Seamless porous metal article and method of making

A method for manufacturing a seamless, hollow, porous article having a graded pore structure comprising:

• (a) rotating a mold containing a stabilized suspension of a metal particulate having a distribution of particle sizes dispersed in a fluid medium, said mold having a coefficient of thermal expansion less than that of said metal particulate, at a first lower rate to first separate larger size particles from said suspension and distribute them over the interior wall of said mold;
• (b) rotating said mold at at least one higher rate of revolution to separate smaller size particles from said suspension and distribute them over the previously distributed larger particles, thereby forming a structure conforming to the interior wall of said mold and supernatant fluid, said mold being rotated at a rate such that at least about 100 Gs of acceleration is achieved at the interior wall of said structure;
• (c) removing said supernatant fluid and drying said structure to provide a dried structure having green or unsintered strength;
• (d) sintering the dried structure to remove volatile material and fuse the individual particles of said particulate to each other to form a seamless, hollow, porous article having a graded pore structure;
• and
• (e) removing the seamless, hollow, porous article having a graded pore structure from said mold.