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Simultaneous detection of trace Cd(II), Pb (II), Cu (II), Hg(II) ions by a boron-doped diamond electrode
Abstracts / Carbon 124 (2017) 725e727
727
[New Carbon Materials 2017, 32(3): 265-270] ABLATION BEHAVIOR OF A THREE-DIMENSIONAL C/C-HfC COMPOSITE PREPARED BY A PRECURSOR INFILTRATION AND PYROLYSIS METHOD
[New Carbon Materials 2017, 32(3): 277-283] SIMULTANEOUS DETECTION OF TRACE Cd(II), Pb (II), Cu (II), Hg(II) IONS BY A BORON-DOPED DIAMOND ELECTRODE
Liang Xue, Zhe-an Su, Xin Yang, Qi-zhong Huang. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China
Cheng-yao Gao a, b, Jian-hua Tong a, Chao Bian a, Shan-hong Xia a. a State Key Laboratory of Transducer Technology, Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China; b Chinese People's Armed Police Force Academy, Langfang 065000, China
Abstract: A three-dimensional C/C-HfC composite with a density of 1.95 g/ cm3 was fabricated by chemical vapor infiltration of carbon into a 3 D woven carbon fiber felt to a density of 1.45 g/cm3 followed by vacuum impregnation and pyrolysis of a solution containing the HfC precursor. Results indicate that HfC particles are uniformly dispersed around the pyrocarbon. The 3D C/C-HfC composite exhibits a good ablation resistance at 2573 K. The mass and linear ablation rates after ablation for 120 s are 0.001 5 g/s and 0.002 4 mm/s, respectively. The resistance to ablation is attributed to the introduction of HfC into the C/C composite. The treecoral-like HfO2 particles formed during the ablation act as thermal and oxygen diffusion barriers, protecting the composite from further ablation. Also, the oxidation of HfC and the volatilization of the ablation product (CO) absorb a large amount of heat from the composite. [New Carbon Materials 2017, 32(3): 271-276] A CARBON FIBER NETWORK/POLYPROPYLENE COMPOSITE WITH A LOW THERMAL EXPANSION COEFFICIENT AND HIGH STIFFNESS Jian-min Yuan a, Yan-rong Feng a, Zhen-jun Wu b, Yan-jun Wang a, Si-yu Li a, Ping Sun a. a College of Material Science and Engineering, Hunan University, Changsha 410082, China; b College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, China Abstract: A carbon fiber network reinforcement (CFNR) was prepared by bonding short carbon fibers with phenol formaldehyde resin followed by carbonization. The CFNR was vacuum-impregnated with molten polypropylene (PP) to produce a CFNR/PP composite with a low thermal expansion coefficient and high stiffness. The microstructure and thermal mechanical properties of the composite were characterized by scanning electron microscopy and thermal mechanical tests. Results show that CFNR is more effective in improving the stiffness and thermal dimensional stability of polymer matrix composites than short carbon fibers. The deformation rate of a conventional short carbon fiber (SCF)/PP composite is 2.3 times higher than that of the CFNR/PP composite under the same load. The decreasing order of the storage and bend moduli is CFNR/PP > SCF/PP > PP. The bend moduli of the CFNR/ PP composite at 30 and 110 C are about 1.8 and 2.5 times that of the SCF/PP composite, respectively. The average thermal expansion coefficient of the CFNR/PP composite between 30 to 120 C is 25% of that of the SCF/PP composite.
Abstract: A boron-doped diamond (BDD) thin-film electrode was prepared and used for the simultaneous detection and quantification of Cd(II), Pb (II), Cu (II) and Hg(II) ions using an anodic stripping voltammetry method. The BDD thin film was prepared by a hot filament chemical vapor deposition technique and used as the working electrode in the detection. The influence of experimental parameters, such as scanning mode, working electrode, supporting electrolyte, pH, boron concentration in the BDD electrode, accumulation potential and accumulation time were investigated. Under the optimized conditions, the stripping peak currents showed a good linear relationship with the concentrations of the four heavy metal ions from 1 to 7 ppb, and the results were very reproducible. [New Carbon Materials 2017, 32(3): 284-288] FOURIER TRANSFORM INFRARED AND DYNAMIC THERMOMECHANICAL ANALYSES OF MESOPHASE PITCH FIBERS DURING OXIDATIVE STABILIZATION Zhu-lin Sun, Li-hua Xi, Hong Li, Fan-long Zeng, Yong-gen Lu. College of Material Science and engineering, Donghua University, Shanghai 201620, China Abstract: The stress in and elongation of mesophase pitch fibers during oxidative stabilization were investigated by a dynamic thermo-mechanical analyzer under a fixed elongation and strainload, respectively. Their functional groups at different temperatures were characterized by Fourier transformed infrared spectroscopy. Results indicated that when the temperature was below 175 C, a distinct decrease in the stress in the fibers and the number of hydroxyl groups was found, accompanied by dehydrogenation reactions. When the temperature was increased above 250 C, the number of ether bonds and the stress increased, and elongation decreased due to cross-linking reactions. When the temperature was increased further, above 270 C, the fibers began to shrink because of the increase in the extent of stabilization. It was found, based on dynamic thermo-mechanical data, that the effect of gravity on the fiber cannot be neglected in designing a stabilization furnace and a vertical furnace is superior to a horizontal one.
