Persistence of Granular Structure during Die Compaction of Ceramic Powders

2000 ◽  
Vol 627 ◽  
Author(s):  
William J. Walker
Keyword(s):  
Low Pressure ◽  
Probability Of Failure ◽  
Model System ◽  
Granular Structure ◽  
Alumina Powder ◽  
Statistical Nature ◽  
Ceramic Powders ◽  
Glass Spheres ◽  
Die Compaction ◽  
Uniform Composition

ABSTRACTGlass spheres were used as a model system to investigate granule failure during die compaction. Stresses within an assembly of spheres follow a network of pathways. When the spheres are of uniform composition, the magnitude of the stresses within a pair of contacting granules is a function of the locally transmitted stress and the diameter of the two spheres. Results obtained using glass spheres demonstrated the statistical nature of granule failure during compaction, with some granules failing at very low applied pressures while others (∼40% by volume) persist at even the highest applied loads. Within a distribution of granule sizes, those granules with smaller diameter were seen to have a higher probability of failure at low pressure than were larger granules. These results are consistent with those observed during die compaction of granulated alumina powder.

scholarly journals Process characterization and analysis of ceramic powder bed fusion

2021 ◽  
Author(s):  
Kevin Florio ◽  
Dario Puccio ◽  
Giorgio Viganò ◽  
Stefan Pfeiffer ◽  
Fabrizio Verga ◽  
...  
Keyword(s):  
High Speed ◽  
Ceramic Powder ◽  
Integrating Sphere ◽  
Alumina Powder ◽  
Powder Bed Fusion ◽  
Single Track ◽  
Ceramic Powders ◽  
Pure Alumina ◽  
Powder Bed ◽  
Melt Pool

AbstractPowder bed fusion (PBF) of ceramics is often limited because of the low absorptance of ceramic powders and lack of process understanding. These challenges have been addressed through a co-development of customized ceramic powders and laser process capabilities. The starting powder is made of a mix of pure alumina powder and alumina granules, to which a metal oxide dopant is added to increase absorptance. The performance of different granules and process parameters depends on a large number of influencing factors. In this study, two methods for characterizing and analyzing the PBF process are presented and used to assess which dopant is the most suitable for the process. The first method allows one to analyze the absorptance of the laser during the melting of a single track using an integrating sphere. The second one relies on in-situ video imaging using a high-speed camera and an external laser illumination. The absorption behavior of the laser power during the melting of both single tracks and full layers is proven to be a non-linear and extremely dynamic process. While for a single track, the manganese oxide doped powder delivers higher and more stable absorptance. When a full layer is analyzed, iron oxide-doped powder is leading to higher absorptance and a larger melt pool. Both dopants allow the generation of a stable melt-pool, which would be impossible with granules made of pure alumina. In addition, the present study sheds light on several phenomena related to powder and melt-pool dynamics, such as the change of melt-pool shape and dimension over time and powder denudation effects.

scholarly journals Laser ablation and low-pressure helium-ICP-MS for the analysis of alumina powder dispersed in glycerol

2004 ◽  
Vol 53 (9) ◽  
pp. 993-996 ◽  
Author(s):  
Taketoshi NAGAYASU ◽  
Hideo HAYASHI ◽  
Masataka HIRAIDE
Keyword(s):  
Laser Ablation ◽  
Low Pressure ◽  
Alumina Powder ◽  
Icp Ms

Modification of the Density-Pressure Relationship due to the Internal Friction and Cohesion of a Powder Mass Undergoing Closed Die Compaction

2009 ◽  
Vol 409 ◽  
pp. 334-337
Author(s):  
Miriam Kupková
Keyword(s):  
Experimental Data ◽  
Internal Friction ◽  
Low Pressure ◽  
Density Dependent ◽  
Pressure Region ◽  
Powder Mass ◽  
Die Compaction

The existing density-pressure laws for a powder undergoing die compaction fit experimental data very well except for the low-pressure end of curves for some materials (SiC, Al2O3). To improve this, density - pressure relationship was modified by considering the internal friction and cohesion. For constant internal friction and vanishing cohesion, the modified relationship became mathematically equivalent to the existing one. For density-dependent friction, the modified and original relationships were able to provide nearly the same densities at medium and higher pressures but slightly different values at the low-pressure region.

