Effect of nozzle configuration, gas pressure, and gas type on coating properties in wire arc spray

Wire are spraying is a coating process in which minor modifications of the configuration and spray parameters can have a strong impact on coating char acteristics. A study on the effects of the fluid dynamics of the atomizing gas on the coating properties is presented. Different types of nozzles, shr ouds, and gases have been used to provide various flow velocities and react ive environments in the metal atomization region. The effects on particle v elocity, coating density, composition, and interface characteristics betwee n the coating and the substrate have been evaluated. It is clear that highe r gas velocities improve practically all coating properties, but also incre ase oxide content in the coating. However, the oxidation can be drastically reduced if nonoxidizing gases are used for atomization in combination with a shroud. A discussion on the physical effects contributing to the observe d adhesion improvements and interfacial properties is provided.