727
[New Carbon Materials 2017, 32(3): 265-270] ABLATION BEHAVIOR OF A THREE-DIMENSIONAL C/C-HfC COMPOSITE PREPARED BY A PRECURSOR INFILTRATION AND PYROLYSIS METHOD
[New Carbon Materials 2017, 32(3): 277-283] SIMULTANEOUS DETECTION OF TRACE Cd(II), Pb (II), Cu (II), Hg(II) IONS BY A BORON-DOPED DIAMOND ELECTRODE
Liang Xue, Zhe-an Su, Xin Yang, Qi-zhong Huang. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China
Cheng-yao Gao a, b, Jian-hua Tong a, Chao Bian a, Shan-hong Xia a. a State Key Laboratory of Transducer Technology, Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China; b Chinese People's Armed Police Force Academy, Langfang 065000, China
Abstract: A three-dimensional C/C-HfC composite with a density of 1.95 g/ cm3 was fabricated by chemical vapor infiltration of carbon into a 3 D woven carbon fiber felt to a density of 1.45 g/cm3 followed by vacuum impregnation and pyrolysis of a solution containing the HfC precursor. Results indicate that HfC particles are uniformly dispersed around the pyrocarbon. The 3D C/C-HfC composite exhibits a good ablation resistance at 2573 K. The mass and linear ablation rates after ablation for 120 s are 0.001 5 g/s and 0.002 4 mm/s, respectively. The resistance to ablation is attributed to the introduction of HfC into the C/C composite. The treecoral-like HfO2 particles formed during the ablation act as thermal and oxygen diffusion barriers, protecting the composite from further ablation. Also, the oxidation of HfC and the volatilization of the ablation product (CO) absorb a large amount of heat from the composite. [New Carbon Materials 2017, 32(3): 271-276] A CARBON FIBER NETWORK/POLYPROPYLENE COMPOSITE WITH A LOW THERMAL EXPANSION COEFFICIENT AND HIGH STIFFNESS Jian-min Yuan a, Yan-rong Feng a, Zhen-jun Wu b, Yan-jun Wang a, Si-yu Li a, Ping Sun a. a College of Material Science and Engineering, Hunan University, Changsha 410082, China; b College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, China Abstract: A carbon fiber network reinforcement (CFNR) was prepared by bonding short carbon fibers with phenol formaldehyde resin followed by carbonization. The CFNR was vacuum-impregnated with molten polypropylene (PP) to produce a CFNR/PP composite with a low thermal expansion coefficient and high stiffness. The microstructure and thermal mechanical properties of the composite were characterized by scanning electron microscopy and thermal mechanical tests. Results show that CFNR is more effective in improving the stiffness and thermal dimensional stability of polymer matrix composites than short carbon fibers. The deformation rate of a conventional short carbon fiber (SCF)/PP composite is 2.3 times higher than that of the CFNR/PP composite under the same load. The decreasing order of the storage and bend moduli is CFNR/PP > SCF/PP > PP. The bend moduli of the CFNR/ PP composite at 30 and 110 C are about 1.8 and 2.5 times that of the SCF/PP composite, respectively. The average thermal expansion coefficient of the CFNR/PP composite between 30 to 120 C is 25% of that of the SCF/PP composite.
Abstract: A boron-doped diamond (BDD) thin-film electrode was prepared and used for the simultaneous detection and quantification of Cd(II), Pb (II), Cu (II) and Hg(II) ions using an anodic stripping voltammetry method. The BDD thin film was prepared by a hot filament chemical vapor deposition technique and used as the working electrode in the detection. The influence of experimental parameters, such as scanning mode, working electrode, supporting electrolyte, pH, boron concentration in the BDD electrode, accumulation potential and accumulation time were investigated. Under the optimized conditions, the stripping peak currents showed a good linear relationship with the concentrations of the four heavy metal ions from 1 to 7 ppb, and the results were very reproducible. [New Carbon Materials 2017, 32(3): 284-288] FOURIER TRANSFORM INFRARED AND DYNAMIC THERMOMECHANICAL ANALYSES OF MESOPHASE PITCH FIBERS DURING OXIDATIVE STABILIZATION Zhu-lin Sun, Li-hua Xi, Hong Li, Fan-long Zeng, Yong-gen Lu. College of Material Science and engineering, Donghua University, Shanghai 201620, China Abstract: The stress in and elongation of mesophase pitch fibers during oxidative stabilization were investigated by a dynamic thermo-mechanical analyzer under a fixed elongation and strainload, respectively. Their functional groups at different temperatures were characterized by Fourier transformed infrared spectroscopy. Results indicated that when the temperature was below 175 C, a distinct decrease in the stress in the fibers and the number of hydroxyl groups was found, accompanied by dehydrogenation reactions. When the temperature was increased above 250 C, the number of ether bonds and the stress increased, and elongation decreased due to cross-linking reactions. When the temperature was increased further, above 270 C, the fibers began to shrink because of the increase in the extent of stabilization. It was found, based on dynamic thermo-mechanical data, that the effect of gravity on the fiber cannot be neglected in designing a stabilization furnace and a vertical furnace is superior to a horizontal one.