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Matsuzawa, M.; Yajima, Naonari; Horibe, S.

doi:10.1023/a:1004759829255

Cited by 9 publications

(4 citation statements)

References 16 publications

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“…Note that, for the cyclic indentation of brittle materials, e.g. ceramics, most studies have been focused on the fatigue damage accumulation [30,31], the strength degradation [32], and the crack evolution in contact area [33]. Few studies have reported the h-t curves.…”

Section: Resultsmentioning

confidence: 99%

Viscoplastic response of tooth enamel under cyclic microindentation

Jia

Xuan

Yang

2015

Materials Science and Engineering: C

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Section: Resultsmentioning

confidence: 99%

Viscoplastic response of tooth enamel under cyclic microindentation

Jia

Xuan

Yang

2015

Materials Science and Engineering: C

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“…Therefore, we insist that this concept should not be applied to the case of the tensile fracture behavior of zirconia ceramics. Besides which, taking into account that at most, only a few dislocations originally exist in the matrix and that even if there are any, slip is so much harder to achieve in brittle ceramics than metal, ADOV 9,10,[13][14][15][16][17][18] presents itself as the most probable thermally-activated mechanism that causes the strain rate dependence in zirconia ceramics. It should be noted that the strain rate dependence of tensile fracture strength is also observed only in Y-TZP and Mg-PSZ, which have the anelastic properties shown in Fig.…”

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confidence: 99%

“…4,6,7) Moreover, these studies have been carried out under compression testing, with the discussion focusing on tensile crack growth. [2][3][4][5][6][7] In this study, we conducted dynamic tensile testing over a wide range of strain rates for four kinds of zirconia ceramics, which have different mechanical properties, transformability, anelastic properties 9,10,[13][14][15][16][17][18] and so on. Dynamic fracture testing was also carried out in vacuum in order to verify the true effect of subcritical microcrack growth on the strain rate dependence of tensile fracture strength.…”

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confidence: 99%

“…This is because the crack initiates more easily in Mg-PSZ than in Ce-TZP, which limits the extent of the subsequent transformation, as verified in our previous indentation testing. 15) In short, the first occurrence of microcracking easily tends to lead to the fatal failure in the case of Mg-PSZ. Even if microcracking occurs in Ce-TZP, it is instantly closed by a remarkable transformation and then the stress concentration is released, resulting in a large disparity between n T and m (Sec.…”

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Strain Rate Dependence of Tensile Behavior and Environmental Effect in Zirconia Ceramics

2003

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The tensile strength of four kinds of zirconia ceramics (two kinds of Y-TZP with different grain sizes, Mg-PSZ and Ce-TZP) has been investigated for a wide range of strain rates (3ϫ10 Ϫ9 -1.0ϫ10 Ϫ1 s Ϫ1) in both air and vacuum. The obviously unique strain rate dependence was observed in Y-TZPs and Mg-PSZ, which have anelastic properties. On the other hand, such strain rate dependence was not observed over the whole range of strain rates for Ce-TZP, which does not exhibit anelasticity. For all of the samples investigated, there was no significant difference between both values of tensile fracture strength in air and vacuum. It was found that a decrease in strength with decreasing strain rate should not be associated with the static fatigue growth of microcracks nucleated during loading. It was concluded that the extent of the occurrence and the exhaustion of anelasticity predominantly controls the tensile strength of zirconia ceramics.KEY WORDS: anelasticity; ADOV; ceramics; fatigue; fracture and fracture toughness. materials are degraded in hydrogen environment. 11,12) However, the extent of the strength degradation or static fatigue in hydrogen is lower than that in air, as reported in alumina and zirconia ceramics.11,12) Therefore, it is much more important to examine the mechanical behavior in air from the view point of clarifying the environmental effect in the ceramic materials loaded. There are quite a few reports that discuss the strain rate effect in zirconia ceramics. 4,6,7) Moreover, these studies have been carried out under compression testing, with the discussion focusing on tensile crack growth. [2][3][4][5][6][7] In this study, we conducted dynamic tensile testing over a wide range of strain rates for four kinds of zirconia ceramics, which have different mechanical properties, transformability, anelastic properties 9,10,13-18) and so on. Dynamic fracture testing was also carried out in vacuum in order to verify the true effect of subcritical microcrack growth on the strain rate dependence of tensile fracture strength. Possible Mechanism of Anelasticity in Zirconia CeramicsIn our recent work, 17,18) we have investigated anelastic behavior in some kinds of zirconia ceramics. Figure 2 shows the anelastic behavior in four kinds of materials (Y-TZP, Y-FSZ, Mg-PSZ and Ce-TZP) at 100 MPa and loadholding time of 10 h.18) This figure indicates that anelastic strain is produced in the Y 2 O 3 -ZrO 2 and MgO-ZrO 2 systems, but almost not in the CeO 2 -ZrO 2 system, irrespectively of the kind of crystallographic phase. This anelastic phenomenon appears even at extremely low stress level (Ͻ100 MPa) and produces time-dependent and recoverable strain.9,10) Therefore, such a unique behavior cannot be explained by conventional mechanism, for example, stress-induced phase transformation, [19][20][21] ferroelastic domain switching, [22][23][24][25] microcracking [26][27][28] and so on. It is well known that the large amount of oxygen vacancy is introduced in matrix of the Y 2 O 3 -ZrO 2 and MgO-ZrO 2 systems in order...

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Effect of fatigue on fracture toughness and phase transformation of Y‐TZP ceramics by X‐ray diffraction and Raman spectroscopy

Nemli¹,

Yılmaz²,

Aydın³

et al. 2011

J Biomed Mater Res

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The aim of this study was to evaluate the effect of fatigue on fracture toughness and phase transformation of yttria-stabilized zirconia polycrystal materials (Cercon and Lava). The specimens were tested for indentation fracture toughness either with or without being subjected to fatigue (20,000 cycles, 2 Hz, 200 N load). X-ray diffraction (XRD) analysis was used to examine the phase composition of specimens. The indentation images were analyzed using Raman spectroscopy at indentation center (p1), indentation corner (p2), points on crack 100 μm (p3), and 200 μm (p4) away from the corner and a point ∼80 μm away from the crack (p5). Fracture toughness results were statistically analyzed by two-way analysis of variance (ANOVA); XRD and Raman spectroscopy results were analyzed by three-way ANOVA. Fracture toughness of Cercon control (CC) and fatigue (CF) groups were 6.8 and 6.9 MPa√m, respectively, with no significant difference (p > 0.01). Fracture toughness of Lava fatigue (LF; 7.3 MPa√m) was significantly higher than Lava control (LC; p < 0.01). XRD analyses showed CC and LC consisted of tetragonal zirconia, monoclinic zirconia detected after fatigue. After indentation, relative amount of monoclinic phase significantly increased in CC, CF, and LC; decreased in LF. The Raman spectroscopy results indicated that monoclinic fraction was the highest at p2, subsequently at p1 and decreased at p3, p4, and p5 for all groups. Mechanical cycling increased fracture toughness of Cercon and Lava, the second being significant. Phase transformation was also detected after fatigue, which is higher in Lava. Analysis of indentations showed that transformation was highest was at the corner, second at center.

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Cited by 9 publications

References 16 publications

Viscoplastic response of tooth enamel under cyclic microindentation

Viscoplastic response of tooth enamel under cyclic microindentation

Strain Rate Dependence of Tensile Behavior and Environmental Effect in Zirconia Ceramics

Effect of fatigue on fracture toughness and phase transformation of Y‐TZP ceramics by X‐ray diffraction and Raman spectroscopy

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