Densification Behavior of Ceramic Powder Under Cold Compaction

1998 ◽  
Vol 122 (2) ◽  
pp. 238-244 ◽  
Author(s):  
K. T. Kim ◽  
S. W. Choi ◽  
H. Park
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Triaxial Compression ◽  
Ceramic Powder ◽  
Densification Behavior ◽  
Zirconia Powder ◽  
Cold Compaction ◽  
Proposed Model ◽  
Die Compaction ◽  
Cap Model

Densification behavior of ceramic powder under cold compaction was investigated. Experimental data were obtained for zirconia powder under triaxial compression with various loading conditions. For densification of ceramic powder during cold compaction, a novel hyperbolic cap model was proposed from the iso-density curves based on experimental data of zirconia powder under triaxial compression. The proposed model was implemented into a finite element program (ABAQUS) to study densification behavior of zirconia powder under die compaction. The modified Drucker–Prager/cap model was also employed to compare with experimental data and the finite element results from the proposed model in the present work. By including the effect of friction between the powder and die wall, density distributions of a zirconia compact were measured and compared with finite element results under die compaction. [S0094-4289(00)00102-X]

Cold Compaction of Composite Powders

1999 ◽  
Vol 122 (1) ◽  
pp. 119-128 ◽  
Author(s):  
K. T. Kim ◽  
J. H. Cho ◽  
J. S. Kim
Keyword(s):  
Experimental Data ◽  
Tungsten Powder ◽  
Cold Isostatic Pressing ◽  
Metal Powders ◽  
Composite Powders ◽  
Cold Compaction ◽  
Isostatic Pressing ◽  
Proposed Model ◽  
Theoretical Predictions ◽  
Die Compaction

Densification behavior of composite powders was investigated under cold compaction. Experimental data were obtained for mixed copper and tungsten powders with various volume fractions of tungsten powder under cold isostatic pressing and die compaction. A model was also proposed for densification of mixed—soft and hard—metal powders under cold compaction. Theoretical predictions from the proposed model and models in the literature were compared with experimental data. The agreements between experimental data and theoretical predictions from the proposed model are very good for composite powders at initial stage under cold isostatic pressing. Theoretical predictions, however, underestimate experimental data under cold die compaction. [S0094-4289(00)01901-0]

Near-Net-Shape Forming of Ceramic Powder Under Cold Combination Pressing and Pressureless Sintering

2001 ◽  
Vol 123 (2) ◽  
pp. 221-228 ◽  
Author(s):  
H. G. Kim ◽  
H. M. Lee ◽  
K. T. Kim
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Density Distribution ◽  
Ceramic Powder ◽  
Cold Isostatic Pressing ◽  
Pressureless Sintering ◽  
Zirconia Powder ◽  
Isostatic Pressing ◽  
Near Net Shape ◽  
Net Shape Forming

Near-net-shape forming of zirconia powder was investigated under the combination of cold die and isostatic pressing and pressureless sintering. A combination pressing technique, i.e., die compaction under cold isostatic pressing, allowed the forming of a complex shaped ceramic powder body with better dimensional control than that achieved by cold isostatic pressing and more uniform density distribution than that by die pressing. The constitutive models proposed by Kim and co-workers were implemented into a finite element program (ABAQUS) to simulate densification of ceramic powder under cold compaction and pressureless sintering. Finite element calculations were compared with experimental data for density distribution and deformation of zirconia powder compacts under cold combination pressing and pressureless sintering. Finite element results agreed well with experimental data.

Finite Element Calculation of Sintering Deformation Using Limited Experimental Data

2008 ◽  
Vol 606 ◽  
pp. 103-118 ◽  
Author(s):  
Jing Zhe Pan ◽  
Ruo Yu Huang
Keyword(s):  
Experimental Data ◽  
Finite Element Method ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Ceramic Powder ◽  
Material Model ◽  
Element Analysis ◽  
Ceramic Components ◽  
On Line ◽  
Element Method

