Cold-spraying coupled to nano-pulsed Nd-YaG laser surface pre-treatment
; Christoulis, D. K.
; Guetta, S.
; Irissou, E.
; Guipont, V.
; Berger, M. H.
; Jeandin, M.
; Legoux, J.-G
; Moreau, C.
; Costil, S.
; Boustie, M.
; Ichikawa, Y.
NRC Industrial Materials Institute; National Research Council Canada
Journal of Thermal Spray Technology
Adhesion; Aluminum; Bond strength; cold-spray; LASAT; Pulsed laser ablation; substrate pre-treatment
NRC INDUSTRIAL MATERIALS INSTITUTE; INSTITUT DES MATÉRIAUX INDUSTRIELS du CNRC
The effect of Al2017 substrate pre-treatment using pulsed laser ablation on adhesion strength of coldsprayed
Al coating is examined. A high energy pulsed laser beam was coupled with a cold-spray gun to
result in laser ablation of the substrate surface a few milliseconds prior to the deposition. The influence of
the laser fluence and repetition rate on substrate surface morphology and physico-chemical properties
are investigated. Coating-substrate interfaces were observed using scanning electron microscopy (SEM)
and transmission electron microscopy (TEM) of thin foils which were prepared using focused ion beam
(FIB). Adhesion strength was evaluated by means of finite element method (FEM) of LAser Shock
Adhesion Tests (LASAT). The results are compared to samples prepared on as received substrate, and
pre-treated by two conventional methods, namely polishing and grit-blasting. It is shown that the coatingsubstrate
interface is significantly improved when pulsed laser ablation is performed at optimized
parameters. No oxide layer was found at the coating-substrate interface on laser ablated sample while
two oxide layers were found on the as-received sample indicating that particle impingement transformed
the native alumina layer in an amorphous Al oxide phase. The observations allow concluding that
bonding of cold spray Al particles on Al2017 substrate requires either the removal of the native oxide
layer or its transformation in an amorphous Al oxide phase.