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 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.

Enhancement of Dry Sliding Tribological Characteristics of Perforated Zirconia Toughened Alumina Ceramic Composite Filled With Nano MoS2 in High Vacuum

2020 ◽  
Vol 143 (6) ◽  
Author(s):  
Kunal Ghosh ◽  
Subhrojyoti Mazumder ◽  
Harish Hirani ◽  
Poulomi Roy ◽  
Nilrudra Mandal
Keyword(s):  
Ceramic Composite ◽  
High Vacuum ◽  
Ceramic Composites ◽  
Alumina Ceramic ◽  
Tribological Characteristics ◽  
Dry Sliding ◽  
Temperature Environment ◽  
Zirconia Toughened Alumina ◽  
Wear Tests ◽  
High Temperature Environment

Abstract An innovative approach was adopted for fabricating zirconia toughened alumina (ZTA)-MoS2 self-lubricating ceramic composites with the inclusion of hydrothermally synthesized nano MoS2 through the micropores of perforated ZTA ceramics. This method avoided the exposure of MoS2 in high-temperature environment due to its in-sensitiveness during traditional sintering techniques. Different weight percentages (wt%: 0, 5, 10, and 15) of graphite were incorporated to produce porous ZTA ceramics with the help of cold press sintering followed by insertion of nano MoS2 into the matrices. Best tribological characteristics were obtained with 10 wt% graphite-ZTA-MoS2 specimen which offered an improvement of ∼66% in coefficient of friction (COF) and ∼96% in specific wear rate when dry sliding tests were carried out against silicon nitride (Si3N4) in high vacuum (5.0 × 10−4 mbar). Nano MoS2 was sheared off at the contacting interface during sliding under load which showed a good tribological characteristics of the composite. Delamination was found as the dominating wear mechanism in ZTA-MoS2 composites during wear tests.

Peridynamical Modelling of Nanoindentation in Ceramic Composites

2016 ◽  
Vol 254 ◽  
pp. 55-59 ◽  
Author(s):  
Tomasz Sadowski ◽  
Błażej Pankowski
Keyword(s):  
Ceramic Composite ◽  
Ceramic Composites ◽  
Intrinsic Stress ◽  
Stress Singularities ◽  
Continuum Approach ◽  
Two Phase ◽  
Brittle Solids ◽  
Complex Phenomena ◽  
Zirconia Toughened Alumina

Indentation in brittle solids involves many complex phenomena related to cleavage and contact, as well as intrinsic stress singularities, which are almost impossible to capture with traditional continuum approach and FEA at mesoscale. In case of a two-phase ceramic composite [1–3] the number of unknown material and interfacial constants, that have to be calibrated experimentally, increases rapidly [4, 5]. In this paper, nanoindentation in zirconia-toughened alumina (ZTA) is modelled using discrete (peridynamical) approach

Physico-mechanical properties and microstructure of multi-phase ceramic composites based on zircon and dolomite mixtures

2021 ◽  
Vol 19 (4) ◽  
pp. 305-314
Author(s):  
M.M.S. Wahsh ◽  
Safyah B. Bakare ◽  
I.M. Bakr ◽  
A.G.M. Othman
Keyword(s):  
Mechanical Properties ◽  
Bulk Density ◽  
Tetragonal Zirconia ◽  
Porous Ceramics ◽  
Ceramic Composites ◽  
Liquid Phase Sintering ◽  
Apparent Porosity ◽  
Transformation Toughening ◽  
Linear Change ◽  
Multi Phase

Four composites containing zircon and dolomite were designed by adding dolomite from 5wt% to 35wt% at the expense of zircon content. Densification parameters in terms of bulk density, apparent porosity and linear change were determined at different firing temperatures (1200°C–1400°C). Cold crushing strength of sintered composites, phase composition and microstructure were investigated. Samples contain 35wt% of dolomite and fired at 1200°C for 2 hours exhibited higher porosity (AP ∼ 51.25%) than other samples and can be used as porous ceramics. This is due to CO2 evaporation through the thermal decomposition of dolomite. Dense ceramics can be obtained by adding 5wt% of dolomite and fired at 1400°C for 2 hours (bulk density ∼3.67 g/cm3 and apparent porosity ∼4.5%). Only zirconia and diopside crystalline phases were detected at composite containing 35wt% of dolomite and fired at 1400°C. Due to the liquid phase sintering process, the densification parameters of the sintered samples have been enhanced by increasing the temperature. The mechanical properties of the sintered samples were improved due to the transformation toughening mechanism of tetragonal zirconia. Microstructure and EDAX analysis of the sintered composites show the presence of sub-prismatic zircon and rounded zirconia crystals as well as irregularly dark diopside crystals.

Effect of Titania and Magnesia on the Physical Properties of Zirconia Toughened Alumina

2016 ◽  
Vol 840 ◽  
pp. 82-86
Author(s):  
Hanisah Manshor ◽  
Wan Muhammad Ihsan Wan Sabri ◽  
Abdul Wahid Ramli ◽  
Ahmad Zahirani Ahmad Azhar ◽  
Ezzat Chan Abdullah ◽  
...  
Keyword(s):  
Physical Properties ◽  
Ceramic Composite ◽  
High Hardness ◽  
Secondary Phase ◽  
Solubility Limit ◽  
Ceramic Composites ◽  
High Temperature Strength ◽  
Constant Weight ◽  
Weight Percentage ◽  
Zirconia Toughened Alumina

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.

