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In this study, we prepared a perfectly ordered nacre-mimetic composite from plate-like alumina particles and epoxy resin using a rolling method. A specific feature of this method is that it progressively aligns the component particles along a single direction regardless of the product thickness at resin contents as low as 25 wt%. The obtained composite exhibited a strength as high as 200 MPa during bending. However, to examine the mechanical properties of artificial nacre, various factors such as the types of initial components and their particle sizes, contents, and orientation degrees must be considered. Hence, this study consists of two parts. The present work (which constitutes the first part) is focused on the orientation effect produced by the plate-like particles and deformation behavior of the composites observed at different orientation degrees. It was found that the obtained composite material with perfectly ordered particles exhibited pull-out behavior similar to that of natural nacre (including the crack propagation route). Further, the fracture toughness of the composite, which was higher than that of alumina, was also affected by its orientation degree.

Nacre is a natural organic-inorganic hybrid composite, whose hierarchical structure has a complex influence on its high strength. Many structural features have been discovered, which influence the mechanical properties of nacre, and the authors have a particular interest in the role of the asperities and organic-inorganic interactions. In this study, a composite was prepared which mimics the asperity structure using clay minerals. Organic-inorganic bonding was induced with silane treatment. Both factors increased the yield strength of the composites; however, different deformation behavior was exhibited. It was found that asperities improved the strength of the composite, and that composition influences the stiffness of the composite. The organic-inorganic interaction between the resin and the other components of the composite reduced the deformation of the composite and consequently improved strength.

Ash deposition of heat exchange boiler, caused mainly by accumulation of particulate matter, reduces heat transfer of the boiler system. Heat and mass transfer through porous media such as ash deposits mainly depend on the microstructure of deposited ash. Therefore, in this study, we investigated microstructural and thermal properties of the ash deposited on the boiler tube. Samples for this research were obtained from the fuel economizer tube in an industrial waste incinerator. To characterize microstructures of the ash deposit samples, scanning electron microscope (SEM), energy-dispersive spectroscopy (EDS), inductively coupled plasma optical emission spectroscopy (ICP-OES), X-ray diffraction (XRD) and BET analysis were employed. The results revealed that it had a porous structure with small particles mostly of less than a few micrometers; the contents of Ca and S were 19.3, 22.6% and 18.5, 18.7%, respectively. Also, the results showed that it consisted mainly of anhydrite (CaSO₄) crystals. - The thermal conductivities of the ash deposit sample obtained from the economizer tube in industrial waste incinerator were measured to be 0.63 and 0.54 W/mK at 200℃, which were about 100 times less than the thermal conductivity (61.32 W/mK) of the boiler tube itself, indicating that ash deposition on the boiler tube was closely related to a decrease in boiler heat transfer.

Mineral filler is used for resin compounds, because it increases the stiffness and thermal stability of a resin compound, and it also cuts down the cost. Calcium carbonate, silica, magnesium oxide, and others are used as filler materials in general, and the type of filler material, the size, and content can affect the physical properties of compounds. Those factors also influence the viscosity of resin mixtures and the workability, and should be adjusted by changing the contents of the filler, which depends on the size. In this study, five kinds of ground calcium carbonate, which were different in size, were used to produce polyester compounds ; the physical properties were compared with the filler size and contents. The mechanical properties were measured by bending strength and tensile strength, and the heat deflection temperature was obtained for thermal stability.

Foam-type porous silicon carbide (SiC) ceramics without cracks and hollow struts were fabricated using the polymer replica method with polycarbosilane (PCS) and polyurethane (PU) foam as the starting materials. The synthesized porous SiC was analyzed using X-ray diffraction and scanning electron microscopy. The results revealed that a porous SiC ceramic structure was formed with a dense framework at a low temperature of 1200°C. During the heat-treatment process, the PCS experienced an organic–inorganic transformation and then converted to the SiC ceramics. It was determined that the organic–inorganic transformation of PCS, which was the stage of silicon oxycarbide formation, is affected by the curing condition. In this study, the optimum curing condition was determined to be an air atmosphere at 200°C for 7 h.

