Low-temperature emissivity of thin Al2O3 layers deposited on copper substrate

0552663 - ÚPT 2022 RIV CZ eng C - Conference Paper (international conference)
Frolec, Jiří - Králík, Tomáš - Nyman, L. - Pudas, M. - Kallio, E.
Low-temperature emissivity of thin Al2O3 layers deposited on copper substrate.
Cryogenics 2021 online. The 16th Cryogenics 2021 IIR International Conference, October 5-7, 2021. Proceedings. Praha: ICCEX, 2021, s. 113-118. ISBN 978-2-36215-047-0. ISSN 0151-1637.
[Cryogenics 2021. IIR International Conference /16./. online (CZ), 05.10.2021-07.10.2021]
R&D Projects: GA MŠMT(CZ) LO1212; GA MŠMT ED0017/01/01
Institutional support: RVO:68081731
Keywords : heat transfer * thermal radiation * cryogenics * surface finish
OECD category: Thermodynamics
https://iifiir.org/fr/fridoc/emissivite-a-basse-temperature-de-couches-minces-144402

Copper is commonly used in cryogenic systems due to its high thermal and electrical conductivity along with excellent solderability. Very low emissivity values of copper surface also reduce in cryogenic systems heat load transferred by thermal radiation. These values may be, however, enhanced by a prospective coating, deposited usually in order to prevent chemical changes on highly reactive copper surface. This paper focuses on protective layers of Al2O3 with thicknesses up to 28 nm, deposited on polished copper. We measured total hemispherical emissivity at cryogenic temperatures before and after the coating process. Contribution of Al2O3 layer to original copper emissivity increased with rising temperature of the layer and with the layer thickness. However, emissivity of the coated copper stayed below 2%, allowing usage of the coated copper in systems where low heat load by thermal radiation is needed. Preliminary tests with oxygen plasma shows that deposited layers can effectively protect the copper surface against oxidation and maintain the original thermal-radiative properties.
Permanent Link: http://hdl.handle.net/11104/0328045