| Densification Behavior, Microstructural Development and
Mechanical Properties of Spark Plasma Sintered ?/?-Silicon
Nitride Ceramics with Different Rare Earth Oxide Additives |
Levent Koroglu, Ozden Kisacik and Semra Kurama*
Pages: 195-201
DOI : 10.1080/0371750X.2023.2224840 |
| Abstract |
| Monolithic Si3N4 ceramics were fabricated by spark plasma sintering at 1750oC for
15 min under 50 MPa applied pressure using ?-Si3N4 powder with 2 wt% Y2O3, 2 wt%
Dy2O3, 2 wt% Eu2O3 and 8 wt% Y2O3 as single rare earth oxide additives. It aimed to
investigate the effects of the composition and content of rare earth oxide additives
on densification, microstructural development, and mechanical properties of ?/?-
silicon nitride ceramics via XRD and SEM analyses, temperature and displacement
curves obtained through spark plasma sintering and mechanical tests. Addition to 2
wt% Y2O3 as an additive into composition resulted in high relative density (98%),
hardness (14.9 GPa), and fracture toughness (9.8 MPa.m1/2). The use of Dy2O3 instead
of Y2O3 decreased ?-Si3N4 phase ratio and densification rate. This behavior continued
further with Eu2O3 addition. The increment of Y2O3 content to 8 wt% provided the
same relative density and fracture toughness (98% and 9.8 MPa.m1/2), whereas
hardness was reduced to 12.6 GPa. As a result, densification was achieved only by
Y2O3 addition regardless of additive content, and both high hardness and fracture
toughness were obtained using only 2 wt% Y2O3 as a single additive.
[Keywords: Silicon nitride, Spark plasma sintering, Rare earth oxide additives,
Microstructure, Mechanical properties] |
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