In this study, alumina plates 9~25 μm in size were used as thermal fillers, and epoxy resin was used as a polymer matrix. Oriented alumina plate/epoxy composites were prepared using a rolling method. The effect of ordering alumina plates increased with alumina plate size. The thermal conductivity and flexural strength of the composites were investigated. The horizontal thermal conductivity of the oriented composite was significantly higher than the vertical thermal conductivity. The horizontal thermal conductivity of the 75 wt% alumina content was 8.78 W/mk, although the vertical thermal conductivity was 1.04 W/mk. Ordering of the alumina plate using a rolling method significantly improved the thermal conductivity in the horizontal direction. The flexural strengths of the ordered alumina/epoxy composites prepared at different curing temperatures were measured.

*Energy & Environmental Devision, Korea Institute of Ceramic Engineering and Technology,77 Digital-ro 10 gil, Geumcheon-gu, Seoul 153-801, Korea**Enbion Inc., 841 Tamnip-dong Yuseong-gu, Daejeon 305-501, Korea(Received 15 November 2014; Received in revised form 8 December 2014; accepted 11 December 2014)

Natural materials often have unique mechanical properties, such as the hierarchical structure of nacre formed through mineral bridges or asperities created between an inorganic particle and a natural-layer surface. As these asperities produce an exceptional shear resistance, in this study, we aimed to emulate the natural structure of nacre by synthesizing inorganic asperities and mineral bridges with different temperatures in the range of 1100 - 1300℃ and clay contents from 10 - 50 wt%. Following the infiltration of methyl methacrylate, we measured the mechanical properties to assess whether they were improved by the asperities. It was confirmed that the asperities improved the bending strength by 10%, and the anchoring effect was observed on the fracture surface.

Si(Al)ON precursor was synthesized by formation of new Si-N bond using organoaluminum imine and liquid type poly(phenyl carbosilane). It was decomposed between 200 - 600℃, and the ceramic yield was 51% after pyrolysis. 150 ? 200 ㎚ in thickness of coating film was obtained by spin coating method. The precursor was easily oxidized during process because it was unstable in air. However the oxygen content was limited to 0.5 - 0.7 to silicon in heat treatment step. Even though the content of nitrogen was decreased by pyrolysis, Al-N and Si-N bonds were formed in ammonia atmosphere, and Si(Al)ON film was formed with 0.2 in content to silicon.

SMC composites consist of chopped glass fiber as a reinforcements, polyester and mineral fillers. Among them, filler is one of the important factors for improving mechanical and thermal properties of composites, but it has not drawn much attention for SMC composites. In this study, the size effect of calcium carbonate as mineral filler on mechanical properties of SMC composites was discussed using five different sizes of commercial calcium carbonates without chopped fiber reinforcement, to focus on the size effect itself. The SMC process was modified to be suitable for a laboratory scale composed of three steps. The mean sizes of the calcium carbonates were 3 – 20 μm, and the specific surface areas were calculated to be 1 – 5 m2/g by BET. Small size of calcium carbonate having high surface area up to 4 m2/g showed high thermal resistance, and showed higher strength comparing to the large fillers because it affected to form a dense packed microstructure.

${\alpha}$ -상 과 ${\beta}$ -상 두 가지 종류의 탄화규소(SiC) 입자 표면에 수열 합성 방법으로 ZSM-5 결정을 형성하였다. SiC는 $50{\mu}m$ 이상이 되는 크기의 입자를 사용하였으며, ZSM-5 결정이 SiC 표면에서부터 성장하도록 유도하기 위하여 합성 단계에 앞서 SiC 표면에 산화층을 형성하였으며, 수열합성 온도와 시간을 변화시켜 보았다. 그 결과 ${\beta}$ -SiC는 $900^{\circ}C$ 조건에서도 산화막이 형성되었으며, 특히 $150^{\circ}C$ 합성 조건에서 ZSM-5가 ${\beta}$ -SiC 표면에서부터 성장하였음이 뚜렷이 관찰되었다. $200^{\circ}C$ 조건에서는 ZSM-5의 결정의 크기가 성장할 뿐 아니라, 시간의 증가에 따라 결정의 형태가 뚜렷해지고 SiC 표면에 도포되는 양이 증가하는 것을 확인할 수 있었다. 【ZSM-5 crystals grew on the surface of ${\alpha}$ -SiC and ${\beta}$ -SiC particles by hydrothermal synthesis method. SiC particles which were > $50{\mu}m$ of size were used, and oxide layer were developed on the surface of the particles to induce growth of ZSM-5 from the surface. Then, synthesis time and temperature condition were considered growing ZSM-5. In this study, oxide layer was formed on ${\beta}$ -SiC at $900^{\circ}C$ in air, and it was controlled to grow ZSM-5 grew from the ${\beta}$ -SiC surface with $150^{\circ}C$ synthesis condition. This is due to Si-O-Si or Si-O-Al bond, which is basic framework of ZSM-5 can be easily formed, from the silicon oxide film on the surface of ${\beta}$ -SiC. When the synthesis temperature was $200^{\circ}C$ , the size of ZSM-5 was increased, and it covered much area of the SiC surface with better crystal shapes with longer synthesis time.】

