Near-Net-Shape Thermoplastic Forming of Alumina-Silicon Carbide Nanocomposites

2010 ◽  
Vol 65 ◽  
pp. 1-10 ◽  
Author(s):  
Frank Kern ◽  
Rainer Gadow
Keyword(s):  
Injection Molding ◽  
Thermomechanical Properties ◽  
Axially Symmetric ◽  
Ceramic Injection Molding ◽  
Forming Technology ◽  
Structural Applications ◽  
Thermoplastic Forming ◽  
Near Net Shape ◽  
Commercial Applications ◽  
Manufacturing Technologies

Alumina-SiC nanocomposites have attracted the interest of material scientists due to their excellent mechanical and thermomechanical properties. Compared to alumina they offer higher strength, toughness and reliability. The high creep resistence of alumina-SiC makes it attractive for high temperature structural applications. Commercial applications however require performing and reliable manufacturing technologies. Ceramic injection molding (CIM) was chosen for the production of small and complex shaped components with narrow dimensional tolerances used in engineering applications. For axially symmetric, elongated component geometries such as tubes or rods, thermoplastic extrusion is a more appropriate forming technology. In this study the complete process cycle of thermoplastic extrusion and injection molding was evaluated with the aim to evaluate their suitability for industrial production of alumina-SiC nanocomposites. Compounding of the feedstocks, forming by CIM and extrusion and the subsequent thermal treatment – debinding and pressureless sintering were investigated. Intermediate and final products were characterized with respect microstructure and mechanical.

scholarly journals Injection Molding of 3-3 Hydroxyapatite Composites

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1907 ◽  
Author(s):  
Jonas Biggemann ◽  
Patrizia Hoffmann ◽  
Ivaylo Hristov ◽  
Swantje Simon ◽  
Philipp Müller ◽  
...  
Keyword(s):  
Injection Molding ◽  
Patient Specific ◽  
Pore Former ◽  
Porous Hydroxyapatite ◽  
Pore Networks ◽  
Ceramic Injection Molding ◽  
Thermal Debinding ◽  
Near Net Shape ◽  
Urethane Dimethacrylate ◽  
Interconnected Pore

The manufacturing of ideal implants requires fabrication processes enabling an adjustment of the shape, porosity and pore sizes to the patient-specific defect. To meet these criteria novel porous hydroxyapatite (HAp) implants were manufactured by combining ceramic injection molding (CIM) with sacrificial templating. Varied amounts (Φ = 0–40 Vol%) of spherical pore formers with a size of 20 µm were added to a HAp-feedstock to generate well-defined porosities of 11.2–45.2 Vol% after thermal debinding and sintering. At pore former contents Φ ≥ 30 Vol% interconnected pore networks were formed. The investigated Young’s modulus and flexural strength decreased with increasing pore former content from 97.3 to 29.1 GPa and 69.0 to 13.0 MPa, agreeing well with a fitted power-law approach. Additionally, interpenetrating HAp/polymer composites were manufactured by infiltrating and afterwards curing of an urethane dimethacrylate-based (UDMA) monomer solution into the porous HAp ceramic preforms. The obtained stiffness (32–46 GPa) and Vickers hardness (1.2–2.1 GPa) of the HAp/UDMA composites were comparable to natural dentin, enamel and other polymer infiltrated ceramic network (PICN) materials. The combination of CIM and sacrificial templating facilitates a near-net shape manufacturing of complex shaped bone and dental implants, whose properties can be directly tailored by the amount, shape and size of the pore formers.

Influence of Carbon Content on Ceramic Injection Molding of Reaction-Bonded Silicon Carbide

2016 ◽  
Vol 13 (5) ◽  
pp. 838-843 ◽  
Author(s):  
Zhao Zhang ◽  
Yujun Zhang ◽  
Hongyu Gong ◽  
Xue Guo ◽  
Yubai Zhang ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Injection Molding ◽  
Carbon Content ◽  
Ceramic Injection Molding

scholarly journals A Conflict of Fineness and Stability: Platinum- and Palladium-Based Bulk Metallic Glasses for Jewellery

2020 ◽  
Author(s):  
O. S. Houghton ◽  
A. L. Greer
Keyword(s):  
Metallic Glasses ◽  
Bulk Metallic Glasses ◽  
Precious Metals ◽  
High Hardness ◽  
Scratch Resistance ◽  
Cast State ◽  
High Definition ◽  
Glass Forming ◽  
Thermoplastic Forming ◽  
Near Net Shape