Composition Dependence of The Electrical Conductivity of n-p Ceramic Composite

1994 ◽  
Vol 357 ◽  
Author(s):  
Seok-Taek Jun ◽  
Gyeong-Man Choi
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Grain Boundaries ◽  
Ceramic Composite ◽  
Composition Dependence ◽  
Volume Fraction ◽  
Ceramic Composites ◽  
Equivalent Circuits ◽  
Total Resistance ◽  
Impedance Response

AbstractElectrical properties of ZnO-CuO ceramic composites with varying composition were investigated. The electrical conductivity increased with increasing CuO volume fraction between 1 mol% to 95 mol%. Impedance response showed three semicircles, indicating three resistive elements contributing to the total resistance of the composite. A new model based on the equivalent circuits was developed to explain the contribution of grain boundaries to the resistance of the composite. The change of electrical conductivity was explained by the probability change of two equivalent circuits.

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.

Design of Ceramic Composite Based on the Impact Resistance and its Machining Application

2007 ◽  
Vol 336-338 ◽  
pp. 2487-2489
Author(s):  
Chong Hai Xu ◽  
H.Y. Wang
Keyword(s):  
Ceramic Composite ◽  
Volume Fraction ◽  
Impact Resistance ◽  
Cutting Tools ◽  
Ceramic Composites ◽  
Pure Alumina ◽  
Optimum Technique ◽  
Optimum Model ◽  
The Impact

An optimum model for the compositional design of advanced ceramic composites is built based on the impact resistance. The relative impact modulus IM0 is defined as an index for the characterization of impact resistance of brittle ceramics. Computer aided optimum technique is used to get the optimum compositions of the material. Results show that the material can be expected to have the highest impact resistance which is nearly 86% higher than that of the pure alumina when the volume fraction of Al2O3, SiC and Ti(C,N) is 72.3%, 14.8% and 12.9%, respectively. An advanced SiC/Ti(C,N)/Al2O3 ceramic composite is then fabricated according to the optimum results. When used as cutting tools, its impact fracture resistance is approximately 71%-76% higher than that of the pure alumina ceramic in the machining of hardened carbon steel. The increment coincides well with that predicted directly from the optimum model. It suggests that the method is feasible in the design and fabrication of ceramic composites especially for machining application.

3D Model of Crack Propagation in Particulate Ceramic Composite Containing Residual Stresses

2017 ◽  
Vol 754 ◽  
pp. 103-106
Author(s):  
Kateřina Štegnerová ◽  
Zdeněk Majer ◽  
Pavel Hutař ◽  
Luboš Náhlík
Keyword(s):  
Residual Stresses ◽  
Crack Propagation ◽  
Ceramic Composite ◽  
Volume Fraction ◽  
Numerical Models ◽  
Ceramic Composites ◽  
Fe Method ◽  
Critical Crack ◽  
Alumina Particles

A crack propagation and fracture behaviour of particulate ceramic composite were investigated. Influence of 3D shape of particles on the crack propagation was studied together with influence of the presence of residual stresses, which are developed inside the composite during manufacturing process. Finite element (FE) method was used for numerical simulation of propagating crack in the composite. Basic numerical models of low-temperature co-fired ceramics (LTCC) with alumina particles homogenously dispersed in the glass matrix were developed. Volume fraction of alumina phase was 20vol.%, which is typical amount for LTCC. The results show that existence of residual stresses retards the crack propagating under conditions of sub-critical crack growth (SCG). Presented results contribute to a better understanding of the role of residual stresses in particulate ceramic composites.

scholarly journals Oxide Bioceramic Composites in Orthopedics and Dentistry

2021 ◽  
Vol 5 (8) ◽  
pp. 206
Author(s):  
Piconi Corrado ◽  
Sprio Simone
Keyword(s):  
Mechanical Behavior ◽  
Hip Replacement ◽  
Ceramic Composites ◽  
Clinical Applications ◽  
Wide Field ◽  
Joint Replacements ◽  
Composite Systems ◽  
Third Phase ◽  
Main Component ◽  
Zirconia Toughened Alumina

Ceramic composites based on alumina and zirconia have found a wide field of application in the present century in orthopedic joint replacements, and their use in dentistry is spreading. The development of this class of bioceramic composites was started in the 1980s, but the first clinical applications of the total hip replacement joint were introduced in the market only in the early 2000s. Since then, several composite systems were introduced in joint replacements. These materials are classified as Zirconia-Toughened Alumina if alumina is the main component or as Alumina-Toughened Zirconia when zirconia is the main component. In addition, some of them may contain a third phase based on strontium exa-aluminate. The flexibility in device design due to the excellent mechanical behavior of this class of bioceramics results in a number of innovative devices for joint replacements in the hip, the knee, and the shoulder, as well in dental implants. This paper gives an overview of the different materials available and on orthopedic and dental devices made out of oxide bioceramic composites today on the market or under development.

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