scholarly journals Relation between mechanical and textural properties of dense materials of tetragonal and cubic zirconia

2016 ◽  
Vol 48 (1) ◽  
pp. 119-130 ◽  
Author(s):  
Sofía Gómez ◽  
Gustavo Suárez ◽  
Nicolás Rendtorff ◽  
Esteban Aglietti
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Vickers Hardness ◽  
Sintering Temperature ◽  
Textural Properties ◽  
Theoretical Models ◽  
Indentation Method ◽  
Cubic Zirconia ◽  
Different Content ◽  
Scanning Electron

In the current paper we present a study of the sinterability of two zirconia (ZrO2) nanopowders with different content of yttrium oxide (Y2O3) 3 and 8 % tetragonal and cubic zirconia, respectively. After sintering between 900-1500?C, the samples were characterized in terms of their density and porosity using Archimedes technique. Their grain size was evaluated using scanning electron microscope (SEM). Vickers hardness and fracture toughness (KIC) were measured by the indentation method. The results showed that pores are almost eliminated at sintering temperatures higher than 1400?C and grain size is larger due to the agglomerates formed as a result of grain growth. Vickers hardness evaluated at 1400?C sintering temperature is greater than that obtained at 1500?C due to the grain growth produced at this temperature. In addition, we show a correlation between Vickers hardness and the porosity, obtained by evaluating empirical and theoretical models.

Study on the Properties of Doped La in BaBi4Ti4O15 Ceramic

2007 ◽  
Vol 26-28 ◽  
pp. 243-246
Author(s):  
Xing Hua Yang ◽  
Jin Liang Huang ◽  
Xiao Wang ◽  
Chun Wei Cui
Keyword(s):  
Crystal Structure ◽  
Grain Size ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Sintering Temperature ◽  
Solid Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lanthanum Content ◽  
Scanning Electron

BaBi4-xLaxTi4O15 (BBLT) ceramics were prepared by conventional solid phase sintering ceramics processing technology. The crystal structure and the microstructure were detected by X-ray diffraction (XRD) and scanning electron microscope (SEM). The XRD analyses show that La3+ ions doping did not change the crystal structure of BBT ceramics. The sintering temperature increased from 1120°C to 1150°C with increasing Lanthanum content from 0 to 0.5, but it widened the sintering temperature range from 20°C to 50°C and refined the grain size of the BBT ceramic. Additionally, polarization treatment was performed and finally piezoelectric property was measured. As a result, the piezoelectric constant d33 of the 0.1at.% doped BBLT ceramics reached its highest value about 22pc/N at polarizing electric field of 8kV/mm and polarizing temperature of 120°C for 30min.

Enhanced Densification and Grain-Size Refinement in Cation-Doped Tetragonal Zirconia

2010 ◽  
Vol 62 ◽  
pp. 227-231
Author(s):  
Keijiro Hiraga ◽  
Hidehiro Yoshida ◽  
Koji Morita ◽  
Byung Nam Kim
Keyword(s):  
Grain Size ◽  
Relative Density ◽  
Grain Growth ◽  
Sintering Temperature ◽  
Initial Density ◽  
Tetragonal Zirconia ◽  
The Other ◽  
Size Refinement ◽  
Grain Sizes ◽  
Materials Used

In tetragonal zirconia, possibility is investigated of densification with finer grain sizes under the combination of doping and sintering in air. The materials used are CIP'ed compacts of 3-mol%-yttria-stabilized tetragonal zirconia (3Y-TZP) doped with a small amount of cations. For a given sintering temperature and initial density of the compacts, while the doped cations enhances densification in the latest stage of sintering, the effect is different in grain growth during densification: a doped cation tended to enhance grain growth, whereas the other cations tended to suppress grain growth. As a result, the doping of the latter cations brings about a grain size finer than that of the undoped 3Y-TZP for a given relative density.

