Environmental Effect on the Crack Behavior of Yttria-Stabilized Zirconia During Laser Drilling

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Hong Shen ◽  
Juan Jiang ◽  
Decai Feng ◽  
Chen Xing ◽  
Xiaofeng Zhao ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Phase Transformation ◽  
Environmental Effect ◽  
Monoclinic Phase ◽  
Oxygen Vacancies ◽  
High Stress ◽  
Laser Drilling ◽  
Yttria Stabilized Zirconia ◽  
Stabilized Zirconia ◽  
Crack Behavior

The crack behaviors of yttrium-stabilized zirconia during laser drilling in air, vacuum, and water environments were investigated. Due to the high stress and low fracture toughness induced by tetragonal-monoclinic phase transformation, tremendous cracks occur during drilling in air. Contrastly, cracks were reduced in vacuum drilling since the phase transformation was suppressed due to the generation of oxygen vacancies. By protection of water, no cracks were observed due to low stress and maintained fracture toughness. The crack mechanisms in different drilling media were discussed.

Thermal and Mechanical Behavior in Laser Trepan Drilling of Yttria-Stabilized Zirconia

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Hong Shen ◽  
Decai Feng
Keyword(s):  
Phase Transformation ◽  
Pulsed Laser ◽  
Laser Drilling ◽  
Yttria Stabilized Zirconia ◽  
Transient Temperature ◽  
Stabilized Zirconia ◽  
Thermomechanical Model ◽  
Cracking Control ◽  
Intrinsic Mechanism ◽  
Laser Trepan Drilling

Cracking control is very important for laser drilling of yttria-stabilized zirconia (YSZ). In this paper, a thermomechanical model is presented to investigate what will be happened in the trepan drilling of YSZ by a picosecond pulsed laser. The thermal model is developed for describing the interaction between laser and YSZ material to obtain the transient temperature. The mechanical model is developed to calculate the stress distribution caused by the phase transformation based on the temperature results. The goal of the present study is to explore the intrinsic mechanism of cracking around the drilled hole from the aspect of the phase transformation in laser drilling of YSZ.

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.

scholarly journals Effect of Crack Bridging on the Toughening of Ceramic/Graphene Composites

2018 ◽  
Vol 57 (1) ◽  
pp. 54-62 ◽  
Author(s):  
S.V. Bobylev ◽  
A.G. Sheinerman
Keyword(s):  
Experimental Data ◽  
Fracture Toughness ◽  
Crack Growth ◽  
Crack Deflection ◽  
Yttria Stabilized Zirconia ◽  
Stabilized Zirconia ◽  
Crack Bridging ◽  
The Matrix ◽  
Graphene Content ◽  
Graphene Platelets

Abstract A model is proposed describing the effect of crack bridging on the fracture toughness of ceramic/graphene composites. The dependences of the fracture toughness on the graphene content and the sizes of the graphene platelets are calculated in the exemplary case of yttria stabilized zirconia (YSZ)/graphene composites. The calculations predict that if crack bridging prevails over crack deflection during crack growth, the maximum toughening can be achieved in the case of long graphene platelets provided that the latter do not rupture and adhere well to the matrix. The model shows good correlation with the experimental data at low graphene concentrations.

Mechanical and Structural Properties of Ion Implanted Yttria Stabiizeed Zirconia Ceramics

1983 ◽  
Vol 24 ◽  
Author(s):  
J. K. Cochran ◽  
K. O. Legg ◽  
H. F. Solnick-Legg
Keyword(s):  
Fracture Toughness ◽  
Penetration Depth ◽  
Yttria Stabilized Zirconia ◽  
Stabilized Zirconia ◽  
Zirconia Ceramics ◽  
Mechanical And Structural Properties ◽  
Knoop Microhardness ◽  
Vicker’S Microhardness ◽  
Reflection Electron Diffraction ◽  
Indenter Penetration

ABSTRACTSingle crystal yttria stabilized zirconia was implanted with 100 keV Ca+, Al+, and O2+ ions at fluences of 1015 to 6 × 1016 ions/cm2; . Blistering was observed at doses of 3 × 1016; O2;+ cm−2; and 6 × 1016; Al+ cm−2; but none was evident with Ca+. Knoop microhardness with a shallow indenter penetration depth peaked at a dose of 1016; ions/cm−2; for both Al+ and O2;+ but Ca+ produced no effect on microhardness. Vicker's microhardness with a much greater indenter penetration depth was not changed detectably by implantation but fracture toughness measurements from the same Vicker's indentations exhibited 10–23% increases at the highest O2+ doses and 20–25% increases at high Al+ doses. Annealing the highest implant doses at 1200° reduced the fracture toughness to pre-implant levels. Reflection electron diffraction showed that the surface had not been made amorphous by the 6 × 1016; Al+ dose as a well crystallized diffraction pattern was obtained.

Elemental, Thermal, and Structural Characterization of ZnO Doped 8 mol% Yttria-Stabilized Zirconia (8YSZ) Ceramics

2017 ◽  
Vol 888 ◽  
pp. 57-61 ◽  
Author(s):  
Johar Banjuraizah ◽  
Tinesha Selvaraj ◽  
Zainal Arifin Ahmad
Keyword(s):  
Structural Characterization ◽  
Tetragonal Phase ◽  
Monoclinic Phase ◽  
Ionic Conductivities ◽  
Secondary Phase ◽  
Yttria Stabilized Zirconia ◽  
Stabilized Zirconia ◽  
Mixed Powder ◽  
Dominant Phase

8 mol% of Yttrium oxide doped Zirconia (8YSZ) is one of the most explored compositions which give high ionic conductivities and good power output at 1000 °C. Generally, dopant was added to improve the sinterability of 8YSZ ceramics. In this present study, granulated 8YSZ powders with multimodal size was mixed with ZnO (0,1,2,3 wt%) using mortar and pestle. The mixed powder was compacted and sintered at 1550°C for 2 hours. 2 distinct endothermic peaks were observed in DTA plot of all samples. However, samples contain high amount of ZnO had a broader endothermic peak which resulted from the melting of ZnO. Rietveld refinement results indicate that the tetragonal phase appeared as the dominant phase for all doped and undoped samples, while cubic and monoclinic phase as the secondary phase. The monoclinic phase decreased as the amount of ZnO increased.

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