Structure Evolution in Al2O3 - ZrO2(Y2O3) Ceramic Composites during Sintering

2010 ◽  
Vol 65 ◽  
pp. 11-15
Author(s):  
Ya. Dyatlova ◽  
S.S. Ordanyan ◽  
Andrey Osmakov ◽  
V. Pesin ◽  
V. Rumyantsev
Keyword(s):  
Mechanical Behavior ◽  
Ceramic Composite ◽  
Large Angle ◽  
Tetragonal Zirconia ◽  
Ceramic Composites ◽  
Structure Evolution ◽  
Composite Ceramics ◽  
X Ray Diffraction ◽  
Composite Powders ◽  
Microstructure Parameters

The paper demonstrates the possibility to control the degree of tetragonal zirconia stabilization, microstructure and physical and mechanical behavior of Al2O3 -ZrO2(Y2O3) ceramic composite. Control is exerted via the process variables during deposition synthesis of nanosized composite powders from hydroxide salts, and their subsequent heat treatment and consolidation. Morphology features of nanosized powder systems and microstructures of the consolidated nanostructured materials were characterized by BET surface are measurements, scanning electron microscopy (both standard and HR), and large-angle X-ray diffraction. Correlations are established between microstructure parameters, physical and mechanical behavior of composite ceramics and a degree of stabilization of tetragonal ZrO2.

Fracture Stress Analysis in Ceramic Composites of Alumina Matrix with Zirconia 3Y-TZP Nanograins for Mechanical Shielding of Satellites

2016 ◽  
Vol 869 ◽  
pp. 64-68
Author(s):  
Eron Fernandes da Silva ◽  
Daniel Alessander Nono ◽  
Sergio Luiz Mineiro ◽  
Francisco Piorino Neto ◽  
Maria do Carmo de Andrade Nono
Keyword(s):  
Fracture Stress ◽  
Ceramic Composite ◽  
Space Debris ◽  
Tetragonal Zirconia ◽  
Ceramic Composites ◽  
Bending Test ◽  
Alumina Matrix ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mechanical Bending

This paper presents the analysis results of fracture stress values for ceramic composites of alumina matrix mixed with nanoparticulate zirconia (3Y-TZP) ((tetragonal zirconia polycrystalline doped with 3 mol% yttria), which will be used in parts of the Brazilian satellites to act as mechanical shield for micrometeoroid and space debris impacts. The ceramic composites were obtained by mixing dispersed suspensions of alumina powders and 18.5 wt % of nanoparticulate zirconia, compacted with isostatic pressure and sintered at 1550 °C. After sintering, the ceramic composite was analyzed by SEM, X-ray diffraction and subjected to 4 points mechanical bending test. The microstructure analyses were performed and rupture stress values with Weibull distribution. The results were compared to previous works obtained after mechanical mixture of same powders. The results analyses showed that the greater homogeneity distribution of zirconia nanograins on alumina matrix contributes to increased fracture stress values.

Synthesis and Characterization of Porous ZrO2-Y2O3-TiO2 Ceramics Prepared by Coprecipitation

2012 ◽  
Vol 727-728 ◽  
pp. 1387-1392 ◽  
Author(s):  
Luan M. Medeiros ◽  
Fernando S. Silva ◽  
Juliana Marchi ◽  
Walter Kenji Yoshito ◽  
Dolores Ribeiro Ricci Lazar ◽  
...  
Keyword(s):  
Ceramic Composite ◽  
High Strength ◽  
Ceramic Composites ◽  
Rice Starch ◽  
X Ray Diffraction ◽  
Zirconia Ceramics ◽  
Pore Former ◽  
X Ray ◽  
Cold Pressed

Zirconium dioxide (zirconia) ceramics are known by its high strength and toughness and titanium dioxide (titania) ceramics has outstanding surface properties. The ceramic composite formed between the two oxides are expected to have advantages of both ceramics, especially when its surface area is increased by pores. In this work, ceramic composites of ZrO2-Y2O3-TiO2were synthesized by coprecipitation and rice starch was added as pore former in 10, 20 and 30 wt%. Powders were cold pressed as cylindrical pellets and sintered at 1500 °C for 01 hour and ceramics were characterized by techniques as Archimedes method for density measurements, X-ray diffraction and scanning electron microscopy. Results showed that pores are inhomogeneously distributed through ceramic bodies.