Numerical Simulation and Experimental Analysis on the Crystal Growth of Excimer-Laser Crystallization of a-Si Film

2008 ◽  
Author(s):  
Long-Sun Chao ◽  
Yu-Ru Chen ◽  
Hsiun-Chang Peng
Keyword(s):  
Electron Microscopy ◽  
Numerical Simulation ◽  
Scanning Electron Microscopy ◽  
Grain Size ◽  
Grain Growth ◽  
Excimer Laser ◽  
Crystallographic Direction ◽  
Grain Distribution ◽  
Induced Crystallization ◽  
Scanning Electron

In this work, the excimer-laser-induced crystallization of amorphous silicon (a-Si) films was investigated numerically and experimentally. The basic structure is an a-Si film on a glass substrate. This study had investigated the effects of irradiating energy density on the grain size and structure by scanning electron microscopy (SEM). In the surface microstructure analysis of the laser-irradiated area, the critical fluences (full-melt threshold, FMT) between the partial melting and complete melting regimes can be found by applying scanning electron microscopy. An efficient two-dimensional numerical model is carried out to predict the critical fluences (FMT) and the transient temperature distribution during the laser processing. Numerical analysis of the temperature profile showed that a temperature drop occurred at the center of melted zone immediately after laser irradiation. From the analysis of temperature responses, the FMT obtained from the simulation results of the proposed model agree fairly well with those from the experimental data reported in the literature and acquired in this research. Furthermore, the grain growth of the poly-Si was studied by the grain observation of the cross section and its corresponding numerical simulation. The cross-sectional grain structure of the resulting poly-Si film was observed with different laser intensities. The grain sizes decreased with increasing irradiating energy intensity in the partial melting regime. From the surface observation, the grain distribution was uniform and most of the grain has a single crystallographic direction. The average grain size had the biggest value at FMT. But some super large grains occurred and combined with more than one crystallographic direction when the film obtained sufficiently high energy intensities that was closed or over the FMT. The grain distribution was not uniform. The super large gain was around the small grain size. The modified cellular automation method (MCA) was used to simulate the grain growth two-dimensionally and explain the grain development during the solidification process. The grain morphology of the numerical simulation was satisfied with the experimental observation. From the analysis of the grain growth, this model was able to simulate the undercooling effect and grain growth phenomenon and fitted for the experimental grain observation in the excimer-laser-induced crystallization.

Effect of (Ni,Mo) and (W,Ti)C on the Microstructure and Mechanical Properties of TiB2 Ceramic Tool Materials

2012 ◽  
Vol 723 ◽  
pp. 233-237 ◽  
Author(s):  
Tong Chun Yang ◽  
Chuan Zhen Huang ◽  
Han Lian Liu ◽  
Bin Zou ◽  
Hong Tao Zhu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Grain Size ◽  
Flexural Strength ◽  
Grain Growth ◽  
Vickers Hardness ◽  
Ceramic Tool ◽  
Tool Materials ◽  
Sintering Additive ◽  
Microstructure And Mechanical Properties

TiB2-(W,Ti)C composites with (Ni,Mo) as sintering additive have been fabricated by hot-pressing technique, and the microstructure and mechanical properties of the composites have been investigated. (Ni,Mo) promotes grain growth of the composites. In the case of 7vol.% (Ni,Mo), the grain size decreases consistently with an increase in the content of (W,Ti)C. When the proper content of (W,Ti)C is added to TiB2 composites, the growth of matrix grains is inhibited and the mechanical properties of the composites are improved. The best mechanical properties of the composites are 1084.13MPa for three-point flexural strength, 7.80MPa•m 1/2 for fracture toughness and 17.92GPa for Vickers hardness.