Alumina nano-asperites were grown on plate-like alumina particles of which the surface had been covered with a capping agent to control the asperite formation sites on the particles. Utilized alumina source for asperite was nano sized γ-alumina, which was prepared by calcination of Al(OH)₃ at 600 ℃; silica suspension was used as the capping agent. Plate like alumina particles were covered by silica suspension and continuously heat-treated to 900 ℃ with nano sized γ-alumina, as the source material, under molten-salt atmosphere. Asperite growing site were controlled by the degree of coating of the capping agent; 10-20 nanosize of θ-alumina were formed on the particle surface. On the other hand, alumina particles without capping agent were observed to undergo only step-like crystal growth during heat-treatment.

Aluminum nitride was synthesized using a carbothermal method from mesoporous alumina having a high surface area (> 1,000 ㎡/g) as an aluminum source and CNTs (carbon nano tubes) as a carbon source. In this case the mesoporous alumina was used as the starting material instead of α-Al₂O₃ with the expectation that the mesopores in mesoporous alumina act as channels for N₂ gas and elimination of CO generated as by-product. It is also expected that the synthetic temperature should be lower compared to the use of α- Al₂O₃ as a starting material due to its high surface area. The crystallinity of the produced aluminum nitride was studied by XRD and FTIR, and the microstructure was investigated by FE-SEM. Also the purity of the aluminum nitride was analyzed through N/O determinator and ICP analysis.

Foam type porous silicon carbide ceramics were fabricated by a polymer replica method using polyurethane foam, carbon black, phenol resin, and silicon powder as raw materials. The influence of the C/Si mole ratio of the ceramic slurry and heat treatment temperature on the porous silicon carbide microstructure was investigated. To characterize the microstructure of porous silicon carbide ceramics, BET, bulk density, X-ray Powder Diffraction (XRD), and Scanning Electron Microscope (SEM) analyses were employed. The results revealed that the surface area of the porous silicon carbide ceramics decreases with increased heat treatment temperature and carbon content at the 2 nd heat treatment stage. The addition of carbon to the ceramic slurry, which was composed of phenol resin and silicon powder, enhanced the direct carbonization reaction of silicon. This is ascribed to a consequent decrease of the wetting angles of carbon to silicon with increasing heat treatment temperature.

AlN single crystal can be grown by physical vapor transport (PVT) method. The purity and particle size of the source material are important factors for single crystal growth to obtain good quality of AlN single crystal. The aim of this study was purification of AlN powder and growth of its particle size through thermocyclic treatment. The initial particle size was about 1.0 μm and the purity was 98.4% containing 1.6% oxygen and metallic impurities such as Fe, Sn, Ca, Na and Mg etc. which were analyzed based on KSL1612. For purification of AlN powder, it was performed using a thermocycle process with various thermocyclic numbers. After the thermocycle treatment, it is able to obtain large particle size AlN powder as much as 30μm and purity was increased to 99.6% based on chemical analysis.

Drug loaded polyurethane (PU) thin layer was prepared on the silicone tube by electrospinning technique. Microstructure of the PU layer was varied from nanoporous web to dense coating depending on the polymer solution concentration and the amount of drug loaded. It can be easily adjusted the coating thickness and porosity accurately and controlled the drug loading and releasing properties. However, adhesive strength between PU layer and silicone tube was very weak and easily broken away and white turbidity also another important problem. So, surface of silicone tube was atmospheric-pressure plasma (APP) treated for improving the adhesive and removing white turbidity phenomenon.

