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Journal of Ceramic Science and Technology 1/2010
Vol. 1, No. 1 · September 2010
SiC/BN Composites by Spark Plasma Sintering (SPS) of Precursor-Derived SiBNC Powders
J. Wilfert, K. Meier, K. Hahn, Y. Grin, M. Jansen
Pages 1-6 · DOI: 10.4416/JCST2010-00012
Preceramic polyborocarbosilazane was pyrolysed at 900 °C and 1400 °C, respectively, yielding amorphous SiBNC. The as-obtained powders were subsequently spark plasma sintered (SPS) at temperatures in a range between 1400 °C and 1800 °C for 10 minutes under uniaxial pressure of 50 MPa. The samples have been characterized by SEM, TEM, XRD, helium pycnometry and Vickers hardness measurements. Independent of the pyrolysis temperature of the starting materials, the most compact samples were obtained by SPS at 1800 °C. In SPS conditions the onset of crystallization and phase separation of the amorpho …
Water Structure Changes within High Solids Loading Calcium Carbonate Slurries
Joshua J. Taylor, Yi-Chung Wang, Wolfgang M. Sigmund
Pages 7-14 · DOI: 10.4416/JCST2010-00003
Slurries with up to 75 ms% calcite were investigated with attenuated total reflectance – Fourier transform infrared spectroscopy (ATR-FTIR). It was found that infrared absorption bands for water and deuterated water in slurries strongly depend on the solids loading. As the solids loading increases there is a decrease in structured water. Aging of the slurry reverses the trend and increases the amount of structured water. These measurements indicate that results obtained in dilute conditions as required by many scientific characterization techniques may not be extrapolated to high solids loadin …
Failure Resistance Optimisation in Layered Ceramics Designed with Strong Interfaces
Raúl Bermejo, Robert Danzer
Pages 15-20 · DOI: 10.4416/JCST2010-00007
Layered ceramics designed with weak interfaces favour interface delamination and provide high failure resistance, while laminates with strong interfaces show higher strength and enhanced mechanical reliability. In this paper it is proposed to combine crack bifurcation and interface delamination in a unique layered architecture with strong interfaces to optimise both failure resistance and mechanical reliability.Theoretical approaches from He and Hutchinson for delamination in bi-materials and from Lange et al. for crack bifurcation in multilayers are here employed to define an optimal design. …
2.5Y-TZP from Yttria-Coated Pyrogenic Zirconia Nanopowder
Frank Kern
Pages 21-26 · DOI: 10.4416/JCST2010-00005
Thanks to their high strength and toughness, yttria-stabilized zirconia polycrystals (Y-TZP) have become one of the most important structural ceramics for engineering and biomedical applications. In this study 2.5Y-TZP powder was produced from monoclinic pyrogenic nanopowder with a nitrate coating and calcination process. The powders were consolidated by hot pressing to obtain specimens for mechanical testing, phase analysis and microstructural investigation. Bending strength, toughness, microstructure and transformability of the nano-TZP were determined depending on sintering temperature in t …
Effect of Co Co-Doping on the Electrical Conductivity of Ce0.9Sm0.1O2-δ
M.J. Pawar, S.S. Chaure, S.B. Deshmukh
Pages 27-31 · DOI: 10.4416/JCST2010-00006
The influence of cobalt doping on the densification and activation energy of Ce0.9Sm0.1O2-δ was studied. Solid solutions of Ce0.9-xCoxSm0.1O2-δ (x = 0, 0.05, 0.1 and 0.15) were prepared by means of a modified EDTA-glycol method. It was found that the degree of densification increases with an increasing concentration of cobalt. Almost full densification could be achieved at a sintering temperature of 1500 °C. The highest density (99.3 %) and minimum activation energy (0.81 eV) were observed for the composition Ce0.8Co0.1Sm0.1O2-δ.
A New Bioactive Glass Composition for Bioceramic Scaffolds
Devis Bellucci, Valeria Cannillo, Antonella Sola
Pages 33-40 · DOI: 10.4416/JCST2010-00008
Bioactive-glass-derived scaffolds are crucial in bone tissue engineering since they act as temporary templates for tissue regrowth, providing structural support to the cells in a resulting 3D architecture. However, many issues remain open with regard to their design. On the one hand, bioceramic scaffolds should be bioactive, highly porous and should possess adequate mechanical properties; on the other hand, attempts to improve the mechanical properties of the widely used 45S5 Bioglass® turn the bioactive glass itself into a glass-ceramic, with non-trivial effects on the resulting scaffold bioa …
Effect of CdO Addition on Microwave Dielectric Properties of BaxSr1-xTiO3 Ceramics
Doaa A. Abdel Aziz, Wagdy N. Nour, Aisha E. Reda, Eglal R. Souya
Pages 41-50 · DOI: 10.4416/JCST2010-00001
Ceramic-based barium strontium titanate (BST) solid solutions with the formula BaxSr1-xTiO3 are very important candidates for millimetre-wave applications (e.g. filters and antennas). Several samples with and without CdO were prepared by means of the conventional solid-state route. Five compositions with (0.00 ≤ × ≤ 0.30) sintered at temperatures in the range 1300 - 1500 °C were investigated. Structural X-ray diffraction analysis confirmed their perovskite structure. The morphology of the sintered ceramic bodies was analysed by means of scanning electron microscopy (SEM) and energy-dispersive …
Effect of Alumina/Iron Catalysts on the Formation of Carbon Nanotubes
Xiaoxue Zhang, Juha-Pekka Nikkanen, Jyri Rintala, Mika Pettersson, Tomi Kanerva, Jarmo Laakso, Erkki Levänen, Tapio Mäntylä
Pages 51-54 · DOI: 10.4416/JCST2010-00013
Two different ferrous compounds, iron nitrate and ferrocene, were applied as the iron precursor in sol-gel processing in order to produce two different iron-containing alumina catalysts. Methane gas was decomposed over the two catalysts under the same conditions to produce carbon nanotubes. Multi-walled carbon nanotubes were formed on the catalyst with iron nitrate, but not obtained on the catalyst produced with ferrocene. X-ray diffraction, transmission electron microscopy, field emission scanning electron microscopy, Raman spectroscopy and nitrogen adsorption/desorption characterization were …
Development of a Novel Sensor-Actuator-Module with Ceramic Multilayer Technology
Markus Flössel, Sylvia Gebhardt, Andreas Schönecker, Alexander Michaelis
Pages 55-58 · DOI: 10.4416/JCST2010-00010
There is a need for low-profile piezoelectric modules directly integrated into structural components like lightweight metals to control the vibration and noise of thin-walled structures and components.This paper reports on a new module design based on LTCC/PZT multilayers. The newly developed packaging technology entails the lamination of sintered PZT ceramic plates with LTCC green layers and subsequent sintering. This module design has the advantage of complete encasement of the PZT by the insulating carrier material. The approach combines LTCC microsystems technology and piezo technology and …
Instrumented Compaction Experiments under Varied Climatic Conditions
Ulrich Klemm, Bettina Schöne, Hermann Svoboda, Manfred Fries, Manfred Nebelung
Pages 59-66 · DOI: 10.4416/JCST2010-00016
From empirical observations in industrial practice it is known that compaction behaviour and quality of uniaxial pressed ceramic compacts may be significantly influenced by climatic conditions during granulate storage and processing. At the same time, the type of basic material, added binders and lubricants can play a major role in most cases. In the present study, an attempt was made to reach a better understanding of the interactions between climatic conditions and compaction behaviour of silicon nitride granulates with different binder/lubricant systems by using instrumented compaction expe …