Microstructure of Nanocrystalline Ceramics

1988 ◽  
Vol 132 ◽  
Author(s):  
H. Hahn ◽  
J. Logas ◽  
H. J. Höfler ◽  
Th. Bier ◽  
R. S. Averback
Keyword(s):  
Grain Growth ◽  
Sintering Temperature ◽  
Total Pore Volume ◽  
Nitrogen Adsorption ◽  
Green Body ◽  
X Ray Diffraction ◽  
Adsorption Method ◽  
X Ray ◽  
Nanocrystalline Ceramics ◽  
Scanning Electron

ABSTRACTThe microstructure of nanocrystalline (n-) TiO2 was studied as a function of sintering temperature up to 1273 K. Grain growth was monitored using x-ray diffraction and scanning electron microscopy. Measurements of density and permeability of He and Ar were also conducted. The specific surface area and the total pore volume were determined quantitatively using the nitrogen adsorption method. These measurements revealed that highly compacted n-TiO2 had green body densities as high as 75 % of bulk density and that sintering occurred at much lower temperatures than in conventional powder. Densification proceeded by loss of the small pores first. The possibilities of achieving high densities with limited grain growth will be discussed.

Influence of Al2O3 Addition on the Microstructure and Mechanical Properties of Pressureless Sintered Ce-TZP

2005 ◽  
Vol 492-493 ◽  
pp. 783-0 ◽  
Author(s):  
Shui Gen Huang ◽  
Lin Li ◽  
Jef Vleugels ◽  
Pei Ling Wang ◽  
Omer Van der Biest
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Grain Size ◽  
Grain Growth ◽  
Vickers Hardness ◽  
Good Combination ◽  
Al2o3 Content ◽  
Pressureless Sintering ◽  
Sintering Time ◽  
Microstructure And Mechanical Properties

Mixtures of 12 mol% CeO2-stabilised ZrO2 with 5 to 20 wt % Al2O3 were prepared and densified through pressureless sintering in air at 1450° C for 1 to 4 h. The influence of the Al2O3 content and sintering time on the phase constitution, microstructure and mechanical properties of the as-sintered composites were investigated. Fully dense Ce-TZP/Al2O3 ceramics with a good combination of hardness and fracture toughness can be obtained by pressureless sintering in air for only 1 h. The addition of Al2O3 to Ce-TZP improves the mechanical properties and suppresses ZrO2 grain growth. The average ZrO2 grain size increases with increasing sintering time and decreasing Al2O3 content. This leads to an increase in toughness. An excellent fracture toughness of 14.3 MPam1/2 in combination with a Vickers hardness of 9.14 GPa was obtained for 12 mol % CeO2-TZP with 5 wt % Al2O3, sintered for 4 h.

scholarly journals Sintering Behavior and Mechanical Properties of Biphasic Calcium Phosphate Ceramics

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Mehmet Yetmez
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Calcium Phosphate ◽  
Grain Growth ◽  
Vickers Hardness ◽  
Tricalcium Phosphate ◽  
Biphasic Calcium Phosphate ◽  
Sintering Temperature ◽  
Sintering Behavior ◽  
Microstructure Observation

The sintering behavior and the mechanical properties of a mechanical mixture of hydroxyapatite and tricalcium phosphate (BCP) ceramics with the composition of 30% HA and 70% TCP are experimentally investigated in the temperature range between 1000°C and 1300°C. The results show that consolidation, grain growth, and Vickers hardness generally increase with increasing sintering temperature up to 1200°C. However, microstructure observation indicates that cracks are formed along the grain boundaries as well as in the bulk of the grains after sintering at 1200°C. Moreover, the best values of compressive strength, modulus of elasticity, and toughness are achieved in the samples sintered at 1100°C. These properties at 1100°C decay with sintering at 1200°C and increase again after sintering at 1300°C.

