scholarly journals Effect of Grain Size on Hardness, Bending Strength and Indentation Toughness of Multi-Doped Zirconia Ceramics

2018 ◽  
Author(s):  
Y.G. Hoo ◽  
Yusheng Shi ◽  
Wenzhong Lu
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Grain Size ◽  
Size Effect ◽  
Bending Strength ◽  
Stabilized Zirconia ◽  
Zirconia Ceramics ◽  
Partially Stabilized Zirconia ◽  
Indentation Toughness ◽  
Wide Range

Partially stabilized zirconia (PSZ) is a promising material with superior combination properties in a wide range of industries. In this study, the effect of grain size on the mechanical properties such as hardness, bending strength and fracture toughness (named as ‘indentation toughness’ in this study) was investigated. The multi-doped zirconia ceramics were prepared by powder processing and pressure-less sintered following four sintering schedules. The measured mechanical properties results show that the polymorph structure sintered at a higher temperature has a lower bending strength and hardness. But 300% more indentation toughness (30.54 Kg/mm) of samples sintered at 1600 °C +1150 °C relative to others was estimated due to the grain size effect by our suggested equation. By contrast, the fracture toughness was calculated with an existing method. The results showed that similar trends were obtained. It appeared to be a novel method for evaluating the toughness of partially stabilized zirconia ceramics with micron grains based on the size effect.

scholarly journals Two-Step Sintering of Partially Stabilized Zirconia for Applications in Ceramic Crowns

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1857
Author(s):  
Bobby Aditya Darmawan ◽  
John G. Fisher ◽  
Doan Thanh Trung ◽  
Kumaresan Sakthiabirami ◽  
Sang-Won Park
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Tooth Enamel ◽  
Milled Powder ◽  
Second Step ◽  
Stabilized Zirconia ◽  
Zirconia Ceramics ◽  
Partially Stabilized Zirconia ◽  
Ceramic Crowns ◽  
Equal Density

Partially-stabilized zirconia is used in ceramic crowns due to its excellent mechanical properties and bio-inertness but does not match the natural color and translucency of tooth enamel. To reduce scattering of light and improve translucency, the grain size of zirconia ceramics should be less than the wavelength of visible light (0.4–0.7 μm), and porosity should be eliminated. The aim of the present work was to study the effect of two-step sintering of a commercial powder (Zpex Smile, Tosoh Corp., Tokyo, Japan) on the grain size and translucency of zirconia for use in ceramic crowns. Samples were sintered at a first step temperature (T1) of 1300, 1375 and 1400 °C for 5 min, followed by a decrease to the second step temperature (T2) and holding at T2 for 5–20 h. Samples were also conventionally sintered at 1450 °C for 2 h for comparison. Two-step sintered samples with an almost equal density, smaller grain size and narrower grain size distribution compared to conventionally sintered samples could be sintered. However, the translucency of two-step sintered samples had lower values compared to conventionally sintered samples. This is due to the slightly higher porosity in the two-step sintered samples. Density and translucency of both conventionally and two-step sintered samples could be increased further by using a ball milled powder.

Mechanical Properties and Microstructure of Partially Sintered Zirconia Ceramics

2008 ◽  
Vol 368-372 ◽  
pp. 1252-1254 ◽  
Author(s):  
Shi Bao Li ◽  
Zhao Hui Chen ◽  
Yi Min Zhao ◽  
Zhong Yi Wang ◽  
Li Hui Tang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Grain Size ◽  
Bending Strength ◽  
Target Material ◽  
Dental Restoration ◽  
Diameter Distribution ◽  
Zirconia Ceramics ◽  
Grain Sizes ◽  
Cad Cam

Partially sintered zirconia ceramics (PSZCs) for dental uses were prepared from zirconia nanopowder via isostatic pressing and partially sintering. The open porosities, pore diameters, grain sizes and mechanical properties of the ceramics with different densities were studied. The results show that the pores formed in the PSZCs are all open pores, with a diameter distribution of 60nm~130nm and a grain size distribution of 120~170nm. The machinability becomes worse when the density of PSZC is higher than 75% of the theoretical density, so a ceramic named PSZC-70% with density of 70%TD was selected as the target material. Its bending strength is 168 MPa and fracture toughness is 1.8 MPa·m1/2. A dental restoration framework can be obtained via machining the PSZC-70% on a dental CAD/CAM system.

