SPS sintering of silicon nitride with fluoride additive

Zafer Tatli; Fatih Çalişkan; James Butler; Clare Crowley; Stuart Hampshire

doi:10.1016/j.ceramint.2013.07.021

SPS sintering of silicon nitride with fluoride additive

Zafer Tatli
, Fatih Çalişkan
, James Butler
, Clare Crowley
, Stuart Hampshire

Research output: Contribution to journal › Article › peer-review

Abstract

Silicon nitride, one of the major structural ceramics, is sintered using additives such as Al₂O₃+MgO to provide conditions for liquid phase sintering to full density. The final microstructure contains high aspect ratio β-Si₃N₄ grains and intergranular glass. In this study, Spark Plasma Sintering (SPS) of silicon nitride, using Al ₂O₃+MgO or MgF₂ as sintering additives, has been investigated in the temperature range 1400-1600 C for 3 min since MgF ₂ should produce liquid phases with lower melting temperatures than with MgO and therefore should sinter at lower temperature. Densification, microstructural development and mechanical behaviour have been compared. Maximum density (3.146 g cm^-3) was obtained for Si₃N ₄+3% Al₂O₃+9.3% MgF₂ sintered by SPS at 1550 C. In all samples, α- to β-Si₃N₄ transformation was incomplete but samples with MgF₂ showed higher β:α ratio than with MgO. Fluoride doped samples also exhibited higher fracture toughness than equivalent samples sintered with MgO.

Original language	English
Pages (from-to)	1399-1404
Number of pages	6
Journal	Ceramics International
Volume	40
Issue number	1 PART B
DOIs	https://doi.org/10.1016/j.ceramint.2013.07.021
Publication status	Published - Jan 2014

Keywords

C. Mechanical properties
Densification
Fluoride additive
Silicon nitride
Spark plasma sintering

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10.1016/j.ceramint.2013.07.021

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title = "SPS sintering of silicon nitride with fluoride additive",

abstract = "Silicon nitride, one of the major structural ceramics, is sintered using additives such as Al2O3+MgO to provide conditions for liquid phase sintering to full density. The final microstructure contains high aspect ratio β-Si3N4 grains and intergranular glass. In this study, Spark Plasma Sintering (SPS) of silicon nitride, using Al 2O3+MgO or MgF2 as sintering additives, has been investigated in the temperature range 1400-1600 C for 3 min since MgF 2 should produce liquid phases with lower melting temperatures than with MgO and therefore should sinter at lower temperature. Densification, microstructural development and mechanical behaviour have been compared. Maximum density (3.146 g cm-3) was obtained for Si3N 4+3\% Al2O3+9.3\% MgF2 sintered by SPS at 1550 C. In all samples, α- to β-Si3N4 transformation was incomplete but samples with MgF2 showed higher β:α ratio than with MgO. Fluoride doped samples also exhibited higher fracture toughness than equivalent samples sintered with MgO.",

keywords = "C. Mechanical properties, Densification, Fluoride additive, Silicon nitride, Spark plasma sintering",

author = "Zafer Tatli and Fatih {\c C}ali{\c s}kan and James Butler and Clare Crowley and Stuart Hampshire",

year = "2014",

month = jan,

doi = "10.1016/j.ceramint.2013.07.021",

language = "English",

volume = "40",

pages = "1399--1404",

journal = "Ceramics International",

issn = "0272-8842",

number = "1 PART B",

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TY - JOUR

T1 - SPS sintering of silicon nitride with fluoride additive

AU - Tatli, Zafer

AU - Çalişkan, Fatih

AU - Butler, James

AU - Crowley, Clare

AU - Hampshire, Stuart

PY - 2014/1

Y1 - 2014/1

N2 - Silicon nitride, one of the major structural ceramics, is sintered using additives such as Al2O3+MgO to provide conditions for liquid phase sintering to full density. The final microstructure contains high aspect ratio β-Si3N4 grains and intergranular glass. In this study, Spark Plasma Sintering (SPS) of silicon nitride, using Al 2O3+MgO or MgF2 as sintering additives, has been investigated in the temperature range 1400-1600 C for 3 min since MgF 2 should produce liquid phases with lower melting temperatures than with MgO and therefore should sinter at lower temperature. Densification, microstructural development and mechanical behaviour have been compared. Maximum density (3.146 g cm-3) was obtained for Si3N 4+3% Al2O3+9.3% MgF2 sintered by SPS at 1550 C. In all samples, α- to β-Si3N4 transformation was incomplete but samples with MgF2 showed higher β:α ratio than with MgO. Fluoride doped samples also exhibited higher fracture toughness than equivalent samples sintered with MgO.

AB - Silicon nitride, one of the major structural ceramics, is sintered using additives such as Al2O3+MgO to provide conditions for liquid phase sintering to full density. The final microstructure contains high aspect ratio β-Si3N4 grains and intergranular glass. In this study, Spark Plasma Sintering (SPS) of silicon nitride, using Al 2O3+MgO or MgF2 as sintering additives, has been investigated in the temperature range 1400-1600 C for 3 min since MgF 2 should produce liquid phases with lower melting temperatures than with MgO and therefore should sinter at lower temperature. Densification, microstructural development and mechanical behaviour have been compared. Maximum density (3.146 g cm-3) was obtained for Si3N 4+3% Al2O3+9.3% MgF2 sintered by SPS at 1550 C. In all samples, α- to β-Si3N4 transformation was incomplete but samples with MgF2 showed higher β:α ratio than with MgO. Fluoride doped samples also exhibited higher fracture toughness than equivalent samples sintered with MgO.

KW - C. Mechanical properties

KW - Densification

KW - Fluoride additive

KW - Silicon nitride

KW - Spark plasma sintering

UR - https://www.scopus.com/pages/publications/84887991530

U2 - 10.1016/j.ceramint.2013.07.021

DO - 10.1016/j.ceramint.2013.07.021

M3 - Article

AN - SCOPUS:84887991530

SN - 0272-8842

VL - 40

SP - 1399

EP - 1404

JO - Ceramics International

JF - Ceramics International

IS - 1 PART B

ER -

SPS sintering of silicon nitride with fluoride additive

Abstract

Keywords

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