scholarly journals An Engineering Zirconia Ceramic Made of Baddeleyite

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4676
Author(s):  
Vyacheslav V. Rodaev ◽  
Andrey O. Zhigachev ◽  
Alexander I. Tyurin ◽  
Svetlana S. Razlivalova ◽  
Viktor V. Korenkov ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Phase Composition ◽  
Mechanical Characteristics ◽  
Sintering Temperature ◽  
Tetragonal Zirconia ◽  
High Energy ◽  
Zirconia Ceramic ◽  
Stabilized Zirconia ◽  
High Energy Milling ◽  
Polycrystalline Ceramic

Wet high-energy milling and uniaxial pressing are used to fabricate CaO-stabilized tetragonal zirconia polycrystalline ceramic (Ca-TZP) with decent mechanical characteristics, i.e., a hardness of 11.5 GPa, Young’s modulus of 230 GPa, and fracture toughness of 13 MPa·m0.5. The effect of CaO concentration and the sintering temperature on phase composition and mechanical characteristics of CaO-stabilized zirconia ceramic made of baddeleyite is investigated.

Effect of High-Energy Milling and Sintering Temperature on the Properties of Al2O3-WC-Co Composites

2021 ◽  
Author(s):  
Heytor V. S. B. Azevêdo ◽  
Rafael A. Raimundo ◽  
David D. S. Silva ◽  
Luís M. F. Morais ◽  
Franciné A. Costa ◽  
...  
Keyword(s):  
Sintering Temperature ◽  
High Energy ◽  
High Energy Milling

scholarly journals Fabrication of Ti3AlC2/Al2O3 nanocomposite by a novel method

2011 ◽  
Vol 43 (3) ◽  
pp. 289-294 ◽  
Author(s):  
J. Zhu ◽  
L. Ye ◽  
F. Wang
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Hot Pressing ◽  
Reaction Path ◽  
Raw Materials ◽  
High Energy ◽  
Good Combination ◽  
High Energy Milling ◽  
Al2o3 Composite ◽  
Novel Method

A Ti3AlC2/Al2O3 nanocomposite was synthesized using Ti, Al, C and TiO2 as raw materials by a novel combination of high-energy milling and hot pressing. The reaction path of the 3Ti-8C-16Al-9TiO2 mixture of powders was investigated, and the results show that the transitional phases TiC, TixAly and Al2O3 are formed in high-energy milling first, and then TixAly is transformed to the TiAl phase during the hot pressing. Finally, a reaction between TiC and TiAl occurs to produce Ti3AlC2 and the nanosized Ti3AlC2/Al2O3 composite is synthesized. The Ti3AlC2/Al2O3 composite possessed a good combination of mechanical properties with a hardness of 6.0 GPa, a flexural strength of 600 MPa, and a fracture toughness (K1C) of 5.8 MPa?m1/2. The strengthening and toughening mechanisms were also discussed.

The Structure-Property-Processing Relationship for Sintered Yttria-Stabilized Zirconia (YSZ)/Alumina Bioceramics

2013 ◽  
Vol 25 (04) ◽  
pp. 1350005 ◽  
Author(s):  
Sea-Fue Wang ◽  
Thomas Chung-Kuang Yang ◽  
Ya-Ting Hsu ◽  
Sheng-Yang Lee ◽  
Jen-Chang Yang
Keyword(s):  
Fracture Toughness ◽  
Relative Density ◽  
Sintering Temperature ◽  
High Hardness ◽  
Solid State Reaction Method ◽  
Sintering Behavior ◽  
Structure Property ◽  
Stabilized Zirconia ◽  
Average Grain Size ◽  
Alumina Addition

The objective of this research is to study the effects of alumina addition on the microstructure-mechanical property relationship and sintering behavior of yttria (3 mol%)-stabilized zirconia (YSZ) ceramics. Well-dispersed YSZ / Al 2 O 3 ceramics containing 10–40 wt.% Al 2 O 3 were prepared by solid state reaction method. The relative density, average grain size, lattice parameters, microhardness, and fracture toughness of YSZ / Al 2 O 3 ceramics system sintered in the temperature range of 1250~1500°C as a function of Al 2 O 3 content were investigated. Experimental results showed that the ceramics with high Al 2 O 3 content and low sintering temperature tended to reveal low bulk densities. But the Al 2 O 3 content dependence on relative density for YSZ / Al 2 O 3 ceramics becomed deminishing when increasing the sintering temperature. Dense ceramics with composition of (80/20) ( YSZ / Al 2 O 3) and sintered at temperature of 1400°C and 1450°C revealed the optimal Vickers hardness and fracture toughness properties. These ceramics with high Al 2 O 3 content tended to reveal small grain sizes. The high sintering temperature governs the slow grain growth and high hardness in materials indicating the good correlation between microstructure of fabricated dense and mechanical properties.

