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Zainal Arifin Ahmad - One of the best experts on this subject based on the ideXlab platform.
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Structural Characteristic and Dielectric Properties of Zirconia Toughened Alumina
Materials Science Forum, 2020Co-Authors: Nik Akmar Rejab, Wan Fahmin Faiz Wan Ali, Mohd Fadzil Ain, Zainal Arifin Ahmad, Norazharuddin Shah AbdullahAbstract:Zirconia Toughened Alumina (ZTA) has shown a great effect in the cutting tool application due to its high hardness and comparable fracture toughness. However, the capability of the materials to be applied in as the dielectric resonator antenna (DRA) is not being discussed in detail. In this study, an attempt is made to further explore the potential of ZTA to be applied in DRA. Various related characterization techniques were applied that is subjected to DRA properties. The addition of CeO2 (0 wt.% to 15 wt.%) on ZTA has been pressed into pellets shape and sintered at 1600 °C for 2 hours under pressureless conditions. Based on the XRD analysis, only corundum and yttria doped Zirconia phases were present. Shift in position of the Zirconia peaks was observed due to an existence of Ce2Zr3O10 phase. For the DRA measurement, ZTA with 10 wt.% CeO2 addition have resonated at 6.76 GHz which is suitable for X-band applications. Meanwhile the radiation pattern indicated the omnidirectional characteristic, which suggested that the signal could be received by this dielectric antenna in various positions. Therefore, ZTA- 10 wt.% CeO2 have high potential to be used as DRA that operates X-band frequency range applications.
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The capability of hibonite elongated grains to influence physical, microstructural, and mechanical properties of Zirconia Toughened Alumina–CeO2–MgO ceramics
International Journal of Refractory Metals & Hard Materials, 2016Co-Authors: Nik Akmar Rejab, Zhwan Dilshad Ibrahim Sktani, Tan Yong Dar, Wan Fahmin Faiz Wan Ali, Abdul Rashid Jamaludin, Zainal Arifin AhmadAbstract:Abstract This work investigated the capability of hibonite (CaAl 12 O 19 ) phase on structure and microstructure of Zirconia Toughened Alumina–CeO 2 –MgO ceramics. Three different additives (CeO 2 , MgO and CaCO 3 ) were introduced into Zirconia Toughened Alumina ceramics prepared by solid state reaction. X-ray diffraction and FESEM analyses were employed to observe the role of secondary phases especially hibonite and its influence on the microstructural features and other properties. Among the secondary phases present, EDX analysis revealed that hibonite phase contributed to elongated grains. Vickers indentations hinted a strong difference in the efficiency of compositional adjustment among the composites. The excellent Vickers hardness and fracture toughness results obtained for 3 wt.% CaCO 3 additions showed the appearance of 5.9% hibonite with the value of 1485 HV and 7.10 MPa·√m, respectively.
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Role of MgO nanoparticles on Zirconia-Toughened Alumina-5 wt-% CeO2 ceramics mechanical properties
Materials Science and Technology, 2016Co-Authors: Nik Akmar Rejab, Ahmad Zahirani Ahmad Azhar, Mani Maran Ratnam, Zainal Arifin AhmadAbstract:The poor hardness of Zirconia-Toughened Alumina (ZTA) with 5 wt-% CeO2 (ZTA5CeO2) ceramic has limited its applications as a cutting insert. Therefore, in this work, the possibility of MgO nanoparticles (20 nm) as reinforcement to ZTA5CeO2 ceramics was investigated. Mgo nanoparticles with different weight percentages (0-2 wt-%) were added to ZTA5CeO2 ceramics. ZTA5CeO2 with 0.5 wt-%MgO showed the highest fracture toughness of 9.14 MPa.√m. The addition of 0.5 wt-%MgO nanoparticles showed the excellent role of MgAl11CeO19 grains as a crack deflector, which consequently produced a reasonable hardness value of 1591 HV and lowered the wear areas to 0.0528 mm2.
