Tailoring of Pore Structure of Coal-based Carbon Foam

doi:10.15541/jim20150628

Abstract

Abstract:

Vitrinite-concentration of fat coal was used as precursor to prepare carbon foams by nitrizing under high pressure. Influences of foaming temperature, pressure and time on the pore structure of carbon foams were investigated, whose prarameters include bulk density, porosity, morphology, pore cell average diameter, and the distribution of pore cell diameter and pore throats. The morphology of pore cell was observed by SEM. The distributions of pore cell diameters and pore throats as well as the mean diameter were calculated using analytical software of Nano Measurer 1.2. Results show that the nucleation of microcellular thermoplastic foam can qualitatively reveal the variable trend of pore cell structure of carbon foams. Rising of the foaming temperature results in nucleation volume density enhancement. Meanwhile, the rising temperature reduces the gas solubility in plastic mass, which is not conducive to the cell growth. Increasing foaming pressure leads to pore cell density enhancement, whereas the critical nucleation radius decrease. In addition, the increased foaming pressure exacerbates thermal polymerization reaction, increasing viscosity of the plastic mass, which is not conducive to the growth of pore cell. Extending foaming time enables thermal polymerization more sufficiently, which influences the viscosity of the plastic mass and further affects the pore structure.

Key words: carbon foam, pore structure, nucleation theory, coal

CLC Number:

TQ383

XU Guo-Zhong, JIN Wen-Wu, ZENG Xie-Rong, ZOU Ji-Zhao, XIONG Xin-Bai, HUANG Lin, ZHAO Zhen-Ning. Tailoring of Pore Structure of Coal-based Carbon Foam[J]. Journal of Inorganic Materials, 2016, 31(9): 961-968.

Figures/Tables 16

Table 1 Proximate analysis and ultimate analysis of the fat coal and its vitrinite-concentration

precursors	Proximate analysis /wt%			Ultimate anasysis/wt%
precursors	M_ad	A_d	V_daf	C	H	O	N	S
Fat coal	1.6	8.52	38.29	88.16	4.92	4.84	1.46	0.62
Vitrinite	1.7	3.50	43.80	86.45	5.73	5.65	1.53	0.64

Fig. 1 TG and DTG curves of the precursor

Fig. 2 Correlation between LNF and temperature

Fig. 3 Schematic diagram of the oxperimental set-up

Fig. 4 Effect of the stamping pressure on the bulk density and porosity of carbon foams

Fig. 5 Effect of stamping pressure on the pore cell morphology of carbon foams (a) 2 MPa; (b) 6 MPa; (c) 10 MPa; (d) 14 MPa

Fig. 6 Influence of stamping pressure on pore cell diameter distribution (a), pore throat distribution (b) and mean cell diameter (c)

Fig. 7 Effect of foaming temperature on the bulk density and porosity of carbon foams

Fig. 8 Influence of foaming temperature on the pore cell morphology of carbon foams(a) 393℃; (b) 413℃; (c) 433℃; (d) 453℃; (e) 473℃

Fig. 9 Influence of foaming temperature on pore cell diameter distribution (a), pore throat distribution (b) and mean cell diameter (c) of carbon foams

Fig. 10 Effect of foaming pressure on the bulk density and porosity of carbon foams

Fig. 11 Effect of foaming pressure on pore cell morphology of carbon foams(a) 0 MPa; (b) 2 MPa; (c) 4 MPa; (d) 6 MPa; (e) 8 MPa

Fig. 12 Effect of foaming pressure on pore cell diameter distribution (a), pore throat distribution diameter (b) and mean cell diameter (c) of carbon foams

Fig. 13 Effect of foaming time on the bulk density and porosity of carbon foams

Fig. 14 Influence of the foaming time on cell morphology of carbon foams(a) 0.5 h; (b) 1 h; (c) 2 h; (a) 2.5 h

Fig. 15 Effect of foaming time on pore cell diameter distribution (a), pore throat distribution (b) and mean cell diameter (c) of carbon foams

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