Conceptual design of a low pressure cold gas dynamic spray (LPCGDS) system
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Date
2010-08-11
Authors
Tinashe, Sanyangare Edwin
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Abstract
Low Pressure Cold Gas Dynamic Spray (LPCGDS) is a coating process that utilises kinetic
energy instead of thermal energy to deposit powder particles (1-50 μm) to substrates at low
temperatures (<400 oC) without going through melting. The deposited coatings provide
improved wear and corrosion protection to underlying surfaces while maintaining the
original phase structure of the particles and minimising oxide formation and residual
stresses associated with conventional thermal spray processes such as flame, arc and
plasma spraying. Bonding occurs when particles impact velocities on the substrates exceed
a certain critical velocity. This critical velocity depends on the propellant gas and particles
characteristics, and the spray system components (gas supply, gas heater, powder feeder
and the supersonic nozzle) design. Consequently, design optimisation of these parameters is
a key to improve the coating quality and reduce the spraying costs.
This study develops an effective and efficient conceptual design of a LPCGDS system.
Requirements for both the overall LPCGDS system and its individual components or subsystems
are established. Components variants that include off-the-shelf, customised and
innovative solutions are generated. An evaluation of these variants is then carried out to
determine components that best performs LPCGDS functions. Subsequently, an optimal
spray system that meets the specifications of the LPCGDS system is assembled from these
best components. Finally, a complete spray set-up that includes the spraying chamber, a gas
and particle recovery system, the data acquisition and control system and, coating quality
measurement equipment is established.