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Effect of Cr2O3-TiO2 Addition on the Physical Properties of Zirconia Toughened Alumina
Materials Science Forum, 2016Co-Authors: Hanisah Manshor, E C Abdullah, Abdul Wahid Ramli, Ahmad Zahirani Ahmad Azhar, Zainal Arifin AhmadAbstract:Zirconia Toughened Alumina (ZTA) has good mechanical properties and widely used in cutting insert application. Although the ZTA is well known of its good mechanical properties, its still can be improved in order to produce better properties. It can be done by adding additives as reinforcement such as magnesium oxide (MgO), cerium oxide (CeO), titania (TiO2) and chromia (Cr2O3). The effect of TiO2-Cr2O3 addition on the physical properties of ZTA were investigated in this study. The composition of TiO2 was varied from 0 wt% to 3.5 wt% while Cr2O3 was fixed at 5 wt%. The starting powder materials were mixed by wet mixing for 30 minutes in acetone. Then the powder mixtures were hydraulically pressed at 260 MPa. The green pellets were sintered at 1600°C for 1 hour using an electrical furnace in presureless condition. The results were characterized by XRD, density, and also Vickers hardness. The ZTA-Cr2O3-TiO2 ceramic composite achieved the highest density of 4.1 g/cm3 and Vickers hardness of 1919 HV prior to the addition of 2.0 wt% TiO2. Therefore, it can be decisively concluded that the addition of Cr2O3-TiO2 does affected the properties of ZTA.
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Effect of Titania and Magnesia on the Physical Properties of Zirconia Toughened Alumina
Materials Science Forum, 2016Co-Authors: Hanisah Manshor, E C Abdullah, Abdul Wahid Ramli, Wan Muhammad Ihsan Wan Sabri, Ahmad Zahirani Ahmad Azhar, Zainal Arifin AhmadAbstract:ZTA based ceramic composite system is widely accepted as cutting tools for many of these harder and wear resistant workpiece materials. This is due to their beneficial mechanical properties i.e. high temperature strength, high hardness and ability to maintain its cutting edge shape at higher temperatures. Although a lot of works have focused on the effect of various sintering additives on the ZTA ceramic system, the effect of Magnesia (MgO) and Titania (TiO2) on ZTA has not yet been studied. In this work, the physical properties of Zirconia Toughened Alumina (ZTA) ceramic composite with MgO and TiO2 as additives was investigated. The composition of TiO2 varied from 0 wt% to 3.5 wt% whereby other materials such as Al2O3, Yttria Stabilized Zirconia (YSZ) and MgO were kept at constant weight percentage. Sintered samples were then tested and analyzed by XRD, Vickers hardness and high precision densimeter to investigate phase content, hardness value and densification respectively. Results showed that the solubility limit of TiO2 in ZTA-MgO ceramic composites is at 2.0 wt%. Further addition of TiO2 resulted in the formation of secondary phase known as Zirconium titanium oxide (Zr0.35TiO0.65O2) which deteriorate the properties exhibited by ZTA-MgO-TiO2 ceramic composites.
Zainal Arifi Ahmad - One of the best experts on this subject based on the ideXlab platform.
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the capability of hibonite elongated grains to influence physical microstructural and mechanical properties of Zirconia Toughened Alumina ceo2 mgo ceramics
International Journal of Refractory Metals & Hard Materials, 2016Co-Authors: Nik Akmar Rejab, Zhwan Dilshad Ibrahim Sktani, Wan Fahmin Faiz Wa Ali, Abdul Rashid Jamaludi, Zainal Arifi AhmadAbstract:Abstract This work investigated the capability of hibonite (CaAl 12 O 19 ) phase on structure and microstructure of Zirconia Toughened Alumina–CeO 2 –MgO ceramics. Three different additives (CeO 2 , MgO and CaCO 3 ) were introduced into Zirconia Toughened Alumina ceramics prepared by solid state reaction. X-ray diffraction and FESEM analyses were employed to observe the role of secondary phases especially hibonite and its influence on the microstructural features and other properties. Among the secondary phases present, EDX analysis revealed that hibonite phase contributed to elongated grains. Vickers indentations hinted a strong difference in the efficiency of compositional adjustment among the composites. The excellent Vickers hardness and fracture toughness results obtained for 3 wt.% CaCO 3 additions showed the appearance of 5.9% hibonite with the value of 1485 HV and 7.10 MPa·√m, respectively.
