Application of microcapsulation technology to the preparation of carbon foam

Figures & data

Figure 1 (a) Digital photograph of microcapsule. (b) SEM image of microcapsule.

Figure 2 (a) SEM image of hollow phenolic resin sphere with pore with overturned cover at high temperature and high heating rate. (b) SEM image of hollow pored phenolic resin sphere at moderately high temperature and relatively high heating rate. (c) SEM image of hollow phenolic resin sphere with closed shell at reasonably high temperature and low heating rate. (d) SEM image of broken hollow phenolic resin with thick wall.

Figure 3 (a) SEM image of carbon sphere with oxidized and rough surface due to impure N₂ or slight leakage of air in furnace. (b) SEM image of carbon sphere with poor shape at low heating and high cooling rates. (c) SEM image of carbon sphere with cracks on its surface at high heating rate. (d) SEM image of carbon sphere with perfect morphology by slow heating and cooling.

Figure 4 SEM image of carbon foams.

Figure 5 TG curves before and after graphitization.

Figure 6 XRD diagrams of carbon foam treated at different temperatures.

Thermal properties of C/C composite and carbon foams of different densities at various temperatures.

	Temperature	Carbon foam 1	Carbon foam 2	C/C composite
	(°C)	(ρ=0.45 g cm^−3)	(ρ=0.73 g cm^−3)	(ρ=1.75 g cm^−3)
Cp	20	0.856	0.813	0.631
	200	1.321	1.145	1.031
	400	1.784	1.572	1.354
	600	2.059	1.827	1.463
	800	2.217	1.939	1.558
a	20	0.0371	0.0438	0.133
	200	0.0293	0.0396	0.102
	400	0.0260	0.0356	0.084
	600	0.0260	0.0349	0.076
	800	0.0260	0.0337	0.078
λ	20	2.358	3.54	14.56
	200	2.873	4.51	18.27
	400	3.445	5.56	19.75
	600	3.975	6.34	19.42
	800	4.281	6.49	21.28

Cp, specific heat capacity (10³ J kg⁻¹ K⁻¹); a, thermal diffusivity (cm² s⁻¹); λ, conductivity (w m⁻¹ K⁻¹).