Patent ID: 6444009
Filing Date: 2002-09-03
Classification: B22F,B82Y

Abstract:
A two-stage method for producing ultra-fine and environmentally stable solid powders from a metal composition containing a reactive alloying element, said method comprising:(a) operating a first-stage heating and atomizing means to provide a stream of super-heated fine-sized metal liquid droplets said super-heated droplets being at a temperature which is at least one of at least two times the melting point of the metal in degrees Kelvin or at least 1000 degrees Kelvin higher than the melting point of the metal, and providing said stream into a chamber of a second-stage atomizing means, said second-stage atomizing means comprising a supply of an atomizing fluid medium being composed of at least a reactive gas and an inert gas; (b) operating said second-stage atomizing means by directing said atomizing fluid medium into said chamber to impinge upon said stream of super-heated metal liquid droplets to further break up said metal liquid droplets into ultra-fine particles and to allow said reactive gas to react with said reactive alloying element for forming a protective layer on the exterior surface of said particles; and (c) cooling said particles to form ultra-fine solid powders.