Mechanical properties and phase-transformation behavior of carbon nanotube-reinforced yttria-stabilized zirconia composites

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.

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Effect of cooling rate on the phase transformation behavior and mechanical properties of Ni-rich NiTi shape memory alloy

Journal of Alloys and Compounds ◽

10.1016/j.jallcom.2008.01.153 ◽

2009 ◽

Vol 469 (1-2) ◽

pp. 164-168 ◽

Cited By ~ 51

Author(s):

Y. Motemani ◽

M. Nili-Ahmadabadi ◽

M.J. Tan ◽

M. Bornapour ◽

Sh. Rayagan

Keyword(s):

Mechanical Properties ◽

Phase Transformation ◽

Shape Memory Alloy ◽

Shape Memory ◽

Cooling Rate ◽

Niti Shape Memory Alloy ◽

Transformation Behavior ◽

Phase Transformation Behavior

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Microstructure and Mechanical Properties of Multiscale Zirconia Ceramics Prepared by Field Assisted Sintering Technique

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.697.354 ◽

2016 ◽

Vol 697 ◽

pp. 354-359

Author(s):

Khalid Eltayeb ◽

Dong Qin Jin ◽

Young Hwan Han ◽

Fei Chen ◽

Qiang Shen ◽

...

Keyword(s):

Mechanical Properties ◽

Flexural Strength ◽

Yttria Stabilized Zirconia ◽

Milling Machine ◽

Stabilized Zirconia ◽

Zirconia Ceramics ◽

Dense Structure ◽

Zirconia Composites ◽

20 Nm ◽

Field Assisted Sintering

Two kinds of powders of 3 mol. % yttria stabilized zirconia (3Y–TZP) with different particles sizes; one was 20 nm denoted by N whereas the other was 0.5 µm denoted by M, were mechanically mixed via ball milling machine using different amounts of N wt. % to obtain multiscale zirconia composite powder. Then the mixed powders were sintered by field assisted sintering technique (FAST). The effect of N content on the microstructure as well as on mechanical properties of zirconia is investigated. Results show that the microstructure of M completely surrounded by N emerged in zirconia composites, and tetragonal phase is presented in all the sintered samples. The obtained zirconia ceramics with 15 wt. % N own a highly dense structure (~ 99.9 % relative density) and high flexural strength of 813.59 MPa wherein a 15 % increase in flexural strength compared to zirconia ceramics without adding N, but the fracture toughness of the composites just lightly decreases. The improved flexural strength of the composites is caused by the multiscale effect.

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Evaluation of Phase Transformation and Mechanical Properties of Metastable Yttria-Stabilized Zirconia by Nanoindentation

Materials ◽

10.3390/ma12101677 ◽

2019 ◽

Vol 12 (10) ◽

pp. 1677 ◽

Cited By ~ 3

Author(s):

Ningning Song ◽

Ziyuan Wang ◽

Yan Xing ◽

Mengfei Zhang ◽

Peng Wu ◽

...

Keyword(s):

