Effect of different oxide additives on the properties of a SiC

coating on carbon/carbon composites

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

C/C Composites Research Center, Key Laboratory of Ultrahigh Compos-

ites, Northwestern Polytechnical University, Xi’an 710072, China

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

were prepared by a wrapping cementation method with different

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

phase morphologies and antioxidation properties of the SiC

coated carbon/carbon composites were investigated by SEM,

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

additive to the inner layer is more compact than those with

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

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.

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

doi:10.1016/j.carbon.2009.03.016

A eutectic effect in the formation of coal based mesophase pitch

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

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

Dongying 257061, China

The toluene soluble part of coal tar pitch (TS) was co-carbon-

ized 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

WPS to TS. FT-IR and 1H NMR spectroscopy showed that an alkyl-

ation reaction took place accompanied by an increase of methy-

lene 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

Polystyrene-based activated carbon spheres (PACS) were pre-

pared by steam activation and their adsorption performance to

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

textural structure of PACS was characterized by scanning electron

microscopy, N2 adsorption, thermal gravimetric, and aqueous

adsorption. Results showed that PACS with BET surface areas

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

pore volumes increased with activation time and steam flow rate

except for the volume of narrow micropores (<0.7 nm). The max-

imum adsorption capacity of PACS to DBT was 109.36 mg/g and

the adsorption capacity was related to the volume of narrow

micropores, independent of surface area and total pore volume.

Irreversible adsorption existed between DBT and PACS. The larger

the volume of the narrow micropores, the higher the desorption

temperature and the larger the amount of sulfur retained after

heating.

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

doi:10.1016/j.carbon.2009.03.018

Bubble growth in the preparation of mesophase-pitch-based

carbon foams

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

Ministry, School of Chemical Engineering and Technology, Tianjin

University, Tianjin 300072, Chinab National Key Laboratory of Advanced Functional Composite Materials,

Aerospace Research Institute of Materials and Processing Technology,

Beijing 100076, China

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 tem-

perature 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 mol-

ten 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-pre-

pared 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, Chinab College of Pharmacy, GuangDong Pharmaceutical University, Guangz-

hou 510006, China

Carbon aerogel (CA) spheres were prepared by an inverse

phase suspension polymerization of resorcinol and formaldehyde

(RF) monomers with hexadecyltrimethylammonium bromide as

C A R B O N 4 7 ( 2 0 0 9 ) 2 1 4 3 – 2 1 4 6 2145