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effect of titania tio2 addition to Zirconia Toughened Alumina zta phases hardness and microstructure
Advanced Materials Research, 2015Co-Authors: Hanisah Mansho, Suriyana Md Aris, Ahmad Zahirani Ahmad Azha, E C Abdullah, Zainal Arifi AhmadAbstract:Ceramic composites consist of Zirconia Toughened Alumina (ZTA) with TiO2 as additive was fabricated via solid state sintering route. Numerous studies have indicated that TiO2 can be used as sintering additives for Al2O3 and the ability of microstructural control introduce by TIO2. The Vickers hardness of the obtained ZTA-TiO2 was evaluated as a function of different TiO2 addition. Each sample was dry mixed, uniaxially pressed and sintered at 1600 °C for 4 hours in pressureless condition. It is noticed that the presence of TiO2 greatly influence the microstructure of Al2O3. Al2O3 grains tend to increase in size with more addition of TiO2. Characteristics of Vickers hardness increases increases from 1516.13 HV (0 wt% TiO2) to 1615.8 HV (3 wt% TiO2). Addition of TiO2 also increases the bulk density of ZTA-TiO2 from 3.90 g/cm3 (0 wt% TiO2) to 4.10 g/cm3 (3 wt% TiO2).
Ramón Torrecillas - One of the best experts on this subject based on the ideXlab platform.
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Low-temperature ageing of Zirconia-Toughened Alumina ceramics and its implication in biomedical implants
Journal of the European Ceramic Society, 2017Co-Authors: Sylvain Deville, Jose Bartolome, Gilbert Fantozzi, Ramón Torrecillas, Jérôme Chevalier, Joaquim Requena, Jose S Moya, L A DiazAbstract:Changes in crystalline phases resulting from low-temperature ageing of different yttria doped and non-doped Zirconia-Toughened Alumina composites and nanocomposites were investigated under controlled humidity and temperature conditions in autoclave. A classical powder mixing processing route and a new modified colloidal processing route were used to process the composites. Different compositions ranging from 2.5 wt.% Zirconia in a matrix of Alumina to pure Zirconia (3YTZP) were studied. It was observed that Al2O3+yttria stabilised ZrO2 composites exhibited significant ageing. However, ageing was much slower than traditionally observed for YTZP ceramics, due to the presence of the Alumina matrix. Ageing was clearly limited for Zirconia content beyond 25 wt.%. On the other side of the spectrum, Al2O3+2.5 wt.% ZrO2 initially presented a monoclinic fraction but did not show any ageing degradation. These composites seem to represent the best choice between slow crack growth and ageing resistance
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slow crack growth behavior of Zirconia Toughened Alumina ceramics processed by different methods
Journal of the American Ceramic Society, 2003Co-Authors: A H De Aza, Gilbert Fantozzi, Jerome Chevalie, M Schehl, Ramón TorrecillasAbstract:A study of slow-crack propagation in Zirconia-Toughened Alumina (ZTA) ceramics is presented. Different ZTA composites, using either unstabilized or yttria-stabilized Zirconia, have been tested. The materials were prepared in the range 0-15 vol % ZrO 2 , using two processing methods: powder mixing and a modified colloidal route. Crack propagation tests have been conducted for crack velocities from 10 -12 to 10 -2 m/s by means of a double-torsion method. The influence of the processing conditions and compositions on the microstructures and the effect of these microstructures on the slow-crack-growth behavior have been studied. The option that these composites may offer in terms of the lifetime of ceramic joint prostheses is discussed.
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low temperature ageing of Zirconia Toughened Alumina ceramics and its implication in biomedical implants
Journal of The European Ceramic Society, 2003Co-Authors: Sylvain Deville, Gilbert Fantozzi, Ramón Torrecillas, Jerome Chevalie, Jose F Artolome, Joaquim Requena, Jose S Moya, L A DiazAbstract:Changes in crystalline phases resulting from low-temperature ageing of different yttria doped and non-doped Zirconia-Toughened Alumina composites and nanocomposites were investigated under controlled humidity and temperature conditions in autoclave. A classical powder mixing processing route and a new modified colloidal processing route were used to process the composites. Different compositions ranging from 2.5 wt.% Zirconia in a matrix of Alumina to pure Zirconia (3Y–TZP) were studied. It was observed that Al2O3+yttria stabilised ZrO2 composites exhibited significant ageing. However, ageing was much slower than traditionally observed for Y–TZP ceramics, due to the presence of the Alumina matrix. Ageing was clearly limited for Zirconia content beyond 25 wt.%. On the other side of the spectrum, Al2O3+2.5 wt.% ZrO2 initially presented a monoclinic fraction but did not show any ageing degradation. These composites seem to represent the best choice between slow crack growth and ageing resistance. # 2003 Elsevier Ltd. All rights reserved.
