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 - http://www.scopus.com/inward/record.url?scp=84887991530&partnerID=8YFLogxK
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 -