Abstract: Articles produced by a powder metallurgy process involving forming of a shape by compaction followed by sintering without the application of external pressure from a stainless steel alloy powder produced by rapid atomization followed by an annealing treatment, which powder consists essentially of in weight percent, chromium 14-30, molybdenum 1 to 5, vanadium 0 to 5, tungsten 0 to 6, silicon 0 to 1.
Type:
Grant
Filed:
December 4, 1997
Date of Patent:
January 5, 1999
Assignee:
Powdrex Limited
Inventors:
John Saunders, Paul Dudfield Nurthen, Nigel Craig Trilk, Peter Ronald Brewin, John Vivian Wood
Abstract: The invention concerns making metal powder by atomizing and quenching a stream of molten metal. According to the invention an anti-foaming agent is included in the atomizing and/or the quenching liquid and this produces more rapid cooling of the metal particles.
Abstract: An atomizer for making powder of the type in which an atomizing chamber above a water bath container defines a path for a falling stream of molten metal and nozzles supply downwardly directed opposed ribbon sectioned jets of water at an angle to the vertical to impinge on the metal stream and atomize it. The atomized particles are then quenched by further water. According to this invention there are two pairs of opposed nozzles on lines mutually at right angles arranged so that the jets from the first pair intersect at a level above the level of intersection of the second pair. The jets from the first pair form the metal stream into a ribbon section in a plane containing the second pair of nozzles and the jets from the second pair atomize the stream.According to another feature the energy of the water flow of these jets is used to induce a circulating secondary flow of quench water in the atomizing zone thus eliminating the need for a purged supply of quench water.