For the metals used in jewellery, high hardness and the associated scratch resistance are much sought after. Conventional crystalline alloys for jewellery are alloyed and extensively processed (thermally and mechanically) to improve hardness, but it is difficult to reach values beyond 300 HV. The advent of bulk metallic glasses, based on precious metals and with hardness exceeding 300 HV in the as-cast state, is therefore of great interest for both jewellery and watchmaking. The non-crystalline structure of these materials not only gives high hardness, but also the opportunity to shape metals like plastics, via thermoplastic forming. For more traditional jewellery manufacture, bulk metallic glasses also exhibit high-definition and near-net-shape casting. Gold-based alloys have long dominated the consideration of bulk metallic glasses for jewellery as they can comply with 18K hallmarks. Although bulk metallic glasses based on platinum or palladium possess excellent thermoplastic formability, and are without known tarnishing problems, achieving useful glass-forming ability within the more restrictive hallmarking standards typically used for jewellery (≥95 wt.% Pt or Pd) is, at best, challenging. In this review, platinum- and palladium-based bulk metallic glasses are discussed, focusing on their potential application in jewellery and on the further research that is necessary.

A Ceramic Tubular Probe For Online Substance Concentration Measurement, Manufactured By Ceramic Injection Molding

2012 ◽  
Vol 2012 (1) ◽  
pp. 000604-000608
Author(s):  
Matthias Hartmann ◽  
Bertram Schmidt
Keyword(s):  
Injection Molding ◽  
Zirconium Oxide ◽  
Large Scale ◽  
Low Cost ◽  
Tetragonal Zirconia ◽  
Scale Production ◽  
Ceramic Injection Molding ◽  
Substance Concentration ◽  
Sensor Effect ◽  
Concentration Measurements

The current research presents recent respective to the work development of a ceramic tubular probe for online substance concentration measurements. The aim was to develop a robust and acid-resistant sensor device, which can be easily included in existing procedural pipeline systems. To archive those goals a lot of factors had to be checked. For the substance concentration measurements a capacitive sensor effect was chosen. With this method even low substance concentrations down to one-tenth of a per cent can be indentified. For the package material zirconium oxide (tetragonal zirconia polycrystal – TZP) was used. Zirconium oxide is a technical ceramic which is wear-resistant, acid-resistant, has a low thermal conductivity, is electrically isolating and can be uses in a ceramic injection molding (CIM) process. In the phase of the sensor design process multiple geometries for the sensor effect and integration space for the evaluation electronics had to be considered. A standardized DN 10 DIN 32676 flanged joint was also added for an unproblematic connection to the pipelines. All these needed geometries had to be integrated into one ceramic element. As a result of these requirements a 3D CAD model of the sensor element was designed. The CAD-file has shown that there was only the CIM technology left to comprehend developed sensor geometry. CIM is a low cost process for large-scale production which is distinguished by high size accuracy. In the CIM process the material shrinkage, this is caused by the needed debindering and sintering steps, had to be considered. The developed ceramic tubular probe was successfully tested in multiple fluidic systems. It has left the test phase and is now ready for maturity phase.

scholarly journals PVB/PEG-Based Feedstocks for Injection Molding of Alumina Microreactor Components

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1219 ◽  
Author(s):  
Anna Julia Medesi ◽  
Dorit Nötzel ◽  
Thomas Hanemann
Keyword(s):  
Injection Molding ◽  
Large Scale ◽  
Metal Oxide Nanoparticles ◽  
Reaction Medium ◽  
Cost Effective ◽  
Polyvinyl Butyral ◽  
Shear Stresses ◽  
Scale Production ◽  
Ceramic Injection Molding ◽  
Functional Components

The ceramic injection molding (CIM) process is a cost-effective powder-based near net shape manufacturing process for large-scale production of complex-shaped ceramic functional components. This paper presents the rheological analysis of environmentally friendly CIM feedstock formulations based on the binder components polyvinyl butyral (PVB) and polyethylene gycol (PEG). The prepared PVB/PEG-based alumina molding compounds were investigated with respect to their PVB:PEG ratios as well as to their powder filling degrees in the range between 50 and 64 vol.%. Corresponding viscosities and shear stresses were determined for increasing shear rates to show the effects of increased PEG content and solid loadings on them. Two single reactor components were injection molded and subsequently joined in their green state for fabrication of an alumina microreactor. The intended purpose of the alumina microreactors is their potential application as wear-resistant and hydrothermal stable multifunctional devices (µ-mixer, µ-reactor, µ-analyzer) for continuous hydrothermal synthesis (CHTS) of metal oxide nanoparticles in supercritical water (sc-H2O) as the reaction medium.

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