Effect of multiple impacts on high velocity pressed iron powder

A review on high velocity compaction mechanism of powder metallurgy

“…Suppression times Under the same impact energy, the density of iron and copper powder compacts is secondary compaction, single compaction and tertiary compaction from high to low. 21 Stress wave Stress wave acting on metal powder leads to the destruction of compound layer on particle surface. Severe friction on the surface causes the surface near the particle to give priority to heating and partial melting or solid-state flow bonding, Compaction velocity When compaction velocity is low, the velocity increases slightly, and the density of the green body increases rapidly.…”

“…(5) Due to the lack of high velocity compaction equipment, most colleges and universities and enterprises do not have the equipment and environmental conditions for high velocity compaction experiments or large-scale production. Only a few such as Beijing University of Science and Technology, 44 South China University of Technology 45 have experimental or production conditions, and it lacks high velocity compaction equipment and technology patents with independent intellectual property rights in China.…”

“…When the impact kinetic energy is constant, if the hammer mass, powder material, particle deformation and initial loose density are different, the impact stress and action time in different States will be produced, and the corresponding compact density will be completely different 21 The compaction effect of a hammer with certain kinetic energy can be seen as the superposition of smaller impact force and longer stroke, or the superposition of larger impact force and shorter stroke.…”

A Numerical Study of Aeolian Sand Particle Flow Incorporating Granular Pseudofluid Optimization and Large Eddy Simulation

“…The kinetic stress is based on the kinetic theory of granular flow and the frictional stress is simply reduced to the Coulomb relationship [26,27]. Consequently, the particle pressure and the shear viscosity are formulated as shown in Equation 3: 3) where e = 0.7 is the interparticle collision restitution coefficient; θ and g 0 are the granular pseudotemperature and the radial distribution function, respectively [28]; F r = 0.05 kg/(m•s 2 ), n = 2.0 and r = 5.0 are the empirical material constants [29]; α s,.max = 0.60 and α s,min = 0.10 are the maximum and the minimum values of the sand volume fraction, respectively [30]. θ = c s 2 /3 is a measure of the single particle velocity fluctuation at a small scale, where c s is the fluctuating velocity [31].…”

Micro-ultrasonic powder moulding of Sn–Bi/Cu composite micro parts in semisolid form

“…HVC is based on a moulding technique under a high-speed peak pressure. Wang et al (2009) used pure iron powder with 0.5 wt.% zinc stearate as the raw material to investigate the effects of HVC forming on the density, flexural strength and stress wave of a green body. The results showed that under identical total impact energies, the green body pressed by double impact had the highest density and bending strength, whereas that of compacts prepared by triple impact was the lowest.…”