Tough Yttria-Stabilized Zirconia Ceramic by Low-Temperature Spark Plasma Sintering of Long-Term Stored Nanopowders

Abstract

Weakly agglomerated 1.75 and 3 mol% yttria stabilized zirconia nanopowders were used in this study after six years of storage in vacuum-processed plastic containers. The proper storage conditions of the Y-TZP nanopowders avoided the hard agglomeration. Untreated and bead-milled nanopowders were used to obtain dense ceramics by slip casting and subsequent low-temperature sintering. Fully dense nanostructured 1.75Y-TZP and 3Y-YZP ceramics with and without doping of 1 wt% Al2O3 were produced by an optimized spark plasma sintering (SPS) technique at the temperatures of 1050-1150 degrees C at a pressure of 100 MPa. The SPS has revealed the clear advantage of consolidation of the weakly agglomerated nanopowders without preliminary deagglomeration. The Vickers hardness of both the low-temperature and spark plasma sintered samples was found to lie in the range of 10.98-13.71 GPa. A maximum fracture toughness of 15.7 MPa m(1/2) (average 14.23 MPa m(1/2)) was achieved by SPS of the 1.75Y-TZP ceramic doped with 1 wt% Al2O3 whereas the toughness of the 3Y-TZP ceramics with and without alumina doping was found to vary between 3.55 and 5.5 MPa m(1/2).

Double-walled carbon nanotube/zirconia composites: Preparation by spark plasma sintering, electrical conductivity and mechanical properties

“…It decreases regularly from C1 to C6 upon the increase in the carbon content ( Table 2). The SENB fracture toughness of C0 (10.3 MPa.m 1/2 - Table 2) is the highest among those reported for such a ceramic with an average grain size below 200 nm [9,[48][49][50], even when the measurements are made by the SEVNB method [15]. The fracture toughness of both C0.5 and C1 is still relatively high (about 7 MPa.m 1/2 ).…”

Restriction of Phase Transformation in Carbon Nanotube-Reinforced Yttria-Stabilized Zirconia

“…It is observed that densification values for the SPSed samples lie in the range~93 to 96 pct, which is slightly lower than the range of values found in literature. [2,[41][42][43] It is to be noted that multi-stage SPS has been employed in the current work with uniaxial pressure of 30 MPa and maximum sintering temperature of 1523 K (1250°C). In contrast, higher temperature or uniaxial pressure has been utilized by other researchers while processing zirconia ceramics, hence accounting for the greater densification (98 to 100 pct) reported in their work.…”

Densification Kinetics of Nanocrystalline Zirconia Powder Using Microwave and Spark Plasma Sintering—A Comparative Study

“…[18][19][20][21] In contrast, comparatively quick processing techniques (5-10 minutes as compared to 40 hours) such as hotpressing and field-assisted (FAST) sintering such as the spark plasma sintering (SPS), microwave sintering (MWS) are usually used for producing dense fine-grained YSZ. [22][23][24][25][26] At the present time the SPS and MWS are considered as the most effective methods of obtaining bulk fine-grained YSZ, because of high heating rates, achieved by electrical heating via graphite die or volumetric dielectric heating. [27][28][29][30] In case of SPS the benefit of the applied external field (i.e., pulsed electric current) is not restricted to Joule heating, other non-thermal benefits are operative, such as current enhanced mass transport, and reactivity.…”