Abstract
In a flattening behavior of the thermal sprayed powder particles, we have pointed out that the flattening pattern change to a disk type from a splash type due to once heating of the substrate to some elevated temperatures. This drastic change may be associated with the change in the wetting of the substrate by the particles. However, the wetting mechanism change by the substrate heating has not been clearly understood. In this study, substrate surface roughness change due to the heating was precisely investigated by AFM and wetting behavior change was observed by a sessile drop method. The results obtained indicated that an increasing of the substrate surface roughness due to heating induced the improvement in the wetting of the substrate by the droplet. Hence, the substrate heating may bring about the change of the wetting condition essentially, and the change in the flattening pattern can be explained by this hypothesis.
