scholarly journals Sintering of Hydroxyapatite/Yttria Stabilized Zirconia Nanocomposites under Nitrogen Gas for Dental Materials

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
C. H. Leong ◽  
A. Muchtar ◽  
C. Y. Tan ◽  
M. Razali ◽  
Noor Faeizah Amat
Keyword(s):  
Relative Density ◽  
Phase Stability ◽  
Dental Materials ◽  
Gas Pressure ◽  
Yttria Stabilized Zirconia ◽  
Stabilized Zirconia ◽  
Nitrogen Gas ◽  
Conventional Sintering ◽  
Gas Pressure Sintering ◽  
The Relationship

This study aims to determine the effect of adding 3 mol% yttria stabilized zirconia (3YSZ) in hydroxyapatite (HA) and sintering HA/3YSZ nanocomposites under nitrogen gas on HA decomposition. This paper presents the relationship between microstructure and mechanical properties of HA/3YSZ nanocomposites. Gas pressure and conventional sintering were performed on HA/3YSZ nanocomposites containing different amounts of 3YSZ (i.e., 0, 0.5, 1, and 7 wt%) at 1250°C. The phase stability, morphology, relative density, and microhardness of the HA/3YSZ nanocomposites were investigated. The phase stability of the HA/3YSZ nanocomposites was affected by adding different amounts of 3YSZ. Overall, gas pressure sintering leads to the formation of greater grain size compared with the conventional sintering method. The severe HA decomposition and the presence of the porosity in HA/7 wt% 3YSZ have led to deterioration in relative density and microhardness. In this study, HA/0.5 wt% 3YSZ with gas pressure sintering exhibited the optimum microstructure with the highest relative density (97%) and microhardness (3.93 GPa).

scholarly journals Influence of Preaging Temperature on the Indentation Strength of 3Y-TZP Aged in Ambient Atmosphere

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2767
Author(s):  
Ki-Won Jeong ◽  
Jung-Suk Han ◽  
Gi-Uk Yang ◽  
Dae-Joon Kim
Keyword(s):  
Residual Stress ◽  
Phase Transformation ◽  
Low Temperature ◽  
Compressive Residual Stress ◽  
Yttria Stabilized Zirconia ◽  
Ambient Atmosphere ◽  
Aged Specimen ◽  
Stabilized Zirconia ◽  
M Phase ◽  
The Relationship

Yttria-stabilized zirconia (3Y-TZP) containing 0.25% Al2O3, which is resistant to low temperature degradation (LTD), was aged for 10 h at 130–220 °C in air. The aged specimens were subsequently indented at loads ranging from 9.8 to 490 N using a Vickers indenter. The influence of preaging temperature on the biaxial strength of the specimens was investigated to elucidate the relationship between the extent of LTD and the strength of zirconia restorations that underwent LTD. The indented strength of the specimens increased as the preaging temperature was increased higher than 160 °C, which was accompanied by extensive t-ZrO2 (t) to m-ZrO2 (m) and c-ZrO2 (c) to r-ZrO2 (r) phase transformations. The influence of preaging temperature on the indented strength was rationalized by the residual stresses raised by the t→m transformation and the reversal of tensile residual stress on the aged specimen surface due to the indentation. The results suggested that the longevity of restorations would not be deteriorated if the aged restorations retain compressive residual stress on the surface, which corresponds to the extent of t→m phase transformation less than 52% in ambient environment.

Effect of Cation Dopant on Phase Stability of Zirconia Bioceramics in Hot Water

2006 ◽  
Vol 49 ◽  
pp. 97-102 ◽  
Author(s):  
Yorinobu Takigawa ◽  
Yukihisa Naka ◽  
Kenji Higashi
Keyword(s):  
Phase Transformation ◽  
Phase Stability ◽  
Ionic Radius ◽  
Hot Water ◽  
Yttria Stabilized Zirconia ◽  
Transformation Behavior ◽  
Stabilized Zirconia

The effect of cation ion dopant on phase transformation of zirconia bioceramics is evaluated by ageing in hot water. The phase transformation progresses with time in all specimens. However, the transformation behavior is much different depending on the dopant. The transformation is promoted when the 1 mol% of pentavalent element is added to 3mol% yttria stabilized zirconia (3Y-TZP). In contrast, the transformation is suppressed when the bivalent element is added. In case that the tetravalent element is added, the transformation is promoted if the ionic radius of the element is larger than that of zirconium, and the transformation is suppressed if the element with smaller ionic radius than zirconium ion is added. This result indicates that the ionic radius and the valency of ions are important factors to control the phase stability in zirconia.