Synthesis of Coloured Dental Zirconia Ceramics and their Mechanical Behaviors

2014 ◽  
Vol 602-603 ◽  
pp. 594-597 ◽  
Author(s):  
Jing Li ◽  
Shi Ming Liu ◽  
Yuan Hua Lin
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Grain Size ◽  
Phase Composition ◽  
Bending Strength ◽  
Linear Shrinkage ◽  
Zirconia Ceramic ◽  
Mechanical Behaviors ◽  
Zirconia Ceramics ◽  
Dental Zirconia Ceramics

The effects of Pr6O11 and Er2O3 dopants on microstructure and mechanical properties of zirconia ceramics were investigated. The phase composition and microstructure analysis indicate that samples are all tetragonal phase and grain size is about 50-100 nm. The relative density of zirconia ceramics was above 99.1%, linear shrinkage was nearly 20%, while Vickers hardness was over 12.5 GPa. Three-points bending strength was over 850 MPa which was slightly lower than that of the pure samples, and fracture toughness was above 4.9 MPa*m1/2. The results show that the dopants can be used to obtain the colored zirconia ceramic, and also have effects on its mechanical properties.

Pressureless Sintering and Properties Investigation of Silicon Nitride

2011 ◽  
Vol 194-196 ◽  
pp. 1464-1469
Author(s):  
Bin Li ◽  
Yi Feng ◽  
Hui Qiang Liu ◽  
Yan Fang Zhu ◽  
Dong Bo Yu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Grain Size ◽  
Bending Strength ◽  
Fracture Morphology ◽  
Pressureless Sintering ◽  
Sintering Aids ◽  
Α Phase ◽  
Different Grain Size ◽  
Si3n4 Ceramics

Different grain size of starting powder was choosed and different sintering additives were used to fabricate Si3N4 ceramics by pressureless sintering. Samples’ relative density and mechanical properties including Vickers hardness, bending strength and fracture toughness were tested. Then XRD, SEM and EDS were carried out to identify phase and observe microstructure and fracture morphology. The result shows that high purity α phase Si3N4 powder of 5 μm is suitable for sintering and combination of 5 wt.% MgO +5 wt.% Y2O3 is most effective within six kinds of sintering aids.

Simultaneous Synthesis and Sintering of Al2O3/Mo2N Composites Using Capsule-Free Nitrogen Hot Isostatic Pressing and their Characterization

2010 ◽  
Vol 62 ◽  
pp. 197-202
Author(s):  
Hirota Ken ◽  
Takaoka Katsuya ◽  
Murase Yasushi ◽  
Kato Masaki
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Grain Size ◽  
Vickers Hardness ◽  
Bending Strength ◽  
Hot Isostatic Pressing ◽  
Isostatic Pressing ◽  
Simultaneous Synthesis ◽  
Powder Compacts ◽  
Al2o3 Matrix

Synthesis of dense materials with the compositions of Al2O3/Mo2N=100/0 ~ 40/60 vol% has been attempted directly from Al2O3/Mo mixed raw powder compacts using capsule-free N2 hot isostatic pressing (HIP). During HIPing [1500°C/(16~20)MPa]/1h], solid/gas reaction between Mo and N2 was introduced to form Mo2N. Most sintered composites consisting of only Al2O3 and Mo2N phases reached a higher relative density than 98.0% with closed pores nevertheless capsule-free HIPing. Distribution of Mo2N particles just formed suppressed the grain growth of Al2O3 during sintering. Mechanical properties, such as bending strength (Σb), Vickers hardness (HV), fracture toughness (K1C), and other properties have been evaluated as a function of their compositions. The best mechanical values of Σb (c.a. 573 MPa), HV (c.a. 20.3 GPa) and K1C (c.a. 5.00 MPa･m1/2) were attained at the composition of Al2O3/Mo2N=90/10 vol%, due to a high density (98.6%) and small grain size of Al2O3 matrix (Gs c.a. 4.70 μm). Further addition of Mo2N reduced the sinterability of matrix grains, resulting in low densities of around 90% at the 40/60 vol% composition.

Mechanical Properties and Microstructure of PMMA-ZrO2 Nanocomposites for Dental CAD/CAM

2013 ◽  
Vol 785-786 ◽  
pp. 533-536 ◽  
Author(s):  
Shi Bao Li ◽  
Yi Min Zhao ◽  
Jian Feng Zhang ◽  
Cheng Xie ◽  
Dong Mei Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Bending Strength ◽  
In Situ Polymerization ◽  
Zirconia Ceramics ◽  
Sem Images ◽  
The Matrix ◽  
Cad Cam ◽  
Organic Resin

A novel PMMA-ZrO2 composite (PZC) was prepared by resin infiltrated to ceramic method. The composite mechanical properties were evaluated and correlated to its microstructure. Partially sintered zirconia ceramics (PSZC) were made by isostatic pressing and partially sintering. Subsequently, the PZC was prepared by vacuum infiltrating prepolymerized MMA into PSZC, followed by in-situ polymerization. When PSZC-70% was used as the matrix, the bending strength, elastic modulus, and fracture toughness of the prepared composite i.e PZC-70% were 202.56±12.09 MPa, 58.71±3.98 GPa, and 4.60±0.26 MPa·m1/2, corresponding to 25.69%, 23.31%, and 169.01% improvement, respectively, in comparison with the control matrix. Among them, the fracture toughness improvement was the most prominent. According to SEM images of the fracture surfaces, each pore of zirconia skeleton was filled by organic resin contributing to the bending strength improvement. These weak interfaces between zirconia skeleton and organic resin absorbed energy and terminated the growth of microcracks which might be responsible for significant improvement in fracture toughness. This PZC material is anticipated to be a new member of the dental CAD/CAM family.

