Arc spraying involves feeding two wire electrodes into a spray gun. An electric arc is struck across the electrode tips within the gun to give molten droplets that are propelled by compressed gas (usually air or an inert gas such asargon) on to the substrate material. The molten droplets, or particles, can reach velocities up to 150ms -1. Arc spraying can be undertaken in air or using an inert or reactive gas shield. A key feature of arc spraying is its high deposition rate. The principal factors controlling spray rate are the current rating ofthe system and the wire feed rate necessary to use this current. As a consequence commercially available equipment follows the general principles described above, with possible differences in power supply currents and the ability touse inert gases as the atomising or shielding gases.