A hydroxyapatite microsphere was prepared using a spray-drying method. The change in the shape as a function of the slurry concentration and the change in the degree of shrinkage according to the heat-treatment temperatures were observed. To obtain biomaterials with improved bio-stability, CaHPO₄4·2H₂O and Ca(OH)₂ were mixed at a ratio of 6 : 4 and then ball-milled to synthesize hydroxyapatite. The hydroxyapatite microsphere was prepared using 30 wt% ~ 80 wt% hydroxyapatite slurry by a spray-drying method. For concentrations lower than 50 wt% or higher than 80 wt%, doughnut-shaped microspheres were produced. However, perfect microspheres were produced when using slurry concentrations of 50 wt% ~ 70 wt%. A dense microstructure was observed after a heat treatment at temperature higher than 1100℃ and the size was reduced by 24.3% at these temperatures.

Since mesoporous silica such as MCM-41 and SBA-15 was developed, the study of the properties of high-surface area materials was accelerated. Moreover, the mesoporous silica is used as a template to produce high-surface materials by nanocasting technology. The purpose of this paper is the synthesis of a high surface silicon carbide sphere by the nanocasting technology. In this study, KCC-1 silica sphere was used as a template, and polycarbosilane and poly (phenyl carbosilane) were selected for precursor of silicon carbide. Carbosilane polymer gives advantage of synthesis silicon carbide under low temperature, and hollow spheres were produced. In this study, the polycarbosilane was more effective for the synthesis of SiC hollow spheres by inversion of template structure showing a fibrous morphology on the sphere wall. And it was confirmed that the sphere was composed of nanosized SiC crystals, and has high surface area using TEM, XRD and BET analysis.

β-SiC particles were synthesized using silicon powder and carbon black at 1300°C. The effect of grinding the silicon powder raw material into smaller particles on the synthesis and crystallinity of the SiC particles was investigated. The size of the silicon particles decreased and the surface of the silicon particles increasingly oxidized into silicon oxide with increasing grinding time, thus decreasing the yield of SiC because of the higher SiO2 content in the ground silicon powder, since SiO2 transforms into SiC at a higher temperature than does silicon. Although the sizes of the silicon particles in the raw materials were different, all the synthesized SiC crystallites showed similar size. Transmission electron microscopy-energy dispersive X-ray spectroscopy analysis showed that although most of the synthesized SiC particles were smaller than 100 nm, the primary SiC particles had aggregated, and some unreacted silicon was observed inside the large aggregated SiC particles.

The influence of a liquid medium duringa wet-milling process in the grinding and oxidation of silicon powder was investigated. Distilled water, dehydrated ethanol and diethylene glycol were used as the liquid media. The applied grinding times were 0.5, 3, and 12 h. Ground silicon powder samples were characterized by means of aparticle size analysis, scanning electron microscopy(SEM), xray powder diffraction (XRD), FT-IR spectroscopy and by a chemical composition analysis. From the results of the characterization process, we found that diethylene glycol is the most efficient liquid medium when silicon powder is ground using a wet-milling process. The FT-IR results show that the Si-O band intensity in an unground silicon powder is quite strongbecause oxygen becomes incorporated with silicon to form SiO₂ in air. By applying deionized water as a liquid medium for the grinding of silicon, the SiO₂ content increased from 4.12% to 31.7%. However, in the cases of dehydrated ethanol and diethylene glycol, it was found that the SiO₂ contents after grinding only changed insignificantly, from 4.12% to 5.91% and 5.28%, respectively.

Nacre is an organic-inorganic composite material; it is composed of CaCO3 platelet and protein. The microstructure of nacre is a matrix that is similar to bricks and mortar. Technology inspired by nature is called biomimetic technology. In this study, to make high thermal conducting ceramic composite materials using biomimetic technology, a porous green body was prepared with BN platelets. PMMA was infiltrated into the porous green body to make a composite. The microstructure of the composite was observed with FESEM, and the thermal properties were measured. The thermal conductivity of the prepared organic ?inorganic composite was 4.19 W/m·K.

Abalone shell is composed of 95 wt% CaCO 3 platelets and 5 wt% of a protein-rich organic matrix which acts as an adhesive layer, connecting aragonite tablets, thus maintaining the structural integrity of the composite. By mimicking abalone shell, we prepared a silicate plate/polymer nanocomposite by infiltrating PMMA between silicate layers and warm-pressing them at 200 o C for 1 h under 15 tons to make organic-inorganic composite materials. To examine the organic-inorganic composite materials after the warm-pressing procedure, the composite sample was analyzed with FE-SEM and TG. The bending strengths and densities of the composites prepared by a silicate plate and PMMA after the warm-pressing process were ~140 MPa and 1.5, respectively.

