Jürgen Haußelt

Manufacturing of Ceramic Microcomponents by a Rapid Prototyping Process Chain

Time-intensive and cost-consuming manufacturing of new ceramic components may be improved significantly by the use of rapid prototyping processes especially in the development of miniaturized or micropatterned components. Their molding is generally very expensive and finishing is difficult to the point of impossibility. Most known generative ceramic molding processes do not provide a sufficient resolution for the fabrication of microstructured components. In contrast to this, a rapid prototyping process chain that combines micro-stereolithography and low-pressure injection molding, for example, allows the rapid manufacturing of ceramic microcomponents from functional models to preliminary or small-lot series, microcomponents from functional models to preliminary or small-lot series.

Micro Powder Injection Molding

The availability of manufacturing processes suitable for medium and large-scale production of microscale devices is an important requirement for the economic success of microsystems technology. Powder injection molding is on its way to become such an established and economically viable process for manufacturing complex shaped metal or ceramic parts in quantity.

Recent developments in micro ceramic injection molding

Abstract Effective material application and miniaturization, both indispensable to modern product development and production, demand enhanced manufacturing processes suitable for both micro devices and economic series production. For micro parts made of polymeric materials, micro injection molding represents such a method and has already reached an industrially viable status. For manufacturing of ceramic products micro powder injection molding is a promising option because it combines the possibility of large-scale series production with a wide range of materials, thus possessing a considerable economic potential. An enhanced variant, micro two-component injection molding enables, for example, the fabrication of micro components consisting of two ceramic materials with different physical properties and, furthermore, significantly minimizes mounting expenditure.

Metal and ceramic micro components made by powder injection molding

To overcome the lack of micro manufacturing processes suitable for medium and large scale production as well as to process high resistive materials a special variant of micro injection molding is currently under development: micro powder injection molding (MicroPIM), which already enables the manufacturing of finest detailed components with structure sizes down to a few ten micrometer. In order to expand the scope of application of MicroPIM, tests are being conducted with pure tungsten powders or tungsten alloy powders. As further improvement, micro twocomponent injection molding allows, for example, the fabrication of micro components consisting of two ceramic materials with different physical properties.

Effect of Particle Size Distribution and Sedimentation Behaviour on Electrophoretic Deposition of Ceramic Suspensions

By systematic interaction of sedimentation and electrical field in electrophoretic deposition the particle size distribution of the deposited green body can be influenced. This can be employed for producing coatings with a very smooth surface by deposition of only the nanosized fraction of a conventional powder with broad or non-monomodal size distribution, thus avoiding preceding classification. In this paper, the preparation of stabilised slurries is described focussing on the criteria particle size distribution, zeta-potential and sedimentation behaviour. The effectiveness of the interaction of sedimentation and electrophoretic deposition is to be shown.

Systematic interaction of sedimentation and electrical field in electrophoretic deposition

The systematic interaction of sedimentation and electrical field in electrophoretic deposition allows the tailoring of specific properties of deposited green bodies. This technique permits a selective deposition of the nanosized fraction of conventional powders with broad or non-monomodal particle size distribution, thus making preceding classification obsolete. Potential applications are coatings with a very smooth surface or the replication of microstructures or moulds which are filled with nanosized particles and subsequently with coarser particles as support in one process step. Also graded structures can be fabricated with regard to particle size distribution, porosity and composition (e.g. zirconia toughened alumina). In this paper, the interaction of sedimentation and electrical field in electrophoretic deposition is described focussing on the characterisation of both processes, sedimentation and electrophoretic deposition. In addition the effectiveness of the combined process will be shown.

Characterization of non-stoichiometric co-sputtered Ba0.6Sr0.4(Ti1 − x Fe x )1 + x O3 − δ thin films for tunable passive microwave applications

AbstractThe fabrication of novel iron-doped barium strontium titanate thin films by means of radio frequency (RF) magnetron co-sputtering is shown. Investigations of the elemental composition and the dopant distribution in the thin films obtained by X-ray photoelectron spectroscopy, Rutherford backscattering spectrometry, and time-of-flight secondary ion mass spectroscopy reveal a homogeneous dopant concentration throughout the thin film. The incorporation of the iron dopant and the temperature-dependent evolution of the crystal structure and morphology are analyzed by electron paramagnetic resonance spectroscopy, X-ray diffraction, Raman spectroscopy, atomic force microscopy, and scanning electron microscopy. In summary, these results emphasize the RF magnetron co-sputter process as a versatile way to fabricate doped thin films. FigureCross section of the RF magnetron co-sputter setup and the X-ray phototelectron spectroscopy iron spectrum of a co-sputtered iron doped Barium strontium titanate thin film

Effects of thermal processing and iron doping in co-sputtered barium strontium titanate thin films

The effects of the thermal processing and iron doping on RF magnetron co-sputtered barium strontium titanate thin film properties have been investigated. X-ray diffraction and Raman spectroscopy have been used to determine the structural evolution of the films as a function of the annealing temperature and the amount of iron dopant. X-ray photoelectron spectroscopy and electron paramagnetic resonance spectroscopy were employed to gain information about the chemical binding states and the defect structure. The enhancement of the quality factor Q, as well as the decreasing permittivity and tunability due to iron acceptor doping are demonstrated.

Distribution of the Local Electric Field during Electrophoretic Deposition of an Alumina Suspension on a Membrane

The spatially distributed local electric field strength during the electrophoretic deposition (EPD) of alumina suspensions on a membrane is within the scope of the present article. The water-based alumina suspensions were optimized in order to achieve stable suspensions, high deposition rates and maximum green densities of the deposited bodies. In-situ measurements of the local potential drop inside the EPD-cell were carried out using a computer assisted process control set-up with electronic data acquisition. The behaviour of the spatial- and time-dependent electric field distribution was calculated from measured potential drops. The influence of varrying input voltages on the output parameters, such as deposition rate and green density for EPD on membranes was investigated and is discussed. It is shown that the distribution of the local electric field depends on the applied voltage and on time for the case of higher voltages. A dependance of the local electrical fields on the deposition rate is suggested as well.