• Title/Summary/Keyword: Cubic zirconia

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Grain size, crystalline phase and fracture toughness of the monolithic zirconia

  • Bocam, Kodchakorn;Anunmana, Chuchai;Eiampongpaiboon, Trinuch
    • The Journal of Advanced Prosthodontics
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    • v.14 no.5
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    • pp.285-293
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    • 2022
  • PURPOSE. This study evaluated the relationship among translucency, crystalline phase, grain size, and fracture toughness of zirconia. MATERIALS AND METHODS. Four commercial zirconia - Prettau®Anterior® (PA), Prettau® (P), InCorisZI (ZI), and InCorisTZI (TZI)- were selected for this study. The bar specimens were prepared to determine fracture toughness by using chevron notched beam method with four-point bending test. The grain size was evaluated by a mean linear intercept method using a scanning electron microscope. X-ray diffraction and Rietveld refinement were performed to evaluate the amount of tetragonal and cubic phases of zirconia. Contrast ratio (CR) was measured to investigate the level of translucency. RESULTS. PA had the lowest fracture toughness among other groups (P < .05). In addition, the mean fracture toughness of P was significantly less than that of ZI, but there was no difference compared with TZI. Regarding grain size measurement, PA had the largest average grain size among the groups. P obtained larger grain size than ZI and TZI (P < .05). However, there was no significant difference between ZI and TZI. Moreover, PA had the lowest CR value compared with the other groups (P < .05). This means PA was the most translucent material in this study. Rietveld refinement found that PA presented the greatest percentage of cubic phase, followed by TZI, ZI, and P, respectively. CONCLUSION. The different approaches are used by manufacturers to fabricate various types of translucent zirconia with different levels of translucency and mechanical properties, which should be concerned for material selection for successful clinical outcome.

Fabrication of Zirconia Ceramic Fiber by Sol-Gel Processing: (II) The Doping Effect of CaO on Their Microstructure and Phase Transition (Sol-Gel법에 의한 $ZrO_2$ Ceramic Fiber 제조 : (II) CaO 첨가가 미세구조 및 상전이에 미치는 영향)

  • 김선욱;윤만순;송인호
    • Journal of the Korean Ceramic Society
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    • v.28 no.10
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    • pp.819-823
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    • 1991
  • Pure zirconia ceramic fiber experiences severe volume changes through thermal cyclings of heating and cooling. Zirconia fiber was doped with CaO to stabilize the phase and its effect of CaO was studied on volumetric ratio of each phases, phase transition temperature and microstructure. Tetragonal phase was increased as CaO increases up to 10 mol% and cubic phase was stabilized when CaO was added more than 10 mol%. The average grain size of zirconia fiber was increased as CaO increased and transition temperature was shifted to lower temperature.

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Thermal Diffusivity of Partially and Fully Stabilized Zirconia (부분 및 완전 안정화 지르코니아의 열확산 계수)

  • ;D. P, H hasselman;L, D. Bentsen;R, Syed
    • Journal of the Korean Ceramic Society
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    • v.22 no.4
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    • pp.40-46
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    • 1985
  • Thermal diffusivities of zirconia samples partially or fully stabilized by MgO and $Y_2O_3$ were measured b laser-flash method up to 140$0^{\circ}C$ The values of thermal diffusivity decreased as the contents of MgO and $Y_2O_3$ increased due to the phonon scattering effect of defect structure of cubic phase formed. The temperature dependence of thermal diffusivity showed that the thermal diffusivity values decreased due to phono-phonon scattering as the temperature increased. The difference in thermal diffusivity was observed on cooling after heating up to 140$0^{\circ}C$ for magnesia stabi-lized zirconia samples but not for yttria stabilized zirconia samples.

