scholarly journals Optimization of Alumina Slurry for Oxide-Oxide Ceramic Composites Manufactured by Injection Molding

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Catherine Billotte ◽  
Edith Roland Fotsing ◽  
Edu Ruiz
Keyword(s):  
Nitric Acid ◽  
Ceramic Composites ◽  
Oxide Ceramic ◽  
Structure Development ◽  
Rheological Study ◽  
Stable Suspension ◽  
Production Constraints ◽  
Low Viscosity ◽  
Oxide Composites ◽  
Newtonian Behavior

This paper focuses on the rheological study of an alumina suspension intended for the manufacturing of oxide-oxide composites by flexible injection. Given the production constraints, it is required to have stable suspension with low viscosity and a Newtonian behavior. This is achieved with a concentration of nitric acid between 0.08 wt% and 0.2 wt% and amount of 3 wt% of PVA binder. The maximum loading of the suspension of 47 vol% suggests that there is no structure development within the suspension with optimized concentration of acid and PVA.

Development of Ultra High Temperature Ceramic Composites for Gas Turbine Combustors

1997 ◽  
Author(s):  
Magnus Holmquist ◽  
Robert Lundberg ◽  
Tony Razzell ◽  
Olivier Sudre ◽  
Ludovic Molliex ◽  
...  
Keyword(s):  
High Temperature ◽  
Single Crystal ◽  
Recent Progress ◽  
Scale Up ◽  
Life Time ◽  
Ceramic Composites ◽  
Oxide Ceramic ◽  
Property Evaluation ◽  
Oxide Fibres ◽  
Oxide Composites

All-oxide ceramic composites as a material with potential for long life-time applications at temperatures in the 1400–1600°C range in combustion environments were studied. The properties of available polycrystalline and single crystal oxide fibres were summarised. The literature on stable weak interfaces in all-oxide composites was reviewed. Composites with single crystal fibres, a polycrystalline matrix of the same material as the fibres, and a compatible high temperature stable weak oxide interphase was suggested to be the most promising approach. Recent progress in an ongoing European project aiming at development, scale-up and property evaluation of all-oxide composites is reported. The composite will be applied to a simple prototype combustor tile and tested in a combustor rig.

scholarly journals Injection Moulding of Oxide Ceramic Matrix Composites: Comparing Two Feedstocks

2019 ◽  
Vol 809 ◽  
pp. 140-147 ◽  
Author(s):  
Maike Böttcher ◽  
Daisy Nestler ◽  
Jonas Stiller ◽  
Lothar Kroll
Keyword(s):  
High Temperature ◽  
Injection Moulding ◽  
Ceramic Matrix ◽  
Ceramic Composites ◽  
Laboratory Scale ◽  
Oxide Ceramic ◽  
Scale Production ◽  
Oxide Ceramics ◽  
Moulding Process ◽  
Injection Moulding Process

Ceramic materials are suitable for use in the high temperature range. Oxide ceramics, in particular, have a high potential for long-term applications under thermal cycling and oxidising atmosphere. However, monolithic oxide ceramics are unsuitable for use in high-temperature technical applications because of their brittleness. Thin-walled, oxidation resistant, and high-temperature resistant materials can be developed by reinforcing oxide ceramics with ceramic fibres such as alumina fibres. The increase of the mechanical stability of the composites in comparison to the non-fibre reinforced material is of outstanding importance. Possible stresses or cracks can be derived along the fibre under mechanical stress or deformation. Components made of fibre-reinforced ceramic composites with oxide ceramic matrix (OCMC) are currently produced in manual and price-intensive processes for small series. Therefore, the manufacturing should be improved. The ceramic injection moulding (CIM) process is established in the production of monolithic oxide ceramics. This process is characterised by its excellent automation capability. In order to realise large scale production, the CIM-process should be transferred to the production of fibre-reinforced oxide ceramics. The CIM-process enables the production of complicated component shapes and contours without the need for complex mechanical post-treatment. This means that components with complex geometries can be manufactured in large quantities.To investigate the suitability of the injection moulding process for the production of OCMCs, two different feedstocks and alumina fibres (Nextel 610) were compounded in a laboratory-scale compounder. The fibre volume fractions were varied. In a laboratory-scale injection moulding device, microbending specimens were produced from the compounds obtained in this way. To characterise the test specimens, microstructure examinations and mechanical-static tests were done. It is shown that the injection moulding process is suitable for the production of fibre-reinforced oxide ceramics. The investigations show that the feedstocks used have potential for further research work and for future applications as material components for high-temperature applications in oxidising atmospheres.