Since SiOC was introduced as an anode material for lithium ion batteries, it has been studied with different chemical compositions and microstructures using various silicon based inorganic polymers. Poly(phenyl carbosilane) is a SiOC precursor with a high carbon supply in the form of the phenyl unit, and it has been investigated for film applications. Unlike any other siloxanebased polymers, oxygen atoms must be utilized in an oxidation process, and the amount of oxygen is controllable. In this study, SiOC anodes were prepared using poly(phenyl carbosilane) with different heat treatment conditions, and their electrochemical properties as an anode material for lithium ion batteries were studied. In detail, cyclic voltammetry and charge-discharge cycling behavior were evaluated using a half-cell. A SiOC anode which was prepared under a heat treatment condition at 1200℃ after an oxidation step showed stable cyclic performance with a reversible capacity of 360 mAh/g.

SiC hollow fiber was fabricated by curing, dissolution and sintering of Al-PCS fiber, which was melt spun the polyaluminocarbosilane. Al-PCS fiber was thermally oxidized and dissolved in toluene to remove the unoxidized area, the core of the cured fiber. The wall thickness (t wall ) of Al-PCS fiber was monotonically increased with an increasing oxidation curing time. The Al-PCS hollow fiber was heat-treated at the temperature between 1200 and 2000°C to make a SiC hollow fibers having porous structure on the fiber wall. The pore size of the fiber wall was increased with the sintering temperature due to the decomposition of the amorphous SiCxOy matrix and the growth of β-SiC in the matrix. At 1400°C, a nano porous wall with a high specific surface area was obtained. However, nano pores grew with the grain growth after the thermal decomposition of the amorphous matrix. This type of SiC hollow fibers are expected to be used as a substrate for a gas separation membrane.

Characterization of silicon kerf from photovoltaic silicon-wafer production was carried out. Also, SiC powder was synthesized using high purity silicon kerf by varying grinding conditions. With increase of grinding time, surface of the silicon was oxidized to form silicon oxide. Also, it was observed that the unreacted silicon oxide and free silicon amount in the SiC powder increases with an increasing grinding times, even though silicon particle size of the starting material is decreased.

In an environmental and economic point of view, recycling of silicon wafer sludge is important. The aim of this work is to investigate the recycling method of silicon wafer sludge. Therefore, drying rate of silicon wafer sludge has been studied for separation of liquid and solid from sludge. Silicon and silicon carbide powder obtained from silicon wafer sludge were analyzed by SEM, XFR, XRD and particle size analyzer. The recovered oil was also characterized using GC-MS. From this work, it can be seen that the falling drying rate of silicon wafer sludge is linear equation. Various metal components have been found in recovered solid powder caused by wire sawing processing.

태양광 산업에서 폐기물로 발생하는 Si/SiC 혼합슬러지를 재활용하는 것은 환경과 경제적인 측면에서 중요하다. 이러한 재활용을 위해서 Si/SiC 혼합물의 소결특성을 분석하는 것이 필요하다. 본 연구에서는 SiC함량에 따른 소결특성을 살펴보기 위해서 공기분급기를 이용하여 Si/SiC 혼합물에서 SiC 함량을 변화시켰다. SiC 함량이 변화된 Si/SiC 혼합물에 카본블랙, 점토 및 수산화알루미늄을 첨가하여 소결하였다. Si/SiC 혼합물의 특성분석 및 첨가제 변화에 따른 Si/SiC 혼합물 소결체의 특성변화를 SEM, XRD, 입도분석 및 겉보기 밀도변화를 측정하여 분석하였다. SEM 및 입도분석결과, SiC 95% 시료의 경우에는 원시료 및 SiC 75% 시료와 비교하여 1 ${\mu}m$ 크기 이하의 미립입자가 크게 감소하여 공기분급을 통한 미세입자 제거가 SiC 함량 제어에 효과가 있음을 확인할 수 있었다. 수산화알루미늄을 첨가함에 따라서 ${\beta}$ -Cristobalite 가 감소하고 mullite 생성량이 증가하였으며, 카본블랙의 첨가가 소결특성 향상에 영향을 주는 것을 확인하였다. 【The recycling of the Si/SiC mixture sludge obtained from solar cell industry is very significant, environmentally and economically. The sintering characteristics of Si/SiC mixture sludge was studied for the purpose of recycling. In this study, to understand sintering behavior, SiC content in the Si/SiC mixture was controlled using an air separator. Various Si/SiC mixtures having different SiC contents were sintered using carbon black, clay and aluminum hydroxide as sintering aids. Physical properties of Si/SiC mixture and sintered bodies have been characterized using SEM, XRD, particle size analyzer and apparent density measurement. SEM and particle size analysis result confirmed that the fine particles less than 1 ${\mu}m$ decreased or removed more effectively through the air separator in the case of 95% SiC sample compared than the case of 75% SiC sample or original SiC sample. Further, with addition of the Aluminum Hydroxide, ${\beta}$ -cristobalite phase gradually decreased while mullite phase gradually increased. The addition of the carbon black improved the sintering characteristics.】

