Particle reinforced noble metal matrix composite and method of making same

Abstract

The present invention relates to particle reinforced noble metal matrix composites and a method of making the same. The composites include a noble metal such as silver, gold, and alloys thereof, as a base or matrix, and a particle reinforced filler material, such as a carbide. A pressureless infrared heating, or superheating, process is used to produce the particle reinforced noble metal matrix composites thereby providing a composite with at least sufficient hardness, i.e. wear resistance, and/or low resistivity. The composites may be used in the jewelry industry, such as for making watches, rings, and other jewelry, and/or in the power, automobile, and aircraft industries, such as for making electrical contact materials.

1 . A method of making a particle reinforced noble metal matrix composite, comprising the steps of: 
 heating a noble metal and a particle material by infrared heating to a temperature above the melting point of the noble metal thereby producing a molten noble metal; and    contacting the particle material with the molten noble metal for a period of time sufficient to allow the molten noble metal to infiltrate the particle material to form a particle reinforced noble metal matrix composite.    
     
     
         2 . The method of  claim 1  wherein the noble metal is silver, gold, or alloys thereof and the particle material includes a carbide.  
     
     
         3 . The method of  claim 2  wherein the carbide includes either molybdenum carbide or tungsten carbide.  
     
     
         4 . The method of  claim 1  wherein the heating step includes heating the noble  5 metal and the particle material by infrared heating at a rate not greater than about 100° C. per second to the temperature above the melting point of the noble metal.  
     
     
         5 . The method of  claim 1  wherein the heating step includes heating the noble metal and the particle material by infrared heating at a wavelength of about 0.6 μm to 10 μm.  
     
     
         6 . The method of  claim 1  wherein the contacting step includes contacting the particle material with the molten noble metal at the temperature above the melting point of the noble metal for about 60 seconds to about 600 seconds to allow the molten noble metal to infiltrate the particle material.  
     
     
         7 . The method of  claim 1  wherein the contacting step is performed in an inert atmosphere and at no greater than a pressure of about 1 atm.  
     
     
         8 . A method of making a particle reinforced noble metal matrix composite, comprising the steps of: 
 heating a noble metal selected from the group consisting of silver, gold, and alloys thereof and either tungsten carbide or molybdenum carbide by infrared heating to a temperature above the melting point of the noble metal thereby producing a molten noble metal;    contacting the tungsten carbide or molybdenum carbide with the molten noble metal for a period of time sufficient to allow the molten noble metal to infiltrate the carbide material to form a particle reinforced noble metal matrix composite; and    cooling the particle reinforced noble metal matrix to about room temperature.    
     
     
         9 . The method of  claim 9  wherein the heating step includes heating the noble metal and the carbide material by infrared heating at a rate not greater than about 100° C. per second to a temperature of about 1200° C. to 1300° C.  
     
     
         10 . The method of  claim 9  wherein the heating step includes heating the noble metal and the particle material by infrared heating at a wavelength of about 0.6 μm to 10 μm.  
     
     
         11 . The method of  claim 9  wherein the contacting step is performed in an inert atmosphere and at no greater than a pressure of about 1 atm.  
     
     
         12 . The method of  claim 9  wherein the contacting step includes contacting the carbide material with the molten noble metal at the temperature above the melting point of the noble metal for about 200 to 300 seconds to allow the molten noble metal to infiltrate the carbide material.  
     
     
         13 . The method of  claim 9  wherein the step of cooling the particle reinforced noble metal matrix composite to about room temperature includes cooling at a rate of no less than about 20° C. per second to about room temperature.  
     
     
         14 . A particle reinforced noble metal matrix composite, comprising: 
 a noble metal and a particle material, wherein the particle reinforced noble metal matrix composite includes a noble metal content of at least about 56% by weight and a Vickers hardness of at least about 171.    
     
     
         15 . The particle reinforced noble metal matrix composite of  claim 14  wherein the noble metal is silver, gold, or alloys thereof and the particle material includes a carbide.  
     
     
         16 . The particle reinforced noble metal matrix composite of  claim 15  wherein the carbide includes tungsten carbide or molybdenum carbide.  
     
     
         17 . The particle reinforced noble metal matrix composite of  claim 14  wherein the noble metal is silver and the particle material includes a carbide, and wherein the particle reinforced noble metal matrix composite includes a Vickers hardness of at least 251.  
     
     
         18 . The particle reinforced noble metal matrix composite of  claim 14  wherein the noble metal is gold or an alloy thereof and the particle material includes a carbide, and wherein the particle reinforced noble metal matrix composite includes a Vickers hardness of at least about 216.  
     
     
         19 . The particle reinforced noble metal matrix composite of claim wherein a density value of the particle reinforced noble metal matrix composite is at least about 97% of a theoretical density value.  
     
     
         20 . A particle reinforced noble metal matrix composite, comprising: 
 a noble metal and a particle material, wherein the particle reinforced noble metal matrix composite includes a noble metal content of at least 56% by weight and a resistivity of no greater than about 1.3E-04 ohm centimeters.    
     
     
         21 . The particle reinforced noble metal matrix composite of  claim 20  wherein the noble metal is silver, gold, or alloys thereof and the particle material includes a carbide.  
     
     
         22 . The particle reinforced noble metal matrix composite of  claim 21  wherein the carbide includes tungsten carbide or molybdenum carbide.  
     
     
         23 . The particle reinforced noble metal matrix composite of  claim 20  wherein the noble metal is a silver alloy and the particle material includes a carbide, and wherein the particle reinforced noble metal matrix composite includes a resistivity of no greater than about 4.9E-06 ohm centimeters.  
     
     
         24 . The particle reinforced noble metal matrix composite of  claim 20  wherein the noble metal is gold or an alloy thereof and the particle material includes tungsten carbide, and wherein the particle reinforced noble metal matrix composite includes a resistivity of no greater than about 8.4E-05 ohm centimeters.  
     
     
         25 . The particle reinforced noble metal matrix composite of  claim 20  wherein a density value of the particle reinforced noble metal matrix composite is at least about 97% of a theoretical density value.  
     
     
         26 . A particle reinforced noble metal matrix composite, comprising: 
 a particle material; and    a noble metal selected from the group consisting of gold, silver, platinum, and alloys thereof wherein the particle reinforced noble metal matrix composite includes a noble metal content of at least about 56% by weight.    
     
     
         27 . The particle reinforced noble metal matrix composite of  claim 26  wherein the particle material includes a carbide.  
     
     
         28 . The particle reinforced noble metal matrix composite of  claim 27  wherein the carbide includes tungsten carbide or molybdenum carbide.