scholarly journals Investigation of Feedstock Preparation for Injection Molding of Oxide–Oxide Ceramic Composites

2019 ◽  
Vol 3 (1) ◽  
pp. 9 ◽  
Author(s):  
Hasan Metin Tülümen ◽  
Thomas Hanemann ◽  
Volker Piotter ◽  
David Stenzel
Keyword(s):  
Fiber Length ◽  
Particle Surface ◽  
Relative Viscosity ◽  
Ceramic Composites ◽  
Solid Content ◽  
Oxide Ceramic ◽  
Capillary Rheometer ◽  
Ceramic Fibers ◽  
Series Of Experiments ◽  
Feedstock Preparation

In this fundamental work, a series of experiments were performed to define the optimal amount of dispersant and solid content for feedstock with and without ceramic fibers (Nextel 610). Based on these fixed conditions, investigations were carried out to discover the effects of binder system, fiber sizing, and increasing fiber content on mixing and viscosity. In addition, the effects of kneading temperature and time, fiber sizing, and different binder systems on fiber length were investigated using a measuring mixer, high-pressure capillary rheometer, and microscopy. Stearic acid, as a dispersant, modified the particle surface and improved the rheological properties. Moreover, increasing the solid content in the feedstocks led to an exponential growth of final torque and relative viscosity, because of the increasing friction between particles. Paraffin wax (PW)- and polyethylene glycol (PEG)-based feedstocks showed different mixing behaviors and rheological results with increasing fiber, whereas PEG-based feedstocks had higher final torques and kneading energies without fibers, whilst PEG feedstocks displayed lower viscosities. Consequently, during kneading, the amount of fiber has been predominating over fiber length, and the effect of the binder, the kneading temperature, and time did not cause significant changes.

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.

scholarly journals Influence of the polymer precursor blend composition on the morphology of the electrospun oxide ceramic fibers

2019 ◽  
Vol 13 ◽  
pp. 102243 ◽  
Author(s):  
I. Shepa ◽  
E. Mudra ◽  
M. Vojtko ◽  
O. Milkovic ◽  
Z. Dankova ◽  
...  
Keyword(s):  
Oxide Ceramic ◽  
Polymer Precursor ◽  
Ceramic Fibers ◽  
Blend Composition

Facility for Continuous CVD Coating of Ceramic Fibers

1991 ◽  
Vol 250 ◽  
Author(s):  
Arthur W. Moore
Keyword(s):  
Boron Nitride ◽  
High Temperatures ◽  
Weight Ratio ◽  
High Strength ◽  
Ceramic Coatings ◽  
Ceramic Composites ◽  
Ceramic Fiber ◽  
Ceramic Fibers ◽  
Fiber Properties ◽  
Nitride Coatings

The development of new and improved ceramic fibers has spurred the development and application of ceramic composites with improved strength, strength/weight ratio, toughness, and durability at increasingly high temperatures. For many systems, the ceramic fibers can be used without modification because their properties are adequate for the chosen application. However, in order to take maximum advantage of the fiber properties, it is often necessary to coat the ceramic fibers with materials of different composition and properties. Examples include (1) boron nitride coatings on a ceramic fiber, such as Nicalon silicon carbide, to prevent reaction with the ceramic matrix during fabrication and to enhance fiber pullout and increase toughness when the ceramic composite is subjected to stress[l]; (2) boron nitride coatings on ceramic yarns, such as Nicalon for use as thermal insulation panels in an aerodynamic environment, to reduce abrasion of the Nicalon and to inhibit the oxidation of free carbon contained within the Nicalon[2]; and (3) ceramic coatings on carbon yarns and carbon-carbon composites to permit use of these high-strength, high-temperature materials in oxidizing environments at very high temperatures[3,4].

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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