Mechanical Properties ◽

Phase Transformation ◽

Young’S Modulus ◽

Tetragonal Phase ◽

Young's Modulus ◽

Traditional Approach ◽

Yttria Stabilized Zirconia ◽

Phase Identification ◽

Stabilized Zirconia ◽

T Phase

Microscopical nonuniformity of mechanical properties caused by phase transformation is one of the main reasons for the failure of the materials in engineering applications. Accurate measurement of the mechanical properties of each phase is of virtual importance, in which the traditional approach like Vickers hardness cannot accomplish, due to the large testing range. In this study, nanoindentation is firstly used to analyze the mechanical properties of each phase and demonstrate the phase transformation in thermal barrier coatings during high-temperature aging. The distribution of T-prime metastable tetragonal phase, cubic and tetragonal phase is determined by mapping mode of nanoindentation and confirmed with X-ray diffraction and scanning electron microscope observation. The results show that during 1300 °C aging, the phase transition of metastable Yttria-Stabilized Zirconia induces the quick decrease of T′ phase content and an increase of T and C phases accordingly. It is found that there are some fluctuations in the mechanical properties of individual phase during annealing. The hardness and Young’s modulus of T′ increase at first 9 h, due to the precipitation of Y3+ lean T phase and then decrease to a constant value accompanied by the precipitation of Y3+ rich C phase. The relevant property of C phases also increases a little firstly and then decreases to a constant, due to the homogenization of Y3+ content, while the hardness and Young’s modulus of T phase remain unchanged. After aging of 24h the hardness of T′, C and T phases are 20.5 GPa, 21.3 GPa and 19.1 GPa, respectively. The Young’s modulus of T′, C and T phases are 274 GPa, 275 GPa and 265 GPa, respectively. Present work reveals the availability of nanoindentation method to demonstrate the phase transformation and measure mechanical properties of composites. It also provides an efficient application for single phase identification of ceramics.

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The Effect of Yttria-Stabilized Zirconia on the Properties of the Fluorine-Substituted Hydroxyapatite Ceramics Prepared by Pressureless Sintering

Journal of Biomimetics Biomaterials and Tissue Engineering ◽

10.4028/www.scientific.net/jbbte.1.57 ◽

2008 ◽

Vol 1 ◽

pp. 57-68 ◽

Cited By ~ 7

Author(s):

Y. Chen ◽

Z. Dong ◽

X. Miao

Keyword(s):

Mechanical Properties ◽

Thermal Decomposition ◽

Sol Gel ◽

Yttria Stabilized Zirconia ◽

Pressureless Sintering ◽

Stabilized Zirconia ◽

Gel Method ◽

Zirconia Composites ◽

Zirconia Phase ◽

Hydroxyapatite Phase

Hydroxyapatite-zirconia composites have received much attention during the last decade due to their combination of the desirable mechanical properties of zirconia and the excellent bioactivity of hydroxyapatite (HA). However, thermal decomposition of the hydroxyapatite phase and reaction between the zirconia phase and the hydroxyapatite phase remain a major problem in the hydroxyapatite-zirconia composites. In this study, thermally stable and fluorine-substituted hydroxyapatite (Ca10(PO4)6(OH)0.8F1.2; coded as HA06F) was prepared by a sol-gel method to replace the hydroxyapatite. Yttria-stabilized zirconia (YTZP) was also prepared by a sol-gel method in order to produce HA06F-YTZP composites with 5, 10, 15, 20, 40, and 60 wt% YTZP by simple and cost-effective pressureless sintering. Thermogravimetric analysis (TGA) and x-ray diffraction (XRD) of the HA06F-YTZP composites showed that the thermal stability of the HA06F matrices could be maintained when the YTZP content did not exceed 20 wt% and for sintering temperatures less than 1400 oC. Dilatometric analysis and microstructural observation revealed that the YTZP phase in the HA06F-YTZP composites retarded the densification of the composites if the zirconia content was over 20 wt%. Electron scanning microscopy (SEM) and high resolution transmission electron microscopy (HR-TEM) of the HA06F-YTZP composites showed that the YTZP second phase had a size in the nanometer scale and the reaction between the HA06F phase and the zirconia phase was suppressed. Mechanical properties including the Knoop hardness, the Young’s modulus, and the fracture toughness of the HA06F-YTZP composites increased with the YTZP content until the optimal content of 20 wt%; higher YTZP contents led to low mechanical properties due to poor densification of the composites and the severe thermal decomposition of the HA06F phase. The optimal HA06F-20YTZP composite also showed desirable attachment and proliferation of osteoblast cells. Nevertheless, the study of the composite system indicated the limitations of the pressureless sintering technique. To achieve the full potential of the composites for medium or low load bearing applications, a pressure-assisted sintering technique would still be necessary.

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