The University of Liverpool Pioneers the Development of a
Novel Approach to Metallic Additive Manufacturing
Cold Gas Dynamic Spraying is an emerging metal deposition process, first
developed in the former Soviet Union during the late 1980’s. A stream of
process gas, at or near room temperature and containing particles of the
material to be deposited, is passed through a nozzle designed to cause
compression and subsequent controlled expansion. This results in
acceleration of the particles to velocities in excess of 1000 m/s, providing
them with sufficient kinetic energy to plastically deform and weld to any
target surface. A significant global research effort is now underway to
further develop this technique as a surface coating tool to compete with
established processes such as HVOF and plasma spraying.
The Division of Manufacturing Engineering at the University of Liverpool
(UK) has recently been awarded £900k ($1.3m) by the Engineering & Physical
Sciences Research Council to fund the first three years of an 8 year
development programme, designed to further develop the CGDS process and
apply it in the additive manufacture of near net shape metallic objects.
This application has been termed Cold Gas Dynamic Manufacturing and is
expected to compete with laser based additive manufacturing processes such
as LENSTM. The programme will be carried out in conjunction with BOC Gases,
BAE SYSTEMS and the Defence Evaluation & Research Agency.
Key characteristics of the CGDM approach include:
a.. High material density
a.. Low residual stress
a.. Minimal heat input to substrate
a.. High deposition efficiency
a.. Low oxide content
a.. Good surface finish
a.. Highly wrought microstructure
a.. Phase and compositional stability
a.. Minimal grain growth – possible to maintain nano-crystalline
structure
a.. Low capital and operating costs (compared with laser)
These process characteristics will allow a broad range of material systems
to be deposited more quickly, with greater material integrity and better
dimensional stability than is currently achievable with laser based systems.
Further, this “non melt” approach could potentially provide a solution to
material compatibility problems associated with the manufacture of graded
alloy structures.
In addition to additive manufacturing technology, key application areas are
expected to include the repair and refurbishment of worn or damaged
components and mould tools. To reflect these potential application areas
the principal material systems under investigation during this work are
aluminium & titanium alloys, nickel based superalloys and tool steels.
Additional investigations will study the deposition of MMCs and the
consolidation of nano-structured powders.
As part of our development programme we are establishing a Special Interest
Group, comprising manufacturers from a range of industrial sectors who could
potentially benefit from this new technology. Members of this group will be
kept up to date with our progress and will have the opportunity to steer our
research toward real industrial applications. If you would like further
information on the Special Interest Group or any other aspect of this
research programme then please contact the Project Manager (preferably by
email):
Dr Matt Murphy
Senior Research Fellow
Research into Advanced Technology Group
Manufacturing Division
Department of Engineering
University of Liverpool
Ashton Building, Brownlow Hill
Liverpool L69 3GH
United Kingdom
Tel: +44 (0) 151 794 4905
Email: cgdm@liv.ac.uk
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