Residual stresses in cold spray Al coatings: The effect of alloying and of process parameters

Al and Al alloy cold spray coatings were deposited on Mg substrates using two different cold spray systems – a Kinetic Metallization system (convergent barrel, sonic nozzle) and a CGT system (convergent-divergent barrel, supersonic nozzle). The residual stress profiles in the coatings were measured...

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Bibliographic Details
Published in:Surface & coatings technology 2012-05, Vol.206 (19-20), p.4249-4255
Main Authors: Spencer, K., Luzin, V., Matthews, N., Zhang, M.-X.
Format: Article
Language:English
Subjects:
Alloying effects
Aluminum
Aluminum base alloys
Applied sciences
Coatings
Cold spray
Cross-disciplinary physics: materials science
rheology
Exact sciences and technology
Internal stress
Kinetic metallization
Materials science
Metallizing
Metals. Metallurgy
Neutron diffraction
Physics
Production techniques
Residual stress
Sprayers
Sprays
Surface treatment
Surface treatments
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Summary:Al and Al alloy cold spray coatings were deposited on Mg substrates using two different cold spray systems – a Kinetic Metallization system (convergent barrel, sonic nozzle) and a CGT system (convergent-divergent barrel, supersonic nozzle). The residual stress profiles in the coatings were measured using neutron diffraction with high spatial resolution. In the first part of the study, the residual stress profile in pure Al coatings was compared when sprayed using the Kinetic Metallization system (using both helium and nitrogen as the driving gas), and with the CGT system using nitrogen gas. In this way the effect of impact velocity and process temperature was studied. In the second part of the study, the residual stress profile was compared in coatings of pure Al, 7075 Al and 6061 Al sprayed using the same process conditions in the CGT system. The residual stress profiles depend more on the alloy content, i.e. intrinsic resistance to plastic deformation, than on the processing conditions, and this is interpreted using a simple model that incorporates the effect of peening stresses in the cold spray process. ► The residual stress in aluminium and aluminium alloy cold spray coatings was measured. ► Coating density and Young's modulus correlate well with impact velocity and pressure. ► The residual stress profiles is largely dominated by the peening process. ► Residual stress depended on thermal effects only at the highest spray temperature examined.
ISSN:0257-8972
1879-3347
DOI:10.1016/j.surfcoat.2012.04.034