Due to their exceptional properties, high-performance ce-ramics are useful for a wide variety of ... more Due to their exceptional properties, high-performance ce-ramics are useful for a wide variety of applications.[' -31 Al-though the current technology is sufficient for many applica-tions, the reliability of high-performance ceramics can still be improved, thus enabling the use of ...
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
International Journal of Applied Ceramic Technology, Nov 18, 2015
In this study, laminates consisting of sintered alumina substrates and green Low Temperature Co-f... more In this study, laminates consisting of sintered alumina substrates and green Low Temperature Co-fired Ceramics (LTCC) tapes have been produced via Cold Low Pressure Lamination which is based on adhesive tapes for joining of layers at room temperature and pressures <5 MPa. The influences of lamination parameters such as temperature, pressure, and time on the quality of the green and sintered multilayer stack have been determined. If the bottom LTCC layer of an alumina–LTCC–LTCC laminate is metallized by screen printing defects such as crack formation can occur due to stress formation caused by constrained sintering. By adapting the lamination parameters, these stresses can be avoided. Another defect observed is cavities which form along the printed circuit lines. This type of defect is caused by the shrinkage of the circuit line width during firing; by reducing the height of the conductor line during screen printing, the cavity size can be reduced. In addition, different screen-printed metallization layouts have been tested to determine the influence of line and spaces on the quality of sintered laminates.
ABSTRACT Due to the need of cost reduction in table porcelain manufacturing new processing techni... more ABSTRACT Due to the need of cost reduction in table porcelain manufacturing new processing techniques like injection moulding, microwave drying or fast firing are of interest. Especially the manufacturing of handles are in the focus of research. Cups and handles are separately produced by jiggering and slip casting, respectively. While jiggering is a profitable technique for rotation-symmetrically parts, slip casting is a very expensive technology, because of degradation of gypsum-moulds, long production time and the necessity of bin location. Thus, wet-pressing is an interesting alternative to avoid these disadvantages. To use this forming technology, a conventional porcelain mass was modified concerning water content and organic additives, and the effects of these modifications on the rheology of the mass, the workability, the sticking behaviour of the mass to the tool, the strength of the green body, and the shrinkage behaviour were analysed.
Journal of Materials Processing Technology, Mar 1, 2016
Abstract Rotationally symmetric refractory nozzles have been fabricated using the spiral winding ... more Abstract Rotationally symmetric refractory nozzles have been fabricated using the spiral winding technique with ceramic alumina green tapes. Different layer designs have been developed in order to obtain a homogeneous fired structure with locally delaminated interfaces, which are expected to improve the thermal shock behavior. In this regard, the microstructure of all fired structures has been investigated. Thermal shock tests have been conducted to evaluate the impact of the layer design on the formation of micro cracks and other damage. Subsequently, the corrosion behavior of these nozzle compositions has been investigated.
Journal of the American Ceramic Society, Feb 3, 2011
... This makes the evaluation and comparison of different printing techniques highly important. .... more ... This makes the evaluation and comparison of different printing techniques highly important. ... adjust the casting head relative to the moving carrier tape and the casting head design limit the ... Afterwards, the slurry was homogenized in a rotating mixer for 24 h (REAX 20, Heidolph ...
This contribution deals with flexographic printing of nanoparticulate tin-doped indium oxide (ITO... more This contribution deals with flexographic printing of nanoparticulate tin-doped indium oxide (ITO) inks for the manufacture of fine lines on PET foils and glass substrates. The development and optimization of ITO inks, based on solutions of water and ethanol, for the flexographic printing process is presented. The influence of the solvent composition, of the particle content, and of the molar mass of the binder polyvinylpyrrolidone on the printing result is shown. ITO lines with a minimum line width of around 120 μm were printed using a printing plate with a feature size of 50 μm; the ITO lines exhibited a thickness of around 1 μm. Laser post-treatment was used to consolidate the top layer of the nanoparticulate ITO structures resulting in improved electrical properties; low sheet resistance values of around 300 Ω/□ were achieved.
Colloids and Surfaces A: Physicochemical and Engineering Aspects, May 1, 2008
ABSTRACT One possible approach to prevent the oxidation of silicon nanoparticles during a dispers... more ABSTRACT One possible approach to prevent the oxidation of silicon nanoparticles during a dispersing process is to use a dispersing medium, which does not contain any oxygen atoms in its structure, e.g. toluene. However, dispersing nanoparticles in such a non-polar organic medium is a major challenge, because the particles tend to aggregate very easily. The attempt of wet-grinding non-stabilized SiNP in toluene with a stirred media mill results in μm-sized aggregates that precipitate rapidly. In order to achieve stable suspensions with regard to aggregation a suitable additive, added during the process of dispersion, is necessary. The stabilizing efficiency of several different additives, mostly oligo- and polymeric compounds, was evaluated by investigating the aggregate formation via dynamic light scattering, complemented by scanning electron micrographs. This work demonstrates that the stability of the particulate system and therefore the formation of aggregates can be adjusted selectively by the choice of the additive towards well-dispersed or densified particles. The attachment of the additives upon the surface of the SiNP was examined by diffuse reflectance infrared Fourier transform spectroscopy and the surface coverage was quantified by a combination of thermogravimetric analysis and gas sorption experiments.