Effect of Y2O3 on the Sintering, Mechanical and Dielectric Properties of Mullite/h-BN Composites

2016 ◽  
Vol 848 ◽  
pp. 28-31
Author(s):  
Han Jin ◽  
Yong Feng Li ◽  
Zhong Qi Shi ◽  
Hong Yan Xia ◽  
Guan Jun Qiao
Keyword(s):  
Fracture Toughness ◽  
Dielectric Constant ◽  
Phase Composition ◽  
High Temperature ◽  
Dielectric Properties ◽  
Liquid Phase ◽  
Flexural Strength ◽  
Sintering Temperature ◽  
Pressureless Sintering ◽  
Different Temperatures

Mullite/10 wt. %h-BN composites with 5 wt. % Y2O3 additive were fabricated by pressureless sintering at different temperatures. The densification, phase composition, microstructure, mechanical and dielectric properties of the mullite/h-BN composites were investigated. With the addition of Y2O3, the sintering temperature of the mullite/h-BN composites declined, while the density, mechanical and dielectric properties all increased. The addition of Y2O3 promoted the formation of liquid phase at high temperature, which accelerated the densification. Besides, Y2O3 particles which were located at the grain boundaries inhibited the grain growth of mullite matrix. For the mullite/h-BN composites with Y2O3 additive, the appropriate sintering temperature was about 1600°C. The relative density, flexural strength, fracture toughness and dielectric constant of the Y2O3 doped mullite/h-BN composite sintered at 1600 °C reached 82%, 135 MPa, 2.3 MPa·m1/2 and 4.9, respectively.

scholarly journals Partially Yttria-Stabilized Zirconia Crystals Co-Doped with Neodymium, Cerium, Terbium, Erbium or Ytterbium Oxides

Crystals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1587
Author(s):  
Mikhail A. Borik ◽  
Alexey V. Kulebyakin ◽  
Elena E. Lomonova ◽  
Filipp O. Milovich ◽  
Valentina A. Myzina ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Rare Earth ◽  
Phase Composition ◽  
Mechanical Characteristics ◽  
Total Concentration ◽  
Rare Earth Ions ◽  
Melt Crystallization ◽  
Composition And Structure ◽  
T Phase ◽  
Co Doped

In this work, we studied the phase composition, local structure and mechanical characteristics of ZrO2 crystals partially stabilized with Y2O3 and co-doped with Nd2O3, CeO2, Er2O3, Tb2O3 and Yb2O3. Crystals were grown by directional melt crystallization in a cold container. The phase composition and structure of crystals were studied by X-ray diffractometry and transmission electron microscopy. The study of the features of the incorporation of rare-earth cations with different ionic radii into the transformable (t) and nontransformable (t’) tetragonal phases was carried out by the method of selective laser spectroscopy and time-resolved spectroscopy. Mechanical characteristics such as microhardness and fracture toughness were studied by the indentation method. It is shown that the phase composition and structure of crystals at the same total concentration of doping oxides depends on the degree of substitution of Y3+ cations by rare-earth cations. Rare earth ions of the beginning of the lanthanide series predominantly occupy positions in the nontransformable tetragonal phase of crystals based on zirconium dioxide. Ions of the end of a series of lanthanides do not show selectivity when entering the transformable (t) phase and nontransformable (t’) phase. The study of the mechanical characteristics of the crystals showed that the values of fracture toughness increase with an increase in the ionic radius of the rare earth element of the co-doped oxide, while the values of the microhardness of the crystals slightly decrease.