Devitrification in SiO2-B2O3-Al2O3-La2O3-TiO2 Glass during the Infiltration of Ceramic Composite

2016 ◽  
Vol 881 ◽  
pp. 77-82
Author(s):  
Afonso Chimanski ◽  
Amanda Martins Jordão ◽  
Paulo Francisco Cesar ◽  
Humberto Naoyuki Yoshimura
Keyword(s):  
Ceramic Composite ◽  
Raw Materials ◽  
Porous Alumina ◽  
Ceramic Composites ◽  
X Ray Diffraction ◽  
Infiltration Process ◽  
X Ray ◽  
Dental Prostheses ◽  
Devitrification Process ◽  
Natural Teeth

Dental prostheses made of ceramic composites infiltrated with glasses have been used due to their biocompatibility and possibility to mimic the natural teeth. In this study, the devitrification behavior of 20SiO2-25B2O3-25Al2O3-15La2O3-15TiO2 glass during the infiltration process in a porous alumina preform was investigated. Glass frits were prepared by melting the raw materials at 1500 °C for 60 min. The glass was infiltrated into the alumina preform at 1,150 or 1,200 °C for 60 min. The specimens were characterized by X-ray diffraction analysis and scanning electron microscopy. After the infiltration, it was possible to note that the devitrification process occurred in the remaining glass (excess glass that did not infiltrate in the preform), forming mostly aluminum borate and mullite crystalline phases. However, within the infiltrated composite no devitrification was noticed in the infiltrated glass. Possible explanations for this behavior are discussed.

scholarly journals Microstructure Characteristics of Ce-ZTA Ceramic Composites Obtained by Liquid Phase Sintering

2006 ◽  
Vol 530-531 ◽  
pp. 421-424
Author(s):  
Haine Beck ◽  
Maria do Carmo de Andrade Nono ◽  
Francisco Piorino Neto
Keyword(s):  
Ceramic Composite ◽  
Glassy Phase ◽  
Volume Fraction ◽  
Tetragonal Zirconia ◽  
Ceramic Composites ◽  
Liquid Phase Sintering ◽  
Scanning Electronic Microscopy ◽  
Powder Samples ◽  
Zirconia Toughened Alumina ◽  
Crystalline Matrix

Zirconia-toughened alumina (ZTA) ceramics with Ce-TZP (tetragonal zirconia polycrystalline doped with ceria) volume fraction on 33% were prepared with the addition.. The influence of glass infiltrated method was investigated. Coprecipitated Zr and Ce hydroxide mixture was obtained from ZrOCl2.8H2O and CeCl3. 7H2O aqueous solution. CeO2-ZrO2 calcinated powder was compacted and the compacted samples were sintered at 1180°C. Powder samples were characterized by scanning electronic microscopy (SEM), The volume fraction of each phase, the grains size and shapes, and the porosity were investigated with SEM. The relative density and shrinkage was investigate too. The results showed that the crystalline matrix was composed by SiO2 -B2O3-La2O3-Al2O3-Ce-TZP and revealed the important role played the glassy phase in the densification of this ceramic composite.

Structure Evolution of La(OH)3 /Fe Composite during Ball Milling

2020 ◽  
Vol 65 ◽  
pp. 123-134
Author(s):  
Samira Lalaoua ◽  
Bouguerra Bouzabata ◽  
Safia Alleg ◽  
Abedelmalik Djekoun ◽  
David Shmool
Keyword(s):  
Ball Milling ◽  
Milling Time ◽  
Magnetic Measurements ◽  
Amorphous Structure ◽  
Structure Evolution ◽  
Vibrating Sample Magnetometer ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Composite Powders ◽  
X Ray

Fe-10wt% La (OH)3 composite powders have been fabricated by ball milling, under argon atmosphere for milling periods of 0, 5 and 10 h, respectively. Changes in structural, morphological, thermal and magnetic properties of the powders during mechanical alloying and during subsequent annealing have been examined by X-ray diffraction, scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and vibrating sample magnetometer (VSM). XRD results: showed the formation of new phases (Fe and LaFeO3 perovskite) created through the ball milling. The results showed that the crystalline size of ball milled powders decreased with increasing the milling time. In fact, after 10 h of ball milling, La (OH)3 changes from nanostructure in amorphous structure. The magnetic measurements display a distinct saturation magnetization and coercivity.

