho Kim, Jeong Yong Lee, Jin-hyo BooAbstract:We have synthesized the simple a-BON and nc-SiC thin films as well as multilayered a-BON/nc-SiC thin film on Si(001) substrates by combining low-frequency RF-derived plasma-assisted MOCVD and thermal MOCVD in the deposition temperature range of 300–900 8C trimethylborate (TMB), and diethylmethylsilane (DEMS) precursors were used to grow a-BON and nc-SiC thin films, respectively. Ar gas was applied as a plasma source and N2 gas was used as a reactive gas as well as additional nitrogen source. To analyze the mechanism of obtaining new materials with high Hardness by combining soft amorphous material with hard crystalline material, in this study, we have mainly investigated the relationship between structure and Hardness enhancement of the coating layers on the effects of different kind of layer and the crystallization of layers. The results show that microstructure of each layer and a new nanocrystalline material that deposited between a-BON thin film and nc-SiC thin film affect the Hardness enhancement in multilayered a-BON/nc-SiC thin films. Hardness obtained from a-BON was about 10 GPa. However, we could obtain strong Hardness enhancement in a multilayered a-BON/nc-SiC thin film up to 36 GPa. D 2004 Elsevier B.V. All rights reserved.