Ion Assisted Deposition of Refractory Oxide Thin Film Coatings for Improved Optical and Structural Properties PDF Download
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Author: N. K. Sahoo
Publisher:
ISBN:
Category : Coatings
Languages : en
Pages : 35
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Book Description
Author: N. K. Sahoo
Publisher:
ISBN:
Category : Coatings
Languages : en
Pages : 35
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Book Description
Author: James Joseph McNally
Publisher:
ISBN:
Category : Optical coatings
Languages : en
Pages : 328
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Book Description
The effects on the properties of Ta2O5, Al2O3, SiO2 and HfO2 single- and multi-layer optical coatings deposited using ion assisted deposition (IAD) were investigated. IAD is a novel deposition technique which utilizes a separate ion source to direct a beam of ions at the growing film. A Kaufman ion source was used to provide a monoenergetic, neutralized beam of oxygen ions independent of the material evaporation process. The optical and physical properties, as well as laser induced damage threshold (LIDT) values, were studied for coatings bombarded with 200, 300, 500 and 1000 eV oxygen ions at values of current density from 0 to 200 microAmp/sq cm. IAD was successfully applied to deposit coatings at low temperature on heavy metal fluoride (HMF) glass substrates. The coatings deposited using IAD were hard and dense. The IAD coatings improved the durability and abrasion resistance of the HMF glass substrates. The results of this investigation show that IAD can be used to improve the optical and physical properties of optical coatings.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 19
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Book Description
An investigation was made by changing the preparation parameters, such as different ion species, ion energy, and ion current density, etc., to determine their effects on refractive indices, absorption, and laser-induced damage threshold, etc. of the coatings of TiO2, ZrO2 and SiO2 whose oxide coatings were prepared by ion-assisted deposition.
Author: GA. Al-Jumaily
Publisher:
ISBN:
Category : Coatings
Languages : en
Pages : 8
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Book Description
Heavy metal fluoride glass materials are attractive for optical applications in the near ultraviolet through infrared wavelength regions. However, many compositions are relatively soft and hygroscopic, and possess low softening temperature (250°C-300°C). We have applied ion assisted deposition (IAD) techniques to deposit MgF2, SiO2 and Al2O3/SiO2 thin film structures on fluoride glass substrates at ambient substrate temperature (100°C). The coatings deposited using IAD improve the environmental durability of the fluoride glass and appear to have reasonably good optical charateristics; without application of IAD, the deposited coatings are not durable and have poor adhesion.
Author: Peter M. Martin
Publisher: William Andrew
ISBN: 0815520328
Category : Technology & Engineering
Languages : en
Pages : 932
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Book Description
This 3e, edited by Peter M. Martin, PNNL 2005 Inventor of the Year, is an extensive update of the many improvements in deposition technologies, mechanisms, and applications. This long-awaited revision includes updated and new chapters on atomic layer deposition, cathodic arc deposition, sculpted thin films, polymer thin films and emerging technologies. Extensive material was added throughout the book, especially in the areas concerned with plasma-assisted vapor deposition processes and metallurgical coating applications.
Author: Ludvig Landälv
Publisher: Linköping University Electronic Press
ISBN: 9176850889
Category :
Languages : en
Pages : 42
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Book Description
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, mainly α-Al2O3, are especially desired because of their high hot-hardness, chemical inertness with respect to the workpiece, and their low friction. The search for possible alloy elements, which may facilitate the deposition of such oxides by means of physical vapor deposition (PVD) techniques, has been the goal of this thesis. The sought alloy should form thermodynamically stable or metastable compounds, compatible with the temperature of use in metal cutting application. This thesis deals with process development and coating characterization of such new oxide alloy thin films, focusing on the Al-V-O, Al-Cr-Si-O, and Cr-Zr-O systems. Alloying aluminum oxide with iso-valent vanadium is a candidate for forming the desired alloys. Therefore, coatings of (Al1-xVx)2O3, with x ranging from 0 to 1, were deposited with reactive sputter deposition. X-ray diffraction showed three different crystal structures depending on V-metal fraction in the coating: α-V2O3 rhombohedral structure for 100 at.% V, a defect spinel structure for the intermediate region, (63 - 42 at.% V), and a gamma-alumina-like solid solution at lower V-content, (18 and 7 at.%), were observed, the later was shifted to larger d-spacing compared to the pure γ-Al2O3 sample obtained if deposited with only Al-target. Annealing the Al-rich coatings in air resulted in formation of V2O5 crystals on the surface of the coating after annealing to 500 °C for 42 at.% V and 700 °C for 18 at.% V metal fraction respectively. The highest thermal stability was shown for pure γ-Al2O3-coating which transformed to α-Al2O3 after annealing to 1100° C. Highest hardness was observed for the Al-rich oxides, ~24 GPa. The hardness then decreases with increasing V-content, larger than 7 at.