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crack growth resistance of Alumina Zirconia and Zirconia Toughened Alumina ceramics for joint prostheses
Biomaterials, 2002Co-Authors: A H De Aza, Gilbert Fantozzi, Jerome Chevalie, M Schehl, Ramón TorrecillasAbstract:Mono-phase bio-ceramics (Alumina and Zirconia) are widely used as femoral heads in total hip replacements (THR) as an alternative to metal devices. Unfortunately, the orthopaedic community reports significant in-vivo failures. Material scientists are already familiar with composites like Alumina Zirconia. Since both are biocompatible, this could prove to be a new approach to implants. This paper deals with a new generation of Alumina-Zirconia nano-composites having a high resistance to crack propagation, and as a consequence may offer the option to improve lifetime and reliability of ceramic joint prostheses. The reliability of the above mentioned three bio-ceramics (Alumina, Zirconia and Zirconia Toughened Alumina) for THR components is analysed based on the study of their slow crack-growth behaviour. The influence of the processing conditions on the microstructure development, of the Zirconia Toughened Alumina composites and the effect of these microstructures, on its mechanical properties, are discussed.
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crack growth resistance of Alumina Zirconia and Zirconia Toughened Alumina ceramics for joint prostheses
Biomaterials, 2002Co-Authors: Jérôme Chevalier, Gilbert Fantozzi, M Schehl, Ramón TorrecillasAbstract:Mono-phase bio-ceramics (Alumina and Zirconia) are widely used as femoral heads in total hip replacements (THR) as an alternative to metal devices. Unfortunately, the orthopaedic community reports significant in-vivo failures. Material scientists are already familiar with composites like Alumina–Zirconia. Since both are biocompatible, this could prove to be a new approach to implants. This paper deals with a new generation of Alumina–Zirconia nano-composites having a high resistance to crack propagation, andas a consequence may offer the option to improve lifetime andreliability of ceramic joint prostheses. The reliability of the above mentionedthree bio-ceramics (Alumina, Zirconia andZirconia ToughenedAlumina) for THR components is analysed based on the study of their slow crack-growth behaviour. The influence of the processing conditions on the microstructure development, of the Zirconia Toughened Alumina composites and the effect of these microstructures, on its mechanical properties, are discussed. r 2001 Publishedby Elsevier Science Ltd .
Nik Akmar Rejab - One of the best experts on this subject based on the ideXlab platform.
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Structural Characteristic and Dielectric Properties of Zirconia Toughened Alumina
Materials Science Forum, 2020Co-Authors: Nik Akmar Rejab, Wan Fahmin Faiz Wan Ali, Mohd Fadzil Ain, Zainal Arifin Ahmad, Norazharuddin Shah AbdullahAbstract:Zirconia Toughened Alumina (ZTA) has shown a great effect in the cutting tool application due to its high hardness and comparable fracture toughness. However, the capability of the materials to be applied in as the dielectric resonator antenna (DRA) is not being discussed in detail. In this study, an attempt is made to further explore the potential of ZTA to be applied in DRA. Various related characterization techniques were applied that is subjected to DRA properties. The addition of CeO2 (0 wt.% to 15 wt.%) on ZTA has been pressed into pellets shape and sintered at 1600 °C for 2 hours under pressureless conditions. Based on the XRD analysis, only corundum and yttria doped Zirconia phases were present. Shift in position of the Zirconia peaks was observed due to an existence of Ce2Zr3O10 phase. For the DRA measurement, ZTA with 10 wt.% CeO2 addition have resonated at 6.76 GHz which is suitable for X-band applications. Meanwhile the radiation pattern indicated the omnidirectional characteristic, which suggested that the signal could be received by this dielectric antenna in various positions. Therefore, ZTA- 10 wt.% CeO2 have high potential to be used as DRA that operates X-band frequency range applications.
