Reactive sintering to eliminate metal inserts in carbon-carbon brake discs

Abstract

A brake disc rotor or stator is manufactured with slots in the interior face of the disc. A paste comprised of a fine powder of a carbide-forming metal along with fine carbon powder, suspended in an organic binder, is applied to the force-bearing areas in the rotor slot faces or the stator slot faces. The disc is then placed into a furnace in a nitrogen atmosphere and heated to the ignition temperature. When the furnace reaches the ignition temperature, a combustion reaction begins that creates a molten liquid ceramic material on the slot face. Upon cooling, the resulting brake disc has a tough, hard, abrasion-resistant ceramic surface on the portion of the brake disc slot that bears pressure.

1 . A method of manufacturing a slotted brake disc rotor or stator that has a tough, hard, abrasion-resistant ceramic surface on the portion of the brake disc slot that bears pressure, which method comprises:
 i.) providing a carbon-carbon composite brake disc rotor or stator having slot slots in the interior face of said brake disc;   ii.) applying a paste, comprised of a fine powder of titanium, zirconium, hafnium, and/or vanadium along with fine carbon powder suspended in an organic binder, to the areas where force will be applied to the rotor or stator slot faces;   iii.) placing the disc into a furnace having a nitrogen-containing atmosphere, and heating the disc to the ignition temperature; and   iv.) cooling the brake disc to ambient temperature.   
   
   
       2 . The method of  claim 1 , wherein the metal powder is titanium powder. 
   
   
       3 . The method of  claim 1 , wherein the average diameter of the titanium powder particles ranges from 25 to 250 microns. 
   
   
       4 . The method of  claim 3 , wherein the average diameter of the titanium powder particles is about 45 microns. 
   
   
       5 . The method of  claim 1 , wherein the carbon powder is powdered graphite and the average diameter of the graphite particles ranges from 1 to 10 microns. 
   
   
       6 . The method of  claim 5 , wherein the average diameter of the graphite particles is about 2 microns. 
   
   
       7 . The method of  claim 1 , wherein the mole ratio of metal powder to carbon powder ranges from 3:1 to 0.5:1. 
   
   
       8 . The method of  claim 1 , wherein the binder is a phenolic binder, an epoxy binder, or an alginate binder. 
   
   
       9 . The method of  claim 1 , wherein the paste is applied in a thickness ranging from 30 microns to ¼ inch. 
   
   
       10 . The method of  claim 9 , wherein the paste is a layer of titanium powder and carbon powder about 1/16 inch in thickness. 
   
   
       11 . The method of  claim 1 , wherein the furnace in step iii.) is provided with an atmosphere containing nitrogen at a pressure ranging from 0.2 to 20 atmospheres. 
   
   
       12 . The method of  claim 11 , wherein said nitrogen-containing atmosphere is air. 
   
   
       13 . The method of  claim 11 , wherein said nitrogen-containing atmosphere is pure nitrogen gas. 
   
   
       14 . The method of  claim 11 , wherein heating step iii.) is conducted at a temperature of from 400-600° C. 
   
   
       15 . A brake disc rotor or stator that has a tough, hard, abrasion-resistant ceramic surface on the portion of the brake disc slot that bears pressure, manufactured by the method of  claim 1 .