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Title: An Arrhenius-type viscosity function to model sintering using the Skorohod Olevsky viscous sintering model within a finite element code.

Abstract

The ease and ability to predict sintering shrinkage and densification with the Skorohod-Olevsky viscous sintering (SOVS) model within a finite-element (FE) code have been improved with the use of an Arrhenius-type viscosity function. The need for a better viscosity function was identified by evaluating SOVS model predictions made using a previously published polynomial viscosity function. Predictions made using the original, polynomial viscosity function do not accurately reflect experimentally observed sintering behavior. To more easily and better predict sintering behavior using FE simulations, a thermally activated viscosity function based on creep theory was used with the SOVS model. In comparison with the polynomial viscosity function, SOVS model predictions made using the Arrhenius-type viscosity function are more representative of experimentally observed viscosity and sintering behavior. Additionally, the effects of changes in heating rate on densification can easily be predicted with the Arrhenius-type viscosity function. Another attribute of the Arrhenius-type viscosity function is that it provides the potential to link different sintering models. For example, the apparent activation energy, Q, for densification used in the construction of the master sintering curve for a low-temperature cofire ceramic dielectric has been used as the apparent activation energy for material flow in the Arrhenius-type viscosity functionmore » to predict heating rate-dependent sintering behavior using the SOVS model.« less

Authors:
; ;
Publication Date:
Research Org.:
Sandia National Laboratories
Sponsoring Org.:
USDOE
OSTI Identifier:
952124
Report Number(s):
SAND2006-1104J
TRN: US200913%%377
DOE Contract Number:
AC04-94AL85000
Resource Type:
Journal Article
Resource Relation:
Journal Name: Proposed for publication in the Journal American Ceramic Society.
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ACTIVATION ENERGY; CERAMICS; CONSTRUCTION; CREEP; DIELECTRIC MATERIALS; HEATING; HEATING RATE; POLYNOMIALS; SHRINKAGE; SINTERING; VISCOSITY

Citation Formats

Ewsuk, Kevin Gregory, Arguello, Jose Guadalupe, Jr., and Reiterer, Markus W. An Arrhenius-type viscosity function to model sintering using the Skorohod Olevsky viscous sintering model within a finite element code.. United States: N. p., 2006. Web.
Ewsuk, Kevin Gregory, Arguello, Jose Guadalupe, Jr., & Reiterer, Markus W. An Arrhenius-type viscosity function to model sintering using the Skorohod Olevsky viscous sintering model within a finite element code.. United States.
Ewsuk, Kevin Gregory, Arguello, Jose Guadalupe, Jr., and Reiterer, Markus W. Wed . "An Arrhenius-type viscosity function to model sintering using the Skorohod Olevsky viscous sintering model within a finite element code.". United States. doi:.
@article{osti_952124,
title = {An Arrhenius-type viscosity function to model sintering using the Skorohod Olevsky viscous sintering model within a finite element code.},
author = {Ewsuk, Kevin Gregory and Arguello, Jose Guadalupe, Jr. and Reiterer, Markus W.},
abstractNote = {The ease and ability to predict sintering shrinkage and densification with the Skorohod-Olevsky viscous sintering (SOVS) model within a finite-element (FE) code have been improved with the use of an Arrhenius-type viscosity function. The need for a better viscosity function was identified by evaluating SOVS model predictions made using a previously published polynomial viscosity function. Predictions made using the original, polynomial viscosity function do not accurately reflect experimentally observed sintering behavior. To more easily and better predict sintering behavior using FE simulations, a thermally activated viscosity function based on creep theory was used with the SOVS model. In comparison with the polynomial viscosity function, SOVS model predictions made using the Arrhenius-type viscosity function are more representative of experimentally observed viscosity and sintering behavior. Additionally, the effects of changes in heating rate on densification can easily be predicted with the Arrhenius-type viscosity function. Another attribute of the Arrhenius-type viscosity function is that it provides the potential to link different sintering models. For example, the apparent activation energy, Q, for densification used in the construction of the master sintering curve for a low-temperature cofire ceramic dielectric has been used as the apparent activation energy for material flow in the Arrhenius-type viscosity function to predict heating rate-dependent sintering behavior using the SOVS model.},
doi = {},
journal = {Proposed for publication in the Journal American Ceramic Society.},
number = ,
volume = ,
place = {United States},
year = {Wed Feb 01 00:00:00 EST 2006},
month = {Wed Feb 01 00:00:00 EST 2006}
}
  • A robust finite element model is employed to study the viscous sintering of three-dimensional, axisymmetric particles initial configurations. Particle shape evolution and flow fields are presented which yield new insight into the behavior of these systems. The effects of the initial particle size distribution and configuration are considered. Model predictions are validated by direct comparisons with experimental measurements.
  • Interaction among the dispersed second phase of rigid inclusions in a ceramic matrix undergoing densification is investigated by a viscoelastic finite element method with a two-dimensional multiple-inclusion model. The interaction is negligible when the volume fraction of inclusions is low (< 20%) and/or when the inclusions are uniformly distributed. The interaction becomes significant when the volume fraction of inclusions is high or the inclusions are agglomerated. The densification rates in the region between the inclusions are enhanced to some degree when the inclusions are closely packed. This enhancement will, however, cease when the inclusions get much closer, eventually coming inmore » contact with each other. In general, the agglomeration or close packing of inclusions results in retardation in the overall densification of the sintering matrix.« less
  • A simplified form of the Arrhenius equation, ln η = A + B(x)/T, where η is the viscosity, T the temperature, x the composition vector, and A and B the Arrhenius coefficients, was fitted to glass-viscosity data for the processing temperature range (the range at which the viscosity is within 1 to 103 Pa.s) while setting A = constant and treating B(x) as a linear function of mass fractions of major components. Fitting the Arrhenius equation to over 550 viscosity data of commercial glasses and approximately 1000 viscosity data of glasses for nuclear-waste glasses resulted in the A values ofmore » -11.35 and -11.48, respectively. The R2 value ranged from 0.92 to 0.99 for commercial glasses and was 0.98 for waste glasses. The Arrhenius models estimate viscosities for melts of commercial glasses containing 42 to 84 mass% SiO2 within the temperature range of 1100 to 1550°C and viscosity range of 5 to 400 Pa.s and for waste glasses containing 32 to 60 mass% SiO2 within the temperature range of 850 to 1450°C and viscosity range of 0.4 to 250 Pa.s.« less
  • The microplane concrete material model is based upon assumptions regarding the behavior of the material components. At any point, the response to the strain tensor on arbitrarily oriented surfaces is considered. Simple, softening stress-strain relationships are assumed in directions perpendicular and parallel to the surfaces. The macroscopic material behavior is then composed of the sum of the effects. The implementation of this model into the explicit, nonlinear, dynamic finite element program, DYNA3D, is described. To avoid the spurious mesh sensitivity that accompanies material failure, a weighted integral strain averaging approach is used to ensure that softening is nonlocal. This methodmore » is shown to be effective for limiting the failure zone in a concrete rod subjected to an impulse loading. 36 refs., 7 figs.« less
  • No abstract prepared.