Metal/ceramic composite molding material

Abstract

A composite molding compound comprising a combination of metal and ceramic powders is disclosed. The powders are combined with a binder, a liquid carrier and other processing additives in a manner to provide uniform distribution of two phases in a material format that facilitates the molding of complex parts at relatively low pressures and temperatures using conventional injection molding machines. The products formed from these molding compounds may be designed with tailored physical and mechanical properties such as thermal conductivity, thermal expansion coefficient, density, elastic modulus and wear properties.

What is claimed is:  
     
         1 . A composite molding compound comprising: 
 a) a mixture of a metal powder and a ceramic powder,    b) a gel-forming material selected from the group of polysaccharides consisting of agaroids, and    c) a gel-forming material solvent,    said mixture being formulated in a blender that provides shearing action thereto and the blender being heated to raise the temperature of the mixture to about 75 to 100° C.    
     
     
         2 . The compound of  claim 1 , wherein the temperature of the mixture is raised to between about 80 to 95° C.  
     
     
         3 . The compound of  claim 1 , further including a dispersant, a pH control substance, a biocide and a carrier.  
     
     
         4 . The compound of  claim 1 , wherein the metal/ceramic powder mixture is in the form of a slip having a particle size of between approximately 1 to 60 μm.  
     
     
         5 . The compound of  claim 1 , wherein the ceramic powder is in the form of oxides, carbides, nitrides, borides, silicides or combinations thereof, and the metal powder is in the form of ferrous and/or non-ferrous metals or metal alloys.  
     
     
         6 . The compound of  claim 1 , wherein the composite mixture of metal powder and ceramic powder form reinforcement particles or a matrix having a volume fraction in a range from about 0.1 to 99%.  
     
     
         7 . The compound of  claim 6 , wherein the volume fraction is in a range from about 15 to 75%.  
     
     
         8 . The compound of  claim 6 , wherein the volume fraction is in a range from about 15 to 40%.  
     
     
         9 . The compound of  claim 1 , further including a gel strength enhancing agent in the form of a borate compound selected from the group consisting of magnesium borate, calcium borate, zinc borate, ammonium borate and boric acid.  
     
     
         10 . The compound of  claim 1 , wherein the weight percent of solid material in the compound mixture is in the range of approximately 75 to 93 wt %.  
     
     
         11 . A process for forming an article comprising the steps of: 
 a) formulating a composite mixture of a metal powder and a ceramic powder, a gel-forming material selected from the group of polysaccharides consisting of agaroids, and a gel-forming material solvent,    said mixture being formulated in a blender that provides shearing action thereto and the blender being heated to raise the temperature of the mixture to about 75 to 100° C.;    b) supplying the mixture at a temperature above the gel point of the gel-forming material into an injection molding machine; and    c) molding the mixture under conditions of temperature and pressure to produce a self-supporting article.    
     
     
         12 . The compound of  claim 11 , wherein the temperature of the mixture is raised to between about 80 to 95° C.  
     
     
         13 . The compound of  claim 11 , further including a dispersant, a pH control substance, a biocide and a carrier.  
     
     
         14 . The compound of  claim 11 , wherein the metal/ceramic powder mixture is in the form of a slip having a particle size of between approximately 1 to 60 μm.  
     
     
         15 . The compound of  claim 11 , wherein the ceramic powder is in the form of oxides, carbides, nitrides, borides, suicides or combinations thereof, and the metal powder is in the form of ferrous and/or non-ferrous metals or metal alloys.  
     
     
         16 . The compound of  claim 11 , wherein the composite mixture of metal powder and ceramic powder form reinforcement particles or a matrix having a volume fraction in a range from about 0.1 to 99%.  
     
     
         17 . The compound of  claim 16 , wherein the volume fraction is in a range from about 15 to 75%.  
     
     
         18 . The compound of  claim 16 , wherein the volume fraction is in a range from about 15 to 40%.  
     
     
         19 . The compound of  claim 11 , further including a gel strength enhancing agent in the form of a borate compound selected from the group consisting of magnesium borate, calcium borate, zinc borate, ammonium borate and boric acid.  
     
     
         20 . The compound of  claim 11 , wherein the weight percent of solid material in the compound mixture is in the range of approximately 75 to 93 wt %.  
     
     
         21 . The process of  claim 11 , further including the step of sintering the composite molded parts at approximately 1300 to 1450° C. for about 2 to 6 hours.  
     
     
         22 . A method for producing a homogeneous composite molding compound comprising the steps of: 
 a) mixing a metal powder with water and a gel-forming material selected from the group of polysaccharides consisting of agaroids;    b) mixing a ceramic powder with water and a dispersant, and ball milling the mixture to reduce the particle size thereof;    c) compounding the metal powder mixture and the ceramic powder mixture; and    d) shredding the compound mixture into a particulate format.    
     
     
         23 . The method of  claim 22 , wherein the ceramic powder is in the form of oxides, carbides, nitrides, borides and silicides, or combinations of two or more of these materials, and the metal powder is in the form of ferrous and/or non-ferrous metals or metal alloys.  
     
     
         24 . The method of  claim 23 , wherein the composite mixture of ceramic powder and metal powder is in a range from about 0.1 to greater than 99 volume %  
     
     
         25 . The method of  claim 23 , wherein the composite mixture is in a range from about 15 to 75 volume %.  
     
     
         26 . The method of  claim 23 , wherein the composite mixture is in a range from about 15 to 40 volume %.  
     
     
         27 . The method of  claim 22 , wherein the amount of water in the composite mixture is between about 5 to 30 weight %.  
     
     
         28 . The method of  claim 22 , wherein the amount of water in the composite mixture is between about 8 to 20 weight %.  
     
     
         28 . The method of  claim 22 , wherein the temperature of the composite mixture is raised to between about 70 to 100° C. during the compounding step.  
     
     
         29 . The method of  claim 22 , wherein the temperature of the composite mixture is raised to between about 80 to 95° C. during the compounding step.  
     
     
         30 . The method of  claim 22 , wherein the compound mixture further includes a dispersant, a pH control substance, a biocide and a carrier.  
     
     
         31 . The method of  claim 22 , wherein the weight percent of solid material in the compound mixture is in the range of approximately 75 to 88 weight %.  
     
     
         32 . The method of  claim 22 , wherein the compound mixture is in the form of a slip having a particle size of between approximately 1 to 60 μm.