The Influence of Zirconia Powder Dispersion Technique on Microstructure and Properties of Al2O3 – ZrO2 Ceramic

2014 ◽  
Vol 682 ◽  
pp. 109-112
Author(s):  
Sergey Veselov ◽  
N.Yu. Cherkasova ◽  
R.S. Timarevskiy
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Grain Size ◽  
Bending Strength ◽  
Preliminary Treatment ◽  
Zirconia Powder ◽  
Powder Dispersion ◽  
Dispersion Technique ◽  
Zirconia Toughened Alumina ◽  
Zirconia Suspension

The results of microstructure and mechanical properties investigation for alumina and zirconia toughened alumina (ZTA) with 20 wt. % 3Y-ZrO2is presented. It was stated that the technique of preliminary treatment for zirconia suspension makes significant influence on sintered specimen microstructure. Introduction of the alloying additive treated with ball milling reduces Al2O3grain size in ceramic from 2-5 μm to 0.2-1 μm. The reduction of grain size increases the bending strength of ceramic material from 270 MPa up to 350 MPa. However fracture toughness of alumina and ZTA is 3.4 and 2.5 MPa·m1/2, respectively. It was shown that the low level of mechanical properties is related to the occurrence of major defects in the form of granule boundaries preserved at the forming stage.

ZrO2-TiN Composites

2007 ◽  
Vol 554 ◽  
pp. 135-140 ◽  
Author(s):  
Sedigheh Salehi ◽  
Omer Vander Biest ◽  
Jef Vleugels
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Vickers Hardness ◽  
Hot Pressing ◽  
Bending Strength ◽  
Transformation Toughening ◽  
Toughening Mechanism ◽  
Indentation Toughness ◽  
Tin Content ◽  
Composite Toughness

1.75 mol % Y2O3-stabilized ZrO2-based composites with 35-95 vol % TiN were fully densified by hot pressing for 1 hour at 1550°C under a load of 28 MPa. The TiN grain size was found to increase with increasing TiN content, resulting in a decreasing hardness and strength. The best mechanical properties, i.e., an indentation toughness of 5.9 MPa.m1/2 in combination with a Vickers hardness of 14.7 GPa and an excellent bending strength of 1674 MPa were obtained for the composites with 40 vol % TiN. The active toughening mechanisms were identified and their contribution to the overall composite toughness is discussed. Transformation toughening was found to be the primary toughening mechanism in all investigated composites.

Effect of SiCp Addition on Microstructure and Mechanical Properties of ZTA Ceramics by Microwave Sintering

2018 ◽  
Vol 281 ◽  
pp. 217-223 ◽  
Author(s):  
Yong Qiang Chen ◽  
Sai Li ◽  
Wei Li ◽  
Ting Ting Su ◽  
Bing Bing Fan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Microwave Heating ◽  
Bending Strength ◽  
Microwave Sintering ◽  
Precipitation Method ◽  
Stabilized Zirconia ◽  
Oriented Growth ◽  
Directional Growth ◽  
Partially Stabilized Zirconia ◽  
Microstructure And Mechanical Properties

The effects of SiCp addition on the microstructure and mechanical properties of ZTA ceramics was investigated by microwave sintering. Partially stabilized zirconia（3Y-ZrO2）nanopowder containing SiCp was prepared by microwave pyrolysing precursor which was was achieved by co-precipitation method. The powders of alumina, yttria partially stabilized zirconia containing SiCp were mixed to prepare ZTA ceramics green body by die pressing and cold isostatic pressing and subsequently sintered at the range of 1350°C-1550°C for 30min by microwave. XRD revealed that 3Y-ZrO2/SiC powder contained more tetragonal phase than 3Y-ZrO2 powder which was also confirmed by SEM and particle size distribution. The phenomenon was because of SiCp forming the microwave heating spot that promoted pyrolysis progress when 3Y-ZrO2/SiC powder was prepared by microwave heating. Microstructure showed that the grain of ZTA ceramics had directional growth by microwave sintering. SiCp firstly absorbed microwave that made more uniform sintering of ZTA ceramics and caused local oriented growth of zirconia and alumina. Thus, the bending strength of ZTA ceramics was higher than ZTA without SiCp. The ladder type heating mode of microwave sintering ZTA ceramics reduced relatively sintering time by 20min due to the addition of SiCp.Introduction

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