Transformation behavior of yttria stabilized tetragonal zirconia polycrystal–TiB2 composites

2001 ◽  
Vol 16 (7) ◽  
pp. 2158-2169 ◽  
Author(s):  
B. Basu ◽  
J. Vleugels ◽  
O. Van Der Biest
Keyword(s):  
Thermal Expansion ◽  
Phase Transformation ◽  
Low Temperature ◽  
Tetragonal Zirconia ◽  
Mechanical Analysis ◽  
Transformation Behavior ◽  
Thermal Expansion Data ◽  
Thermally Induced ◽  
First Time ◽  
Tetragonal Zirconia Polycrystal

The objective of the present article is to study the influence of TiB2 addition on the transformation behavior of yttria stabilized tetragonal zirconia polycrystals (Y-TZP). A range of TZP(Y)–TiB2 composites with different zirconia starting powder grades and TiB2 phase contents (up to 50 vol%) were processed by the hot-pressing route. Thermal expansion data, as obtained by thermo-mechanical analysis were used to assess the ZrO2 phase transformation in the composites. The thermal expansion hysteresis of the transformable ceramics provides information concerning the transformation behavior in the temperature range of the martensitic transformation and the low-temperature degradation. Furthermore, the transformation behavior and susceptibility to low-temperature degradation during thermal cycling were characterized in terms of the overall amount and distribution of the yttria stabilizer, zirconia grain size, possible dissolution of TiB2 phase, and the amount of residual stress generated in the Y-TZP matrix due to the addition of titanium diboride particles. For the first time, it is demonstrated in the present work that the thermally induced phase transformation of tetragonal zirconia in the Y-TZP composites can be controlled by the intentional addition of the monoclinic zirconia particles into the 3Y-TZP matrix.

Effect of Grain Boundary Segregated Dopant on Phase Stability in Tetragonal Zirconia Polycrystal

2010 ◽  
Vol 654-656 ◽  
pp. 2208-2211
Author(s):  
Yorinobu Takigawa ◽  
Takahisa Yamamoto ◽  
Kenji Higashi
Keyword(s):  
Grain Size ◽  
Phase Transformation ◽  
Grain Boundary ◽  
Phase Stability ◽  
Boundary Diffusion ◽  
Tetragonal Zirconia ◽  
Transformation Behavior ◽  
Hydroxyl Ion ◽  
Boundary Stress ◽  
Tetragonal Zirconia Polycrystal

The effect of grain boundary segregated dopant on phase stability of tetragonal zirconia polycrystal (TZP) is examined by accelerated exposure tests ageing in hot water. The materials used in this study are 3 mol%Y2O3 stabilized TZP (3Y-TZP) and 0.1mol%SiO2-doped 3Y-TZP. Accelerated exposure tests in an autoclave reveal that the tetragonal phase stability of 3Y-TZP in water is highly affected by the grain boundary segregated dopant and the grain size. When the grain size of TZP is about 0.55μm, the change in phase transformation behavior with dopant is explained from the change in grain boundary diffusivity of hydroxyl ion. Grain boundary diffusion of hydroxyl ion must be blocked by the presence of some segregated ion which reduces the effective area of grain boundary diffusion. On the other hand, when the grain size is about 0.35μm, the phase transformation behavior seems to be controlled by the grain boundary stress. Decreased grain boundary stress by the segregation of some dopant must enhance the phase transformation of 3Y-TZP.

scholarly journals Real-time observation of the thermally-induced phase transformation in GeTe and its thermal expansion properties

2019 ◽  
Vol 165 ◽  
pp. 327-335 ◽  
Author(s):  
Xuan Quy Tran ◽  
Min Hong ◽  
Hiroshi Maeno ◽  
Youichirou Kawami ◽  
Takaaki Toriyama ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Phase Transformation ◽  
Real Time ◽  
Thermally Induced ◽  
Time Observation ◽  
Real Time Observation

Thermal Expansion

1983 ◽  
pp. 75-132
Author(s):  
A. F. Clark
Keyword(s):  
Thermal Expansion ◽  
Low Temperature ◽  
Specific Heat ◽  
Measurement Techniques ◽  
Short Discussion ◽  
Thermal Expansion Data ◽  
Novel Materials ◽  
Advantages And Disadvantages ◽  
Expansion Theory ◽  
Methods Of Measurement

Abstract Specific heat and thermal expansion are closely related. Following a discussion on thermal expansion theory, methods of measurement techniques are presented along with their advantages and disadvantages. The results of the measurements are then summarized for three classes of materials: metallics, nonmetallics, and composites. Because predicting thermal expansion values for unmeasured or novel materials is useful, the chapter also describes the means of making educated guesses for low-temperature values. A short discussion on how thermal expansion data can be used is followed by a section describing where such data can be found.

scholarly journals Study of the Fracture Behavior of Tetragonal Zirconia Polycrystal with a Modified Phase Field Model

