Morphology, Oxidation, and Mechanical Behavior of Nanoporous Cu Foams

Nanoporous copper foams (6580% porosity) are synthesized by dealloying different copper alloys, including Cu20Zn80, Cu35Zn65, and Cu30Al70. Ligament sizes, porosity, and oxide content are examined by scanning electron microscopy, Raman spectroscopy, and X-ray powder diffraction to determine the nanoporous foam's structure and thermal stability. The pores and ligaments of the copper foams can range in size from 35 to 220?nm. Both parameters can be controlled by either the dealloying process or a subsequent heat treatment. The results show no copper oxide peaks for the as-prepared samples; however, any heat treatments above 200 degrees C lead to the formation of Cu oxide (CuO and Cu2O). These foams are shown to retain their structural integrity even after oxidation. A novel method is thus developed for synthesizing nanoporous Cu oxide foams by heat treating nanoporous copper.