Investigation on the phase stability of yttria-stabilized zirconia electrolytes for high-temperature electrochemical application

2019 ◽  
Vol 45 (7) ◽  
pp. 9462-9467 ◽  
Author(s):  
Kuk-Jin Hwang ◽  
Miyoung Shin ◽  
Myung-Hyun Lee ◽  
Heesoo Lee ◽  
Mi Young Oh ◽  
...  
Keyword(s):  
High Temperature ◽  
Phase Stability ◽  
Yttria Stabilized Zirconia ◽  
Stabilized Zirconia ◽  
Electrochemical Application

Silicon Nitride Containing Rare Earth Silicate Intergranular Phases

1992 ◽  
Vol 287 ◽  
Author(s):  
Stephen D. Nunn ◽  
Terry N. Tiegs ◽  
Kristin L. Ploetz ◽  
Claudia A. Walls ◽  
Nelson Bell
Keyword(s):  
Rare Earth ◽  
Ternary Phase ◽  
Gas Pressure ◽  
Trivalent Cation ◽  
Processing Conditions ◽  
Microstructure Development ◽  
Sintering Aids ◽  
Conventional Sintering ◽  
Compositional Variations ◽  
Gas Pressure Sintering

ABSTRACTSi3N4 ceramics prepared with refractory grain boundary phases to improve high temperature properties are difficult to densify by conventional sintering methods. Gas-pressure sintering may be used to promote densification and development of acicular grains for improved fracture toughness. The current study examined rare earth silicate sintering aids with the composition M2Si2O7, where M is a trivalent cation (Y, La, Nd). M2O3 and Si02 additions were varied to develop a number of compositions in the Si3N4—Si2N2O—M2Si2O7 ternary phase field. Pressureless sintering and gas-pressure sintering were used to densify the samples. Densification, microstructure development, oxidation resistance, and mechanical properties were evaluated and compared with respect to compositional variations and processing conditions.

Effect of Alumina Additions on Mechanical and Electrical Properties of 8mol% Yttria-Stabilized Zirconia Prepared by Spark Plasma Sintering

2006 ◽  
Vol 317-318 ◽  
pp. 917-920
Author(s):  
Jae Kwang Kim ◽  
Kyung Hun Kim ◽  
Yong Ho Choa ◽  
Jong Won Yoon ◽  
Kwang Bo Shim
Keyword(s):  
Electrical Conductivity ◽  
Grain Size ◽  
Relative Density ◽  
Spark Plasma Sintering ◽  
Average Particle Size ◽  
Yttria Stabilized Zirconia ◽  
Average Particle ◽  
Stabilized Zirconia ◽  
Plasma Sintering ◽  
Spark Plasma

Dense 8mol% yttria-stabilized zirconia (8YSZ) consisting of submicrometer-sized grains was prepared using spark plasma sintering (SPS) along with Al2O3 additives. The starting powder with average particle size of 50nm was densified to 98% of the relative density with short sintering time (5min) at 1200 while preserving a submicrometer grain size. The fracture toughness and bending strength showed maximum values of 2.54MPam1/2 and 380MPa at 2vol% alumina-added 8YSZ, due mainly to the higher relative density and small grain size. The electrical conductivity of 2vol% alumina-added 8YSZ was 0.0278 S/cm at 700 in airThus, alumina additions in 8YSZ using the SPS method are an effective process to improve the mechanical strength and electrical conductivity.

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