Thermal stability of alumina thin films containing γ-Al2O3 phase prepared by reactive magnetron sputtering

Musil, J.; Blažek, J.; Zeman, Petr; Prokšová, Š.; Šašek, Martin; Čerstvý, R.

doi:10.1016/j.apsusc.2010.07.107

Cited by 121 publications

(38 citation statements)

References 40 publications

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“…In order to obtain γ-Al2O3 without amorphous phase, by means of reactively pulsed DC sputtering, a substrate temperature of at least 500 °C was needed as well as high power densities (with floating bias voltage) [29]. Similar deposition temperatures for reactive pulsed DC processes has been reported by several authors [16,17,30,31]. With RF-sputtering it has been obtained at 450 °C -500 °C [32,33].…”

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confidence: 77%

Thin Film and Plasma Characterization of PVD Oxides

Landälv¹

2017

Linköping Studies in Science and Technology. Dissertations

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The state-of-the-art tools for machining metals are primarily based on a metal-ceramic composite (WC-Co) coated with different combinations of carbide, nitride and oxide coatings. Combinations of these coating materials are optimized to withstand specific wear conditions. Oxide coatings are especially desired because of their possible high hot hardness, chemical inertness with respect to the workpiece, and their low friction.This thesis deals with process and coating characterization of new oxide coatings deposited by physical vapor deposition (PVD) techniques, focusing on the Cr-Zr-O and Al-Cr-Si-O systems.The thermal stability of α-Cr0.28Zr0.10O0.61 deposited by reactive radio frequency (RF)-magnetron sputtering at 500 °C was investigated after annealing up to 870 °C. The annealed samples showed transformation of α-(Cr,Zr)2O3 and amorphous ZrOx-rich areas into tetragonal ZrO2 and bcc Cr. The instability of the α-(Cr,Zr)2O3 is surprising and possibly related to the annealing being done under vacuum, facilitating the loss of oxygen. The stabilization of the room temperature metastable tetragonal ZrO2 phase, due to surface energy effects, may prove to be useful for metal cutting applications. The observed phase segregation of α-(Cr,Zr)2O3 and formation of tetragonal ZrO2 with corresponding increase in hardness for this pseudo-binary oxide system also opens up design routes for pseudo-binary oxides with tunable microstructural and mechanical properties.The inherent difficulties of depositing insulating oxide films with PVD, demanding a closed circuit, makes the investigation of process stability an important part of this research. In this context, we investigated the influence of adding small amount of Si in Al-Cr cathode on plasma characteristics, process parameters, and coating properties. Si was chosen here due to a previous study showing improved erosion behavior of Al-Cr-Si over pure Al-Cr cathode without Si incorporation in the coating.This work shows small improvements in cathode erosion and process stability (lower pressure and cathode voltage) when introducing 5 at % Si in the Al70Cr30-cathode. This also led to fewer droplets at low cathode current and intermediate O2 flow. A larger positive effect on cathode erosion was observed with respect to cleaning the cathode from oxide contamination by increasing cathode current with 50%. However, higher cathode current also resulted in increased amount of droplets in the coating which is undesirable. Through plasma analysis the presence of volatile SiO species could be confirmed but the loss of Si through volatile SiO species was negligible, since the coating composition matched the cathode composition. The positive effect of added Si on the process stability at the cathode surface should be weighed against Si incorporation in the coating. This incorporation may or may not be beneficial for the final application since literature states that Si promotes the metastable γ-phase over the thermodynamically stable α-phase of pure Al2O3, contrary to the effect o...

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confidence: 77%

Thin Film and Plasma Characterization of PVD Oxides

Landälv¹

2017

Linköping Studies in Science and Technology. Dissertations

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“…This work was followed by Yamada et al who reported on the reactive deposition of α-Al 2 O 3 from a filtered vacuum arc at 780 ∘ C [14]. The lowest temperature for the deposition of α-alumina in the literature is 280 ∘ C [15] and the maximum deposition rate reported was 150 nm/h [11]. The process of reactive sputter deposition involves (1) the sputtering process (2) the physics of the plasma discharge (3) transport of the sputtered and gas species (4) the kinetics of film growth (5) and the chemical interactions at the target and film surfaces.…”

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confidence: 97%

Corrosion studies of DC reactive magnetron sputtered alumina coating on 304 SS

Thangaraj¹,

Mahadevan²

2017

Electrochemical Energy Technology

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Aluminum oxide films on SS 304 deposited by DC reactive magnetron sputtering technique were studied with respect to the composition of the sputter gas (Ar:O 2 ), gas pressure, substrate temperature, current etc. to achieve good insulating films with high corrosion resistance. The films were characterized by XRD and SEM techniques. Potentiodynamic polarization and electrochemical impedance spectroscopy measurements were made under static conditions in order to evaluate the corrosion performance of the alumina-coated SS 304 for various immersion durations in 0.5 M and 1 M NaCl solution. Alumina-coated SS 304 has low corrosion value of 0.4550 and 1.1090 MPY for 24 h immersion time in both solutions. The impedance plots for the alumina coated SS 304 in 1 M NaCl solution at different durations are slightly different to when compared to its immersion in 0.5 M NaCl solutions and are composed of two depressed semi circles. For the alumina coated film, the impedance spectrum decreased, when immersion time increased.

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“…Since the alumina has high thermal conductivity among them, 8) the functional materials will be thermally stabilized with their incorporation into the alumina films.…”

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confidence: 99%

Fabrication of transparent self-supporting alumina films by homogeneous precipitation process

Inoue

Kurebayashi

Hama

et al. 2013

J. Ceram. Soc. Japan

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This paper reports fabrication of transparent self-supporting alumina films by using homogeneous precipitation and peptization processes. White precipitate of aluminum hydroxide was prepared with a homogeneous precipitation method using aluminum nitrate and urea in aqueous solution. The obtained aluminum hydroxide precipitate was peptized by using acetic acid at room temperature, which resulted in production of a transparent alumina sol. The alumina sol was transformed to an alumina gel film by drying the sol at room temperature. The alumina film was amorphous or fine crystallites even after annealed at a temperature as high as 500°C, and was crystallized to £-Al 2 O 3 at 900°C.

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Thermal stability of alumina thin films containing γ-Al2O3 phase prepared by reactive magnetron sputtering

Cited by 121 publications

References 40 publications

Thin Film and Plasma Characterization of PVD Oxides

Thin Film and Plasma Characterization of PVD Oxides

Corrosion studies of DC reactive magnetron sputtered alumina coating on 304 SS

Fabrication of transparent self-supporting alumina films by homogeneous precipitation process

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