Patent ID: 7776255

Claim:
A manufacturing process for producing hollow shell proppants composed of a metal or metal alloy comprising: combining non-metallic metal precursor particles and binder to form a slurry; coating a sacrificial core of a predetermined shape with the slurry, said core having a density of about 0.03 g/cm 3 to 1.5 g/cm 3 , a melting temperature of about 100° C. to 150° C., and a diameter of about 200 to 5000 microns; heating the coated core so as to completely pyrolize the core leaving a hollow shell with the predetermined shape of the pyrolized core; reducing the shell in a reducing atmosphere so as to convert the metal precursor particles into metal particles while substantially maintaining the predetermined shape of the shell; sintering the hollow shell in a reducing or inert atmosphere into a strong contiguous and impervious metal structure while substantially maintaining the predetermined shape of the shell; and quenching and annealing the metal shell so as to optimize the hardness, tensile strength and ductility.