New Low Toxic Water-Soluble Monomers for Gelcasting of Ceramic Powders

2010 ◽  
Vol 62 ◽  
pp. 163-168 ◽  
Author(s):  
Mikolaj Szafran ◽  
Agnieszka Szudarska ◽  
Paulina Bednarek
Keyword(s):  
In Situ Polymerization ◽  
Polymer Network ◽  
Water Soluble ◽  
Cross Linking ◽  
Alumina Powder ◽  
Hydroxyl Groups ◽  
Ceramic Powders ◽  
Ceramic Slurry ◽  
Low Toxic

In this paper the two new low toxic water-soluble monomers: glycerol monoacrylate and 3-O-acrylic-D-glucose are introduced and their application in gelcasting of alumina powder is reported, in comparison with 2-hydroxyethyl acrylate, the commercial monomer. Both synthesized substances do not need an addition of cross-linking agent to the ceramic slurry, because hydrogen bonds can be formed in the polymer network, owing to the presence of two or more hydroxyl groups in their molecules, unlike in the case of 2-hydroxyethyl acrylate. Rheological behavior of alumina gelcasting suspensions containing these monomers has been studied, as well as the characteristics of raw and sintered elements formed from these slurries by initializing an in situ polymerization.

Effect of pre-calcined ceramic powders at different temperatures on Ni-YSZ anode-supported SOFC cell/stack by low pressure injection molding

2019 ◽  
Vol 45 (16) ◽  
pp. 20066-20072 ◽  
Author(s):  
Jie Xiao ◽  
Xiaoyuan Zeng ◽  
Mian Li ◽  
Peng Dong ◽  
Hao Wu ◽  
...  
Keyword(s):  
Injection Molding ◽  
Low Pressure ◽  
Ceramic Powders ◽  
Pressure Injection ◽  
Different Temperatures

Rheological properties of paraffin suspensions of surface-modified alumina powder for low-pressure injection moulding

2004 ◽  
Vol 43 (5) ◽  
pp. 559-566 ◽  
Author(s):  
Saša Novak ◽  
Susana Maria Henriques Olhero ◽  
José Maria Fonte Ferreira ◽  
Andreja Zupančič
Keyword(s):  
Rheological Properties ◽  
Injection Moulding ◽  
Low Pressure ◽  
Alumina Powder ◽  
Modified Alumina ◽  
Pressure Injection ◽  
Surface Modified

Constitutive Data for Powder Compaction Modeling

2000 ◽  
Vol 123 (2) ◽  
pp. 176-183 ◽  
Author(s):  
I. C. Sinka ◽  
A. C. F. Cocks ◽  
J. H. Tweed
Keyword(s):  
Constitutive Modeling ◽  
Triaxial Testing ◽  
Stress Space ◽  
Ceramic Powders ◽  
Compaction Behavior ◽  
Isostatic Compaction ◽  
Hard Metals ◽  
Testing Facility ◽  
Die Compaction ◽  
Radial Loading

The compaction behavior of steel powders, hard metals, and ceramic powders have been investigated using a newly developed high pressure triaxial testing facility. Results from isostatic compaction, simulated closed die compaction, and compaction along different radial loading paths in stress space are presented for six commercial powders. The experimental data are compared and considerations regarding the constitutive modeling of the compaction response of the different classes of materials are presented.

scholarly journals Laser Ablation and Low-Pressure Helium-ICP-MS for the Analysis of Alumina Powder Dispersed in Glycerol

2005 ◽  
Vol 21 (12) ◽  
pp. 1411-1413 ◽  
Author(s):  
Taketoshi NAGAYASU ◽  
Hideo HAYASHI ◽  
Masataka HIRAIDE
Keyword(s):  
Laser Ablation ◽  
Low Pressure ◽  
Alumina Powder ◽  
Icp Ms

Granule Structure Evolution during Powder Compaction

2002 ◽  
Vol 759 ◽  
Author(s):  
William J. Walker
Keyword(s):  
Large Fraction ◽  
Particle Size Analysis ◽  
Particle Packing ◽  
Structure Evolution ◽  
Size Analysis ◽  
Forming Process ◽  
Glass Spheres ◽  
Granule Structure ◽  
Die Compaction ◽  
Ceramics Industry

ABSTRACTDie compaction of granulated powder is a common forming process used in the ceramics industry. Glass spheres were used as a model system to investigate granule failure during die compaction. Since glass spheres are brittle, failure results in fragmentation. Particle size analysis of the resulting fragments demonstrates the statistical nature of granule failure during compaction, with some granules failing at very low applied pressures while a large fraction persist at even the highest applied loads. The results are discussed in terms of the Andreasen, Furnas and Dinger-Funk particle packing models for continuous size distributions.

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