scholarly journals Investigating the Shock Compaction Behavior of Brittle Powders

2018 ◽  
Author(s):  
Travis John Voorhees
Keyword(s):  
Compaction Behavior ◽  
Shock Compaction

Shock consolidation of Ni-Ti alloy powder

1986 ◽  
Vol 44 ◽  
pp. 430-431
Author(s):  
Naresh N. Thadhani ◽  
Thad Vreeland ◽  
Thomas J. Ahrens
Keyword(s):  
Alloy Powder ◽  
Amorphous Material ◽  
Ti Alloy ◽  
Two Phase ◽  
Near Surface ◽  
Optical Micrograph ◽  
Shock Compaction ◽  
Powder Particles ◽  
Ti Powder ◽  
Rapidly Solidified

A spherically-shaped, microcrystalline Ni-Ti alloy powder having fairly nonhomogeneous particle size distribution and chemical composition was consolidated with shock input energy of 316 kJ/kg. In the process of consolidation, shock energy is preferentially input at particle surfaces, resulting in melting of near-surface material and interparticle welding. The Ni-Ti powder particles were 2-60 μm in diameter (Fig. 1). About 30-40% of the powder particles were Ni-65wt% and balance were Ni-45wt%Ti (estimated by EMPA).Upon shock compaction, the two phase Ni-Ti powder particles were bonded together by the interparticle melt which rapidly solidified, usually to amorphous material. Fig. 2 is an optical micrograph (in plane of shock) of the consolidated Ni-Ti alloy powder, showing the particles with different etching contrast.

A Hybrid Model to Predict the Gyratory Compaction of Hot Mixed Asphalt

2019 ◽  
Author(s):  
Teng Man
Keyword(s):  
Hybrid Model ◽  
Asphalt Binder ◽  
Asphalt Mixture ◽  
Aggregate Size ◽  
Asphalt Mixtures ◽  
Compaction Process ◽  
Particle Rearrangement ◽  
Compaction Behavior ◽  
Grain Size Distributions ◽  
Gyratory Compaction

The compaction of asphalt mixture is crucial to the mechanical properties and the maintenance of the pavement. However, the mix design, which based on the compaction properties, remains largely on empirical data. We found difficulties to relate the aggregate size distribution and the asphalt binder properties to the compaction behavior in both the field and laboratory compaction of asphalt mixtures. In this paper, we would like to propose a simple hybrid model to predict the compaction of asphalt mixtures. In this model, we divided the compaction process into two mechanisms: (i) visco-plastic deformation of an ordered thickly-coated granular assembly, and (ii) the transition from an ordered system to a disordered system due to particle rearrangement. This model could take into account both the viscous properties of the asphalt binder and grain size distributions of the aggregates. Additionally, we suggest to use the discrete element method to understand the particle rearrangement during the compaction process. This model is calibrated based on the SuperPave gyratory compaction tests in the pavement lab. In the end, we compared the model results to experimental data to show that this model prediction had a good agreement with the experiments, thus, had great potentials to be implemented to improve the design of asphalt mixtures.

Selective laser melting of polymers: influence of powder coating on mechanical part properties

2018 ◽  
Vol 38 (7) ◽  
pp. 667-674 ◽  
Author(s):  
Maximilian Drexler ◽  
Sandra Greiner ◽  
Matthias Lexow ◽  
Lydia Lanzl ◽  
Katrin Wudy ◽  
...  
Keyword(s):  
Selective Laser Melting ◽  
Powder Coating ◽  
Mechanical Tests ◽  
Laser Melting ◽  
Part Quality ◽  
Thermal Fields ◽  
Compaction Behavior ◽  
Processing Strategies ◽  
Force Impact ◽  
New Processing

Abstract For the derivation of part quality increasing process strategies, knowledge about interactions between sub-processes of selective laser melting (SLM) and resulting part properties is necessary. The SLM process consists of three major sub-processes: powder coating, exposure, and material consolidation. According to the interaction of sub-processes, resulting processing conditions during SLM determine the part properties by changing micro structural pore number and distribution. In addition to absolute temperatures, the time-dependency of the thermal fields also influences the porosity of molten parts. Present process strategies tend to decrease building time by acceleration of the subprocesses. Apart from prior investigated acceleration of the exposure, the powder coating step is focused. Within the paper, the authors analyze the basic interactions between different coating parameters and part properties. The authors estimate an interaction between coating speed and resulting part properties due to a force impact caused by the moved coating mechanism. Therefore, specimens produced with different coating speeds are analyzed with imaging technologies as well as mechanical tests. Based on the investigations, new processing strategies can be established considering the forces applied to the powder bed during the coating process, as well as the unique compaction behavior of current and future used powders.

scholarly journals Sonocrystallization Yields Monoclinic Paracetamol with Significantly Improved Compaction Behavior

2014 ◽  
Vol 54 (1) ◽  
pp. 249-253 ◽  
Author(s):  
Dejan-Krešimir Bučar ◽  
James A. Elliott ◽  
Mark D. Eddleston ◽  
Jeremy K. Cockcroft ◽  
William Jones
Keyword(s):  
Compaction Behavior
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