Papers by Keyword: Explosive Compaction

Abstract: The research on the explosive compaction of reactive powders is a hot issue. In this work, unreacted Ti-Si block with high compactness has been successfully fabricated under explosive-driven compaction process. The precursors of Ti-Si powder with different stoichiometric ratios undergo pre-compaction shaping by hydraulic press and then shock loading treatment by using low-detonation-velocity explosives of varying loading conditions. The results show that the chemical reaction between Ti and Si powders are partly initiated even under low detonation pressures, indicating extremely low reaction threshold in the Ti-Si system. Meanwhile, optimal experimental conditions are displayed as the initial pressing compactness degree of 61%, and shock pressure of 11GPa. A compactness of 97% is achieved in the synthesized Ti-Si block with the lowest reactivity.

Abstract: In this study, aluminum based composites with stainless steel wire-mesh as reinforcement is fabricated by explosive compaction technique. Stacks containing four layers of alternatively positioned aluminum sheets and stainless steel wire-meshes are explosively compacted at varied explosive masses and the results are reported. Microstructure of explosive compacted aluminum composite reveal a smooth interface at lower explosive mass, while formation of reacted products are observed at higher energetic conditions. Though the hardness of the post clad composite is higher than pre-clad materials, the maximum hardness is observed at the first interface.

Abstract: This paper uses the explosive compaction method to produce Cu-matrix composites. The powders of Cu and WC were prepared by high-energy ball-milling. Experiments have been performed to compact powders of Cu and WC using cylindrical configuration. The results showed that the detonation velocity had effects on the density of the compacts. The effect has been detailedly studied. The compacted WC/Cu composites have been subjected to hot rolling. The microstructure, hardness, electrical conductivity and softening temperature of the composites have also been mentioned.

Abstract: The metallic glass particles reinforced aluminum matrix composites without obvious defects were obtained successfully by explosive compaction of mixed powders. The quasi-static compressive mechanical properties of the composites with the reinforcement matrix mass fraction 10%, 15% and 20% respectively were researched recur to universal testing machine of Instron 3367 and self-consistent theory. Finally, reinforcement mechanism of the metallic glass particles on the matrix was analyzed by numerical simulation recur to LS-DYNA program. The results show that the mechanical properties obtained by self-consistent theory are well accord with the experimental results; compared with pure aluminum, the yield stress of the composites with metallic glass particles reinforcement of the mass fraction 20% enhances 46.8 percent; the main reinforcement mechanism is the amorphous particles can undertake higher loading, the combined quality of the reinforcement particles with the matrix and the distribute uniformity of the reinforcement particles are important factors which will affect the reinforcement effects.

Abstract: Steel-bonded cemented carbide sheet considered as cladding was successfully bonded with carbon steel plate by a technological combination of powder explosive compaction and liquid sintering. The microstructural interface between steel-bonded cemented carbide cladding and carbon steel plate was characterized by SEM, EDS analysis and hardness testing. The results showed that the gradient distributions of the elements Fe, C and W were found in the normal direction of the interface. The element W permeated about 100μm in depth through the side of carbon steel. The improved hardness of about 600～700HV of cladding was attributed to multiple carbides.

Abstract: The nanocrystalline WC-10Co hard alloys with high density (97.5% T.D.) have been prepared by use of mixing and explosion compaction technology and the average crystalline size is less than 100 nm. The microstructure analysis shows that, the particle size of the mixing powders is less than 200nm and that of the explosive compaction billet is even fine about 100nm. If explosive speed of any explosive is either big or small, we can not get density billets because the initial density of mixing powders is too low. If using secondary explosive compaction process (low-speed explosive Ammonium Nitrate 280g + high-speed explosive TNT 200g), we can get about 97% (maximum density of 97.58%) of the theory density of bulk nanocrystalline WC-10Co hard alloys.

Abstract: In this paper the metallic glass particles reinforced aluminium matrix composites without obvious defects were obtained successfully by explosive compaction of mixed powders. The mass fraction of the amorphous phase is 10%, 15% and 20% respectively in the specimens. The scaning electric microscope micrographs of the composites show that the metallic glass particles are uniformly distributed in the matrix. The x-ray diffraction and differential thermal analysis of the composite specimens show that the amorphous phase is maintained in the composites without crystallization during the compaction. Finally the influences of macro-temperature rise and micro-heat transfer on the crystallization were analyzed.

Abstract: Zinc sulfide is inorganic material for electroluminescent applications. This work examines the possibility of obtaining good luminescent properties of the zinc sulfide mixture by double implosion experiment at elevated temperature.

Abstract: High Tc MgB2 superconductors were fabricated using the ex-situ and in-situ powder in tube (PIT) technique. During treatment, the precursor materials were shock consolidated under high strain-rates using PETN as the explosive medium. After compaction, the superconducting properties of the steel-sheathed MgB2 samples were examined by means of magnetization measurements using a SQUID magnetometer. Bean’s critical state model was applied to investigate the critical current density characteristics of the samples at fields up to 5T. The superconducting transition temperature of the specimens was determined by examining the material temperature dependence of magnetisation in zero field cooled (ZFC) and field cooled (FC) states. An assessment of the explosive compaction technique was carried out by simulating the procedure using the LS-DYNA explicit finite element code. The sample is modelled as a porous soil-like material with a customised yield surface. The numerically estimated final product dimensions, porosity and hardness are compared to the experimental results; furthermore, the numerically obtained pressure, temperature and strain rate profiles are used to assess the efficiency of the compaction process for different explosive quantities and powder compositions.

Abstract: WC steel bond hard alloy powders were compacted by explosive compaction on the surface of carbon steel, then the composite layer was prepared by liquid-phase sintering in vacuum. The phases and microstructures of the interface of composite layer were observed by SEM, EDS, TEM. Result showed that the thickness of the interface was about 30μm, and the elements of W, Cr, C were detected in the interface. The structures of the interface were pearlites which were composed of the layered tablets of M23C6 and ferrite. The layered tablets were perpendicular to the interface. The structures were the pearlites and ferrites in the side of the carbon steel near the interface but globular carbides, whose phase is W3Fe3C, and pearlites in side of steel bond hard alloy. During sintering at 1623K, all elements of metal-powder and C, V, which were decomposed by hard-phase, interdiffused in the interface. The multiple carbides were found in the interface and steel bond hard alloy. As a result, the powders formed into compact alloy by itself, and at the same time there was a good metallurgical bonding between the carbon steel and the hard alloy.