Laser pre-treatment of aluminum - An investigation of the adhesive bonding after surface modification
Typ
Examensarbete för masterexamen
Master's Thesis
Master's Thesis
Program
Materials chemistry (MPMCN), MSc
Publicerad
2024
Författare
Sellén, Hannes
Björkman, Wilma
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
This project focused on the laser pre-treatment of aluminum sheet and extruded
aluminum within the 6xxx-series, applied on battery pack applications at Volvo Cars.
Laser parameters were evaluated by surface characterization and lap shear testing,
correlating adhesion to surface properties. Four different adhesives were investigated
together with three different laser parameters. The results were compared towards
untreated surfaces as well as plasma treated surfaces.
Results showed that laser effectively cleaned the treated surfaces, and that it altered
the surface structure. Clean and structured surfaces was shown to improve adhesion
by increasing the strength, and giving a more favorable failure mode of the adhesives.
After tropical ageing, three of the adhesives increased in strength due to post curing,
whereas one degraded below the desired strength.
XPS measurements showed that laser treatment induced thermal oxide growth, and
confirmed cleanliness results, both enabling stronger bonding. The oxide layer
thickness of untreated aluminum was 3–4 nm, while laser treated surfaces showed
oxide thickness of 25–55 nm. SEM-EDX was not applicable to study the oxide layers
due to insufficient resolution.
Laser parameter T2 showed the greatest potential, however new sets of laser
parameters need to be studied, with a particular emphasis on a high %overlap scan.
Beskrivning
Ämne/nyckelord
Structural adhesives , Aluminum , Laser pre-treatment , Lap shear testing , Surface characterization