Determination of the structure parameters and characters of foamed metals

The structure parameters and characters of foamed nickel, copper and silver were determined by means of SEM, X-ray diffraction and image analysis etc. The results indicate that the foamed metals have the structure of dodecahedron with pentagon casement outspreading toward space. The framework itself is tube shape channel, which is caverned and non-entirely sealed. The whole framework is a maze structure connected by this kind of channels. Folds and hollows besprinkle the surface of foamed nickel skeleton. Lump shape preiections besprinkle the surface of foamed copper skeleton and plenty of particles besprinkle the surface of foamed silver skeleton. The X-ray diffraction results show that the three foamed metals are all face-centered cubic lattice structure. The pore diameter distributions are determined by equal area circle method. And the average apertures of foamed nickel, copper and silver are 0.245, 0.238 and 0.245 mm respectively. The method of measuring the thickness dispersing ratio by image analysis was established, and the obtained TDR of the three foamed metals were 1.18, 1.12 and 1.13 respectively. The special surface areas of the three foamed metals were measured by BET method and liquid pressure drop method separately. The special surface areas of foamed nickel, copper and silver are 1.35 × 106, 2.85 × 106 and 1.85 × 106 m-1 respectively from BET method, and by liquid pressure drop method the results were 4.42 × 105, 4.98 × 105 and 3.99 × 105 m-1 respectively. The hot strengths of the three foamed metals were determined by using maximum load method and the results were 1.39, 3.98 and 0.98 N/mm2 respectively. The electrical resistivities, void ratios, surface densities of foamed nickel, copper and silver were also measured.