• Journal of the Korean Ceramic Society
• /
• v.49 no.4
• /
• pp.279-286
• /
• 2012

Microstructure tailoring of filler loaded preceramic polymer systems offers a high potential for property improvement of Si-based ceramics and composites. Advancements in manufacturing of bulk materials by controlling microstructure evolution during thermal induced polymer-ceramic transforma-tion and polymer-filler reactions will be presented. Rate controlled pyrolysis, multilayer gradient laminate design and surface modification by gas solid reaction are demonstrated to yield ceramic components of high fractional density and superior mechanical properties. Emerging fields of applications are presented.

• Ceramist
• /
• v.23 no.1
• /
• pp.4-15
• /
• 2020

The recent advances and popularity of 3D printing technology have centered around building polymerbased 'plastic' materials, due to their low cost, simple and efficient processing, and mechanical toughness. For this reason, printable polymers are actively recruited to create 'ceramic resins' that allow more facile fabrication of ceramic materials that are difficult to print directly. Herein, a brief history and the current state of ceramic 3D printing technology aided by polymer is summarized. In addition, a new ceramic 3D printing technology using polymer-derived ceramics (PDC) is also introduced.

• Polymer(Korea)
• /
• v.30 no.5
• /
• pp.407-411
• /
• 2006

The SiC-based ceramic nanopatterns were prepared by placing polydimethylsiloxane (PDMS) mold from DVD master on the spincoated polyvinylsilaeane (PVS) or allylhydridopolycaybosilane (AHPCS) as ceramic precursors to fabricate line pattern via UV-nanoimprint lithography (UV-NIL), and subsequent pyrolysis at $800^{\circ}C$ in nitrogen atmosphere. As the dimensional change of polymeric and ceramic patterns was comparatively investigated by AFM and SEM, the shrinkage in height was 38.5% for PVS derived pattern and 24.1% for AHPCS derived pattern while the shrinkage in width was 18.8% for PVS and 16.7% for AHPCS. It indicates that higher ceramic yield of the ceramic precursor resulted in less shrinkage, and the strong adhesion between the substrate and the pattern caused anisotropic shrinkage. This preliminary work suggests that NIL is a promissing route for fabricating ceramic MEMS devices, with the development on the shrinkage control.

• Journal of the Korean Ceramic Society
• /
• v.48 no.5
• /
• pp.412-417
• /
• 2011

Formation and characterization of hydroxyapatite-based porous ceramics derived from polymer pyroysis were investigated. Polymer based process is chosen for preparing porous hydroxyapatite-based ceramics having a high mechanical strength. The hydroxyapatite-based porous ceramic was prepared by a self-blowing process of a polymethylsiloxane with filler and pyrolyzed at above $1000^{\circ}C$. Biphasic material consisted of hydroxyapatite and CaO has been prepared by solid state reaction from calcium hydroxide($Ca(OH)_2$) and calcium hydrogen phosphate dihydrate($CaHPO_4{\cdot}2H_2O$) as a filler material. The influence of filler content on mechanical properties was evaluated. The change of crystalline phase, microstructure and mechanical properties were investigated and discussed.

• Journal of the Korean Ceramic Society
• /
• v.35 no.9
• /
• pp.939-944
• /
• 1998

The formation microstructure and properties of novel ceramic composite materials by active filler con-trolled polymer pyrolysis were investigated. Polymethlsiloxane filled with W is of particular interested be-cause of the formation of ceramic bonded hard materials (WC-$W_{2}C$-$S_{1}OC$) for wear resistant applications. Highly metal-filled polymer suspensions were prepared and their conversion to ceramic composites by an-nealing in $N_{2}C$ atmosphere at 1000-$1600^{\circ}C$ were studied. Dimensional change porosity and phase distribution (filler network) were analyzed and correlated to the resulting material properties. Microcrystalline com-posites with the filler reaction products embedded to the resulting material properties. Microcrystalline com-posites with the filler reaction products embedded in a silicon oxycarbide glass matrix were produced. De-pending on the pyrolysis conditions ceramic composites with a density up to 95 TD% a hardness of 7-8.8GPa Yong's modulus of 220-230 GPa a fracture toughness of 6-6.8$MPam^{1/2}$ and a flexual strength of 380-470 MPa were obtained.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09b
• /
• pp.1106-1106
• /
• 2006

• Journal of the Korean Ceramic Society
• /
• v.49 no.1
• /
• pp.95-99
• /
• 2012

Silicon carbide ceramics are used for oxidation resistive coating films due to their excellent properties like high strength, good oxidation resistance, and good abrasion resistance, but they have poor formability and are prepared by vapor process which is complicated, costly, and sometimes hazardous. In this study, preparation of silicon carbide coating film by liquid process using polymer precursor was attempted. Coating film was prepared by dip coating on substrate followed by heat treatment in argon at $1200^{\circ}C$. By changing the dipping speed, the thickness was controlled. The effects of plasticizer, binder, or fiber addition on suppression of crack generation in the polymer and ceramic films were examined. It was found that fiber additives was effective for suppressing crack generation.

• Journal of the Korean Ceramic Society
• /
• v.47 no.3
• /
• pp.205-209
• /
• 2010

In the last (fourth) section, the discussion will entail a silicon-nitride/silicon-carbide nanocomposite, produced by pyrolysis of liquid polymer precursors, demonstrating one of the lowest creep rates reported so far in ceramics at the comparable temperature of $1400^{\circ}C$. This was first achieved by avoiding the oxynitride glass phase at the intergrain boundaries. One important factor in the processing of these nanocomposites was the use of the electrical field assisted sintering method.

• Journal of the Korean Ceramic Society
• /
• v.46 no.5
• /
• pp.462-466
• /
• 2009

We investigated the pore properties of inorganic membranes applied for hydrogen separation industry. Inorganic membranes were derived from polysilazanes. The thermal reactions involved were studied using thermogravimetry(TG) and IR spectroscopy(FTIR) of the solids. To determine the thermal effect of pore properties, polysilazanes were pyrolysed in inert atmosphere. Pore volume and BET surface area showed the maximum value at a pyrolysis temperature of $500^{\circ}C$. For amorphous SiCN membrane derived from polysilazanes, selectivity of $H_2/N_2$ was 4.81 at $600^{\circ}C$.

• Journal of the Korean Ceramic Society
• /
• v.54 no.6
• /
• pp.499-505
• /
• 2017

Flexible silicon carbide fibrous mats were fabricated by a combination of electrospinning and a polymer-derived ceramics route. Polycarbosilane was used as a solute with various solvent mixtures, such as toluene and dimethylformamide. The electrospun PCS fibrous mats were cured under a halogen vapor atmosphere and heat treated at $1300^{\circ}C$. The structure, fiber morphology, thermal behavior, and crystallization of the fabricated SiC fibrous mats were analyzed via scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermal imaging. The prepared SiC fibrous mats were composed of randomly distributed fibers approximately $3{\mu}m$ in diameter. The heat radiation of the SiC fiber mats reached $1600^{\circ}C$ under microwave radiation at a frequency of 2.45 GHz.