Abstract

The detonation gun (D-Gun) coating technology which results in coatings with outstanding properties has found extensive applications especially in the aerospace and engineering industry. Though the D-Gun process has been in use for the last 30 years or so, the basic mechanisms which lead to such an outstanding combinations of properties is not yet fully understood. This has been primarily due to the fact that the coating property ultimately depends on the combination of powder particle temperature and velocity at the time of its impact on the substrate to be coated and so far measurement of these parameters has not been possible. As a result, indirect correlations between D-Gun variables like fuel gas to oxygen ratio, powder feed rate, firing frequency and working distance and coating properties have been developed but without the knowledge base of how these D-Gun variables affect the powder particle temperature and velocity. An in-flight particle diagnostic sensing system has been recently installed in our laboratory and this system allows for the simultaneous measurement of particle velocity and temperature. In view of the above, a major programme has been launched to study the effect of particle velocity and temperature on the coating properties (like coating hardness, porosity, bond strength, XRD etc.) for a wide range of coatings. The preliminary results from the above investigation, pertaining to Cr3C2-25NiCr coatings obtained using D-Gun, will be presented and discussed in this paper.

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