Predicting the sintering deformation of ceramic powder compacts is very important to manufactures of ceramic components. In theory the finite element method can be used to calculate the sintering deformation. In practice the method has not been used very often by the industry for a very simple reason – it is more expensive to obtain the material data required in a finite element analysis than it is to develop a product through trial and error. A finite element analysis of sintering deformation requires the shear and bulk viscosities of the powder compact. The viscosities are strong functions of temperature, density and grain-size, all of which change dramatically in the sintering process. There are two ways to establish the dependence of the viscosities on the microstructure: (a) by using a material model and (b) by fitting the experimental data. The materials models differ from each other widely and it can be difficult to know which one to use. On the other hand, obtaining fitting functions is very time consuming. To overcome this difficulty, Pan and his co-workers developed a reduced finite element method (Kiani et. al. J. Eur. Ceram. Soc., 2007, 27, 2377-2383; Huang and Pan, J. Eur. Ceram. Soc., available on line, 2008) which does not require the viscosities; rather the densification data (density as function of time) is used to predict sintering deformation. This paper provides an overview of the reduced method and a series of case studies.

YIELD DESIGN HOMOGENIZATION METHOD FOR COMPACTION OF MONOSIZED SPHERICAL POWDERS

2010 ◽  
Vol 02 (03) ◽  
pp. 457-488 ◽  
Author(s):  
BENABBES ANOUAR ◽  
SIAD LARBI ◽  
DORMIEUX LUC ◽  
WING KAM LIU
Keyword(s):  
New York ◽  
Finite Element ◽  
Triaxial Compression ◽  
Ceramic Powder ◽  
Material Model ◽  
Homogenization Method ◽  
Spherical Particles ◽  
Initial State ◽  
Whole Process ◽  
Kinematic Approach

The compaction of a package of monosized spherical solid grains by rate-independent plasticity deformation is examined in this paper through the use of both yield design homogenization method and finite element simulation. Both modes of compaction, isostatic and closed die, are considered. In this study, the arrangement of powder consists of hexagonal array of identical spherical grains touching each other in its initial state. During the compaction process the response of the powder compacts is monitored in terms of behaviors of appropriate representative unit cells subject to axisymmetrical loading conditions. The kinematic approach of the yield design homogenization method has been used to determine external estimates of macroscopic strength criteria of powders at various stages of compaction. The obtained upper bound estimates are based on consideration of discontinuous incompressible velocity fields satisfying conditions of homogeneous strain rate. The shapes and sizes of the macroscopic yield surfaces are determined at various stages of compaction and it has been found that they depend upon the loading history as well as the relative density of the compact. Finite element simulations similar to those of Ogbonna N. and Fleck N. A. [1995] "Compaction of an array of spherical particles," Acta Metall. Mater.43(2), 603–620. have also been performed in order to (i) obtain the deformation modes as well as the evolution of the deformation mechanism of the powder compact during the whole process of compaction; (ii) derive the evolution of contact sizes between adjacent grains; (iii) examine the dependence of the macroscopic yield surface upon the degree of compaction, using the "yield probing technique" Gurson, A. L. and Yuan, D. W. [1995] A Material Model for a Ceramic Powder Based on Ultrasound, TRS Bend Bar, and Axisymmetric Triaxial Compression Test Results (ASME, New York), pp. 57–68, and (iv) validate, to some extent, the results provided by the kinematic approach.

Densification Behavior of Iron Powder during Cold Stepped Compaction

2007 ◽  
Vol 534-536 ◽  
pp. 257-260
Author(s):  
Choun Sung Kang ◽  
S.C. Lee ◽  
K.T. Kim ◽  
Oleg Rozenberg
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Hydrostatic Pressure ◽  
Constitutive Equation ◽  
Density Distribution ◽  
Iron Powder ◽  
Yield Function ◽  
Densification Behavior ◽  
Finite Element Program ◽  
Element Program

Densification behavior of iron powder under cold stepped compaction was studied. Experimental data were also obtained for iron powder under cold stepped compaction. The elastoplastic constitutive equation based on the yield function of Shima and Oyane was implemented into a finite element program (ABAQUS) to simulate compaction responses of iron powder during cold stepped compaction. Finite element results were compared with experimental data for densification, deformed geometry and density distribution. The agreement between finite element results and experimental data was very good for iron powder. The distributions of hydrostatic pressure and the Mises stress of iron powder under cold stepped compaction were also studied.

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