Graphene oxide (GO) was prepared by the Hummers and Offeman method from graphite. Two different types of functionalized graphene sheets (FGSs) were synthesized by using GO. Hexamethylamine (HDA) substituted vertically to the graphene sheet (Ver-HDA-GS) was synthesized from HDA and epoxy group in GSs. Whereas, horizontally substituted hexadecanol (HDO) to the GS(Hor-HDO-GS) was synthesized from HDO and alcohol groups via reduced GO (RGO), respectively. The structures of the GO, RGO, Ver-HDA-GS, and Hor-HDO-GS were identified by Fourier transform infrared (FTIR). In addition, we examined the thermal stability and morphology. Atomic force microscope (AFM) disclosed that Ver-HDA-GS consisted of one-or two-layer graphene regions. However, the Ver-HDA-GS layers showed average thickness of 1.76 nm. The thermal stabilities of the FGSs were better than those of the GO and RGO. The Ver-HDA-GS was well dispersed in common solvents such as dimethyl sulfoxide (DMSO), toluene, chloroform, and decalin.
To mitigate global warming and climate change, many countries are investing massively on the development of CCS technology, which is assumed to be the key technology to reduce CO2 emissions. CCS technology is comprised of the capture, transport, and storage processes. During the capture process, impurities other than CO2 are inevitably flowed into the CO2 stream. In the present study, corrosion characteristics of a phosphate coated tube for CO2 transportation was investigated with a CO2 stream composed of CO2, H2O, SO2, and NO2. The test specimen was a phosphate coated steel tube, which was filled with CO2 stream with the impurities mentioned above. SEM-EDS analysis is conducted to investigate the corrosion behavior. The results showed that although the H2O concentration did not exceed the solubility limit, corrosion occurred in the specimen, which has an inflow of SO2 or NO2. This suggests that the SO2, NO2 and H2O concentration should be strictly controlled. These results suggest that the SO2 and NO2 concentration should be controlled below 175ppm and 65ppm, respectively.
In the present study, coating corrosion characteristics of the heat exchanger for sea water are experimentally investigated. Coating types by a teflon, an electrodeposition and a ceramic+silicon were tested and compared with the corrosion characteristics of an aluminum. For the acceleration of corrosion by sea water, the temperature of sea water 70℃ and the concentration of salt 3.5% were considered. And the specimens were immersed in sea water during 9 weeks. Coating corrosion characteristics were measured by using the impedance method and SEM. Experimental results showed that polarization resistances obtained from Bode plot were related to the corrosion resistance of coating types, and the corrosion resistance of double coating were maintained during 4 weeks. From SEM photograph, we saw that blisters was generated on the interface between metal and coating.
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