Silicon-Based Polymer-Derived Ceramics: Synthesis Properties and Applications-A Review

The luminescence properties related to the thermal polymer/ceramic conversion behavior of silicon dicarbodiimide {SDC, [Si(N=C=N) 2 ] n } have been investigated. SDC was synthesized by the non-oxidic solgel condensation reaction of silicon tetrachloride with bis(trimethylsilyl)carbodiimide. As-synthesized SDC showed no luminescence under UV light, while heat-treated SDC showed an appreciable photoluminescence (PL) and the maximum visible PL emission intensity was achieved by heat treatment at 400°C. Even after the heat treatment up to 970°C, the SDC preserved most of the N=C=N groups to keep whitish gray color without distinct free carbon formation, and emitted visible blue luminescence. The 400°C-heat treated SDC exhibited the intense luminescence excited at 281 and 379 nm wavelengths, while there was no PL emission excited by the N=C=N groupderived host absorption at 214 nm. The PL properties of the heat-treated SDCs could be correlated with their preservation of the local structure including N=C=N groups and defects formation during the heat treatment. Moreover, Eu 3+ -modified SDC was prepared by the same solgel method using Eu(III) chloride as the Eu 3+ -source. The results of Si NMR spectroscopic analyses revealed a complex formation between the Eu(III) chloride and bis(trimethylsilyl)carbodiimide. As a result, the Eu 3+ -modified SDC exhibited a characteristic PL red emission at around 600 nm attributed to the f-f-transition of Eu .

show abstract

“…4), 5) These findings indicate that the amorphous SiCN ceramics are good candidates for high temperature applications.…”

Section: Introductionmentioning

confidence: 81%

“…During the heat-treatment, the polymeric structure undergoes a transformation into a three-dimensional solid network structure (ceramic). 4) Therefore, as the temperature increases, the formation of defects (e.g. dangling bonds) could be occurred.…”

Section: Jcs-japanmentioning

confidence: 99%

Synthesis and characterization of luminescent properties of ceramics derived from polysilylcarbodiimides

Shimokawa

Fujiwara

Ionescu

et al. 2014

J. Ceram. Soc. Japan

Self Cite

View full text Add to dashboard Cite

show abstract

“…In recent years, with the development of high yield preceramic precursors, the polymer infiltration and pyrolysis (PIP) method has aroused interest for net-shape fabrication of ceramic based materials, for various applications ranging from disc brakes to nuclear reactor fuels [17]. The pyrolysis of preceramic polymers allows a wide variety of ceramic materials to be processed at relatively low temperatures.…”

Section: Motivationmentioning

confidence: 99%

“…Preceramic polymers can be processed and shaped using conventional polymer forming techniques such as polymer infiltration and pyrolysis (PIP), injection molding, coating from solvent, extrusion, or resin transfer molding (RTM) [17]. This allows for fabrication of highly three-dimensional covalent refractory components (fibers, films, membranes, foams monolithic bodies, ceramic matrix composites) that are difficult to fabricate via the traditional powder-processing route [110], and also allows for the incorporation of reinforcements.…”

Section: Polymer-precursor Derived Ceramicsmentioning

confidence: 99%

Novel Processing of Unique Ceramic-Based Nuclear Materials and Fuels

Zhang¹,

Singh²

2008

View full text Add to dashboard Cite

Advances in nuclear reactor technology and the use of gas-cooled fast reactors require the development of new materials that can operate at the higher temperatures expected in these systems. These include refractory alloys based on Nb, Zr, Ta, Mo, W, and Re; ceramics and composites such as those based on silicon carbide (SiC f -SiC); carbon-carbon composites; and advanced coatings. Besides the ability to handle higher expected temperatures, effective heat transfer between reactor components is necessary for improved efficiency. Improving thermal conductivity of the materials used in nuclear fuels and other temperature critical components can lower the center-line fuel temperature and thereby enhance durability and reduce the risk of premature failure.Silicon carbide (SiC) is an important ceramic, most commonly used because of its excellent properties such as high strength, high modulus, excellent creep resistance and its high temperature stability. Moreover, crystalline silicon carbide is attracting wide attention as a promising candidate for several applications in nuclear reactors owing to its high thermal conductivity, high melting temperature, good chemical stability, and resistance to swelling under heavy ion bombardment. There have been many efforts to develop SiC based composites in various forms for use in advanced energy systems. However, fabricating SiC based composites by traditional powder processing route generally requires very high temperatures for pressureless sintering. In recent years, with the development of high yield preceramic precursors, the polymer infiltration and pyrolysis (PIP) method has aroused interest for the fabrication of ceramic based materials. Polymer derived ceramic materials offer unique advantages such as ability to fabricate net shaped components, incorporate reinforcements, along with lower processing temperatures, and perhaps most importantly relatively easy control over the microstructure. The raw materials are element-organic polymers whose composition and architecture can be tailored and varied.The primary focus of this work is to use a pyrolysis-based process to fabricate a host of novel silicon carbide-metal carbide/oxide composites, and to synthesize new materials based on mixed-metal (metal/silicon) carbides that cannot be processed using conventional techniques. These mixedcarbide material systems are expected to offer improved material properties for higher-temperature applications. Our fabrication technique resulted in both amorphous and nano-grained SiC matrix composites by controlled pyrolysis of allylhydridopolycarbosilane (AHPCS), the precursor for SiC for our study, under inert argon atmosphere.Cylindrical pellets, φ25 × 25 mm, were fabricated for bulk scale characterization. These samples were analyzed in terms of density and porosity, thermal conductivity, and flexural strength under multiaxial loading conditions. The final composition in the fabricated composite was studied use Xray diffraction (XRD). This was useful in understanding the relative stabil...

show abstract

“…High resolution transmission electron microscopy measurements conducted on composites showed that LSMO [3][4][5] Polymer derived ceramics offer the high temperature materials that are otherwise difficult to be synthesized and open new possibilities for developing smart composites. Several nonoxide ceramics have been synthesized starting from molecular precursor in the systems Si-B-C-N, Si-B-C-N-O and Si-C-N. 6 Recent investigation on SiCN ceramic derived by thermal decomposition of a liquid-phase polyurea͑methyvinyl͒ silazane shows promising piezoresistance behavior. 7 In addition, SiCN shows excellent high temperature creep and oxidation resistance.…”

mentioning

confidence: 99%