Theory of sintering: from discrete to continuum

Olevsky, Eugene A.

doi:10.1016/s0927-796x(98)00009-6

Cited by 576 publications

(489 citation statements)

References 228 publications

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“…The kinetic, Monte Carlo model for simulation sintering is a rigorous, science-based model with all the necessary materials physics to predict sintering behavior of a porous body. These mesoscale simulations of sintering provide two important results, (1) constitutive equations used in continuum models to predict shrinkage and shape change of a sintering powder compact and (2) microstructures of sintered compacts for engineering properties evaluation. We have also developed finite element capability to incorporate the constitutive equations generated by the mesoscale model.…”

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confidence: 99%

Microstructural and continuum evolution modeling of sintering.

Braginsky¹,

Olevsky²,

Johnson

et al. 2003

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All ceramics and powder metals, including the ceramics components that Sandia uses in critical weapons components such as PZT voltage bars and current stacks, multilayer ceramic MET'S, ahmindmolybdenum & alumina cermets, and ZnO varistors, are manufactured by sintering. Sintering is a critical, possibly the most important, processing step during manufacturing of ceramics. The microstructural evolution, the macroscopic shrinkage, and shape distortions during sintering will control the engineering performance of the resulting ceramic component. Yet, modeling and prediction of sintering behavior is in its infancy, lagging far behind the other manufacturing models, such as powder synthesis and powder compaction models, and behind models that predict engineering properties and reliability. In this project, we developed a model that was 3 capable of simulating microstructural evolution during sintering, providing constitutive equations for macroscale simulation of shrinkage and distortion during sintering. And we developed macroscale sintering simulation capability in JAS3D.The mesoscale model can simulate microstructural evolution in a complex powder compact of hundreds or even thousands of particles of arbitrary shape and size by 1. curvature-driven grain growth, 2. pore migration and coalescence by surface diffusion, 3. vacancy formation, grain boundary difhsion and annihilation. This model was validated by comparing predictions of the simulation to analytical predictions for simple geometries. The model was then used to simulate sintering in complex powder compacts. Sintering stress and materials viscous moduli were obtained from the simulations. These constitutive equations were then used by macroscopic simulations for simulating shrinkage and shape changes i n FEM simulations.The continuum theory of sintering embodied in the constitutive description of Skorohod and Olevsky was combined with results from microstructure evolution simulations to model shrinkage and deformation during. The continuum portion is based on a finite element formulation that allows 3D components to be modeled using SNL's nonlinear large-deformation finite element code, JAS3D. This tool provides a capability to model sintering of complex three-dimensional components. The model was verified by comparing to simulations results published in the literature. The model was validated using experimental results from various laboratory experiments performed by Garino. In addition, the mesoscale simulations were used to study anisotropic shrinkage in aligned, elongated powder compacts. Anisotropic shrinkage occurred in all compacts with aligned, elongated particles. However, the direction of higher shrinkage was in some cases along the direction of elongation and in other cases in the perpendicular direction depending on the details of the powder compact. In compacts of simplepacked, mono-sized, elongated particles, shrinkage was higher in the direction of elongation. In compacts of close-packed, mono-sized, elongated particles and of elonga...

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confidence: 99%

Microstructural and continuum evolution modeling of sintering.

Braginsky¹,

Olevsky²,

Johnson

et al. 2003

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“…Reiterer (2006) Poisson Skorohod-Olevsky Viscous Sintering (SOVS) (Skorohod, 1972, Olevsky, 1998 Coble Arrhenius…”

Section: % 10%mentioning

confidence: 99%

Constitutive equations of earthenware material during firing processes and determination of their function forms

Matsubara

Saitou²,

Oide

et al. 2016

Transactions of the JSME (In Japanese)

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We propose a set of constitutive equations of earthenware material subjected to the firing process and appropriate ways of determining their function forms and relevant material parameters from a series of respective experiments. The firing process under a specific heat curves is generally divided into three different phases; "thermal dilatation phase", "sintering phase" and "thermal contraction phase". These non-mechanical deformations are assumed not to be coincident, and the mechanical ones are assumed to be represented by viscoplastic constitutive model. Then, the key issue must be how to determine sintering strains by calibrating the employed function form of the densification rate with the data obtained from the stairway thermal cycle (STC) tests. Also, the presentations of the dependencies of the elastic and creep properties on both temperature and density are of particular importance to accurately predict the overall deformation of earthware.All the relevant material parameters as well as coefficients of thermal expansion and contraction are identified with the data obtained from respective mechanical experiments conducted in testing equipments for thermo-mechanical analysis (TMA) under several levels of termperature. The method of differential evolution, which is one of the metaheuristic optimization techniques, is employed to identify the creep parameters, since the mechanical responses to several levels of loading during firing processes involve all the non-mechanical and mechanical deformation of specimens simultaneously.The calculation results with the proposed constitutive equations are compared with the original experimental data to demonstrate the applicability for practical use of their function forms determined by the proposed strategy.

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“…In more formal terms, the continuum theory of sintering defines the sintering stress as the derivative of the free energy per unit mass with respect to the volumetric mass of the porous material [4]. This definition provides a procedure to obtain a quantitative measure of sintering stress as: (4) where: F is the surface free energy and is proportional to the pore surface area.…”

Section: Sintering Stressmentioning

confidence: 99%

Nanocrystal-enabled solid state bonding.

Report¹,

Holm²,

Puskar³

et al. 2010

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In this project, we performed a preliminary set of sintering experiments to examine nanocrystalenabled diffusion bonding (NEDB) in Ag-on-Ag and Cu-on-Cu using Ag nanoparticles. The experimental test matrix included the effects of material system, temperature, pressure, and particle size. The nanoparticle compacts were bonded between plates using a customized hot press, tested in shear, and examined post mortem using microscopy techniques. NEDB was found to be a feasible mechanism for low-temperature, low-pressure, solid-state bonding of like materials, creating bonded interfaces that were able to support substantial loads. The maximum supported shear strength varied substantially within sample cohorts due to variation in bonded area; however, systematic variation with fabrication conditions was also observed. Mesoscale sintering simulations were performed in order to understand whether sintering models can aid in understanding the NEDB process. A pressure-assisted sintering model was incorporated into the SPPARKS kinetic Monte Carlo sintering code. Results reproduce most of the qualitative behavior observed in experiments, indicating that simulation can augment experiments during the development of the NEDB process. Because NEDB offers a promising route to lowtemperature, low-pressure, solid-state bonding, we recommend further research and development with a goal of devising new NEDB bonding processes to support Sandia's customers. 4

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Theory of sintering: from discrete to continuum

Cited by 576 publications

References 228 publications

Microstructural and continuum evolution modeling of sintering.

Microstructural and continuum evolution modeling of sintering.

Constitutive equations of earthenware material during firing processes and determination of their function forms

Nanocrystal-enabled solid state bonding.

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