In order to improve the high temperature oxidation resistance and lifespan of mat type porous carbon insulation, SiC was coated on carbon insulation by solution coating using polycarbosilane solution, curing in an oxidizing atmosphere at 200 oC, and pyrolysis at temperatures up to 1200 oC. The SiOC phase formed during the pyrolysis process was converted into SiC crystals as the heat treatment temperature increased, and a SiC coating with a thickness of 10-15 nm was formed at 1600 oC. The SiC coated specimen showed a weight reduction of 8.6 % when it was kept in an atmospheric environment of 700 oC for 1 hour. On the other hand, the thermal conductivity was 0.17W/mK, and no difference between states before and after coating was observed at all.

This study experimentally investigated dicyclohexylammonium 2-cyanoacrylate (CA) as a potential comonomer for polyacrylonitrile (PAN) based carbon fiber precursors. The P(AN-CA) copolymers with different CA contents (0.19-0.78 mol% in the feed) were polymerized using solution polymerization with 2,2-azobis(isobutyronitrile) as an initiator. The chemical structure and composition of P(AN-CA) copolymers were determined by proton nuclear magnetic resonance and elemental analysis, and the copolymer composition was similar to the feeding ratio of the monomers. The effects of CA comonomer on the thermal properties of its copolymers were characterized differential scanning calorimetry (DSC) in nitrogen and air atmospheres. The DSC curves of P(AN-CA) under nitrogen atmosphere indicated that the initiation temperature for cyclization of nitrile groups was reduced to around 235℃. The heat release and the activation energy for cyclization reactions were decreased in comparison with those of PAN homopolymers. On the other hand, under air atmosphere, the P(AN-CA) with 0.78 mol% CA content showed that the initiation temperature of cyclization was significantly lowered to 160.1℃. The activation energy value showed 116 kJ/mol, that was smaller than that of the copolymers with 0.82 mol% of itaconic acids. The thermal stability of P(AN-CA), evidenced by thermogravimetric analyses in air atmosphere, was found higher than PAN homopolymer and similar to P(AN-IA) copolymers. Therefore, this study successfully demonstrated the great potential of P(AN-CA) copolymers as carbon fiber precursors, taking advantages of the temperature-lowering effects of CA comonomers and higher thermal stability of the CA copolymers for the stabilizing processes.

High temperature corrosion is a major issue in waste-to-energy (WTE) facilities because it effects running cost and energy utilization efficiency. Corrosion of heating surfaces in WTE boilers is a complex phenomenon. The purpose of this study was to analyze the high temperature corrosion characteristics of WTE boiler tubes and to determine the influences of high temperature corrosion on heat exchange. Heating surface corrosion samples for this research were obtained from a superheater tube in municipal solid refuse fuel-fired power plant. Surface morphology, microstructure and phase composition were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction analysis. The morphology of the heating surface was rough and had porous structures. The chlorine content of the surface was 7.4wt.% and the samples were mainly composed of hematite (Fe2O3) and magnetite (Fe3O4). The thermal conductivity of the corrosion samples was characterized using thermal conductivity measurements and was found to be 2.33 W/mK at 500oC. This result, which is 17 times less than that of boiler tube carbon steel (40.40 W/mK), indicates that corrosion of WTE boiler tubes is closely related to a decrease in boiler heat exchange efficiency.