The lamellar structure of a detonation gun sprayed Al₂O₃ coating

The structural features of a detonation gun sprayed Al₂O₃ coating were examined using a copper electroplating technique. It is revealed that the detonation gun sprayed Al₂O₃ coating has a typical layer structure similar to that of coatings deposited using other thermal spraying processes. Despite having the highest particle velocity of the thermal spraying processes, lamellar bonding at the interfaces between flattened particles in detonation gun sprayed Al₂O₃ coatings is very poor. The mean bonding ratio of bonded interface area to apparent bonding interface for a typical detonation gun Al₂O₃ coating is about 10%, which is less than one-third the value for a typical plasma-sprayed Al₂O₃ coating. However, the high particle velocity results in the formation of a rough surface on the spray splat, which may be effective in enhancing interlocking between flattened particles.