Synthesis of open-cell metal foams by templated directed vapor deposition

Low-density, open-cell nickel base superalloy foams have been synthesized by a high-rate, electron beam-directed vapor deposition process and their mechanical properties evaluated. The deposition process uses an open-cell polymer foam template upon which is deposited a metal alloy coating. The electron beam evaporated flux was entrained in a rarefied transonic gas jet and propagated along the flow stream lines through the polymer structure. After vapor deposition, the polymer template was removed by low-temperature thermal decomposition. The resultant ultralightweight metal foams consisted of a three-dimensional open cell, reticulated structure possessing hollow triangular ligaments with relative densities of <3%. Their mechanical integrity was increased by either pressureless or transient liquid phase sintering. The mechanical properties of these ultralightweight metal foams were comparable to theoretical predictions for open-cell, reticulated foams.

Electron Beam - Directed Vapor Deposition of Multifunctional Structures

ABSTRACTMultifunctional structures are those that combine load bearing support in addition to supplemental functions such as actuation, electrochemical energy storage or thermal management. Electron beam - directed vapor deposition (EB- DVD) technology has been used for the deposition of templated cellular structures for micro heat-pipe structures and porous electrode coatings for rechargeable nickel - metal hydride cells. In addition to load bearing support, the tem- plated cellular structures exhibit enhanced thermal management characteristics and the electrochemical cells can be integrated into the load bearing supports of linear and truss based structures leading to their multifunctionality. Dur- ing EB-DVD, the electron beam evaporated vapor flux is encompassed by a rarefied transonic inert gas jet, entraining the vapor in a non-reactive gas flow and transporting it onto a polymer or metal template structure. Here, EB-DVD technology has been used to synthesize copper based templated cellular structures for thermal management systems and porous nickel coatings for the positive electrode of rechargeable nickel - metal hydride cells.