Abstract: A method for enabling cold spray of steels, particularly transformation hardenable steels including tool steels, has been made possible by: heat treating steel powder while agitating the powder to limit agglomeration and particle growth; cooling it slowly enough to avoid retransformation hardening; and protecting the powder from cold working or retransformation hardening until cold sprayed. Surprisingly the softening, as well as the agglomerated morphology of powders, has been found to allow for deposition of steel powders. Furthermore, the cooling has been found to be possible within 8 hour heat treatments, and high density, and reasonably high deposition efficiencies have been achieved. Water- and gas-atomized starting powders have been treated and cold sprayed.

Abstract: A method of lubricating the wall surfaces of a die cavity used in powder metallurgy involves spraying the wall surfaces with tribocharged particles of a lubricant material. The method is carried out by means of an apparatus centered about a plug member which has a three-dimensional shape conforming generally to that of the article to be formed. The plug member is slightly smaller than the article so that when the plug member is inserted into the die cavity there is a small, but uniform, gap created between the outer wall surfaces of the plug member and the walls of the die cavity. The plug member is secured to a closing plate which can be inserted into the die cavity so as to be sealed therewith. The closing plate is provided with vent holes and the plug member has a plurality of spaced apart tubes extending therethrough, which tubes exit at one or more of the wall surfaces of the plug member.

Abstract: Complex-shaped parts can be produced from powders, for example metal-matrix composites, by injection molding using a mixture of the powders with a suitable binder. The binder must be removed from the powder mixture before the final thermal treatment of the so-called green part. The present invention proposes to remove the binder by surrounding a cast part with a layer of a particulate material and to subject the cast part to isostatic pressure through the surrounding layer which can thus act as an absorbent. The surrounding layer is removed after the isostatic pressing and the part can be subjected to sintering. The method is suitable for example for aluminum-ceramic powder mixtures.