Explosive Compaction of powders, principle and prospects

Abstract

The explosive compaction method consisting of a cylindrical container surrounded by a proper type and amount of explosive is an inexpensive method to achieve high densities close to theoretical density. The explosive's parameters have to be adjusted to the type of the powder to be compacted. The required explosive's pressure is linearly related to the Vickers hardness of the metal powder particles. If higher pressures are applied, an “explosive liquid phase sinter” ‐ process can be achieved, allowing the welding of individual particles. The residual properties of the material are characterized by a high defect structure and by dislocation densities and subgrain sizes comparable to those after heavy plastic deformation. The same is true of compacted ceramic powders. Enhanced sinter reactivity, chemical and catalytic reactivity may be the result of high values of stored energy observed in the ceramic materials, shock wave treated under conditions of explosive compaction. The properties of materials produced by shock‐wave synthesis or by shock‐wave transformation are also determined by a high‐density defect structure.

Investigation of the Structure and Distribution of Chemical Elements between the Phases of Hard Alloys of the Cr₃C₂-Ti System, Obtained at Various Modes of Explosive Compaction

“…Explosive pressing was carried out using a scheme of loading with a flat, normally falling detonation wave through an intermediate steel gasket separating the detonation products from the powder [5]. The ammonium nitrate explosive with a 4200 m/s detonation speed was used.…”

CMT Additive Manufacturing Parameters Defining Aluminium Alloy Object Geometry and Mechanical Properties

“…However, serious disadvantages are present, like relatively high investment and maintenance prices [ 7 ]. In addition, handling highly explosive metal powders requires special attention and safety precautions [ 8 ]. In Table 1 a detailed comparison is made using data and calculation formulas of Laureijs et al [ 7 ].…”

Thermally Activated Jamming in Ultrasonic Powder Compaction

“…These parameters correspond to ≈10 4 oscillation cycles, macroscopic shear strain rates of ≈10 3 s −1 , and cumulative plastic shear strains of ≈10 3 . Such high strain rates and deviatoric strains are not encountered in standard compaction processes used in powder metallurgy, which tend to be much slower and involve relatively low deviatoric stress and strain components (notable exceptions to this generalization include roll compaction [ 5,6 ] and explosive compaction [ 7–9 ] ). As a result, the underlying assumptions of conventional powder metallurgy frameworks often conflict with the behaviors expected in ultrasonic compaction.…”