Microwave processing of pressed boron powders for use as cathodes in vacuum arc sources

Abstract

Boron powders are sintered and densified utilizing a microwave environment for so doing.

What is claimed:  
     
         1 . A process for sintering boron comprising the steps of: 
 dry pressing powders of boron and a binder to form a disk;    baking said disk at a temperature sufficient to remove the binder therefrom; and    sintering said disk in a microwave environment utilizing microwave energy to heat said disk.    
     
     
         2 . The process according to  claim 1 , comprising prior to said step of dry pressing, mixing said boron and binders with alcohol.  
     
     
         3 . The process according to  claim 1 , wherein said microwave environment is provided from a 24 gigahertz microwave generator from a 3-kilowatt power supply.  
     
     
         4 . The process according to  claim 1  wherein the sintering atmosphere is an inert gas  
     
     
         5 . The process according to  claim 1  wherein said temperature of baking is 600° C. or lower.  
     
     
         6 . The process according to  claim 1  wherein the sintering temperature is between 2000° C. and 2070° C. for a period of 15 to 90 minutes.  
     
     
         7 . A process for providing a vacuum arc deposition of boron comprising the steps of: 
 dry pressing powders of boron and a binder to form a disk;    baking said disk at a temperature sufficient to remove the binder therefrom; and    sintering said disk in a microwave environment utilizing microwave energy to heat said disk;    cooling said disk to room temperature;    attaching said disk to a heater assembly to form a heated cathode assembly;    heating said disk to a temperature of about 700° C.;    bringing said boron disk into contact with an anode;    establishing an arc between said boron disk and said anode to produce a boron plasma.    
     
     
         8 . A sintered boron disk produced by the process of  claim 1 .  
     
     
         9 . A sintered boron object having a density of greater than 40% of theoretical density.  
     
     
         10 . A cathode disk consisting essentially of a boron having a density of greater than 40% of theoretical density.  
     
     
         11 . A process for improving the performance of a boron disk cathode, said process comprising: 
 sintering a boron disk to a density of greater than 40% of theoretical density.