Coated air-stable cobalt-rare earth alloy particles and method

Claim 1

AN AIR-STABLE PRODUCT FOR THE MANUFACTURE OF A PERMANENT MAGNET, SAID PRODUCT BEING COMPRISED OF PARTICLES OF COBALTRARE EARTH ALLOY ENVELOPED BY A COATING IMPERVIOUS TO AIR, SAID COATING BEING SELECTED FROM THE GROUP CONSISTING OF A VAPORDEPOSITED METAL HAVING A MELTING POINT HIGHER THAN 500*C OR AN OXIDE OF SAID VAPOR-DEPOSITED METAL, SAID PRODUCT BEING PRODUCED BY A PROCESS FOR COATING A METAL HAVING A MELTING POINT ABOVE 500*C ON COBALT-RARE EARTH ALLOY PARTICLES WITHOUT SIGNIFICANTLY DETERIORATING THEIR PERMANENT MAGNET PROPERTIES PRODUCING MAGNETICALLY AIR-STABLE PARTICLES WHICH COMPRISES PROVIDING PARTICLES OF COBALT-RARE EARTH ALLOY HAVING AN AVERAGE SIZE UP TO ABOUT 10 MICRONS, PROVIDING AN ORGANOMETALLIC COMPOUND WHICH AT A TEMPERATURE BELOW 500*C DECOMPOSES AND YIELDS PRODUCTS OF DECOMPOSITION CONSISTING OF GASEOUS NON-METALLIC PRODUCT AND A METAL VAPOR, PLACING SAID COMPOUND AND SAID PARTICLES IN A SUBSTANTIALLY INERT ATMOSPHERE WHICH IS A FLOWING ATMOSPHERE OR A SUBSTANTIAL VACUUM, HEATING SAID ORGANOMETALLIC COMPOUND AT A TEMPERATURE BELOW 500*C AND SUBSTANTIALLY COMPLETELY DECOMPOSING IT AND PRODUCING SAID GASEOUS PRODUCT OF DECOMPOSITION AND A METAL VAPOR, CONTACTING THE RESULTING METAL VAPOR WITH THE COBALTRARE EARTH ALLOY PARTICLES DEPOSITING A COHERENT SUBSTANTIALLY UNIFORM METAL COATING WHICH AT LEAST ENVELOPS THE PARTICLES PROVIDING AN EFFECTIVE BARRIER TO THE ATMOSPHRE AND WHICH HAS NO SIGNIFICANT DETERIORATING EFFECT ON THEIR MAGNETIC PROPERTIES AN DIFFUSING AWAY THE NON-METALLIC GASEOUS PRODUCTS OF DECOMPOSITION, SAID ORGANOMETALLIC COMPOUND BEING USED IN AN AMOUNT WHICH ON DECOMPOSITION YIELDS A PARTIAL PRESSURE OF METAL VAPOR OFAT LAST ABOUT 10**7 ATMOSPHERE AND PRODUCES THE METAL IN AN AMOUNT RANGING FROM 1 TO 5% BY WEIGHT OF SAID COBALT-RARE EARTH ALLOY PARTICLES AND SAID DEPOSITED METAL HAVING A MELTING POINT ABOVE 500*C.