A novel assembly used for hot-shock consolidation

A novel assembly was developed for hot-shock consolidations of powders. The under-water shock wave and the high-temperature preheating, which are considered as two effective ways to eliminate cracks, were combined in the system. In this work, a SHS (self-propagating high-temperature synthesis) reaction mixture was used as chemical furnace to preheat the precursor powder, and the water column as well as the explosive attached to it was detached from the furnace by a solenoid valve fixed on the slide guide. When the precursor powders were preheated to the designed temperature, the solenoid valve was switched on, and then the water column and the explosive slid down along the slide guide by gravity. At the moment the water container contacted with the lower part, the explosive was initiated, and the generated shock wave propagated through the water column to compact the powders. So the explosive and water column can be kept cool during the preheating process. The intensity of shock wave loading can be adjusted by changing the heights of water column. And the preheating temperature is controlled in the range of 700 similar to 1300 degrees C by changing the mass of the SHS mixture. In this work, pure tungsten powders and tungsten-copper mixture were separately compacted using this new assembly. The pure tungsten powder with a grain size of 2 mu m were compacted to high density (96 % T. D.) at 1300 degrees C, and the 90W-10Cu (wt pct) mixtures were compacted to 95.3 % T. D. at 970 degrees C. The results showed that both samples were free of cracks. The consolidated specimens were then characterized using SEM analysis and micro-hardness testing.