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4430 ◽  
Author(s):  
Jingming Zhu ◽  
Jun Luo ◽  
Yuanzun Sun
Keyword(s):  
Phase Transformation ◽  
Crack Propagation ◽  
Phase Field ◽  
Fracture Behavior ◽  
Tetragonal Zirconia ◽  
Finite Size ◽  
Phase Field Model ◽  
Crack Tip ◽  
Propagation Mode ◽  
Tetragonal Zirconia Polycrystal

The superior fracture toughness of zirconia is closely correlated with stress-induced martensitic phase transformation around a crack tip. In this study, a modified phase field (PF) model coupling phase transformation and fracture is proposed to study the fracture behavior and toughening effect of tetragonal zirconia polycrystal (TZP). The stress-induced tetragonal to monoclinic (t–m) phase transformation around a static or propagating crack is characterized with PF simulations. It is shown that the finite size and shape of the transformation zone under different loads and ambient temperatures can be well predicted with the proposed PF model. The phase transformation may decrease the stress level around the crack tip, which implies the toughening effect. After that, crack propagation in TZP is studied. As the stress field is perturbed by the phase transformation patterns, the crack may experience deflection and branching in the propagation process. It is found that the toughness of the grain boundaries (GBs) has important influences on the crack propagation mode. For TZP with strong GBs, the crack is more likely to propagate transgranularly while, for TZP with weak GBs, intergranular crack propagation is prevalent. Besides that, the crystal orientation and the external load can also influence the topology of crack propagation.

Effect of Low-Temperature Aging on Thermally-Induced Phase Transformation of NiTi Wire with a Wide Range of Grain Sizes

2021 ◽  
Vol 1042 ◽  
pp. 9-16
Author(s):  
Zhi Hao Zhao ◽  
Jian Ping Lin ◽  
Jun Ying Min ◽  
Yong Hou ◽  
Bo Sun
Keyword(s):  
Grain Size ◽  
Phase Transformation ◽  
Low Temperature ◽  
Thermally Induced ◽  
Grain Sizes ◽  
Average Grain Size ◽  
Wide Range ◽  
Low Temperature Aging ◽  
Niti Wires ◽  
Temperature Aging

Thermally-induced phase transformation (PT) is of significance and value to the application of NiTi alloy components. Low-temperature aging (LTA) treatment was used to alter PT characteristics of NiTi alloys avoiding undesirable grain growth. Effect of LTA on PT of NiTi wires with a wide range of grain sizes from 34 nm to 8021 nm was investigated in this study. As the average grain size varies from 34 to 217 nm, the temperature of the B2↔R transformation increase as a result of LTA, and the increasing effect is more obvious at a larger grain size. For NiTi alloys with average grain sizes ranging from 523 to 1106 nm, transformation sequence changes from B2↔B19' to B2↔R due to LTA. For the sample with an average grain size of 2190 nm, the B2↔B19' transformation is replaced by B2↔R←B19' after LTA. When the average grain size is larger than 2190 nm, transformation sequence changes from B2↔B19' to B2↔R↔B19' after LTA. Transmission emission microscope observations reveal that the above-mentioned PT behavior correlates with the coupled effect of grain size and precipitation. The precipitation of Ni4Ti3 in the grains with a size smaller than ~150 nm is inhibited after LTA, the temperature of B2→R of samples with average GS smaller than ~150 nm still is elevated due to the inhomogeneous grain size of NiTi wires.

Application of Micro-Raman Spectroscopy to the Study of Yttria-Stabilized Tetragonal Zirconia Polycrystal (Y-TZP) Phase Transformation

2015 ◽  
Vol 69 (7) ◽  
pp. 810-814 ◽  
Author(s):  
Carla Müller Ramos ◽  
Américo Sheitiro Tabata ◽  
Paulo Francisco Cesar ◽  
José Henrique Rubo ◽  
Paulo Afonso Silveira Fracisconi ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Phase Transformation ◽  
Tetragonal Zirconia ◽  
Micro Raman Spectroscopy ◽  
Tetragonal Zirconia Polycrystal

The Coefficients of Thermal Expansion of La2O3, TaVO5 and Ta16W18O94 Below Room Temperature

1986 ◽  
Vol 108 (3) ◽  
pp. 275-277 ◽  
Author(s):  
C. N. Chu ◽  
N. Saka ◽  
N. P. Suh
Keyword(s):  
Thermal Expansion ◽  
Phase Transformation ◽  
Room Temperature ◽  
Space Applications ◽  
Thermal Expansion Data ◽  
Temperature Range ◽  
Reversible Phase

The coefficients of thermal expansion (CTE) of La2O3, TaVO5 and Ta16W18O94 were measured in the temperature range 150–300 K for space applications. Hot pressed La2O3 showed a positive CTE of 8.6 × 10−6 K−1. Sintered TaVO5 had a positive and extraordinarily large CTE (50 × 10−6 K−1), but the CTE was negative (−4.0 × 10−6 K−1) in the temperature range 340–380 K. The thermal expansion data suggest a reversible phase transformation near 260 K. The CTE of hot pressed Ta16W18O94 was −1.52 × 10−6 K−1. Sintered Ta16W18O94 showed slight hysteresis, but the CTE was about −1.0 × 10−6 K−1.

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