Microwave melting and processing of metal–ceramic composite castings

2016 ◽  
Vol 232 (7) ◽  
pp. 1235-1243 ◽  
Author(s):  
Satnam Singh ◽  
Dheeraj Gupta ◽  
Vivek Jain
Keyword(s):  
Microwave Heating ◽  
Ceramic Composite ◽  
Ceramic Composites ◽  
Advanced Materials ◽  
X Ray Diffraction ◽  
Uniform Dispersion ◽  
Metal Ceramic ◽  
The Cost ◽  
Equiaxed Grain ◽  
Structure Properties

Applications of metal–ceramic composites are increasing in advanced materials field; however, efficient utilization of these materials depends on the cost involved in processing and structure–properties correlations. Processing of materials through microwave energy has already been accepted as a well-established route for many materials. In this work, composites of nickel-based metallic powder (matrix) and SiC powder (reinforcement) were successfully casted by microwave heating. The mechanism for the development of composite castings using microwaves is discussed with proper illustrations. The results of microstructure analysis of the developed cast revealed that uniform equiaxed grain growth with uniform dispersion of reinforcement. The results of X-ray diffraction analysis revealed that during microwave heating some metallurgical changes took place, which led to higher microhardness of cast. Micowave processed casting revealed lower defects (~1.75% porosity) and average Vickers microhardness of 920 ± 208 HV. This work reports the successful applications of microwaves in manufacturing, in the form of melting and casting of metallic powders.

scholarly journals Synthesis of CaF2 Nanoparticles Coated by SiO2 for Improved Al2O3/TiC Self-Lubricating Ceramic Composites

Nanomaterials ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1522 ◽  
Author(s):  
Zhaoqiang Chen ◽  
Niansheng Guo ◽  
Lianggang Ji ◽  
Chonghai Xu
Keyword(s):  
Mechanical Properties ◽  
Wear Resistance ◽  
Ceramic Material ◽  
Ceramic Composites ◽  
X Ray Diffraction ◽  
Composite Powders ◽  
Sio2 Coating ◽  
X Ray ◽  
Coated Nanoparticles ◽  
Transmission Electron

In order to reduce the influence of CaF2 addition on the mechanical properties of self-lubricating ceramic tools, we applied a silicon dioxide (SiO2) coating on calcium fluoride (CaF2) nanoparticles through hydrolysis and condensation reactions using the tetraethoxysilane (TEOS) method. The powder was dried by the azeotropic method, so that it acquired a better dispersibility. The resulting composite powders were characterized using XRD (X-ray diffraction) and TEM (transmission electron microscopy), showing that the surface of CaF2 was coated with a layer of uniform and compact SiO2. SiO2 shells with different thicknesses could be obtained by changing the amount of TEOS added, and the thickness of the SiO2 shells could be controlled between 1.5 and 15 nm. At the same time, a ceramic material containing CaF2 nanoparticles and CaF2@SiO2-coated nanoparticles was prepared. It had the best mechanical properties when CaF2@SiO2-coated nanoparticles were added; its flexural strength, fracture toughness, and hardness were 562 ± 28 MPa, 5.51 ± 0.26 MPa·m1/2, and 15.26 ± 0.16 GPa, respectively. Compared with the ceramic tool containing CaF2 nanoparticles, these mechanical properties were increased by 17.57%, 12.67%, and 4.88%, respectively. The addition of CaF2@SiO2-coated nanoparticles greatly improved the antifriction and wear resistance of the ceramic material, and the antifriction and wear resistance were balanced.

Study on the Crystal Bonding Mechanism of Al2O3–ZrO2 Ceramic Composite

2014 ◽  
Vol 941-944 ◽  
pp. 555-559
Author(s):  
Xiao Li Tian ◽  
Qun Hu Xue ◽  
Chong Bo Xue
Keyword(s):  
Growth Model ◽  
Ceramic Composite ◽  
Sol Gel ◽  
Tetragonal Zirconia ◽  
Bonding Mechanism ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mineral Phases ◽  
Gel Processing ◽  
Composite Samples

Al2O3–ZrO2 ceramic composite samples were prepared using Al2O3–ZrO2 composite powder synthesized by sol-gel processing as the main starting material and zirconia gel as the binder. Then the mineral phases were analyzed by X-ray diffraction (XRD) and the crystal bonding mechanism was analyzed by scanning electron microscopy (SEM). The results show that: 1) the mineral phases were monoclinic zirconia, tetragonal zirconia and corundum. The microstructure shows an alumina-zirconia diffusion mosaic structure and the grain boundary interface with direct bonding state. 2) The crystal growth model was the Ostwald dual growth model of the alumina and zirconia grains, and the crystal bonding mechanism was that the intragranular zirconia grain exited within the alumina grain and the intergranular zirconia grain exited during the alumina grain boundaries.

