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Journal of Ceramic Science and Technology 4/2014
Vol. 5, No. 4 · December 2014
Additive Manufacturing of Ceramics: A Review
J. Deckers, J. Vleugels, J.-P. Kruth
Pages 245-260 · DOI: 10.4416/JCST2014-00032
Additive manufacturing (AM) of ceramics is coming to an aera where the first industrial applications are becoming economically profitable. This review paper provides a survey of AM methods reported in literature to shape ceramic components. It demonstrates that AM has produced ceramic parts that have no cracks or large pores and have mechanical properties close to those of conventionally produced ceramics. Crack- and pore-free ceramics can be manufactured by optimizing the AM process parameters or performing extra densification steps after the AM process. It is also advisable to incorporate co …
Additive Manufacturing: Controllable Fabrication for Integrated Micro and Macro Structures
X. Tian, D. Li, B. Lu
Pages 261-268 · DOI: 10.4416/JCST2014-00044
Additive manufacturing technology has been developed at Xi\'an Jiaotong University for almost twenty years. Innovative process development and frontier application for additive manufacturing technologies have been conducted here since then. In the present paper, the newly developed processes, such as low-cost UV-LED and high-efficiency stereolithography, ceramic stereolithography, and direct metal forming, will be briefly reviewed. Some results of the frontier application research, such as indirect fabrication of ceramic casting molds, wind-tunnel-testing models, and photonic crystals and meta …
High-Temperature Joining of Ceramics and Sapphire by Laser-Based Process
S. Kasch, D. Conrad, S. Sändig
Pages 269-274 · DOI: 10.4416/JCST2014-00027
Ceramics and sapphire are housing materials that are resistant to extreme stress and used in extreme environments today. The necessary high temperatures in conventional joining procedures are not suitable for encapsulating components owing to the functional requirements. Therefore new technologies are being developed in order to achieve local and time-limited heat input into the joining zone and thus to reach the necessary joining temperature.This following paper deals with high-temperature joining with laser beams using high-temperature glass filler material e.g. glass solder. Even if the wor …
Preparation of Ceramic Nanoparticles by CO2 Laser Vaporization
H.-D. Kurland, J. Grabow, Chr. Stötzel, F.A. Müller
Pages 275-280 · DOI: 10.4416/JCST2014-00025
Functional ceramic nanopowders are prepared by means of CO2 laser vaporization (LAVA) starting from coarse ceramic powders. The vaporization proceeds in a continuously flowing process gas at normal pressure. The nanoparticles (NP) are formed as a result of rapid gas phase condensation. Selected LAVA nanopowders are presented as promising candidates for future applications, e.g. drug targeting and magnetic resonance imaging, load-bearing ceramic implants, and biological fluorescence labeling, respectively. Starting from a hematite raw powder, ferrimagnetic Fe2O3 nanopowders are prepared. It is …
CO2-Laser-Assisted Surface Modification of Titanium Alloys for Biomedical Applications
S. Gräf, F. A. Müller
Pages 281-286 · DOI: 10.4416/JCST2014-00022
The surface of Ti6Al4V alloys was activated by means of selective laser microstructuring and subsequent sintering of hydroxyapatite (HAp) nanopowders into the generated structures. For structuring, a novel Q-switched CO2 laser with pulse durations of about 400 ns and a peak power of up to 7 kW was used. This laser system provides defined blind-holes with structural sizes in the range of 100 – 500 μm. The influence of different process gases (Ar, O2, N2) on the formation of titanium oxide (TiO2) and titanium nitride (TiN) interfaces during laser structuring was investigated with glow discharge …
Effect of Alumina Substitution on Porosity and Thermal Expansion of Triaxial Porcelain-Like Bodies
M. Ghaffari, E. Salahi, A. Rajabi
Pages 287-292 · DOI: 10.4416/JCST2014-00021
Aluminous bodies are used in a wide variety of applications as a medium-strength ceramic. In this work, a full composition range of alumina, kaolin, and feldspar were fired at 1230 °C and 1400 °C, and were shown in a triaxial presentation, which can be used to make body calculations. Domestic kaolin has been studied for its potential as a raw material to produce aluminous bodies. The porosity and shrinkage of the samples were measured. When fired at 1400 °C, a wider composition range would result in porcelain-like bodies. The thermal expansion of the selected samples showed that the substituti …
Preparation and Characterization of Hydroxyapatite/Alumina Nanocomposites by High-Energy Vibratory Ball Milling
A. E. Hannora
Pages 293-298 · DOI: 10.4416/JCST2014-00019
Hydroxyapatite/alpha-alumina composites were prepared by means of high-energy vibratory ball milling. The effect of the addition of alumina, from 5 to 25 wt%, was investigated. x-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) results indicated that hydroxyapatite and alumina were the major phases after mechanical milling and only small peak shifts were observed. Transmission electron microscope (TEM) photomicrographs revealed that the powder obtained after mechanical milling was composed of nanoparticles in the size of ∼ 40 nm. After 3h of air sintering at 1000 – 120 …
Mullitization of Manganese-Doped Aluminosilicate Diphasic Gel
J. Roy, S. Das, S. Maitra
Pages 299-308 · DOI: 10.4416/JCST2014-00016
Diphasic mullite precursor gel was synthesized from inorganic salts of aluminum and silicon. The synthesized gel was characterized by means of chemical analyses, FTIR spectroscopic studies as well as measurement of surface area and bulk density. Manganese dioxide (MnO2) as an additive was mixed with the dried gel in different ratios (w/w) by co-grinding followed by compaction. The compacted masses were sintered at different elevated temperatures. The mullitization process was studied by performing differential thermal analysis (DTA) at four different heating rates and the activation energy for …
Performance and Stability of Mixed Conducting Composite Membranes Based on Substituted Ceria
U. Pippardt, J. Böer, Ch. Bollert, A. Hoffmann, M. Heidenreich, R. Kriegel, M. Schulz, A. Simon
Pages 309-316 · DOI: 10.4416/JCST2014-00014
High-temperature dual-phase oxygen separation membranes were successfully prepared from different Ce0.8Gd0.2O2-δ (CG)-spinel mixtures according to the mixed oxide route. MnCo1.9Fe0.1O4 (C19) and Cu0.6Ni0.4Mn2O4 (M2) were used as the spinel components with volume fractions of 10, 20, 30, 40 and 50 vol% respectively. The formation of an electron-conducting percolative network by the spinel components was investigated based on electrical resistivity measurements at room temperature. The oxygen permeation behaviour of the composites was determined as a function of the material composition and the …
Effect of Repeated Firing on the Resistance of Screen-Printed Thick-Film Conductors
D. Ortolino, A. Engelbrecht, H. Lauterbach, M. Bräu, J. Kita, R. Moos
Pages 317-326 · DOI: 10.4416/JCST2014-00029
In this paper, the effect of repeated sintering cycles on the resistance of four different thick-film conductor pastes was investigated. Silver, gold, silver-platinum and silver-palladium pastes are widely used in thick-film technology. Their electrical resistance (R) and their temperature coefficient of resistance (TCR) are important material properties. Screen-printed metallization layers were fired repeatedly and their electrical resistance was measured simultaneously during heating and cooling. It was found that the resistances change with increasing number of firing steps and that they ru …
