Deconvolving Ferroelastic and Phase Transformation Toughening in Pb(Zr1−x Ti x )O3 and Pb1−y La y (Zr1−x Ti x )O3

2012 ◽  
Vol 95 (12) ◽  
pp. 3713-3715 ◽  
Author(s):  
Yo-Han Seo ◽  
Kyle G. Webber ◽  
Andreja Benčan ◽  
Jurij Koruza ◽  
Barbara Malič ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Transformation Toughening ◽  
Phase Transformation Toughening

Toughening Analysis of Mixed Cracks in Transformation Toughened Ceramics on Influence of SD Effect

2010 ◽  
Vol 452-453 ◽  
pp. 145-148
Author(s):  
Zhen Qing Wang ◽  
Zeng Jie Yang ◽  
Li Qiang Tang
Keyword(s):  
Phase Transformation ◽  
Poisson Ratio ◽  
Yield Criterion ◽  
Parabolic Type ◽  
Zirconia Ceramic ◽  
Flow Rule ◽  
Mode I ◽  
Transformation Toughening ◽  
Ceramic Phase ◽  
Phase Transformation Toughening

Considering the SD effect, the parabolic-type yield criterion is obtained by using a new parameter. And by analogy with associated plastic flow rule, the ceramic phase transformation constitutive model is established. Under plane strain condition, the theoretical toughening expressions of mixed-mode I-II stationary cracks and steady-state growing cracks are developed by applying the weight function method. And the toughening effect is discussed under the influence of Poisson ratio, parameter and . The simulation results show that these phase transformation toughening effects are in good agreement with experimental results. And comparing with other yield criterions, it is more in line with actual characteristics of zirconia ceramic materials, when the expression of mixed I-II crack is reduced to mode I crack. And it also could provide theoretical support and reference for the further research of ceramic phase transformation toughening.

Ceramics Toughening Mechanism Study of Mixed-Mode I-III Cracks with a New Yield Criterion

2011 ◽  
Vol 27 (3) ◽  
pp. 409-414 ◽  
Author(s):  
Z.-J. Yang ◽  
Z.-Q. Wang ◽  
L.-Q Tang ◽  
X.-Y. Sun
Keyword(s):  
Phase Transformation ◽  
Steady State ◽  
Mixed Mode ◽  
Yield Criterion ◽  
Zirconia Ceramic ◽  
Mode I ◽  
Mode I Crack ◽  
Transformation Toughening ◽  
Phase Transformation Toughening ◽  
Growing Cracks

ABSTRACTConsidering the SD (strength differential) effect on compressive strength and tensile strength in zirconia ceramic material, a yield criterion with a special parameter is introduced. In addition, by analogy with associated flow rule, the constitutive model of phase transformation ceramic material has been established. Under generalized plane strain condition, the theoretical toughening expressions of mixed-mode I-III stationary cracks and steady-state growing cracks have been developed with the constitutive model. The crack toughening effect has been discussed in detail with the Poisson ratio, parameters k / α (the ratio of nominal yield strength and SD effect factor) and ω (the scale factor of mode I crack and mode III). The integral calculation shows that phase transformation toughening of stationary cracks is negative shielding effect and the toughening effect of the steady-state growing cracks change obviously with the increase of parameter k / α. Comparison between experimental data and theoretical data indicates that the yield criterion is in accord with the actual characteristics of the zirconia ceramic, when the expression of mixed-mode I-III crack is reduced to mode I crack. The results obtained in present paper can provide the useful theoretical reference for the research of phase transformation toughening in ceramic materials.

Two Morphologies of Tetragonal Phase in the MgO-PSZ Ceramics

2013 ◽  
Vol 750-752 ◽  
pp. 497-500
Author(s):  
Yun Fei Wang ◽  
Yun Kai Li ◽  
Chun Sun
Keyword(s):  
Heat Treatment ◽  
Phase Transformation ◽  
Tetragonal Phase ◽  
Isothermal Holding ◽  
Transformation Toughening ◽  
Treatment Processes ◽  
Result Show ◽  
Phase Transformation Toughening ◽  
T Phase ◽  
The Relationship

The relationship between microstructures and sintering, heat treatment processes have been investigated in 8mol% MgO-0.5mol% Y2O3-PSZ ceramics. The result show that the T phase exhibits two different morphologies during sintering below 1800°C and isothermal holding or aging anew at 1500°C. Their shape, size, distribution and stability all have obvious difference, so they have different effects on the phase transformation toughening.

