Sinterable semi-crystalline powder and near-fully dense article formed

Abstract

A laser-sinterable powder product has been prepared having unique properties which allow the powder to be sintered in a selective laser sintering machine to form a sintered part which is near-fully dense. For most purposes, the sintered part is indistinguishable from another part having the same dimensions made by isotropically molding the powder. In addition to being freely flowable at a temperature near its softening temperature, a useful powder is disclosed that has a two-tier distribution in which substantially no primary particles have an average diameter greater than 180 .mu.m, provided further that the number average ratio of particles smaller than 53 .mu.m is greater than 80%, the remaining larger particles being in the size range from 53 .mu.m to 180 .mu.m. A powder with slow recrystallization rates, as evidenced by non-overlapping endothermic and exothermic peaks in their differential scanning calorimetry characteristics for scan rates of on the order of 10.degree. C. to 20.degree. C. per minute, will also result in sintered parts that are near-fully dense, with minimal dimensional distortion.