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The Fabrication and Their Properties of Zirconia-spinel COmposites by Reaction Sintering (반응소결에 의한 지르코니아-스피넬 복합체의 제조 및 성질)

  • 황규홍;김상모
    • Journal of the Korean Ceramic Society
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    • v.33 no.7
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    • pp.779-784
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    • 1996
  • The spinel/cubic stabilized zirconia composites were fabricated via, The reaction sintering of monoclinic zirco-nia(baddeleyite) added with MgAl powder. During heating Mg and Al were oxidizedfirst and subsequently the oxides formed spinel (MgAl2O4) and finally remained MgO stabilized the zirconia, Because the oxides formed during the oxidation process would have very fine grain size (order of submicron) mainly due to the effects of attrition milling the reaction sintering was more effective in densification and improvement of strength and fracture toughness than conventional sintering with direct addition of MgO. The sintering behavior phase transformation during firing and mechanical properties of sintered body were investigated with emphasis on the relations between spinel formation due to MgAl addition and sintering and mechanical properties.

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fabrication of Zirconia Thin Films by Plasma Enhanced Metal-Organic Chemical Vapor Deposition (플라즈마 유기금속 화학증착을 이용한 지르코니아 박막제조)

  • Kim, Gi-Dong;Jo, Yeong-A;Sin, Dong-Geun;Jeon, Jin-Seok;Choe, Dong-Su;Park, Jong-Jin
    • Korean Journal of Materials Research
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    • v.9 no.2
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    • pp.155-162
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    • 1999
  • Zirconia thin films of uniform structure were fabricated by plasma-enhanced metal-organic chemical vapor deposition. Deposition conditions such as substrate temperature were observed to have much influence on the formation of zirconia films, therefore the mechanism of decomposition of $Zr[TMHD]_4$precursor and film growth were examined by XRD, FT-IR etc., as well as the determination of the optimal deposition condition. From temperature dependence on zirconia, below the deposition temperature of 523K, the amorphous zirconia was formed while the crystalline of zirconia with preferred orientation of cubic (200) was obtained above the temperature. Deposits at low temperatures were investigated by FT-IR and the absorption band of films revealed that the zirconia thin film was in amorphous structure and has the same organic band as that of Zr precursor. In case of high temperature, it was found that Zr precursor was completely decomposed and crystalline zirconia was obtained. In addition, at 623K the higher RF power yielded the increased crystallinity of zirconia implying an increase in decomposition rate of precursor. However, it seems that RF power has nothing with the zirconia deposition process at 773K. It was found that the proper bubbler temperature of TEX>$Zr[TMHD]<_4$ precursor is needed along with high flow rate of carrier gas. Through AFM analysis it was determined that the growth mechanism of the zirconia thin film showed island model.

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Preparation of Yttria-stabilized Zirconia with Irregular Grain Shapes by Ceria Doping (CeO$_2$ 도핑에 의한 불규칙 입자형상의 이트리아 안정화 지르코니아 제조)

  • Lee, Jong-Kook;Kang, Hyun-Hee;Kim, Young-J.;Kim, Hwan
    • Journal of the Korean Ceramic Society
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    • v.35 no.12
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    • pp.1294-1300
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    • 1998
  • Yttria-stabilized zirconia ceramics with irregular grain shapes and curved grain boundaries was prepared by ceria doping. The amount of ceria doped into zirconia compacts by a dipping method were at range of 2 to 20 mol% Irregular grain shapes and curved grain boundaries were formed only inspecimens doped with more than 8mol% cerial. Ceria-doped specimens showed large grain size and low sintered density compared with pure yttria-stabilized zirconia which was due to the increase in the contents of stabilizer and cubic phase. The amount of doped ceria was larger on the surface than the inside regions and therefore mi-crostructure and phase on the surface were different from those in the inside regions. Transgranular frac-ture mode was observed ion ceria doped specimens due to irregular large grain sizes.