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the capability of hibonite elongated grains to influence physical microstructural and mechanical properties of Zirconia Toughened Alumina ceo2 mgo ceramics
International Journal of Refractory Metals & Hard Materials, 2016Co-Authors: Nik Akmar Rejab, Zhwan Dilshad Ibrahim Sktani, Wan Fahmin Faiz Wa Ali, Abdul Rashid Jamaludi, Zainal Arifi AhmadAbstract:Abstract This work investigated the capability of hibonite (CaAl 12 O 19 ) phase on structure and microstructure of Zirconia Toughened Alumina–CeO 2 –MgO ceramics. Three different additives (CeO 2 , MgO and CaCO 3 ) were introduced into Zirconia Toughened Alumina ceramics prepared by solid state reaction. X-ray diffraction and FESEM analyses were employed to observe the role of secondary phases especially hibonite and its influence on the microstructural features and other properties. Among the secondary phases present, EDX analysis revealed that hibonite phase contributed to elongated grains. Vickers indentations hinted a strong difference in the efficiency of compositional adjustment among the composites. The excellent Vickers hardness and fracture toughness results obtained for 3 wt.% CaCO 3 additions showed the appearance of 5.9% hibonite with the value of 1485 HV and 7.10 MPa·√m, respectively.
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The capability of hibonite elongated grains to influence physical, microstructural, and mechanical properties of Zirconia Toughened Alumina–CeO2–MgO ceramics
International Journal of Refractory Metals & Hard Materials, 2016Co-Authors: Nik Akmar Rejab, Zhwan Dilshad Ibrahim Sktani, Tan Yong Dar, Wan Fahmin Faiz Wan Ali, Abdul Rashid Jamaludin, Zainal Arifin AhmadAbstract:Abstract This work investigated the capability of hibonite (CaAl 12 O 19 ) phase on structure and microstructure of Zirconia Toughened Alumina–CeO 2 –MgO ceramics. Three different additives (CeO 2 , MgO and CaCO 3 ) were introduced into Zirconia Toughened Alumina ceramics prepared by solid state reaction. X-ray diffraction and FESEM analyses were employed to observe the role of secondary phases especially hibonite and its influence on the microstructural features and other properties. Among the secondary phases present, EDX analysis revealed that hibonite phase contributed to elongated grains. Vickers indentations hinted a strong difference in the efficiency of compositional adjustment among the composites. The excellent Vickers hardness and fracture toughness results obtained for 3 wt.% CaCO 3 additions showed the appearance of 5.9% hibonite with the value of 1485 HV and 7.10 MPa·√m, respectively.
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Role of MgO nanoparticles on Zirconia-Toughened Alumina-5 wt-% CeO2 ceramics mechanical properties
Materials Science and Technology, 2016Co-Authors: Nik Akmar Rejab, Ahmad Zahirani Ahmad Azhar, Mani Maran Ratnam, Zainal Arifin AhmadAbstract:The poor hardness of Zirconia-Toughened Alumina (ZTA) with 5 wt-% CeO2 (ZTA5CeO2) ceramic has limited its applications as a cutting insert. Therefore, in this work, the possibility of MgO nanoparticles (20 nm) as reinforcement to ZTA5CeO2 ceramics was investigated. Mgo nanoparticles with different weight percentages (0-2 wt-%) were added to ZTA5CeO2 ceramics. ZTA5CeO2 with 0.5 wt-%MgO showed the highest fracture toughness of 9.14 MPa.√m. The addition of 0.5 wt-%MgO nanoparticles showed the excellent role of MgAl11CeO19 grains as a crack deflector, which consequently produced a reasonable hardness value of 1591 HV and lowered the wear areas to 0.0528 mm2.
