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Serial crystallography experiments at X-ray free-electron lasers can utilize specially designed ceramic nozzles to generate a strongly focused liquid jet of sample. Several nozzle design options have been evaluated and a concept using a sharpened glass capillary mounted in a self-centering ceramic nozzles is detailed. Filling simulations and tool construction are given for micro ceramic injection molding manufacture of the nozzles. Produced parts are found to meet the specifications for nozzle dimensions and bearing features. Functionality tests show superior performance with respect to liquid jet straightness and reproducibility compared to flame polished glass nozzles. [ABSTRACT FROM AUTHOR]

The progress in microinjection molding has paved the way for the fabrication of complex components. Particularly, the integration of different functionalities made possible by two-component injection molding is a challenging facet of this technology. For the production of robust microdevices consisting of two different metals or ceramics a special variant of this technology has to be implemented: two-component micropowder injection molding (2C MicroPIM). The study presents the materials and powder combinations suitable for 2C MicroPIM. The investigations included considerations on materials behavior during feedstock compounding, injection molding, debinding, and sintering of the assemblies. As a result of dilatometric measurements and on the basis of theoretical considerations and characterization of a 2C MicroPIM part at the phase boundary the requirements beneficial for either a fixed or a movable junction were defined. A shaft-to-collar connection was used to demonstrate the applicability of the selected materials. The investigated ceramic powders and the organic components for the feedstock development for the realization of a shaft-to-collar connection with 2C MicroPIM are clearly applicable when a dispersant like stearic acid is added. [ABSTRACT FROM AUTHOR]

Microminiature powder injection molding (μPIM) is a premising variant of powder injection molding (PIM) with development profiting by the demand for highly resistive micro products made of metal or ceramic materials, μPIM involves low-pressure or high-pressure injection molding; the former is commonly used for prototypes and small runs while the latter reflects medium and large-scale production. In relation to feedstock improvement, current research focuses on the exploitation of additives and the application of ultrafine powders. In terms of the μPIM shaping process, primary challenges are further miniaturization and the production of micro components with increased complexity. Presently, variants of multi-component μPIM are under development and the process parameters have to be adjusted for metals and ceramics to address issues of disconnection in micro areas. Examples are shaft-wheel combinations consisting of different couples of ceramics or metals. Depending on the powders and process parameters, mobile or immobile joints can be fabricated. [ABSTRACT FROM AUTHOR]

We present the application of the smoothed particle hydrodynamics (SPH) discretization scheme to Phillips' model for shear-induced particle migration in concentrated suspensions. This model provides an evolution equation for the scalar mean volume fraction of idealized spherical solid particles of equal diameter which is discretized by the SPH formalism. In order to obtain a discrete evolution equation with exact conservation properties we treat in fact the occupied volume of the solid particles as the degree of freedom for the fluid particles. We present simulation results in two- and three-dimensional channel flow. The two-dimensional results serve as a verification by a comparison to analytic solutions. The three-dimensional results are used for a comparison with experimental measurements obtained from computer tomography of injection moulded ceramic microparts. We observe the best agreement of measurements with snapshots of the transient simulation for a ratio D(c)/D(η)=0.1 of the two model parameters.