Annealing air-stable magnetic materials having superior magnetic characteristics and method

Claim 1

A PROCESS FOR INCREASING THE INTRINISIC COERCIVE FORCE OF MAGNETICALLY AIR-STABLE COBALT-RARE EARTH ALLOP PARTICLES COATED WITH A METAL HAVING A MELTING POINT ABOVE 500*C WHICH COMPRISES ANNEALING THE COATED PARTICLES IN AN INERT ATMOSPHERE OR IN A SUBSTANTIAL VACUUM OR IN A TEMPERATURE RANGING FROM ABOUT 50* TO 200*C FOR A PERIOD OF TIME RANGING FROM 30 MINUTES TO 100 HOURS, SAID ANNEALING INCREASING THE INTRINSIC COERCIVE FORCE OF SAID COATED COBALT-RARE EARTH ALLOY PARTICLES BY AT LEAST 10 PERCENT, SAID MAGNETICALLY AIR-STABLE PARTICLES HAVING BEEN PRODUCED BY PROVIDING PARTICLES OF COBALT-RARE EARTH ALLOY HAVING AN AVERAGE SIZE UP TO ABOUT 10 MICRONS, PROVVIDING 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 DECOMPOSITING IT AND PRODUCING SAID GASEOUS PRODUCT OF DECOMPOSITION AND A METAL VAPOR, CONTACTING THE RESULTING METAL VAPOR WITH THE COBALT-RARE EARTH ALLOY PARTICLES DEPOSITING A COHERENT SUBSTANTIALLY UNIFORM METAL COATING WHICH AT LEAST ENVELOPS THE PARTICLES PROVIDING AN EFFECTIVE BARRIER TO THE ATMOSPHERE AND WHICH HAS NO SIGNIFICANT DETERIORATING EFFECT ON THEIR MAGNETIC PROPERTIES AND DIFFUSING AWAY THE NON-METALLIC GASEOUS PRODUCT OF DECOMPOSITION, SAID ORGANOMETALLIC COMPOUND BEING USED IN AN AMOUNT WHICH ON DECOMPOSITION YIELDS A PARTIAL PRESSURE OF METAL VAPOR OF AT LEAST ABOUT 10-7 ATMOSPHERE AND PRODUCES THE METAL IN AN AMOUNT RANGING FROM 1 PERCENT TO 5 PERCENT BY WEIGHT OF SAID COBALTRARE EARTH ALLOY PARTICLES AND SAID DEPOSITED METAL HAVING A MELTING POINT ABOVE 500*C.