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.

High-Cycle Fatigue Strength and Residual Stress in Welded Joints of Structural Steels

2004 ◽  
Author(s):  
Masahito Mochizuki ◽  
Masao Toyoda
Keyword(s):  
Residual Stress ◽  
Phase Transformation ◽  
Fatigue Strength ◽  
Low Temperature ◽  
Weld Metal ◽  
Welded Joints ◽  
Compressive Residual Stress ◽  
High Cycle Fatigue ◽  
Temperature Phase ◽  
Cycle Fatigue

Improvement of high-cycle fatigue strength by reducing residual stress in welded joints is studied in this paper. 10% Nickel and 10% Chromium are involved in the developed welding material for producing the property of thermal shrinkage by martensitic phase transformation at a low temperature and for generating compressive residual stress during cooling process. A cruciform fillet-welded joint is used for the numerical simulation of the thermal elastic-plastic finite-element analysis with coupling phase transformation effect. Distribution of the computed residual stress agrees with the measuring values by strain gauge. Compressive residual stress mostly distributes in the weld metal for both longitudinal and transverse directions with weld line. Fatigue test is also performed in order to clarify the effect of the developed weld material on fatigue strength. Developed weld metal has much higher characteristics for high-cycle fatigue strength than a conventional one. Increase effect of fatigue strength is shown by the modified Goodman diagram when residual stress is treated as mean stress. Weld metal with the property of low-temperature phase transformation is effective to reduce residual stress and to improve fatigue strength.

Residual Stress Redcution by Using Weld Metal With Property of Low-Temperature Phase Transformation

2004 ◽  
Author(s):  
Masahito Mochizuki ◽  
Masao Toyoda ◽  
Takahiro Kubo ◽  
Yasushi Morikage
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Phase Transformation ◽  
Low Temperature ◽  
Weld Metal ◽  
Compressive Residual Stress ◽  
Weld Line ◽  
Temperature Phase ◽  
Element Analysis ◽  
Low Temperature Phase

Residual stress in welded joints by using a new weld metal with the property of low-temperature phase transformation is numerically analyzed. 10 % Nickel and 10 % Chromium are involved in the developed welding material for producing the property of martensitic phase transformation at a low temperature and for generating compressive residual stress. A fillet-welded joint between plate and stiffener is used for the numerical simulation of the thermal elastic-plastic finite-element analysis with coupling phase transformation effect. Moving heat source is considered by using the gradual deposition of the finite-element during welding. Distribution of the computed residual stress mostly agrees with the measuring values by strain gauge. Compressive residual stress distributes in the weld metal for both longitudinal and transverse directions with weld line. The effects of the material of weld metal and welding pass sequence on residual stress are investigated. Residual stresses on the weld toe and root are improved lower by using the low-temperature transformation weld wire than the conventional one, regardless of the sequence of welding deposition. It is found that the weld metal with property of low-temperature phase transformation is effective to reduce residual stress near weld metal.

Evidence of stress-induced tetragonal-to-monoclinic phase transformation during sputter deposition of yttria-stabilized zirconia

2007 ◽  
Vol 22 (4) ◽  
pp. 1105-1111 ◽  
Author(s):  
Jeffrey R. Piascik ◽  
Qi Zhang ◽  
Christopher A. Bower ◽  
Jeffrey Y. Thompson ◽  
Brian R. Stoner
Keyword(s):  
Electron Microscopy ◽  
Phase Transformation ◽  
Compressive Stress ◽  
Sputter Deposition ◽  
Yttria Stabilized Zirconia ◽  
Film Stress ◽  
Steady Increase ◽  
Substrate Bias ◽  
Stabilized Zirconia ◽  
M Phase

