TY - JOUR

T1 - Investigations into Flux-Free Plasma Brazing of Aluminum in a Local XHV-Atmosphere

AU - Klett, Jan

AU - Bongartz, Benedict

AU - Viebranz, Vincent Fabian

AU - Kramer, David

AU - Hao, Chentong

AU - Maier, Hans Jürgen

AU - Hassel, Thomas

N1 - Funding Information: The publication of this article was supported by the TIB Open Access Fund of the Leibniz Universität Hannover and Technische Informationsbibliothek (TIB). The authors gratefully acknowledge financial support from DFG. This research was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)—Project-ID 394563137—SFB 1368.

PY - 2022/11/22

Y1 - 2022/11/22

N2 - As a lightweight construction material, aluminum plays a key role in weight reduction and, thus, sustainability in the transport industry. The brazing of aluminum and its alloys is impeded by the natural passivating oxide layer, which interferes with the brazing process. The presented study investigates the possibility of using a thermal silane-doped argon plasma to reduce this oxide layer in situ and thus eliminating the need to use hazardous chemical fluxes to enable high-quality brazing. Using plasma spectroscopy and an oxygen partial pressure probe, it was shown that a silane-doped argon plasma could significantly reduce the oxygen concentration around the plasma in a thermal plasma brazing process. Oxygen concentrations below 10−16 vol.-% were achieved. Additionally, metallographic analyses showed that the thickness of an artificially produced Al2O3-Layer on top of AlMg1 samples could be substantially reduced by more than 50%. With the oxide layer removed and inhibition of re-oxidation, silane-doped plasma brazing has the potential to become an economically efficient new joining method.

AB - As a lightweight construction material, aluminum plays a key role in weight reduction and, thus, sustainability in the transport industry. The brazing of aluminum and its alloys is impeded by the natural passivating oxide layer, which interferes with the brazing process. The presented study investigates the possibility of using a thermal silane-doped argon plasma to reduce this oxide layer in situ and thus eliminating the need to use hazardous chemical fluxes to enable high-quality brazing. Using plasma spectroscopy and an oxygen partial pressure probe, it was shown that a silane-doped argon plasma could significantly reduce the oxygen concentration around the plasma in a thermal plasma brazing process. Oxygen concentrations below 10−16 vol.-% were achieved. Additionally, metallographic analyses showed that the thickness of an artificially produced Al2O3-Layer on top of AlMg1 samples could be substantially reduced by more than 50%. With the oxide layer removed and inhibition of re-oxidation, silane-doped plasma brazing has the potential to become an economically efficient new joining method.

KW - aluminum

KW - local XHV-atmosphere

KW - oxide layer

KW - plasma brazing

KW - plasma spectroscopy

UR - http://www.scopus.com/inward/record.url?scp=85143772169&partnerID=8YFLogxK

U2 - 10.3390/ma15238292

DO - 10.3390/ma15238292

M3 - Article

AN - SCOPUS:85143772169

VL - 15

JO - MATERIALS

JF - MATERIALS

SN - 1996-1944

IS - 23

M1 - 8292

ER -