The latter two coatings were formed
using a PCSe1000 system (Plasma Giken Co. Ltd., Japan) using
larger Cu powders (40e50 mm) and two carrier gases; He to bond
and coat the initial ~ 100 mm, followed by nitrogen (N2) to develop
the final coating thickness. It has been demonstrated that the use of
He leads to better coating-substrate bonding [15], while the use of
the less-expensive N2 improves cost-efficiency. Measured average
powder velocities, during application of the N2 layer were
695 ± 170 m/s and 637 ± 137 m/s for cold spray temperature and
pressure conditions of n800 C, 5 MPa and n600 C, 5 MPa, respectively
[21]. Cold spray velocities were not measured for the n300 C, 4 MPa
condition. The effect of annealing was investigated by applying a
4 h, 400 C, post-coating heating using an Argon (Ar) cover gas.