Preparation of nano-Al2O3 dispersion strengthened coating via coating-substrate co-sintering and underwater shock wave compaction

This paper aims at developing a process technology to fabricate an aluminum dispersion strengthened coating on a copper substrate. First, nanostructured Cu–Al2O3 powder was prepared by hydrogen-reduction of mechanical alloyed Cu and Al2O3 mixed powders. Low-density coating was then achieved through die pressing and pre-co sintering. Finally, dynamic consolidation by underwater shock wave was used to densify the Cu–Al2O3 sintering body, ensuring strong bonding between the coating and substrate. The compressing process was simulated using the commercially available package LS-DYNA. Numerical simulation gave deformation of the coating layer and pressure distribution during the compressing process. Microstructure characteristics indicate that the coating layer has a uniform and fine-grained composite structure and a strong surface bonding between coating layer and copper substrate. The fracture surface, analyzed by SEM, showed intergranular fracturing. Measurement of hardness showed a high hardness value, indicating sound mechanical properties of the coating layer. This method has thus been proven feasible for preparation of aluminum dispersion strengthened coating on copper substrate.