Diamond/silver composites

Abstract

A process for preparing a diamond particle/silver metal matrix composite ucture by coating diamond particles with molten silver nitrate, decomposing the silver nitrate to form a silver metal coating on the surfaces of the diamond particles, consolidating the silver metal coated diamond particles into a composite structure having continuous pores between the silver metal coated diamond particles, infiltrating the continuous pores of the composite with molten silver nitrate and decomposing the silver nitrate to form silver metal which fills the continuous pores of the composite structure.

What is claimed is: 
     
       1. A process for preparing a diamond particle/silver metal matrix composite material object comprising: A. coating the surfaces of diamond powder particles with molten silver nitrate at a temperature of from just above the melting point of silver nitrate to just below the decomposition temperature of silver nitrate;   B. heating the molten silver nitrate coated diamond particles produced in step A at a temperature from the decomposition temperature of silver nitrate up to 550° C. until the molten silver nitrate decomposes to form a coating of silver metal on the surfaces of the diamond particles;   C. consolidating the silver metal coated particles produced in step B into a composite structure having continuous pores between the silver coated diamond particles;   D. infiltrating the continuous pores of the composite structure produced in step C with molten silver nitrate at a temperature of from just above the melting point of silver nitrate to just below the decomposition temperature of silver nitrate;   E. heating composite structure at a temperature of from the decomposition temperature of silver nitrate to 550° C. until the molten silver nitrate in the pores of the composite structure decomposes to silver metal; and   F. repeating steps D and E until the pores of the composite structure are essentially filled with silver metal.   
     
     
       2. The process of claim 1 wherein in step A the surfaces of the diamond particles are coated with molten silver nitrate by (1) intimately mixing the diamond powder with silver nitrate powder;   (2) heating the diamond/silver nitrate powder mixture at a temperature of from just above the melting point of silver nitrate to just below the decomposition temperature of silver nitrate until the silver nitrate melts, and   (3) agitating the diamond powder/molten silver nitrate mixture until the molten silver nitrate coats all the diamond particles.   
     
     
       3. The process of claim 1 wherein in step A the surfaces of the diamond particles are coated with molten silver nitrate by (1) mixing the diamond powder with a saturated solution of silver nitrate in a solvent that is water or ethylene glycol,   (2) removing the solvent to form small crystals of silver nitrate on the surfaces of the diamond particles; and   (3) heating the silver nitrate coated diamond particles to a temperature of from just above the melting point of silver nitrate to just below the decomposition temperature of silver nitrate until the silver nitrate melts to form the coating of molten silver nitrate on the surfaces of the diamond particles.   
     
     
       4. The process of claim 1 wherein in step B the molten silver nitrate coated particles are heated at a temperature of from 450° C. to 525° C. until the molten silver nitrate decomposes to form a coating of silver metal on the surfaces of the diamond particles. 
     
     
       5. The process of claim 4 wherein in step B the molten silver nitrate coated particles are heated at a temperature of from 475° C. to 500° C. until the molten silver nitrate decomposes to form a coating of silver metal on the surfaces of the diamond particles. 
     
     
       6. The process of claim 1 wherein in step E the composite structure is heated at a temperature of from 450° C. to 525° C. until the molten silver nitrate in the pores of the composite structure decompose to silver metal. 
     
     
       7. The process of claim 6 wherein in step E the composite structure is heated at a temperature of from 475° C. to 500° C. until the molten silver nitrate in the pores of the composite structure decompose to silver metal. 
     
     
       8. The process of claim 1 wherein the amount of silver nitrate and the amount of diamond powder are selected in step A to produce in step B silver metal coated diamond particles comprising from about 10 to about 60 weight percent silver metal with the remainder being diamond. 
     
     
       9. The process of claim 8 wherein the amount of silver nitrate and the amount of diamond powder are selected in step A to produce in step B silver metal coated diamond particles comprising from 15 to 50 weight percent of silver metal with the remainder being diamond. 
     
     
       10. The process of claim 9 wherein the amount of silver nitrate and the amount of diamond powder are selected in step A to produce in step B silver metal coated diamond particles comprising from 20 to 40 weight percent of silver metal with the remainder being diamond.