Microstructure Formation and Performance of Reactive Sintered Titanium Oxycarbide Base Ceramic-Ceramic Composites

2019 ◽  
Vol 799 ◽  
pp. 131-135
Author(s):  
Kristjan Juhani ◽  
Jakob Kübarsepp ◽  
Marek Tarraste ◽  
Jüri Pirso ◽  
Mart Viljus
Keyword(s):  
Phase Formation ◽  
Mechanical Performance ◽  
Aluminium Oxide ◽  
High Energy ◽  
Ceramic Composites ◽  
Oxide Ceramic ◽  
Reactive Sintering ◽  
Attritor Milling ◽  
Different Temperatures ◽  
And Performance

Reactive sintering is a process where synthesis reaction of the ceramic phases is combined with sintering (densification) of the composite. Dense lightweight titanium oxycarbide-aluminium oxide ceramic-ceramic composites were produced from titanium dioxide, carbon black as graphite source and aluminium precursors by high energy attritor milling, followed by reactive sintering. Titanium oxycarbide and aluminium oxide phases were synthesized during reactive sintering in situ. To investigate the microstructure evolution and phase formation, the specimens were sintered at different temperatures (600-1725 °C) in vacuum. Scanning electron microscopy and X-ray diffraction were used to analyze the microstructure and phase formation. Mechanical performance (hardness and fracture toughness) was evaluated.

Stability analysis of a particle band on the fluid–fluid interface

2019 ◽  
Vol 869 ◽  
Author(s):  
Alireza Hooshanginejad ◽  
Benjamin C. Druecke ◽  
Sungyon Lee
Keyword(s):  
Stability Analysis ◽  
Colloidal Particles ◽  
Radial Flow ◽  
High Viscosity ◽  
High Concentration ◽  
Stable Suspension ◽  
Low Viscosity ◽  
Air Interface ◽  
Critical Wavelength ◽  
Hele Shaw Cell

We present experiments and theory for viscous fingering of a suspension of non-colloidal particles undergoing radial flow in a Hele-Shaw cell. As the suspension displaces air, shear-induced migration causes particles to move faster than the average suspension velocity and to accumulate on the suspension–air interface. The resultant particle accumulation generates a pattern in which low-concentration, low-viscosity suspension displaces high-concentration, high-viscosity suspension and is unstable due to the classic Saffman–Taylor instability mechanism. While the destabilising mechanism is well-understood, what remains unknown is the stabilising mechanism that suppresses fine fingers characteristic of miscible fingering. In this work, we demonstrate how the stable suspension–air interface interacts with the unstable miscible interface to set the critical wavelength. We present a linear stability analysis for the time-dependent radial flow and show that the wavenumber predicted by the analysis is in good agreement with parametric experiments investigating the effect of suspension concentration and gap thickness of the Hele-Shaw cell.

Obtaining complex-shaped oxide ceramic composites via ionotropic gelation

2018 ◽  
Vol 102 (1) ◽  
pp. 53-57 ◽  
Author(s):  
Renato S. M. Almeida ◽  
Tamires F. S. Pereira ◽  
Kamen Tushtev ◽  
Kurosch Rezwan
Keyword(s):  
Ceramic Composites ◽  
Oxide Ceramic ◽  
Ionotropic Gelation
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