Fabrication of porous SiC-based ceramic microchannels via pyrolysis of templated preceramic polymers

2006 ◽  
Vol 21 (6) ◽  
pp. 1543-1549 ◽  
Author(s):  
Quoc Dat Nghiem ◽  
Amit Asthana ◽  
In-Kyung Sung ◽  
Dong-Pyo. Kim
Keyword(s):  
Early Stage ◽  
Inert Atmosphere ◽  
Silicon Carbonitride ◽  
Silica Spheres ◽  
Void Space ◽  
Polystyrene Spheres ◽  
Ceramic Phase ◽  
Preceramic Polymers ◽  
Polymer Sphere ◽  
Porous Sic

This article reports conversion chemistry of preceramic polymer to ceramic phase during the fabrication of high-temperature stable silicon carbide and silicon carbonitride monolithic porous microchannels. The micromolding in capillariesmethod is used to fabricate porous channels by the initial infiltration of a solution of 1.5-μm diameter silica spheres or 1-μm diameter polystyrene spheres into polydimethylsiloxane channels followed by filling the void space among the spheres by using viscous commercial polymeric precursors. Subsequently, the polymer-sphere composite channel was cured and pyrolysed at 1200 °C under inert atmosphere, and final wet etching step of silica spheres with 10% hydrofluoric acid solution developed the pore structures by removing the silica spheres, whereas polystyrene sphere decomposes at the early stage of pyrolysis.

scholarly journals Ceramic microparticles and capsules via microfluidic processing of a preceramic polymer

2010 ◽  
Vol 7 (suppl_4) ◽  
Author(s):  
Congwang Ye ◽  
Anthony Chen ◽  
Paolo Colombo ◽  
Carlos Martinez
Keyword(s):  
Porous Ceramic ◽  
Double Emulsion ◽  
Inert Atmosphere ◽  
Single Step ◽  
Fluid Composition ◽  
Void Space ◽  
Preceramic Polymer ◽  
Preceramic Polymers ◽  
Oxycarbide Glass ◽  
Emulsion Drops

We have developed a robust technique to fabricate monodispersed solid and porous ceramic particles and capsules from single and double emulsion drops composed of silsesquioxane preceramic polymer. A microcapillary microfluidic device was used to generate the monodispersed drops. In this device, two round capillaries are aligned facing each other inside a square capillary. Three fluids are needed to generate the double emulsions. The inner fluid, which flows through the input capillary, and the middle fluid, which flows through the void space between the square and inner fluid capillaries, form a coaxial co-flow in a direction that is opposite to the flow of the outer fluid. As the three fluids are forced through the exit capillary, the inner and middle fluids break into monodispersed double emulsion drops in a single-step process, at rates of up to 2000 drops s −1 . Once the drops are generated, the silsesquioxane is cross-linked in solution and the cross-linked particles are dried and pyrolysed in an inert atmosphere to form oxycarbide glass particles. Particles with diameters ranging from 30 to 180 µm, shell thicknesses ranging from 10 to 50 µm and shell pore diameters ranging from 1 to 10 µm were easily prepared by changing fluid flow rates, device dimensions and fluid composition. The produced particles and capsules can be used in their polymeric state or pyrolysed to ceramic. This technique can be extended to other preceramic polymers and can be used to generate unique core–shell multimaterial particles.

