Scientific and technological objectives in the area of joining of materials
for the transportation and energy industry have been the motivation for the
development of a new joining method.For integral structures in aircraft a
joining technology that is capable of joining metals which differ
significantly in melting temperature and strength like titanium and
aluminium is needed. In composite structures thin aluminium foils should be
welded without degrading or destroying the intermediate polymers. Joining
at low temperatures without mixing the joining partners is therefore
desirable. Most of today’s joining methods do not fulfil these
requirements. In the course of this thesis a new joining technology named
HFDB (Hybrid Friction Diffusion Bonding) has been developed. With this new
joining technology the joining of similar and dissimilar materials of
varying thicknesses (AA 2024 ; Al 7075; Al 99,5; 1.4301; Ti6Al4V; AZ31 in
0,1 mm up to 0,7 mm) as well as the manufacturing of a prototype for a
heat-exchanger has been investigated. In addition a clamping set-up for the
thin sheets has been developed and tested to avoid buckling during joining.
Characterisation of the new bonding method has been established by means of
metallographic procedures as well as mechanical testing (REM, µCT,
Nanoindenter, EDX, peel- and shear tensile tests, optical
microscopy).Results of EDX as well as nano-indentation show a metallic
joint in Aluminium / Aluminium as well as Aluminium / Titanium joints.A
comparison of HFDB and DB results of the mechanical characterisation show
comparable peel results at a significant lower heat input and processing
time for HFDB.µCT results show no vertical mixing of the materials across
the bonding line. Only horizontal movement of the marker material can be
observed. A micro structural investigation in combination with an
analytical comparison shows a diffusion dominated joining
mechanism.Furthermore the energy input and the bonding mechanism of the new
joining process has been investigated by comparing experimental and
analytical data.DB (Diffusion Bonding) has been used as a basis to
correlate as well as verify the conclusions and further understand the
diffusion based bonding mechanism of the new process.