Enhancement of high-temperature oxidation resistance and thermal stability of hard and optically transparent Hf‒B‒Si‒C‒N films by Y or Ho addition

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F49777513%3A23520%2F21%3A43962658" target="_blank" >RIV/49777513:23520/21:43962658 - isvavai.cz</a>

Alternative codes found

RIV/49777513:23640/21:43962658

Result on the web

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DOI - Digital Object Identifier

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Result language

angličtina

Original language name

Enhancement of high-temperature oxidation resistance and thermal stability of hard and optically transparent Hf‒B‒Si‒C‒N films by Y or Ho addition

Original language description

Multielement ceramic coatings are appropriate candidates for high-temperature applications due to their excellent behavior at temperatures exceeding 1000 °C. When a very high oxidation resistance is combined with the thermal stability of a high optical transparency, they can be considered for high-temperature passive protection of optical and optoelectronic devices. Therefore, this work focuses on a systematic investigation of high-temperature behavior of Hf–B–Si–Y/Ho–C–N films with a high hardness and optical transparency The films were deposited using pulsed dc magnetron co-sputtering of a target consisting of a B4C plate overlapped by Hf, Si and Y or Ho stripes with the fixed 15% Hf + 50% Si + 5% Hf/Y/Ho fractions in the target erosion area in an argon-nitrogen gas mixture (25% N2 fraction) onto Si and SiC substrates heated to 450 °C and held at a floating potential. The oxidation resistance of the films in air (up to 1500 °C) and the thermal stability of their structure in inert gases (up to 1600 °C) were investigated by high-resolution thermogravimetry and differential scanning calorimetry. Other analytical techniques were employed to characterize changes in the structure and properties of the films after their heat-treatment. All as-deposited films were amorphous, highly optically transparent, electrically non-conductive and possessed a sufficiently high hardness (around 22 GPa) and low compressive stress (&lt; –1.5 GPa). Very low mass changes (around 25 µg/cm^2) were detected upon heating to 1500 °C in air. Hf6B12Si29Y2C2N45 and Hf5B13Si25Ho3C2N48 films exhibited a lower thickness of a protective surface oxide layer (194 nm and 202 nm, respectively) compared to a Hf6B10Si38C2N44 film (243 nm). The oxide layer was composed of HfO2 nanocrystallites of different structures embedded in an amorphous matrix. Heating of the films in helium up to 1100 °C resulted in an increase of their hardness while retaining optical transparency. In case of the Hf6B12Si29Y2C2N45 film, the hardness increased even up to 1300 °C and the film remained optically transparent up to 1400 °C. It was also found that the transformation of the amorphous structure to the crystalline one starts in all cases around 1400 °C at the film/substrate interface. The lowest thickness of the crystallizing zone was observed for the Hf6B12Si29Y2C2N45 film confirming its highest thermal stability among the films investigated. Multielement Hf-B-Si-Y/Ho-C-N films were proven to have a high potential to be good candidates as high-temperature protective coatings for optical and optoelectronic devices.

Czech name

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Czech description

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Type

O - Miscellaneous

CEP classification

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OECD FORD branch

20506 - Coating and films

Project

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Continuities

S - Specificky vyzkum na vysokych skolach

Publication year

2021

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů