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Journal of Ceramic Science and Technology 3/2015
Vol. 6, No. 3 · August 2015
An Overview of the Aerosol Deposition Method: Process Fundamentals and New Trends in Materials Applications
D. Hanft, J. Exner, M. Schubert, T. Stöcker, P. Fuierer, R. Moos
Pages 147-182 · DOI: 10.4416/JCST2015-00018
Ceramic materials typically have to be sintered at high temperatures, often above 1000 °C. This precludes the coating of lower-melting substrate materials, such as metals, glasses and polymers, with dense and robust thin or thick ceramic films. In addition, decomposition or uncontrolled volatilization of the ceramic components can occur at elevated temperatures. As an alternative, the Aerosol Deposition (AD) method is a spray coating process to produce dense and nanocrystalline ceramic films at room temperature directly from an initial bulk powder on almost any substrate material with no need …
Characterization of Mechanical Properties under Shear Load of a Short-Carbon-Fiber-Reinforced C/SiC Ceramic
Y. Shi, K. Tushtev, D. Koch
Pages 183-190 · DOI: 10.4416/JCST2014-00051
The main objective of this work is the evaluation of the mechanical shear properties of a short-carbon-fiber-reinforced ceramic, which shows strong non-homogeneity in its microstructure and anisotropy through different fiber orientations. In this work, the shear modulus (G-modulus) and shear strength of this material were determined with the Iosipescu shear test and the Asymmetric-Four-Point-Bend shear test (AFPB test) at room temperature. Both test methods provide a nearly pure shear stress state in the shear plane and are therefore suitable for determination of the mechanical properties unde …
The Role of Powder Preparation Method in Enhancing Fracture Toughness of Zirconia Ceramics with Low Alumina Amount
I. Danilenko, T. Konstantinova, G. Volkova, V. Burkhovetski, V. Glazunova
Pages 191-200 · DOI: 10.4416/JCST2015-00020
In most cases zirconia-alumina composites for scientific investigations and industry are prepared by means of mechanical mixing of powders, compaction and sintering. In our opinion, this is one of the reasons for the low values for fracture toughness of the sintered materials. In this study, we investigated the effect of nanopowder synthesis methods on the structure and mechanical properties of 3Y-TZP/alumina ceramic composites and determined the mechanisms involved in composite toughening. We show that the addition of a small amount of alumina (1 – 2 wt%) to zirconia ceramics has the potentia …
Preparation of glass-ceramics in the MgO-Al2O3-SiO2 system via low-Temperature combustion synthesis technique
Y. He, J. M. Guo, G. W. Zhang, X. L. Chen, J. C. Zhang, Z. L. Huang, G. Y. Liu, Q. Cai
Pages 201-206 · DOI: 10.4416/JCST2015-00004
MgO-Al2O3-SiO2 (MAS) glass powders have been successfully synthesized by means of the low-temperature combustion technique using magnesium nitrate, aluminium nitrate and silicic acid as raw materials, and urea as fuel. The sintering behavior, crystallization process and dielectric properties of the MAS were investigated with DCS, XRD, TMA and SEM techniques. The results indicate that the sintering temperature of the as-prepared glass powders decreased with the addition of B2O3 and only α-cordierite was precipitated as a main crystal phase, i.e. without μ-cordierite, for the glass powders heate …
Microstructure and Mechanical Properties of Al2O3-C Refractories Using Carbon Black and Multi-Walled Carbon Nanotubes as Carbon Sources
Y. W. Li, N. Liao, S. B. Sang, H. Peng
Pages 207-214 · DOI: 10.4416/JCST2015-00003
Low-carbon Al2O3-C refractories were prepared using tabular alumina and reactive alumina powder as the main raw materials and silicon powder as an additive, while nano carbon black and multi-walled carbon nanotubes (MWCNTs) were added as nano carbon sources. The low-carbon Al2O3-C refractories were first fired at 800 °C, 1000 °C, 1200 °C and 1400 °C in a coke bed. Then the phase compositions and microstructures of the samples coked at the above temperatures were analyzed by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). Finally, the mechanical properties and thermal s …
The Effect of the Glass Phase on the Modulus of Rupture of High-Alumina Refractories
W. Yuan, Q. Zhu, C. Deng, H. Zhu
Pages 215-220 · DOI: 10.4416/JCST2015-00009
Owing to their high refractoriness and slag resistance, high-alumina refractories are widely used in the lining of steelmaking furnaces, glass furnaces and cement rotary kilns in high-temperature industries. The impurities in the raw materials react to form the glass phase, which can melt into liquid at high temperatures. The modulus of rupture of refractories depends intensively on the content and composition of the glass phase. In this work, the cold and hot modulus of rupture for high-alumina bricks were investigated by means of fitting based on different theories. The effect of the glass p …
A Study on the Polymer Precursor Formation and Microstructure Evolution of Square-Shaped (La0.5Ba0.5)(Mn0.5Fe0.5)O3 Ceramic Nanoparticles
M. Romero, M. Romero, H. Pardo, H. Pardo, R. Faccio, R. Faccio, L. Suescun, L. Suescun, S. Vázquez, I. Laborda, L. Fernández-Werner, L. Fernández-Werner, Á. Acosta, J. Castiglioni, Á.W. Mombrú, Á.W. Mombrú
Pages 221-230 · DOI: 10.4416/JCST2015-00005
The polymer precursor formation and the growth mechanism of (La0.5Ba0.5)(Mn0.5Fe0.5)O3 ceramic nanoparticles have been studied. First, we focused on the influence of isolated metals (La, Ba, Mn, Fe) on the polymer precursor formation by means of Raman, FT-IR, scanning electron microscopy and differential scanning calorimetry, showing that the presence of metal ions, especially iron, increases the oxidation rate of the polymer precursor, while the presence of barium leads to a higher degree of polymerization, preventing partial oxidation of the polymer at low temperatures and allowing the prese …
Water-Glass-Based Composite Materials – Investigation into their Thermal Conductivity
R.A. Shishkin
Pages 231-236 · DOI: 10.4416/JCST2014-00050
Inorganic water-glass-based thermal pastes exhibit a higher thermal conductivity coefficient than silicon-based pastes. They can also be used at elevated temperatures. The dependence of thermal conductivity on filler content, curing agent, urea and hybrid fillers is studied. Special attention is paid to the curing chemistry of the thermal pastes during manufacturing. As a result, a number of composite materials with a significant improvement in thermal conductivity has been produced.
Highly Porous Scaffolds Made of Nanosized Hydroxyapatite Powder Synthesized from Eggshells
S.M. Naga, H.F. El-Maghraby, M. Sayed, E.A. Saad
Pages 237-244 · DOI: 10.4416/JCST2014-00058
Nanosize hydroxyapatite powder synthesized indirectly from eggshells is used to produce 3D porous scaffolds. They are fabricated via a polymeric sponge method. X-ray diffraction (XRD) and transmission electron microscopy (TEM) are used to characterize the phase composition and grain size of the scaffolds, respectively. The results showed that the prepared powder is composed of pure hydroxyapatite with a grain size ranging between 35 and 122 nm. The prepared scaffolds calcined at 1250 °C for 2 h possess interconnected porosity (≈ 73 %). The studied scaffolds showed suitable mechanical strength …
The Effect of Thermal Treatment on Tensile Properties of Basalt Fibers
S.M.M. Sabet, F. Akhlaghi, R. Eslami-Farsani
Pages 245-248 · DOI: 10.4416/JCST2014-00053
The use of basalt fibers as a reinforcement in various composites requires the application of elevated temperatures during synthesis and processing conditions depending on the technique utilized. In this study, the tensile strength of basalt fibers at room temperature and also after exposure to 300, 350, 400, 450 and 500 °C in a furnace for durations of 5, 10, 15 and 20 min was investigated. The results indicate that the residual strength of basalt fibers drastically decreases after 20 min exposure at 300 and 400 °C and is only about 57 % and 35 % of that of fibers at room temperature, respect …
Introduction of Glassy Spheres in an Acrylic Matrix: A New Solution for Low-Pressure Sanitaryware Moulds
A. Fortuna, D. M. Fortuna, E. Martini, V. Tagliaferri, G. Rubino
Pages 249-254 · DOI: 10.4416/JCST2015-00019
In this work we have conducted a study to improve the mechanical strength and abrasive wear of the moulds used for traditional casting in the sanitaryware industry. We replaced the beta gypsum commonly employed in low-pressure moulds with a mix of alpha plaster and acrylic resin (Poolkemie Ecoresin). This product greatly improves the mechanical properties of the mould, but does not enable adequate thickness formation owing to the low porosity of the compound. For this reason we introduced increasing amounts of Poraver glassy spheres (10 %, 20 %, 30 %, 40 %) with the goal of ensuring the same t …
