Reticulated Open-Celled Zinc Oxide Ceramic Foams: Manufacturing, Microstructure, Mechanical, and Thermal Properties

Table 2

Properties of open-celled zinc oxide ceramic foams. The total porosity and cell porosity values refer to the geometric foam volume and the ratio V_pores/V_foam. The strut porosity is based on the strut volume and the ratio V_{strut pores}/V_struts as determined by the water immersion technique.

		ZnO, 20 ppi
Foam porosity (Vpores/Vfoam)	Total	93.6 ± 0.4%
	Cell^a	93.5 ± 0.9%
Strut porosity (Vstrut pores/Vstrut)	Total^b	32 ± 5%
	Hollow strut^b	32 ± 3%
	Strut material^c	<0.5%
Shrinkage	Linear	15.8 ± 1.1%
	Volumetric	41 ± 4%
Morphology (CT)	Strut thickness	0.38 ± 0.15 mm
	Cell size	2.69 ± 0.23 mm
Thermal conductivity	Foam	0.82 ± 0.07 W·m^−1·K^−1
	Bulk material^d	37 W·m^−1·K^−1
Compressive strength	Average strength	0.15 ± 0.03 MPa
	Weibull modulus	5.6

^aIncluding the cavities resulting from the PU template burnout. ^bRelated to the overall strut volume; V_{hollow strut}/(V_{hollow strut} + V_{strut material pores} + V_solid) and V_{strut material pores}/(V_{hollow strut} + V_{strut material pores} + V_solid). ^cRelated to the volume of the strut material excluding the cavities resulting from the PU template burnout; V_{strut material pores}/(V_{strut material pores} + V_solid). ^dExtrapolated thermal conductivity of the bulk strut material according to Ashby’s model [43].