The characteristics of coatings applied by the DEMETON detonation gun process

The characteristics of a detonation spray process, using a Detonation Gun developed at the Institute for Materials Science in Kiev, is described. This process has achieved measured velocities in the vicinity of 1,200 m/sec. It is shown that because the powder particles are carried by a high velocity pressure wave, the amount of heat transferred to the substrate is relatively low. Therefore, this process will be able to apply coatings to some materials that could not be coated by other processes that heated the substrate to the point of distortion or melting. The coatings produced have very high densities, in the range of 1--3% porosity, and excellent adhesion, up to 240 MPa. It is proposed that the high densities and adhesion observed for these coatings result from an anomalously high diffusion rate of atoms at the surface. When the high velocity particles strike the substrate surface, mixing rates are significantly enhanced under the driving force of the highly unstable system. A series of coatings were applied to several substrates using the D-gun process, the HVOF and the plasma spray process. Coatings were examined and compared. The results of this study are presented.