1. Introduction
Electric arc spraying involves the projection of hot liquid
metal droplets onto a substrate and is used to deposit a
variety of protective coatings for anti-corrosion, wear resistance
and other applications [1]. These coatings are usually
less than 1mm thick and have a lamellar microstructure in
cross-section arising from an interleaving network of discrete
droplet splats.
Electric arc spraying has also been used to make thick,
free-standing Zn tools and moulds by spraying onto a 3D
pattern. The sprayed shell is removed from the pattern
after spraying, trimmed and backed to produce a tooling
insert suitable for prototype tooling [2–7]. Until recently,
the manufacture of large sprayed steel shells for production
applications has been impossible, because of excessive shell
warping and distortion during manufacture and subsequent
cooling. However, by careful control of the depositing shell
surface temperature [8], steel phase changes can be manipulated
to minimise thermal stresses [9] and electric arc
spraying has been demonstrated for the rapid manufacture