In situ studies of aluminium oxide break-up at flux-free brazing conditions

Reference number 2018-04410
Funding from Vinnova SEK 499 000
Project duration November 2018 - November 2019
Status Ongoing
Venture Research infrastructure - utilisation and collaboration
Call Research infrastructure - utilisation and collaboration: Industrial pilot projects for neutron and photon experiments at large scale research infrastructures

Purpose and goal

Brazing of aluminium is a process that require flux to break up the naturally formed oxide on the aluminium surface. An environmental-friendly alternative is to use magnesium as an oxide break-up agent. The mechanisms behind the magnesium-assisted oxide break-up are, however, unclear and it is therefore difficult to find a stable flux-free brazing process. Gränges Sweden will therefore, together with Linköping university and Uppsala Synchrotronix, study the magnesium assisted oxide break-up process in operando using spectroscopic techniques at MAX IV.

Expected results and effects

Brazing of aluminium occurs mainly in controlled atmosphere where a fluoride-based flux breaks up the protective surface oxide in an early stage of the brazing process. Using magnesium as an oxide break-up agent enables a significantly more environment-friendly alternative where flux is not needed. The role of magnesium will be investigated through spectroscopic operando techniques, which will provide a better understanding of the flux-free brazing processes. Further work at Gränges will continue aiming at more environmentally friendly brazing of aluminium components.

Planned approach and implementation

Materials samples will be prepared and characterized by Gränges in Finspång. Spectroscopic measurements through XPS, XAS, and RIXS will be performed at MAX IV to gain chemical-state information about the mechanisms involved in the magnesium-assisted oxygen break up. The XPS studies will be performed in realistic brazing conditions, i.e. at high temperatures and gaseous atmospheres, while XAS and RIXS proceeds after interrupted processes. While XPS is surface sensitive, XAS (fluorescence-based) and RIXS probe deeper into the materials for complementary information.

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