Surface Modification of Metallic Materials by Shock Coating

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Coating of the hard materials on the various metals has been made by using shock energy in the present study, which is the first attempt in the world. The process was named the shock coating or the explosive coating. The principle of the explosive coating is as follows. The coating powder was accelerated and collided with base metal by detonation of explosive. The obtained coating layer was highly densified and it also had substantial bonding strength with metal substrate by mechanical anchoring effect. The axisymmetric and the newly developed explosive coating techniques were applied in the present study. Underwater-shock wave was utilized in the latter technique. The coating materials used were TiAl intermetallic compound, self-smelting spray powders. Metal and ceramics composite powders treatedly high energy ball mill were also used. Metal substratum used were pure copper and austenitic stainless steel.The following conclusions were led.(1) In the case of axisymmetric explosive coating technique using explosive with detonation velocity of 26OOm/s, the coating layer of highly densified TiAl and self-smelting spray powders without cracks was completed on austenitic stainless steel rod.(2) Detonation velocity of the explosive used in the explosive coating using underwater-shock wave was 69OOm/s. Highly densified coating layer of TiAl and TiAl/Ti composite powders was produced on copper plate without crack. Vickers hardness of the layer was 400 to 60ODPN in the both cases.(3) Thermal shock test of the coating layers described above was carried out by thermal cycling. All the layers were still sound after 100 thermal cycles. Heat treatments after shock coating were effective for developments of the thermal shock properties.