Highly Ordered Macroporous BN-Based Ceramics Prepared from Templated Preceramic Polymers

2005 ◽  
Vol 287 ◽  
pp. 323-328 ◽  
Author(s):  
Lan Young Hong ◽  
Dong Pyo Kim
Keyword(s):  
Weight Loss ◽  
Pore Structure ◽  
Colloidal Silica ◽  
Three Dimensional ◽  
Silica Spheres ◽  
Preceramic Polymers ◽  
Surface Areas ◽  
Resistance To Oxidation ◽  
Ordered Macroporous ◽  
Crystalline Array

Macroporous SiCBN and BCN ceramic were prepared by infiltrating these preceramic polymers into the colloidal silica crystalline array, followed by pyrolysis at 1400ı and subsequently etching off the silica spheres. It is generally observed by SEM and TEM that a highly ordered and interconnected 'honeycomb' pore structure was obtained by replicating the three dimensional close packed silica spheres which was fabricated by natural sedimentation. And BET surface areas in range 413 ~ 315 m2/g and pore sizes of 113 ~ 395 nm in the porous materials were tailored by controlling the sacrificial silica sphere sizes in range 145~500 nm even under volume shrinkage involved during pyrolytic step. The porous SiCBN ceramics and BCN ceramic showed a slight weight loss of 0.2~0.8% and 4%, respectively, indicating excellent resistance to oxidation.

Polycarbosilane Conversion Bonded Porous SiC Ceramics

2007 ◽  
Vol 280-283 ◽  
pp. 1267-1270 ◽  
Author(s):  
Su Min Zhu ◽  
Ruo Ding Wang ◽  
Na Li ◽  
Hong'an Xi ◽  
Qin Li ◽  
...  
Keyword(s):  
Flexural Strength ◽  
Inert Atmosphere ◽  
Pyrolysis Process ◽  
Critical Feature ◽  
Sic Ceramics ◽  
Sic Particles ◽  
Heat Treated ◽  
Powder Compacts ◽  
Porous Sic ◽  
Bonding Technique

Porous silicon carbide (SiC) ceramics were fabricated by a polycarbosilane (PCS) conversion bonding technique, in which PCS was used as a binder to bond SiC particles with each other. In the preparing process, SiC particles were first coated with PCS, and then the powder compacts were heat-treated in an inert atmosphere. During the heat-treatment, the PCS decomposed and gradually converted to inorganic covalent solids composed mainly of Si-C networks. The pyrolysis process of PCS, the pore structures and flexural strength of the as-prepared specimens were analyzed and discussed. Preparing temperature as low as 1100°C was adopted in this process and the porous SiC ceramics with a flexural strength of 20 MPa at an open porosity of 43% was obtained. Since PCS was used as a binder, the critical feature of this technique was that the preparation of porous SiC body was achieved at a low temperature.

Electrodeposition of Three-Dimensionally Periodic Metal Meshes and Spheres

2000 ◽  
Vol 636 ◽  
Author(s):  
Lianbin Xu ◽  
Weilie L. Zhou ◽  
Ray H. Baughman ◽  
Anvar A. Zakhidov ◽  
John B. Wiley
Keyword(s):  
Electrochemical Methods ◽  
Silica Spheres ◽  
Void Space ◽  
Metal Sphere ◽  
Mesh Structures ◽  
Metal Meshes

AbstractElectrochemical methods have been used to produce three-dimensionally periodic metal meshes and spheres. Nickel is initially deposited into porous opal sheets. The opals themselves consist of close-packed silica spheres, which serve as a template for the growth of the nickel arrays within the void space between SiO2 spheres. Dissolution of the SiO2 spheres results in open, three-dimensionally periodic nickel mesh structures. The metal meshes can then be oxidized in air to produce nonconducting NiO meshes. This results in an inverse template that can be used for the growth of three-dimensionally periodic metal sphere arrays. Details on the preparation and characterization of these materials are presented.