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Structural and Microstructure Relationship with Fracture Toughness of CeO2 Addition into Zirconia Toughened Alumina (ZTA) Ceramic Composites
Advanced Materials Research, 2012Co-Authors: Nik Akmar Rejab, Ahmad Zahirani Ahmad Azhar, Mani Maran Ratnam, Zainal Arifin AhmadAbstract:The effect of CeO2 addition in Zirconia Toughened Alumina (ZTA) was examined. The CeO2 addition in weight percent (wt %) was varied from 0 wt% to 15 wt%. The fabricated samples were sintered at a temperature of 1600°C. The sintered samples were characterized their properties such as fracture toughness and phase determination. X-ray diffraction patterns confirm the constituent phases present in the samples were Alumina and Zirconia. Fracture toughness for each sample in the range of 5.878.38 MPam1/2 respectively. It was observed that the addition of ceria increased the fracture toughness of the Zirconia Toughened Alumina ceramic composites.
Raine Gadow - One of the best experts on this subject based on the ideXlab platform.
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Mechanical properties of Zirconia Toughened Alumina with 10–24 vol.% 1Y-TZP reinforcement
Journal of The European Ceramic Society, 2012Co-Authors: Frank Sommer, Richard Landfried, Frank Kern, Raine GadowAbstract:Abstract Zirconia Toughened Alumina ceramics have found broad applications in industrial scale as they can provide high strength, toughness and wear resistance. Processing and compositional parameters have to be properly adjusted to achieve optimum mechanical properties. ZTA ceramics with an yttria content of 1 mol% and Zirconia contents ranging from 10 to 24 vol.% were hot-pressed at 1475 °C at 50 MPa axial pressure and different dwell of 1–3 h. Stabilization of the reinforcement phase in ZTA with yttria was performed by a nitrate coating process of monoclinic Zirconia nanopowders and subsequent blending with sub-micron size Alumina. Microstructure and mechanical properties were investigated. A high ISB toughness of 8.5 MPa √m in combination with a 3-point bending strength of 1198 MPa was determined for the 1 mol% yttria 17 vol.% ZTA overmatching previous studies of coated ZTA ceramics. The interaction between stabilizer and reinforcement phase has a strong influence on the mechanical properties.
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mechanical properties of Zirconia Toughened Alumina with 10 24 vol 1y tzp reinforcement
Journal of The European Ceramic Society, 2012Co-Authors: Frank Somme, Richard Landfried, Raine GadowAbstract:Abstract Zirconia Toughened Alumina ceramics have found broad applications in industrial scale as they can provide high strength, toughness and wear resistance. Processing and compositional parameters have to be properly adjusted to achieve optimum mechanical properties. ZTA ceramics with an yttria content of 1 mol% and Zirconia contents ranging from 10 to 24 vol.% were hot-pressed at 1475 °C at 50 MPa axial pressure and different dwell of 1–3 h. Stabilization of the reinforcement phase in ZTA with yttria was performed by a nitrate coating process of monoclinic Zirconia nanopowders and subsequent blending with sub-micron size Alumina. Microstructure and mechanical properties were investigated. A high ISB toughness of 8.5 MPa √m in combination with a 3-point bending strength of 1198 MPa was determined for the 1 mol% yttria 17 vol.% ZTA overmatching previous studies of coated ZTA ceramics. The interaction between stabilizer and reinforcement phase has a strong influence on the mechanical properties.
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pressureless sintering of injection molded Zirconia Toughened Alumina nanocomposites
Journal of the Ceramic Society of Japan, 2006Co-Authors: Raine GadowAbstract:Ceramic injection molding (CIM) is the most suitable shaping method for mass production of small ceramic components with complex shape in near net shape quality. Due to its high strength and fracture toughness Zirconia Toughened Alumina (ZTA) is an interesting material for ceramic machine components and for biomedical applications. The ability to sinter ZTA to full density while retaining an extremely fine grained microstructure is the prerequisite to exploit the potential of the material. CIM components of ZTA which have much lower powder packing density and a lower homogeneity than e.g. isopressed or cast components normally show a very sluggish sintering behaviour even if very fine sub-μm or even nanosized powders are used. In this study a tailored pressureless sintering process for ZTA microcomponents was developed in order to be able to exploit the full technical and economic potential of the near-net-shape manufacturing process. Depending on the feedstock recipe a reduction in sintering temperature by more than 100 K was achieved and even higher densities reached than by conventional sintering. This leads to a refinement in microstructure and a reduction in Alumina grain size by a factor of 2-3.
