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Journal of Ceramic Science and Technology 1/2014
Vol. 5, No. 1 · March 2014
Bioinorganics in Bioactive Calcium Silicate Ceramics for Bone Tissue Repair: Bioactivity and Biological Properties
H. Mohammadi, M. Hafezi, N. Nezafati, S. Heasarki, A. Nadernezhad, S. M. H. Ghazanfari, M. Sepantafar
Pages 1-12 · DOI: 10.4416/JCST2013-00027
Bioinorganics and the use of metal ions in the synthesis and design of new materials have received considerable attention with regard to use as new biomaterials. One of the important roles of metal ions is the control of dissolution in biomaterials, which has an influence on their biological and chemical properties. Up until now, metal ions such as magnesium (Mg), zinc (Zn), titanium (Ti) and zirconium (Zr) have been used to dope silicate- and phosphate-based ceramics. Calcium silicate (CaSiO3, CS) ceramics are biocompatible and bioactive. Some CS ceramics have exhibited superior apatite forma …
Evaluating Porosity in Cordierite Diesel Particulate Filter Materials, Part 2 Statistical Analysis of Computed Tomography Data
Y. Onel, A. Lange, A. Staude, K. Ehrig, A. Kupsch, M.P. Hentschel, T. Wolk, B.R. Müller, G. Bruno
Pages 13-22 · DOI: 10.4416/JCST2013-00022
Complementary to Part 1 of this work, the bi-continuous microstructure of porous synthetic cordierite ceramics for filtration applications was investigated using 3D x-ray computed tomography at different resolutions. Applying both Fast Fourier Transform and a newly developed image analysis algorithm, we quantitatively evaluated porosity and pore orientation. The statistical approach allows extraction of spatially resolved or average values. Porosity values based on x-ray absorption agree with mercury intrusion measurements, while pore orientation factors agree with x-ray refraction data (Part …
Structural, Mechanical and Optical Properties of Nanocrystalline (K0.34Na0.65)NbO3.01Thin Films Deposited by RF Sputtering
P. Mahesh, D. Pamu
Pages 23-30 · DOI: 10.4416/JCST2013-00026
(K0.34Na0.65)NbO3.01(KNN) thin films were deposited at ambient temperatures by means of RF magnetron sputtering. The X-ray diffraction patterns (XRD) reveal that the as-deposited films are amorphous and on annealing at 500 °C for 1 h induced nanocrystallinity with improved microstructure and optical properties. The crystallite size in the films varies between 44 and 20 nm and is dependent on both O2 SCCM and the thickness of the films. The annealing process increased the grain size along with the roughness in the films. It is observed that the amorphous films exhibited higher band-gap energies …
Determination of Elastic Properties for a Wound Oxide Ceramic Composite
Y. Shi, S. Hofmann, R. Jemmali, S. Hackemann , D. Koch
Pages 31-38 · DOI: 10.4416/JCST2013-00028
Thanks to its low cost and high flexibility, in the last few years the winding technique has been successfully adapted for the production of complex Ceramic Matrix Composite (CMC) components with load-oriented fibre alignment. Since the winding angle can be adjusted in any direction (from 0° to 90°) during the fabrication process, it is important for the design of components to evaluate the elastic properties of CMCs as a function of the winding angle.In this study, an inverse method based on the Classic Laminate Theory (CLT) has been used for the prediction of the elastic properties, i.e. You …
Preparation of Lithium Disilicate Glass-Ceramics as Dental Bridge Material
Z. Khalkhali, B. Eftekhari Yekta, V.K. Marghussian
Pages 39-44 · DOI: 10.4416/JCST2013-00030
Sintering and crystallization behaviors of three lithium-silicate-based glass compositions were determined by heating the pressed specimens above their DTA crystallization peak temperatures.The crystallization procedure and microstructure of the heat-treated specimens were investigated by means of differential thermal analysis, X-ray diffraction and scanning electron microscopy.According to the results, while P2O5 encouraged the crystallization of both Li2SiO3 and Li2Si2O5 phases, ZrO2 did not show such capability. Furthermore, while Li2SiO3 was crystallized directly as the result of a bulk cr …
Characteristics of Micro-Gold-Particle/Glass-Ceramic Composite from Post-Sintering Thermal Treatment
W. Yi, X. Sun, D. Niu, X. Hu
Pages 45-50 · DOI: 10.4416/JCST2013-00038
Microstructural characteristics of a gold-particle (GP)-reinforced glass-ceramic (GC) composite at the GP/GC interface were investigated before and after heat treatment at 900, 1100 and 1300 °C. The interfacial regions between the GP and GC exposed on the fracture surface and relevant chemical reactions were examined. The as-processed GC matrix had a nano-scaled biphasic microstructure, with isolated amorphous leucite phase evenly distributed in the continuous feldspar matrix. After the GP/GC composite was heated at 900 °C, the amorphous leucite phases were transformed into leucite crystalline …
Densification Behavior and Mechanical Properties of Niobium-Oxide-Doped Alumina Ceramics
A.M. Hassan, M. Awaad, F. Bondioli, S.M. Naga
Pages 51-56 · DOI: 10.4416/JCST2013-00045
The densification behavior, microstructure and mechanical properties of high-purity α-Al2O3 doped with 0.25, 0.5 and 0.75 wt% Nb2O5 were investigated. The batches were uniaxially pressed at 220 MPa into discs and rectangular bars and pressureless-sintered at temperature ranging between 1500º and 1650 °C for 1 h. The phase composition of the sintered bodies was followed up with an x-ray diffractometer, while their microstructure was characterized with a scanning electron microscope. The mechanical properties in terms of Vickers hardness (HV1), three-point bending strength and fracture toughnes …
Synthesis and Characterization of Sol-Gel-Derived Chemical Mullite
J. Roy, S. Maitra
Pages 57-62 · DOI: 10.4416/JCST2013-00046
Mullite (3Al2O3·2SiO2) precursor gel was synthesized using aluminum nitrate nonahydrate and liquid sodium silicate as starting materials based on the sol-gel route. The gel was characterized by means of chemical analysis, surface area and bulk density measurements. Fourier transformation infrared spectroscopic (FTIR) and differential thermal analysis (DTA) were performed to study the course of mullitization. The gel was calcined at 800 °C and compacted at 100 MPa pressure. The compacted masses were sintered at different elevated temperatures and subjected to SEM and XRD analysis for microstruc …
Oxidative Crack Healing in Al2O3 Composites Loaded with Ti2AC (A = Al, Sn) Repair Fillers
B.J. Pedimonte, G. Bei, D. Pourjafar, T. Fey, P. Greil
Pages 63-68 · DOI: 10.4416/JCST2013-00044
Crack healing of alumina composites loaded with 5, 10, and 20 vol% Ti2AC (A = Al or Sn) MAX phase was investigated. Surface cracks were prepared by means of indent loading and the modulus of rupture was measured on virgin, indented, and healed specimens. The MAX phase particles serve as repair filler which reacts with oxygen penetrating along a surface crack and filling disrupted crack surfaces with the oxidation reaction products. After annealing for 3 h composites loaded with 20 vol% Ti2AlC showed full recovery at a healing temperature of approximately 900 °C, whereas lower temperatures of 7 …