Effect of CoO Doping on the Sintering Ability and Mechanical Properties of Y-TZP

2004 ◽  
Vol 449-452 ◽  
pp. 265-268 ◽  
Author(s):  
Tetsuhiko Onda ◽  
H. Yamauchi ◽  
Motozo Hayakawa
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Grain Boundary ◽  
Grain Refinement ◽  
Grain Growth ◽  
Sintering Temperature ◽  
Tetragonal Zirconia ◽  
Boundary Structure ◽  
Grain Boundary Structure ◽  
Boundary Strength

The effect of CoO addition into Y-TZP (Yttria doped Tetragonal Zirconia Polycrystals) was studied on the evolution of its sintering ability, grain size, grain boundary structure and mechanical properties. The doping of a small amount of CoO effectively reduced the sintering temperature. A small amount of CoO up to ~ 0.3 mol% was effective for the suppression of grain growth, but the addition of 1.0 mole % resulted in an enhanced grain growth. The hardness and toughness of the CoO doped TZP were about the same as those of undoped TZP. Furthermore, despite the grain refinement, CoO doped TZP did not exhibit improved mechanical properties. This may be suggesting that CoO dopant had weakened the grain boundary strength.

scholarly journals Influence of sintering temperature on raw and beneficiated clay “Klokoti”

2012 ◽  
Vol 44 (2) ◽  
pp. 161-168 ◽  
Author(s):  
Marina Jovanovic ◽  
Tatjana Volkov-Husovic
Keyword(s):  
Grain Size ◽  
Chemical Composition ◽  
Glassy Phase ◽  
Sintering Temperature ◽  
Phase Content ◽  
Sintering Process ◽  
Characteristic Temperatures ◽  
Higher Temperature ◽  
Increasing Temperature ◽  
Scanning Electron

The raw clay ?Klokoti? from middle Bosnia was beneficiated by method of wet separation which results in removing fraction over 20 ?m. The raw clay was characterized by chemical composition, grain size distribution and characteristic temperatures on heating microscope. The beneficiated clay was characterized by chemical composition and characteristic temperatures. The phase composition of raw and beneficiated clay was observed by RDA while the microstructure was monitored on scanning electron microscope (SEM). The sintering process was performed at 1100?C, 1250?C, 1320?C and 1400?C with two hours holding time at the highest temperature. The obtained results indicate a big content of coarse quartz in raw clay and gradually increase of crystalline mullite content with increasing temperature of sintering. Beneficiated clay at higher temperature of sintering produces larger glassy phase content, which is result of larger fluxing content in its composition. It is also observed that from beneficiated clay by sintering at 1250?C crystallize the most mullite along with minimum porosity and the lowest glassy phase content.

Sintering and crystal growth of magnesia in the presence of lime and forsterite

1970 ◽  
Vol 37 (291) ◽  
pp. 839-851 ◽  
Author(s):  
D. R. F. Spencer ◽  
D. S. Coleman
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Sintering Temperature ◽  
Shrinkage Porosity ◽  
Growth Data ◽  
Kcal Mole ◽  
Electron Probe Analysis ◽  
A Value ◽  
Temperature Constant ◽  
Sintering Behaviour

SummaryThe densification of pure magnesia was examined along with mixtures containing 0·5 and 1·0 mol % of calcium oxide and forsterite. The sintering behaviour at temperatures between 1400 and 1800 °C was studied and measurements made of changes in shrinkage, porosity, bulk density, and grain size for sintering times of up to 8 h at sintering temperature. It was found that both the 0·5 and 1·0 mol % additions enhanced the sintering of pure magnesia in the temperature range 1500–1700 °C Increased grain growth was found for mixtures containing forsterite but little change occurred for mixtures containing lime. Examination of the grain growth data showed that the mixtures obeyed a relationship: Time at temperature × Constant = (grain size)n, where n = 2 for the grain growth of pure magnesia and mixtures containing lime, but n = 3 for mixtures of magnesia with additions of a silicate such as forsterite. A value of 78 kcal/mole was obtained for the grain growth of pure magnesia, which agrees with other researches.The extent of the solubility of lime in periclase for each lime-magnesia mixture at each temperature was also examined using electron probe analysis and related to the sintering behaviour observed for these mixtures.

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