% V metal fraction. Doping the Al2O3 coating with 7 at.% V resulted in a significant surface smoothening compared to the binary oxide. The measured hardness after annealing in air decreased in conjunction with the onset of further oxidation of the coatings. This work increases the understanding of this complicated material system with respect to possible phases formed with pulsed DC magnetron sputtering deposition as well as their response to annealing in air. The inherent difficulties of depositing insulating oxide films with PVD, requiring a closed electrical circuit, makes the investigation of process stability an important part of this research. In this context, I investigated the influence of adding small amount of Si in Al-Cr cathode on the coating properties in a pulsed DC industrial cathodic arc system and the plasma characteristics, process parameters, and coating properties in a lab DC cathodic arc system. 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. The effect of Si in the Al-Cr cathode in the industrial cathodic arc system showed slight improvements on the cathode erosion but Si was found in all coatings where Si was added in the cathode. The Si addition promoted the formation of the B1-like metastable cubic oxide phase and the incorporation led to reduced or equal hardness values compared to the corresponding Si-free processes. The DC-arc plasma study on the same material system showed only small improvements in the cathode erosion and process stability (lower pressure and cathode voltage) when introducing 5 at.% Si in the Al70Cr30-cathode. The presence of volatile SiO species could be confirmed through plasma analysis, but the loss of Si through these species was negligible, since the coating composition matched the cathode composition also under these conditions. 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 seems to lead to a reduction in mechanical properties in the as-deposited coatings and promote the formation of a B1-like cubic metastable oxide structure for the (Al,Cr)2O3 oxide. This formation may or may not be beneficial for the final application since literature indicates a slight stabilization of the metastable phase upon Si-incorporation, contrary to the effect of Cr, which stabilizes the α-phase. The thermal stability of alloys for metal cutting application is crucial for their use. Previous studies on another alloy system, Cr-Zr-O, had shown solid solution, for Cr-rich compositions in that material system, in the sought corundum structure. The thermal stability of α-Cr0.28Zr0.10O0.61 coating deposited by reactive radio frequency (RF)-magnetron sputtering at 500 °C was therefore investigated here after annealing in vacuum 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. Further in situ synchrotron XRD annealing studies on the α-Cr0.28Zr0.10O0.61 coating in air and in vacuum showed increased stability for the air annealed sample up to at least 975 °C, accompanied with a slight increase in ex-situ measured nanohardness. The onset temperature for formation of tetragonal ZrO2 was similar to that for isothermally vacuum annealing. The synchrotron-vacuum annealed coating again decomposed into bcc-Cr and t-ZrO2, with an addition of monoclinic–ZrO2 due to grain growth. The stabilization of the room temperature metastable tetragonal ZrO2 phase, due to surface energy effects present with small grains sizes, 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 pseudobinary oxide system also opens up design routes for pseudobinary oxides with tunable microstructural and mechanical properties.
Author: JJ. McNally
Publisher:
ISBN:
Category : Coatings
Languages : en
Pages : 9
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Book Description
We have investigated the properties of Al2O3/SiO2 and Ta2O5/SiO2 anti-reflection coatings which have been fabricated using ion-assisted deposition (IAD) techniques. The coatings were deposited with simultaneous 02+ bombardment during film growth. Preliminary laser damage results are presented. We describe the importance of oxygen-ion energy and flux in applying IAD to dielectric materials. Results illustrating increased values of film refractive index, reduction in optical scatter and improved environmental stability are reported.
Author: GJ. Exarhos
Publisher:
ISBN:
Category : Laser beams
Languages : en
Pages : 1
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Book Description
Ion assisted deposition (IAD) involves bombarding a thin film with low energy ions (Ei
Author: James D. Targove
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Author: JJ. McNally
Publisher:
ISBN:
Category : Laser-damage
Languages : en
Pages : 9
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Book Description
Properties of oxide thin films deposited using oxygen-ion assisted deposition (IAD) were studied. Previously, we reported on the properties of Al2O3/SiO2 and Ta2O5/SiO2 anti-reflection coatings fabricated using IAD. In this report we present results illustrating the effects of ion bombardment during the deposition of single-layer films of Ta2O5, Al2O3 and SiO2. The optical constants and stress measurements of these films are reported. Oxygen ion bombardment during deposition produced Ta2O5 and Al2O3 coatings with larger values of refractive index (n). No increase in n was observed for IAD SiO2. Laser damage results at 351 nm for Al2O3/SiO2 and Ta2O5/SiO2 AR coatings are presented. It appears that the IAD coatings did not have higher damage threshold values than the coatings deposited with no ion bombardment. A number of coatings were exposed to fluorine gas tests. The results from these tests are reported.
