Surface Modification of Metallic Materials by Shock Coating

本研究利用冲击能在各种金属表面进行硬质涂层，这在国际上尚属首次。该工艺被称为冲击涂层或爆炸涂层。爆炸涂层的原理如下。炸药的爆炸加速了涂层粉末与基体金属的碰撞。所得涂层具有高度致密性，并通过机械锚定效应与金属基体具有相当的结合强度。本文采用了轴对称和新近发展的爆炸包覆技术。后一种技术利用水下冲击波。涂层材料为TiAl金属间化合物、自熔喷涂粉末。采用高能球磨法制备了金属陶瓷复合粉末.实验中采用纯铜和奥氏体不锈钢作为金属基底。(1)采用爆速为2600 m/s的炸药进行轴对称爆炸涂层，在奥氏体不锈钢棒上获得了致密的TiAl和自熔喷涂粉末的无裂纹涂层。(2)水下冲击波爆炸包覆所用炸药的爆速为6900 m/s。在无裂纹的铜板上制备了高致密的TiAl和TiAl/Ti复合粉末涂层。在这两种情况下，层的维氏硬度为400至600 DPN。(3)通过热循环进行上述涂层的热冲击试验。所有的层在100次热循环后仍然完好。冲击涂层后的热处理是有效的热冲击性能的发展。

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.