The recycling technology of carbon residue produced from the process of oil recovery in waste tire pyrolysis is significant in environmental and economical aspects. This study was done to figure out the recycling possibility of carbon residue to activated carbon. For this, the characteristics of the carbon residue obtained from the commercial pyrolysis process of waste tire were studied. Also, the variation of pore structure of carbon residue was studied after 1 hour of carbonization at 600 ? C 600?C and 800 ? C 800?C and 3 hours of activation at 950 ? C 950?C . The specific surface area of the carbon residue was 8.0m 2 /g 8.0m2/g and it increased to 548.3m 2 /g 548.3m2/g after carbonization and activation.

Uniform nanosized β-SiC powders have been prepared in a flow reactor by thermal pyrolysis using organometallic precursors with different C/Si mole ratios such as methyltrichlorosilane and triphenylsilane. The temperature was varied from 1200°C to 1400°C. In order to examine the pyrolysis residue after the reaction, the sample was collected and analyzed with XRD, Raman and TEM. The X-ray diffraction result of the pyrolysis residue shows that the diffraction peaks around 35°, 60°, and 73° correspond to the beta SiC phase. All the diffraction peaks were quite broad, which indicated that the SiC powder was in the early stage of crystallization at this heat treatment temperature.

Abalone shell is a high strength and light weighted ceramic composite material, which is composed of CaCO₃ platelet and protein. Microstructure of abalone shell has a matrix structure that is similar to the bricks and mortar. The technology inspired from nature which consumes low energy at low temperature is called bioinspired technology. In this study, to make high strength and light weighted ceramic composite materials using bioinspired technology, porous green body was prepared with Al₂O₃ platelet. PMMA was infiltrated into the porous green body, then warm pressed to eliminate pores present in the composite. The microstructure of the composite was observed with FESEM, and the mechanical/ thermal properties were measured.

SiC powder can be produced generally through the Acheson process and it is required long carbothermic reaction time of SiO2 with carbon powder around 2200 °C ~ 2400 °C. Due to the high reaction temperature and long reaction time of the process, the powders produced have a large particle size and consist of mostly alpha phase SiC. Synthetic temperature of beta phase SiC powder is known to produce at 1700 °C ~ 1900 °C which is lower temperature than that of alpha phase SiC powder. We prepared β-SiC powder by heating precursor derived from the mixture of phenolic resin and tetraethyl orthosilicate. The precursor was heated at 1800 °C for 4 h in an Ar atmosphere. In order to examine the pyrolysis residue after the heat treatment, the SiC powder was analyzed with XRD and SEM. The X-ray diffraction result of the SiC powder shows the diffraction peaks around 35°, 60°, and 73° corresponded to the beta SiC phase. β-SiC powder prepared in this study contains lower metallic impurities compare than that of α-SiC powder prepared from Acheson method and is able to use as a good starting material for SiC single crystal growing.

β-SiC powder was synthesized using silicon sludge from photovoltaic silicon-wafer production by varying heat treatment temperature and carbon contents. The synthesized β-SiC powder and silicon sludge was analyzed by XRD, SEM, FT-IR and Particle size analysis. It is known that the conversion of SiC from the mixture of Silicon and Carbon is mainly affected by the mole ratio of C/Si and heat treatment temperature. In this study, the influence of reaction temperature and carbon contents on the synthesis of β-SiC from silicon sludge was examined.

β-SiC powder was synthesized directly from silicon sludge with carbon black. Large amount of silicon sludge is generated from Solar Cell industry. In an environmental and economic point of view, recycling silicon sludge is important. In this study, two kinds of silicon sludge were characterized using XRD, SEM/EDS and FT-IR. SiC powder was synthesized by the reaction of ball-milled silicon powder for 3h in vacuum at different temperatures (1350 and 1600). Physical properties of the heat treated SiC have been characterized using a SEM, XRD, Particle size analyzer and FT-IR Spectroscopy.

