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Uniform TitleDetermination of sintering parameters for liquid phase sintering of silicon nitride
NameTheron, Claire (author), Cannon, W. (chair), Danforth, Stephen (internal member), Matthewson, M. (internal member), Pujari, Vimal (outside member), Abouaf, Marc (outside member), Rutgers University, Graduate School - New Brunswick,
Degree Date2008-01
Date Created2008
SubjectCeramic and Materials Science and Engineering,
Silicon nitride,
Sintering
DescriptionThe sintering parameters of silicon nitride were determined during the second stage of liquid phase sintering via interrupted sinter forging tests under compressive uniaxial load.
The silicon nitride with an yttria-alumina rich secondary phase (Saint-Gobain composition NB D300) was submitted to seven level of stress (from 0.24MPa to 9.41MPa) at three different temperatures (1500°C, 1550°C and 1600°C) with continuous monitoring of the axial and longitudinal shrinkage during all experiments to directly obtain the sintering stress, Poisson's ratio and bulk viscosity.
The sintering stress measured in the first 1.5 minutes after reaching temperature was 7.5MPa at 1500°C (~60% theoretical density), 21.5 MPa at 1550°C (~70% dense) and 11.5MPa at 1600°C (~80% dense). The bulk viscosity also peaks at the intermediate density at about 48GPas .
This variation is largely attributed to the noticeable changes of microstructure during the second stage of liquid phase sintering, especially the overall pore size distribution as well as the degree to which the liquid phase is fully melted and partially or fully fills the smallest pores.
The experimental data were then inserted into a numerical model developed by Abouaf. Proper fit of the model could not be obtained without considering the rearrangement stage of sintering. Considering both the rearrangement and solution-precipitation stages of densification, it was possible to determine the variation during sintering of different parameters that influences the liquid phase sintering and therefore the microstructure development.
The silicon nitride with an yttria-alumina rich secondary phase (Saint-Gobain composition NB D300) was submitted to seven level of stress (from 0.24MPa to 9.41MPa) at three different temperatures (1500°C, 1550°C and 1600°C) with continuous monitoring of the axial and longitudinal shrinkage during all experiments to directly obtain the sintering stress, Poisson's ratio and bulk viscosity.
The sintering stress measured in the first 1.5 minutes after reaching temperature was 7.5MPa at 1500°C (~60% theoretical density), 21.5 MPa at 1550°C (~70% dense) and 11.5MPa at 1600°C (~80% dense). The bulk viscosity also peaks at the intermediate density at about 48GPas .
This variation is largely attributed to the noticeable changes of microstructure during the second stage of liquid phase sintering, especially the overall pore size distribution as well as the degree to which the liquid phase is fully melted and partially or fully fills the smallest pores.
The experimental data were then inserted into a numerical model developed by Abouaf. Proper fit of the model could not be obtained without considering the rearrangement stage of sintering. Considering both the rearrangement and solution-precipitation stages of densification, it was possible to determine the variation during sintering of different parameters that influences the liquid phase sintering and therefore the microstructure development.
NotePh.D.
NoteIncludes bibliographical references (p. 213-218).
Genretheses
Persistent URLhttp://hdl.rutgers.edu/1782.2/rucore10001600001.ETD.17229
LanguageEnglish
CollectionGraduate School - New Brunswick Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.