carbon composites

CARBON

4 7 ( 20 0 9 ) 2 1 4 3–21 4 6

2145

Effect of different oxide additives on the properties of a SiC

microscopy, N2 adsorption, thermal gravimetric, and aqueous

coating on carbon/carbon composites

adsorption. Results showed that PACS with BET surface areas

Xiao-Hong Shi, He-Jun Li, Qian-Gang Fu, Jin-Hua Lu, Ke-Zhi Li

up to 979–1672 m2/g were obtained. The BET surface areas and

C/C Composites Research Center, Key Laboratory of Ultrahigh Composites, Northwestern Polytechnical University, Xi’an 710072, China

pore volumes increased with activation time and steam flow rate except for the volume of narrow micropores (<0.7 nm). The maximum adsorption capacity of PACS to DBT was 109.36 mg/g and

Double-layer SiC-based coatings on carbon/carbon composites

the adsorption capacity was related to the volume of narrow

were prepared by a wrapping cementation method with different

micropores, independent of surface area and total pore volume.

oxides (MgO, Al2O3 or B2O3) as additives to the inner layer. The

Irreversible adsorption existed between DBT and PACS. The larger

phase morphologies and antioxidation properties of the SiC

the volume of the narrow micropores, the higher the desorption

coated carbon/carbon composites were investigated by SEM,

temperature and the larger the amount of sulfur retained after

EDS and XRD. Results show that the SiC coating with B2O3 as an

heating.

additive to the inner layer is more compact than those with

[New Carbon Materials 2009;24(1):55–60]

MgO or Al2O3 as the additive. Different phases exist in the three

doi:10.1016/j.carbon.2009.03.018

different inner layer SiC coatings. The double-layer SiC coating modified by B2O3 is dense and uniform with few flaws and holes, and can protect carbon/carbon composites from oxidation at 1500 °C for 200 h in air.

Bubble growth in the preparation of mesophase-pitch-based

[New Carbon Materials 2009;24(1):45–9]

carbon foams

doi:10.1016/j.carbon.2009.03.016

Mei-Xian Wanga, Cheng-Yang Wanga, Ming-Ming Chena, Tong-Qi Lia, Zi-Jun Hua,b a

Key Laboratory for Green Chemical Technology of State Education

A eutectic effect in the formation of coal based mesophase pitch

Ministry, School of Chemical Engineering and Technology, Tianjin

Xiang-Lin Cheng, Qing-Fang Zha, Xue-Jun Li, Xiao-Jun Yang

University, Tianjin 300072, China

State Key Laboratory of Heavy Oil, China University of Petroleum,

Aerospace Research Institute of Materials and Processing Technology,

Dongying 257061, China

Beijing 100076, China

The toluene soluble part of coal tar pitch (TS) was co-carbonized with waste polystyrene (WPS) to produce mesophase pitch. Results showed that the properties of the mesophase were improved greatly due to the eutectic effect. The solubilities of the TS mesophase pitch and TS-WPS mesophase pitch were 10 and 52 wt.%, respectively. The anisotropic volume fractions of the TS mesophase pitch and TS-WPS mesophase pitch were 65% (coarse mosaic texture) and 100% (flow domain texture) respectively. Apparent viscosities showed that the mesophase pitch was changed from thixotropic to unthixotropic by adding 1

WPS to TS. FT-IR and H NMR spectroscopy showed that an alkylation reaction took place accompanied by an increase of methylene groups when WPS was added to TS. The increase of alkyl groups led to an assembly of mesogen molecules, resulting in a eutectic effect. [New Carbon Materials 2009;24(1):50–4] doi:10.1016/j.carbon.2009.03.017

Preparation of polystyrene-based activated carbon spheres and their adsorption of dibenzothiophene Qin Wang, Xiao-Yi Liang, Rui Zhang, Chao-Jun Liu, Xiao-Jun Liu, Wen-Ming Qiao, Liang Zhan, Li-Cheng Ling State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China

b

National Key Laboratory of Advanced Functional Composite Materials,

A synthetic mesophase pitch from naphthalene was used as a precursor to prepare carbon foams under different temperatures in order to study the bubble growth process and the effect of temperature on the bubble shape during the formation of carbon foams. Scanning electron microscopy and optical microscopy were used to analyze the microstructure of the as-prepared foams. Results show that the bubble size increases from 500 lm to 800 lm when the temperature increases from 480 °C to 540 °C. The initial bubbles are not uniformly dispersed in the molten pitch, but start to grow at the upper section of the pitch. The cross-section bubble shape in the direction of the gravitational force is elliptical but perpendicular to the direction it is circular. The non-spherical shape of the bubble is closely related to the bulk density of the mesophase-pitch based carbon foams, and there is a bulk density gradient in the Z direction of the as-prepared foam. [New Carbon Materials 2009;24(1):61–6] doi:10.1016/j.carbon.2009.03.019

The gelation mechanism of carbon aerogel spheres Ning Liua,b, Ming-Yuan Lia, Ruo-Wen Fua a

Materials Science Institute, PCFM Lab, Zhongshan (Sun Yat-sen)

University, Guangzhou 510275, China b

College of Pharmacy, GuangDong Pharmaceutical University, Guangz-

hou 510006, China

Polystyrene-based activated carbon spheres (PACS) were prepared by steam activation and their adsorption performance to

Carbon aerogel (CA) spheres were prepared by an inverse

a sulfur-containing dibenzothiophene (DBT) was studied. The

phase suspension polymerization of resorcinol and formaldehyde

textural structure of PACS was characterized by scanning electron

(RF) monomers with hexadecyltrimethylammonium bromide as