The Translucency of Yttria-Stabilized Zirconia in Dental Crowns: A Review

2015 ◽  
Vol 761 ◽  
pp. 436-440
Author(s):  
Chuin Hao Chin ◽  
Andanastuti Muchtar ◽  
Masfueh Razali ◽  
C.H. Azhari
Keyword(s):  
Primary Particle ◽  
Sintering Temperature ◽  
Tetragonal Zirconia ◽  
Dental Restoration ◽  
Future Research ◽  
Particle Sizes ◽  
Stabilized Zirconia ◽  
Homogeneous Microstructure ◽  
Dental Crowns ◽  
Light Scattering Effect

Ceramics are increasingly popular in dental restoration after metal restoration has been found to be less esthetic. One such example is yttria-stabilized tetragonal zirconia polycrystalline (Y-TZP). However, one of the challenges of this application is its insufficient translucency to ensure high esthetic restoration. This study reviews the effect of sintering parameters, primary particle size, microstructure homogeneity, and thickness of zirconia on its translucency. Several studies remarked that the thickness of the framework had the greatest effect on zirconia translucency. Thus, a rigorous thickness control is necessary. The consideration for optimal sintering parameters (sintering temperature and holding time) and the use of smaller particle sizes help in the densification and elimination of porosity in zirconia, which, consequently, improve its translucency. Finally, a homogeneous microstructure can reduce the light scattering effect in zirconia and increase its translucency. Identifying the factors that influence zirconia translucency can contribute to future research in improving the esthetic dental restoration.

Influence of Grinding Media Size and Sintering Time in the Processing of AISI D2 Tool Steel by High-Energy Milling

2017 ◽  
Vol 899 ◽  
pp. 511-516
Author(s):  
Selauco Vurobi Jr. ◽  
Marcio Ferreira Hupalo ◽  
Ricardo Sanson Namur ◽  
Thiago Augustin Lucas Fernandes ◽  
Osvaldo Mitsuyuki Cintho
Keyword(s):  
Sintering Temperature ◽  
Cold Work ◽  
High Energy ◽  
High Wear Resistance ◽  
Tool Steels ◽  
High Energy Milling ◽  
Sintering Time ◽  
Grinding Media ◽  
Aisi D2 ◽  
Microstructure Of The Material

Tool steels are fundamental in the current production processes, as they are used in dies and molds, essential for the transformation of raw materials into the final product. The tool steels for cold work have a low hot hardness, so their use is limited to temperatures below 200° C. The D-X series of tool steels, high carbon and high chromium, have a high wear resistance and is much used in the manufacture of dies and molds. Despite the high hardness, these steels have a microstructure with coarse carbides, which affects the hardness of the material. An alternative to the processing tool steels is the high-energy milling and subsequent powder metallurgy, in order to refine the microstructure of the material. This work aimed to study the influence of the size of the grinding media in the refining of the microstructure of AISI D2 by high-energy milling and the microstructural changes with the increase in sintering temperature. The results indicated that grinding media of smaller diameters had higher efficiency in high-energy milling due to smaller mean particle size obtained by grinding and subsequent final reduction in the average size of carbides. The sintering time had a direct influence on the microstructure of the material, higher sintering times led to formation of lower bainite, after cooling from sintering temperature.

Sintering Behaviour and Properties of Flyash-Doped Zirconia

2017 ◽  
Vol 894 ◽  
pp. 85-88
Author(s):  
Singh Ramesh ◽  
Wai Jin Kelvin Chew ◽  
H.C. Alexender Chee ◽  
C.Y. Tan
Keyword(s):  
Fracture Toughness ◽  
Young’S Modulus ◽  
Vickers Hardness ◽  
Monoclinic Phase ◽  
Sintering Temperature ◽  
Young's Modulus ◽  
Tetragonal Zirconia ◽  
Lower Amount ◽  
Common Trend ◽  
Sintering Behaviour

The effect of flyash (FA) additions of 0.05 wt% to 1 wt% on yttria-stabilized tetragonal zirconia polycrystals (Y-TZP), sintered in air at temperatures ranging from 1250°C to 1500°C, was examined. The bulk density, Young’s modulus, Vickers hardness and fracture toughness for each addition were determined while ageing behaviour were observed by subjecting them to superheated steam at 180°C/10 bar in an autoclave for 24 hours. Additions of FA, particularly of 0.05 wt% and 0.1 wt%, were found to be beneficial in aiding densification and increasing Young’s modulus beyond 200 GPa for sintering temperatures up to 1350°C. A common trend was observed for the Vickers hardness of all additions including undoped; hardness continues to rise from 1250°C and peaked at 1350°C before gradually decreasing as the sintering temperature increases further. No pronounced effect of flyash was seen on the fracture toughness of all samples. The ageing resistance of Y-TZP improved with addition of FA resulting in relatively lower amount of ageing-induced tetragonal to monoclinic phase transformation exhibited by doped samples compared to the undoped.

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