Effect of Nitrogen Content on the Mechanical Properties of Amorphous SiCN Films

2015 ◽  
Vol 662 ◽  
pp. 95-98 ◽  
Author(s):  
Radim Ctvrtlik ◽  
Valeriy Kulikovsky ◽  
Jan Tomastik
Keyword(s):  
Thin Films ◽  
Mechanical Properties ◽  
Nitrogen Content ◽  
Creep Test ◽  
Inert Atmosphere ◽  
Steady State Creep ◽  
Silicon Carbonitride ◽  
Reactive Magnetron ◽  
Sic Film ◽  
Deposited Films

Amorphous silicon carbonitride (a-SiCxNy) thin films were deposited using reactive magnetron sputtering of SiC target in the mixture of Ar and N gasses. The films with nitrogen content from 0 - 40 at.% were sputtered at various N2/Ar flow ratios in the range of 0 - 0.48. The as deposited films were additionally annealed in argon at 700 °C and vacuum at 900 °C. Analysis of mechanical properties was performed using the regular nanoindentation and short duration nanoindentation creep test (600 s).Hardness of the a-SiCxNy films increases with the decrease of nitrogen content from approx. 19 GPa (a-Si30C30N40) to 22 GPa (a-SiC). Annealing of the films in inert atmosphere or vacuum leads to the increase of both the hardness and the elastic modulus. This increase is more pronounced for the SiC film than for the SiCN films. The nanoindentation creep test (600 s) showed that the rate of the steady-state creep growths with the increase of nitrogen content.

The layer multiple-scattering method applied to phononic crystals

2005 ◽  
Vol 220 (9-10) ◽  
Author(s):  
Rebecca Sainidou ◽  
Nikolaos Stefanou ◽  
Ioannis E. Psarobas ◽  
Antonis Modinos
Keyword(s):  
Band Structure ◽  
Multiple Scattering ◽  
Phononic Crystals ◽  
Scattering Method ◽  
Silica Spheres ◽  
Transmission Characteristics ◽  
Polystyrene Spheres ◽  
Multiple Scattering Method

AbstractAfter a brief description of the layer multiple scattering method as applied to phononic crystals, we present some results obtained by this method, relating to: crystals of polystyrene spheres in water; crystals of silica spheres in air; and crystals of steel spheres in polyester. We relate the transmission characteristics of slabs of these ma terials to the complex band structure of the corresponding infinite crystals. We emphasize aspects of the underlying physics which have not been discussed previously.

Effect of laser irradiation on the early-stage seed formation of laser-induced submicrometer-scale silica spheres

2013 ◽  
Vol 169 (4) ◽  
pp. 277-284 ◽  
Author(s):  
H.J. Kim ◽  
S.Y. Ha ◽  
Y.J. Hong ◽  
S. Nam ◽  
S.Y. Oh ◽  
...  
Keyword(s):  
Laser Irradiation ◽  
Early Stage ◽  
Silica Spheres ◽  
Seed Formation

Raising pyrolysis yield of preceramic polymers of silicon carbonitride

1995 ◽  
Vol 30 (17) ◽  
pp. 4463-4468 ◽  
Author(s):  
Der-Lern Yang ◽  
Dah-Shyang Tsai ◽  
Hui-Chi Liu
Keyword(s):  
Silicon Carbonitride ◽  
Preceramic Polymers

Hierarchically porous biomorphic polymer derived C–SiOC ceramics

RSC Advances ◽  
2016 ◽  
Vol 6 (98) ◽  
pp. 95897-95902 ◽  
Author(s):  
Abhisek Choudhary ◽  
Swadesh K. Pratihar ◽  
Shantanu K. Behera
Keyword(s):  
Inert Atmosphere ◽  
Silicon Oxycarbide ◽  
Hierarchically Porous ◽  
Preceramic Polymers

Pinewood derived carbon templates were infiltrated with preceramic polymers and pyrolyzed in inert atmosphere to fabricate hierarchically porous biomorphic silicon oxycarbide amorphous ceramics with ∼80% porosity.

Porous SiC-Preforms by Intergranular Binding with Preceramic Polymers

2004 ◽  
Vol 6 (3) ◽  
pp. 167-172 ◽  
Author(s):  
M. Thünemann ◽  
A. Herzog ◽  
U. Vogt ◽  
O. Beffort
Keyword(s):  
Preceramic Polymers ◽  
Porous Sic
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