The formation of organic-inorganic hybrid composite with ceramic platelets and polymeric compound can have the higher strength and higher elasticity than metal, which is a nanocomposite with high strength and light weight. Ceramic platelet such as Al2O3has been used to form organic-inorganic composite material using PMMA as an organic polymer. Bending strength and density of the composites prepared by infiltration and post-warm pressing were measured. FE-SEM and TG analysis were carried out to determine the microstructure of the organic-inorganic composite materials. Bending strengths and densities of the composites prepared by Al2O3ceramic plate and PMMA after post-warm pressing were ~70MPa and ranged from 2.4 to 2.6, respectively.

Antimony doped tin oxide (ATO) is a typical p-type semiconductor and widely used due to its good properties such as electrical conductivity and transparency in visible range, while reflects infrared light. These features allow ATO to be used as transparent electrodes, heat mirrors and energy storage device, display panel. However, the use of tin oxide ceramics is limited by the low densification during sintering due to the dominance of non-densification mechanism such as surface diffusion or evaporation condensation. So, sintering agents such as Cobalt (II) oxide (CoO), zinc oxide (ZnO), manganese dioxide (MnO2) used to improve the densification of SnO2 by forming lattice solid solution or liquid phase. In this study, we studied the effect of the sintering agents. The antimony-doped tin oxide nanoparticles were synthesized by a sol-gel method. After sintering ATO with sintering agents such as MnO2 and CoO, sintered body characteristics were investigated by XRD, SEM, thermal conductivity, resistivity and interesting characteristic.

A pure TiO2 thin film without adding any organic binder was fabricated by using a self-polymeric titania nano-sol (14 mass%), which was prepared by the acid peptization method. The particle size distribution in the 14 mass% TiO2 sol, in which almost of particles had a size below 10.2 nm and the crystal phase confirmed by X-ray diffraction analysis was anatase. The diluted nano-sol had a capability to form a thin film at a low temperature (100-400 degrees C) on the slide glass by dipping method. The average thickness of a coating film was measured to be about 0.25-0.30 microm. A coated film had a high refractive index over 1.88 at least irrespective of the heat-treatment even at room temperature drying and showed a super-hydrophilicity (< 5 degrees) after 20 minutes under Ultra Violet light irradiation, and it sustained in the darkness during a long period over 7 days depending on the heat-treatment conditions. Atomic Force Microscopic observation shows that the morphology of a heat-treated film had a relationship with the long-term hydrophilicity in the darkness.

Recently, variety of organic and inorganic hybrid materials have recently investigated as alternative routes to SiOC, SiO 2 thin film formation at low temperatures for applications in electronic ceramics. Specially, silicon based polymers, such as polycarbosilane, polysilane and polysilazane derivatives have been studied for use in electronic ceramics and have been applied as dielectric or insulating materials. In this study, Polycarbosilane(PCS), which Si-CH 2 -Si bonds build up the backbone of the polymer, has been investigated as low-k materials using a solution process. After heat treatment at 350℃ under N 2 atmosphere, chemical composition and dielectric constant of the thin film were SiO 0.27 C 1.94 and 1.2, respectively. Mechanical property measured using nanoindentor shows 1.37 GPa.

The polymerization and molecular weight distribution of poly(phenylcarbosilane) (PPCS) depend on the temperature and pressure conditions under which it is synthesized using the Kumada rearrangement reaction. Its degree of polymerization is related not only to its physical properties such as solubility and boiling point but also to its chemical structure. In this study, soluble PPCS having a weight-average molecular weight (Mw) in the range of 2,500–3,000 was selectively isolated through distillation or fractional precipitation, and its chemical structure and physical properties were studied via FT-IR, NMR, GPC, and thermal analysis. The analytical data indicate that the Si–CH2–Si backbone and Si–Si bond are formed through step-growth polymerization and are clearly detected after purification. The differences in the thermal behavior of PPCS in air and in nitrogen were also investigated.

