Plasma spray powders and process for producing same

Abstract

A process is disclosed for producing plasma type spray powders. The process involves forming, an admixture of a base metal, chromium, aluminum, and yttrium or master alloy powders containing these elements, and dry milling the admixture by high shearing to produce a homogeneous mixture. A slurry of this mixture and an aqueous solution of a binder is then spray dried to produce agglomerates, the major portion of which has a particle size of from about 20 to about 53 microns. This major portion is then separated from the remainder of the agglomerates and sintered in a reducing atmosphere to remove the binder and form a sintered powder. The sintered powder is then passed through a high temperature plasma reactor to melt the powder and produce a homogeneous plasma spray powder. A plasma spray powder is disclosed which consists essentially of substantially spherical, melt solidified particles of from about 15 to about 44 microns in size, and having a weight composition of from about 14% to about 19% chromium, from about 10% to about 14% aluminum, from about 0.5% to about 1.0% yttrium and the balance a base metal selected from the group consisting of nickel, cobalt, iron and mixtures thereof.