Influence of Spray Gun Moving Direction on Properties of Twin Wire Arc Sprayed Hard Material Based Layers

Asymmetric melting behaviour of the electrodes is a process related feature of the twin wire arc spraying (TWAS) technique since the heating of the negative connected wire is different from that of the positive connected wire. The differences in melting behaviour affect the spraying jet on the whole and lead to a spraying cone of particles with different characteristics. To investigate the effect of asymmetry in spraying jet on coating performances coatings were produced with spraying gun moving in different directions, with respect to the electrodes. In order to have the same heating of substrate by means of spraying device for all experimental setups an adjustment of the manipulation system was realized. The coatings were investigated regarding porosity, micro-cracks, hardness and thickness for different wire types. This study will help to understand the effect of the movement of the spraying gun on coating quality. In addition this investigation will give an experimental support to build spraying gun moving strategies to get the best coating quality.