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Crack-Free Fabrications of Yttria-Stabilized Zirconia Films Using Successive-Ionic-Layer-Adsorption-and-Reaction and Air-Spray Plus Method

  • Taeyoon Kim;Sangmoon Park
    • Korean Journal of Materials Research
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    • v.34 no.2
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    • pp.79-84
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    • 2024
  • Thin films of yttria-stabilized zirconia (YSZ) nanoparticles were prepared using a low-temperature deposition and crystallization process involving successive ionic layer adsorption and reaction (SILAR) or SILAR-Air spray Plus (SILAR-A+) methods, coupled with hydrothermal (175 ℃) and furnace (500 ℃) post-annealing. The annealed YSZ films resulted in crystalline products, and their phases of monoclinic, tetragonal, and cubic were categorized through X-ray diffraction analysis. The morphologies of the as-prepared films, fabricated by SILAR and SILAR-A+ processes, including hydrothermal dehydration and annealing, were characterized by the degree of surface cracking using scanning electron microscopy images. Additionally, the thicknesses of the YSZ thin films were compared by removing diffusion layers such as spectator anions and water accumulated during the air spray plus process. Crack-free YSZ thin films were successfully fabricated on glass substrates using the SILAR-A+ method, followed by hydrothermal and furnace annealing, making them suitable for application in solid oxide fuel cells.

Comparison of mechanical and biological properties of zirconia and titanium alloy orthodontic micro-implants

  • Choi, Hae Won;Park, Young Seok;Chung, Shin Hye;Jung, Min Ho;Moon, Won;Rhee, Sang Hoon
    • The korean journal of orthodontics
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    • v.47 no.4
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    • pp.229-237
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    • 2017
  • Objective: The aim of this study was to compare the initial stability as insertion and removal torque and the clinical applicability of novel orthodontic zirconia micro-implants made using a powder injection molding (PIM) technique with those parameters in conventional titanium micro-implants. Methods: Sixty zirconia and 60 titanium micro-implants of similar design (diameter, 1.6 mm; length, 8.0 mm) were inserted perpendicularly in solid polyurethane foam with varying densities of 20 pounds per cubic foot (pcf), 30 pcf, and 40 pcf. Primary stability was measured as maximum insertion torque (MIT) and maximum removal torque (MRT). To investigate clinical applicability, compressive and tensile forces were recorded at 0.01, 0.02, and 0.03 mm displacement of the implants at angles of $0^{\circ}$, $10^{\circ}$, $20^{\circ}$, $30^{\circ}$, and $40^{\circ}$. The biocompatibility of zirconia micro-implants was assessed via an experimental animal study. Results: There were no statistically significant differences between zirconia micro-implants and titanium alloy implants with regard to MIT, MRT, or the amount of movement in the angulated lateral displacement test. As angulation increased, the mean compressive and tensile forces required to displace both types of micro-implants increased substantially at all distances. The average bone-to-implant contact ratio of prototype zirconia micro-implants was $56.88{\pm}6.72%$. Conclusions: Zirconia micro-implants showed initial stability and clinical applicability for diverse orthodontic treatments comparable to that of titanium micro-implants under compressive and tensile forces.

Absence of Distinctively High Grain-Boundary Impedance in Polycrystalline Cubic Bismuth Oxide

  • Jung, Hyun Joon;Chung, Sung-Yoon
    • Journal of the Korean Ceramic Society
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    • v.54 no.5
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    • pp.413-421
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    • 2017
  • In this work, we studied a fluorite structure oxides: Yttria stabilized zirconia, (YSZ); Gd doped $CeO_2$ (GDC); erbia stabilized $Bi_2O_3$ (ESB); Zr doped erbia stabilized $Bi_2O_3$ (ZESB); Ca doped erbia stabilized $Bi_2O_3$ (CESB) in the temperature range of 250 to $600^{\circ}C$ using electrochemical impedance spectroscopy (EIS). As is well known, grain boundary blocking effect was observed in YSZ and GDC. However, there is no grain boundary effect on ESB, ZESB, and CESB. The Nyquist plots of these materials exhibit a single arc at low temperature. This means that there is no space charge effect on ${\delta}-Bi_2O_3$. In addition, impedance data were analyzed by using the brick layer model. We indirectly demonstrate that grain boundary ionic conductivity is similar to or even higher than bulk ionic conductivity on cubic bismuth oxide.