Fabrication of ultra-low density beryllium. Final report

An experimental program, directed to determining the feasibility of producing porous beryllium structures of 15% of theoretical density with nominal 1-mm-diameter pores by a technique involving the use of evaporable pore-forming filler material, is described. The experimental work carried through from the initial forming of near-spherical particles of evaporable filler materials to the evaluation of fabricated porous beryllium specimens. Naphthalene and ammonium chloride were selected and evaluated for their utility in this fabrication concept. The overall concept involves the following basic steps: (1) forming near-spherical evaporable pore-forming particles, (2) coating these particles with beryllium powder, (3) cold consolidating the composite material into a self-supporting body by isostatic pressing, (4) removing the pore-forming material by its evaporation through the finely porous beryllium network, and finally (5) sintering the beryllium to obtain a strong, ultra-low-density structure.