Due to their exceptional properties, high-performance ce-ramics are useful for a wide variety of ... more Due to their exceptional properties, high-performance ce-ramics are useful for a wide variety of applications.[' -31 Al-though the current technology is sufficient for many applica-tions, the reliability of high-performance ceramics can still be improved, thus enabling the use of ...
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
International Journal of Applied Ceramic Technology, Nov 18, 2015
In this study, laminates consisting of sintered alumina substrates and green Low Temperature Co-f... more In this study, laminates consisting of sintered alumina substrates and green Low Temperature Co-fired Ceramics (LTCC) tapes have been produced via Cold Low Pressure Lamination which is based on adhesive tapes for joining of layers at room temperature and pressures <5 MPa. The influences of lamination parameters such as temperature, pressure, and time on the quality of the green and sintered multilayer stack have been determined. If the bottom LTCC layer of an alumina–LTCC–LTCC laminate is metallized by screen printing defects such as crack formation can occur due to stress formation caused by constrained sintering. By adapting the lamination parameters, these stresses can be avoided. Another defect observed is cavities which form along the printed circuit lines. This type of defect is caused by the shrinkage of the circuit line width during firing; by reducing the height of the conductor line during screen printing, the cavity size can be reduced. In addition, different screen-printed metallization layouts have been tested to determine the influence of line and spaces on the quality of sintered laminates.
ABSTRACT Due to the need of cost reduction in table porcelain manufacturing new processing techni... more ABSTRACT Due to the need of cost reduction in table porcelain manufacturing new processing techniques like injection moulding, microwave drying or fast firing are of interest. Especially the manufacturing of handles are in the focus of research. Cups and handles are separately produced by jiggering and slip casting, respectively. While jiggering is a profitable technique for rotation-symmetrically parts, slip casting is a very expensive technology, because of degradation of gypsum-moulds, long production time and the necessity of bin location. Thus, wet-pressing is an interesting alternative to avoid these disadvantages. To use this forming technology, a conventional porcelain mass was modified concerning water content and organic additives, and the effects of these modifications on the rheology of the mass, the workability, the sticking behaviour of the mass to the tool, the strength of the green body, and the shrinkage behaviour were analysed.
Journal of Materials Processing Technology, Mar 1, 2016
Abstract Rotationally symmetric refractory nozzles have been fabricated using the spiral winding ... more Abstract Rotationally symmetric refractory nozzles have been fabricated using the spiral winding technique with ceramic alumina green tapes. Different layer designs have been developed in order to obtain a homogeneous fired structure with locally delaminated interfaces, which are expected to improve the thermal shock behavior. In this regard, the microstructure of all fired structures has been investigated. Thermal shock tests have been conducted to evaluate the impact of the layer design on the formation of micro cracks and other damage. Subsequently, the corrosion behavior of these nozzle compositions has been investigated.
Journal of the American Ceramic Society, Feb 3, 2011
... This makes the evaluation and comparison of different printing techniques highly important. .... more ... This makes the evaluation and comparison of different printing techniques highly important. ... adjust the casting head relative to the moving carrier tape and the casting head design limit the ... Afterwards, the slurry was homogenized in a rotating mixer for 24 h (REAX 20, Heidolph ...
This contribution deals with flexographic printing of nanoparticulate tin-doped indium oxide (ITO... more This contribution deals with flexographic printing of nanoparticulate tin-doped indium oxide (ITO) inks for the manufacture of fine lines on PET foils and glass substrates. The development and optimization of ITO inks, based on solutions of water and ethanol, for the flexographic printing process is presented. The influence of the solvent composition, of the particle content, and of the molar mass of the binder polyvinylpyrrolidone on the printing result is shown. ITO lines with a minimum line width of around 120 μm were printed using a printing plate with a feature size of 50 μm; the ITO lines exhibited a thickness of around 1 μm. Laser post-treatment was used to consolidate the top layer of the nanoparticulate ITO structures resulting in improved electrical properties; low sheet resistance values of around 300 Ω/□ were achieved.
Colloids and Surfaces A: Physicochemical and Engineering Aspects, May 1, 2008
ABSTRACT One possible approach to prevent the oxidation of silicon nanoparticles during a dispers... more ABSTRACT One possible approach to prevent the oxidation of silicon nanoparticles during a dispersing process is to use a dispersing medium, which does not contain any oxygen atoms in its structure, e.g. toluene. However, dispersing nanoparticles in such a non-polar organic medium is a major challenge, because the particles tend to aggregate very easily. The attempt of wet-grinding non-stabilized SiNP in toluene with a stirred media mill results in μm-sized aggregates that precipitate rapidly. In order to achieve stable suspensions with regard to aggregation a suitable additive, added during the process of dispersion, is necessary. The stabilizing efficiency of several different additives, mostly oligo- and polymeric compounds, was evaluated by investigating the aggregate formation via dynamic light scattering, complemented by scanning electron micrographs. This work demonstrates that the stability of the particulate system and therefore the formation of aggregates can be adjusted selectively by the choice of the additive towards well-dispersed or densified particles. The attachment of the additives upon the surface of the SiNP was examined by diffuse reflectance infrared Fourier transform spectroscopy and the surface coverage was quantified by a combination of thermogravimetric analysis and gas sorption experiments.
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