The phase transformation toughening and synergism in poly(butylene terephthalate)/poly(tetramethyleneglycol) copolymer-modified epoxies

1998 ◽  
Vol 33 (9) ◽  
pp. 2421-2429 ◽  
Author(s):  
Sung Tae Kim ◽  
Junkyung Kim ◽  
Soonho Lim ◽  
Chul Rim Choe ◽  
Sung Tae Kim
Keyword(s):  
Phase Transformation ◽  
Transformation Toughening ◽  
Butylene Terephthalate ◽  
Phase Transformation Toughening

Effects of CeO2 on the Mechanical Property and Microstructure of 3Y-TZP Nanocomposite Ceramic Die Material

2010 ◽  
Vol 434-435 ◽  
pp. 42-44 ◽  
Author(s):  
Shi Kui Zhao ◽  
Chong Hai Xu
Keyword(s):  
Mechanical Property ◽  
Fracture Toughness ◽  
Phase Transformation ◽  
Flexural Strength ◽  
Raw Materials ◽  
Transformation Toughening ◽  
Toughening Mechanism ◽  
Obvious Effect ◽  
Die Material ◽  
Phase Transformation Toughening

Thermal stability and wear resistance of nanoceramic materials are excellent, so it is an ideal die material and has become one of the increasingly important topics in the field of die research. A new 3Y-TZP nanocomposite die material was prepared with hot pressing technique by using 3Y-TZP, CeO2, Al2O3 and nanometer sized TiC as raw materials. Effects of CeO2 on the mechanical property and microstructure of 3Y-TZP nanocomposite die material were investigated. The addition of CeO2 has obvious effect on the flexural strength and fracture toughness. When the content of CeO2 is 2mol%, the fracture toughness of the composite material reaches 11.22MPa•m1/2. With the increase of CeO2 content, the fracture toughness becomes lower, the flexural strength and hardness first increase and then decrease. When the CeO2 content is 6mol%, the maximum flexural strength reaches 866MPa. The reason for the improvement of mechanical property can be attributed to the effect of CeO2 on the phase transformation of t-ZrO2 and microstructure and the resulted phase transformation toughening mechanism.

Effect of Second Sintering on Intragranular Structure and Mechanical Properties of 10vol%Al2O3/3Y-TZP Composites

2007 ◽  
Vol 336-338 ◽  
pp. 1324-1326
Author(s):  
Xiu Hua Li ◽  
Rong Lei Men ◽  
Guan Wei Suo ◽  
Zheng Fang Yang
Keyword(s):  
Mechanical Properties ◽  
Phase Transformation ◽  
Electron Microscope ◽  
Intergranular Fracture ◽  
Transgranular Fracture ◽  
Transformation Toughening ◽  
Transmission Electron ◽  
Abnormal Increase ◽  
Small Grains ◽  
Phase Transformation Toughening

To study the effect of second sintering on intragranular structure and mechanical properties of 10vol%Al2O3/3Y-TZP composites, the composites were prepared by ball-milling nano-γ-Al2O3 and nano-ZrO2(3mol%Y2O3), pressing unidirectionally, cold-pressing isostatically, then first sintering at 1400°C for 2h and second sintering at 1600°C for 5h in air. The composition and microstructure of the composites were examined by X-ray diffractometer and scanning electron microscope, transmission electron microscope. The results showed that the second sintering changed the microstructure and fracture mode. After second sintering, the structure of fine grains was changed into the mixed one of large grains and small grains . Many large grains contained small grains, forming intragranular stucture that could be produced by the interblending of not only Al2O3 and ZrO2 but also ZrO2 itself. The intergranular fracture after first sintering was changed into transgranular fracture and intergranular fracture after second sintering . The second sintering led to grinds growing up and intragranular forming, which enhanced the contribution of the phase transformation toughening. Although the second sintering resulted in abnormal increase of grain size, the fracture strength and the fracture toughness of the composite were 667 MPa and 12.9 MPa⋅m1/2, respectively, due to the intragranular structure and the enhanced phase transformation toughening.

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