Polyphenylcarbosilane (PPCS) was synthesized from thermal rearrangement of the polymethylphenylsilane around 350 ~ 430°C. Characterization of synthesized PPCS was performed with FT-IR spectroscopy analysis. From FT-IR data, the band at 1035cm-1 is very strong and assigned to CH2 bending vibration in Si-CH2-Si group, indicating the formation of the PPCS. Ceramic thin film was fabricated onto stainless substrate by dip coating using a 20wt% PPCS in toluene. Heat treatment of the samples was performed at various temperatures (600°C and 800°C) under nitrogen atmospheres. The prepared PPCS samples and the coating layers on SUS316 after heat treatment were analyzed using FT-IR and XPS, respectively.

A PVP (Polyvinylpyrrolidone)-assisted TiO2 film with thickness over 100 nm by one step dip coating was prepared by adding polyvinylpyrrolidone (PVP) to TiO2 nano sol and heat-treatment at the relative low temperature (450°C). The maximum refractive index of PVP-assisted TiO2 film was measured to be 1.8764 after 5th dip coating and heat-treatment in this work. As the amount of TiO2 sol increased, it increased, while it decreased as the quantity of PVP increased. The crystalline phase by X-ray diffraction was identified to be anatase and the intensity increased with film thickness’s increase. The maximum thickness of pure TiO2 film prepared without crack was 1.89 µm and U.V. absorption of PVP–TiO2 nano hybrid film before heat-treatment was measured to be over 98% at 340 nm wavelength.

In this work, the decomposition characteristics of wood using supercritical methanol have been studied. The kinetic analysis was carried out for three heating rates of 5.2, 11.6 and 16.3 oC/min. And the liquid products analysis has been performed for reaction temperatures of 300-320 oC and reaction times of 0-120 min, respectively. The activation energies of wood decomposition in supercritical methanol were 45.2-48.8 kJ/mol, depending on the heating rates. And the reaction orders were 0.25 for all heating rates. And the liquid product has been analyzed by GC-MS. From this work, the yields of liquid product increased as increasing of reaction temperature and reaction time. And it was also found that the components of liquid products were mainly acetic acid, latic acid, pentanol and phenol.

The present investigation deals with the synthesis of silver coated copper powder for potential application as filler material in conductive polymers for electro magnetic interference (EMI) shielding. Copper powders were obtained by the reaction of cuprous oxide and, hydrazine in a mixed solvent (H2O:ethanol) at various reaction conditions. The cuprous oxide powder was produced by the reaction of CuSO4, NaOH and D-glucose. The synthesized copper powder was silver coated by its reaction with (NH4)2SO4, C4H4O6KNa and AgNO3. The prepared powders were characterized by XRD, SEM, TGA and XPS. The coaxial transmission line method was used to measure the EMI shielding effectiveness of the powders. The silver coated copper powders exhibited an improved oxidation resistance and higher EMI shielding effectiveness as compared to the uncoated copper powders.

In our study, the dielectric properties of SiOC low k thin film derived from polyphenylcarbosilane were investigated as a potential interlayer dielectrics for Cu interconnect technology. A SiOC low k thin film was fabricated onto a n-type silicon wafer by dip coating using 30wt % polyphenylcarbosilane in cyclohexane. Curing of the film was performed in air at 300°C for 2h. The thickness of the film ranges from 1 μm to 1.7 μm. The dielectric constant was determined from the capacitance data obtained from metal/polyphenylcarbosilane/conductive Si MIM capacitors and shows a dielectric constant as low as 3.26 without porosity added. The SiOC low k thin film derived from polyphenylcarbosilane shows promising application as an interlayer dielectrics for Cu interconnect technology.

The synthesis of AlN via self-propagating high-temperature synthesis (SHS) was attempted, using various ratio of Al powder mixed with AlN powder as diluents. Al and AlN powder mixtures with various weight ratios were ignited a nitrogen atmosphere with various amounts of carbon as additives. High crystalline AlN by SHS were successfully synthesized. The microstructure development during the reaction and the influence of these additives were determined by SEM and XRD analysis. A mechanism for the formation of high purity AlN with a very low content of residual oxygen (

AlN powders by the chemical vapor synthesis (CVS) process in the AlCl3-NH3-N2-H2 system were successfully synthesized. Gasified AlCl3 as a starting material was generated by pre-heating system and transported to the tube furnace in NH3-N2-H2 atmosphere. High crystalline AlN was synthesized at over 900°C. The average particle size of spherical AlN powders decreased from 250 to 40nm with increasing the reaction temperature of the tube furnace. Porous nano-size particles synthesized at high reaction temperature have low oxygen contents.