Yttria-Doped Zirconia-Hydroxyapatite Composite Coating on Cp-Ti Implants by Biomimetic Method

2012 ◽  
Vol 445 ◽  
pp. 691-696 ◽  
Author(s):  
Aysu Karakas ◽  
A. Binnaz Hazar Yoruc ◽  
Duygu Ceylan Erdogan ◽  
Oktay Elkoca
Keyword(s):  
Tetragonal Phase ◽  
Sol Gel ◽  
Tetragonal Zirconia ◽  
Stress Shielding ◽  
Ceramic Composites ◽  
Composite Powders ◽  
Ti Alloys ◽  
High Fatigue ◽  
Superior Corrosion Resistance ◽  
Cp Ti

Titanium (Ti) and Ti-alloys are often used in dental and orthopedic applications because of their good mechanical properties and biocompatibility. The advantages of Ti and Ti-alloys are its superior corrosion resistance, high fatigue strength and low elastic modulus which reduce stress shielding. Morover biocompatibility of them can be improved coating with bioceramics such as hydroxyapatite (HA) or other ceramic composites. The hydroxyapatite [Ca10(PO4)6(OH)2, H is frequently used as a coating material on the surfaces of Ti-based medical implants to improve the bone fixation and thus the lifetime of the implant is increased. However, the main weakness of HA lies on its poor mechanical strength that makes it unsuitable for load-bearing applications. An attractive way to produce the tougher HA is to use composite powders such as Yttria-Doped Zirconia-Hydroxyapatite (YSZ-HA) consisting of 8 mol% yttria-stabilized tetragonal zirconia (YSZ) so that the apatite phase increases the biocompatibility and zirconia (ZrO2) phase improves the strength. Y2O3addition into zirconia can stabilize the tetragonal phase at room temperature (YSZ) and the tetragonal phase plays a major role to increase the fracture toughness. In the present study yttria-dopped zirconia powders by using ZrO(NO3)2.xH2O and Y(NO3)3.6H2O were produced to synthesize HA-YSZ composites. In accordance with this purpose, at the first step, Ca (NO3)2.4H2O, (NH4)2HPO4and YSZ powders were dissolved in simulated body fluids (SBF) to obtain sol. The gelatin solutions with different concentration were added into sol to provide the gelation. Then the surfaces of Ti implants were soaked in this solution. The coating rate of Ti samples was arranged as 14 cm/s and coated implants were sintered at 900°C. Structural analysis of coated powders was obtained by using XRD. Morphological examinations and coating thickness were investigated by SEM. After the sol-gel solution was dried at 80°C, dried-powder was sintered at 900°C. Sintered powders were analyzed by FT-IR to determine any gelatin residue.

scholarly journals Insights Into the Microstructure and Dielectric Properties of Cold Sintered NaCa2Mg2V3O12 Based Composites

2021 ◽  
Vol 8 ◽  
Author(s):  
Rakhi Madhuri ◽  
Santha Narayana Iyer ◽  
Subodh Ganesanpotti
Keyword(s):  
Dielectric Properties ◽  
Secondary Phase ◽  
Ceramic Composites ◽  
Sintering Process ◽  
Composite Ceramics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Microwave Dielectric ◽  
Dielectric Ceramics ◽  
Quality Factor Q

Cold sintering process (CSP) was successfully employed to fabricate (1 − x) NaCa2Mg2V3O12-xNaCl [abbreviated as (1 − x) NCMVO-xNaCl] microwave dielectric ceramics. (1 − x)NCMVO-xNaCl ceramics prepared at 200°C and at a pressure of 450 MPa had a high relative density of 80–94%. X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), and Raman spectroscopy showed that both NCMVO and NaCl phases co-exist in all composite ceramics without forming any secondary phase. Further, dependence of microstructure and dielectric properties on cold sintering temperature and duration were investigated in detail and their optimized values to obtain maximum density of ceramic composites were 200°C and 50 min, respectively. (1 − x)NCMVO-xNaCl (x = 0.4–0.7) composites have relative permittivity (εr) in the range of 6.9–7.4, and a reasonably high microwave quality factor (Q × f) of 5,000 to 13,830 GHz.

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