Partially stabilized zirconia (PSZ) has been studied extensively, due to its high-temperature stability and stress-induced tetragonal (T)-to-monoclinic (M) martensitic phase transformation. This T ⇒ M phase transformation has been well-documented for bulk PSZ, but limited data exist for PSZ thin films. Data will be presented that support a stress-induced T ⇒ M transformation mechanism that occurs during sputter deposition in the presence of a substrate bias. Substrate bias (0–50 W) was originally applied to increase film density, modify microstructure, and vary film stress. The films were deposited using radio-frequency magnetron sputtering from a sintered yttria-stabilized zirconia target and were subsequently characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), x-ray diffraction (XRD), and wafer bow measurement (for stress analysis). With no substrate bias, the films exhibited a columnar grain structure that was consistent with sputter-deposited films, with a majority T phase as determined by XRD. Under higher substrate bias, wafer bow measurements indicated a steady increase in compressive stress as substrate bias increased (maximum, 310 MPa at 50-W bias), while XRD indicated a corresponding increase in the percentage of the M phase. Both SEM and TEM analyses revealed a shift from a defect-free columnar structure to one consisting of lateral intracolumnar or transgranular defects for films deposited under substrate-bias conditions. It is hypothesized that these defects form as a result of stress relief in the growing film via the T ⇒ M phase transformation due to bias-induced compressive stress.

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.

Medium-Low-Temperature NO2 Sensor Based on YSZ Solid Electrolyte and Mesoporous WO3 Sensing Electrode for Detection of Vehicle Emissions

NANO ◽  
2021 ◽  
pp. 2150083
Author(s):  
Cheng Zhang ◽  
Chuning Jiang ◽  
Xiaohong Zheng ◽  
Xin Hong
Keyword(s):  
Low Temperature ◽  
Electromotive Force ◽  
Electrochemical Impedance ◽  
Yttria Stabilized Zirconia ◽  
Mixed Potential ◽  
Stabilized Zirconia ◽  
Excellent Performance ◽  
Hard Template ◽  
No2 Sensor ◽  
Hard Template Method

A mixed potential-type NO2 sensor was fabricated using yttria-stabilized zirconia (YSZ) as the electrolyte and mesoporous WO3 as the sensing electrode for the detection of NO2 in vehicle exhausts. The mesoporous WO3 with a diameter of 7 nm was synthesized using the hard template method. The sensor showed excellent performance in the detection of 30–500[Formula: see text]ppm of NO2 at 300∘C and 500∘C. However, commercial WO3 only operate well at 500∘C. The response of the mesoporous WO3 was higher and the test temperature was lower compared to that of commercial WO3. XPS combined with NO2-TPD was used to explain the high activity of mesoporous WO3 at medium-low temperature, and the mechanism of mixed electromotive force was verified by electrochemical impedance spectroscopy. Furthermore, the sensor exhibited high NO2 selectivity in the presence of interfering gases, such as NO, CO, CO2 and NH3. Most importantly, the sensor had excellent repeatability and stability.

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.

Multiscale Surface Patterning of Zirconia by Picosecond Pulsed Laser Irradiation

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Yuka Yamamuro ◽  
Tomotaka Shimoyama ◽  
Isao Yamashita ◽  
Jiwang Yan
Keyword(s):  
Phase Transformation ◽  
Laser Irradiation ◽  
Pulsed Laser ◽  
Surface Patterning ◽  
Yttria Stabilized Zirconia ◽  
Surface Structures ◽  
Stabilized Zirconia ◽  
Periodic Surface ◽  
Thermally Induced ◽  
Pulsed Laser Irradiation

Abstract Irradiation of yttria-stabilized zirconia (YSZ) was performed by a picosecond pulsed laser to investigate the possibility for multiscale surface patterning. Nanoscale laser-induced periodic surface structures (LIPSS) were successfully generated inside microscale grooves over a large surface area under specific conditions. A thermally induced phase transformation of YSZ was identified after laser irradiation, and this phase transformation was restrained by reducing the laser power or the number of irradiations. Moreover, it was found that the generation of LIPSS greatly changed the surface wettability of YSZ. These results demonstrated the possibility of creating zirconia hybrid patterns with high functionality, which may expand the applications of YSZ in industry.

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