Wednesday afternoon, 13 October

Chairmen:
Dr Tassilo Moritz, Fraunhofer Institut – IKTS

Oral

Feedthrough - Hearing Implants
Ilic, S (Cochlear Ltd, Lane Cove, Australia)

Ceramic injection moulding is used for decades in many different applications. It is known that ceramic is used in various implantable components as well. In hearing implants developed by Cochlear Ltd (Australia) ceramic injection moulding was adopted as a main technology for manufacturing of one of the most critical component, “feedthrough”. To achieve mechanical integrity and electrical functionality insert moulding using noble materials (e.g. platinum) has been chosen to achieve desired outcomes. Challenges of insert moulding, debinding and sintering processes have been analysed. The reasons why the Al2O3 ceramic feedstock was used and how undesirable attributes of the sintering process are converted in positive outcomes will be presented. The reasons of having the pure alumina feedstock failing and successful use of Al2O3 ceramic feedstock with controlled level of “impurities” was studied and will be the topic of this presentation as well. Sintering process had to be specifically developed to control coherent structure and achieve tough hermetic requirements. Biocompatibility and long term implantation stability (70+ years) are some of the requirements that had to be met.

The CIM Process Applied to Aesthetical Zirconia Ceramics
Ter Maat, J (BASF SE, Ludwigshafen, Germany)

Coloured zirconia ceramics can be produced by the Ceramic Injection Moulding process, yielding entirely dense sintered materials, suitable for high gloss polishing. In several segments hand-touched objects have been introduced as an exclusive designer material with unique haptic properties. Watches, mobile phones, writing instruments and automotive interior offer striking examples of the capabilities of the CIM process.

The PIM process utilises ultrafine submicron zirconia ceramic powders and ceramic pigments. Moulding is performed with a POM-based binder, having good green strength and allowing catalytic debinding; sintering is done under air at 1350 - 1500°C, depending upon the type of pigment.

Processing and Characterization of Ceramic Injection Molded ZrO2/WC Composites
Unal, N (IFKB, Stuttgart, Germany)

In recent years, CIM became a most charming production technique to manufacture complex parts with reliable dimension tolerances. Up to date, although there are many studies which are based on injection molding of pure zirconia, zirconia based matrix ceramics were mostly produced by hot pressing technique to obtain high mechanical properties with the help of applying pressure during sintering. However, in the present study, various amounts of WC refractory carbide reinforced ZrO2 matrix composites were produced using CIM technique prior to pressureless sintering. The difficulty in the CIM processing was to determine the binder amount, debinding schedule and sintering conditions due to longer sintering times and temperatures compared to hot pressing. Many different composite compositions, injection molding parameters and characterization techniques were used to optimize the production variables.

Analysis Of Sintered Strontium Hexaferrite Shaped By Injection Molding In Unidirectional Magnetic And Electromagnetic Field
Zlatkov, B (FOTEC Forschungs- und Technologietransfer GmbH, Wiener Neustadt, Austria)

Strontium hexaferrite permanent magnets were produced by powder injection molding (PIM). The feedstock for powder injection molding was prepared by mixing strontium hexaferrite powder with a “Solvent system” organic binder. Injection was performed in the cylindrical cavity of the mold both for isotropic and anisotropic green samples. Diametrical alignment was enabled using high energy permanent magnets embedded in the mold (unidirectional magnetic field), while axial magnetic alignment was enabled by DC current and a solenoid placed in round the cavity (electromagnetic field). Green samples (with and without magnetic alignment) were subjected to solvent debinding and subsequent thermal debinding followed by sintering. Sintering conditions were optimized in order to achieve a maximum energy product value. Magneto-crystalline aligning in strontium hexaferrite was studied on both green and sintered samples using X-ray diffraction, scanning electron microscopy (SEM) and magnetic measurements (hysteresisgraphs). All measurements were made in the direction parallel to the aligning magnetic field. The obtained results confirmed a high degree of magneto-crystalline alignment.

Poster

Fabrication of Glass Components by Powder Inujection Moulding (PIM) Recycling Glass Waste
Torralba Castello, J M (Universidad Carlos III de Madrid, Madrid, Spain)

The potential of using glass waste as raw material for powder injection moulding (PIM) processes is studied in this work. This alternative for glass recycling could wide the market of applications for this material taking advantage of the synergy of PIM process features for creating products with high added value. Common foodstuff industry transparent glass type was used for the study. Raw material was first milled to transform it into powder with a particle size less than 75 microns and then they were mixed with a conventional wax based binder. The optimal solid loading was determined by torque rheometry and bending testing bars were successfully moulded with a low pressure transfer injection machine. Solvent debinding of the parts was carried out in hexane to remove the soluble portion. Next, thermal debinding and sintering were conducted in air using the same thermal cycle. This process stage resulted critical due to the tough shape control because of the presence of melting substances in the glass composition.

Novel Process for the Fabrication of Metallic and Ceramic Components by Powder Injection (PIM) Using a Thermoplastic Binder System Based on Polysaccharides
Torralba Castello, J M (Universidad Carlos III de Madrid, Madrid, Spain)

In this work a novel powder injection moulding (PIM) process for the fabrication of metallic and ceramic components is proposed. The binder system that is used for the feedstock fabrication is based on a polysaccharide thermoplastic polymer that presents as main constituent cellulose acetate butyrate (CAB). This binder system was mixed with three different materials (316L stainless steel, T15 tool steel and a ferrite) to fabricate feedstock and injection moulded to prepare bending testing specimens using a low pressure transfer machine. The monomers constituents groups of the binder system make it suitable for an efficient catalytic debinding with different types of acid substances. In this way, the green specimens so-created were subjected to catalytic debinding cycles with nitric acid. Finally, the brown parts were sintered and some properties of the final products were evaluated.

Related features for download:

• Ceramic injection moulding: a review of developments in production technology, materials and applications
• Developments in multi-component powder injection moulding of steel-ceramic compounds using green tapes for inmould label process
• Material homogeneity in powder injection moulded ceramic microchannel arrays
• Micro-channelled heat exchanger manufactured by Ceramic Injection Moulding and co-firing
• Oechsler AG proves its competence in ceramic injection moulding with new BMW applications