Materials and methods for making ceramic matrix composites

Abstract

Ceramic matrix composites and fiber reinforced ceramic matrix composite components of brake systems and other friction tolerant composite articles of this invention are made by providing a fiber preform, coating the fibers with an interface layer of carbon or ceramic, infiltrating the coated fiber preform with a composition comprising a liquid ceramic forming polymer including friction controlling additives, and pyrolyzing the polymer in the infiltrated preform to form a ceramic matrix around the fibers of the preform.

1 . A fiber reinforced ceramic matrix composite comprising a polymer derived silicon carbide matrix, reinforcing fibers incorporated within the matrix, and an amorphous glass interface coating on the surface of the reinforcing fibers.  
   
   
       2 . Friction materials for high energy applications characterized by enhanced frictional properties and high temperature stability comprised of a structural fiber reinforced silicon carbide composite having an amorphous glass coated reinforcing fiber system disposed throughout a polymer derived silicon carbide matrix.  
   
   
       3 . The friction materials of  claim 2  wherein the silicon carbide ceramic matrix is derived from a stoichiometeric or near stoichiometeric silicon carbide polymeric precursor infused into a fiber preform by polymer infusion and pyrolyzed to for a stoichiometric or near stoichiometric silicon carbide matrix  
   
   
       4 . The friction materials of  claim 3  wherein the silicon carbide forming polymers are one or more of the following polymer compositions polycarbosilanes, hydridopolycarbosilanes, polyhydridosiloxanes, polymethylsiloxanes, polyphenylsiloxanes, and polyhydridosilanes.  
   
   
       5 . The friction materials of  claim 3  wherein the fiber has an interface coating of amorphous glass coating of about 0.01 to about 1.5 micron s in thickness.  
   
   
       6 . The friction materials according to  claim 3  wherein the fiber is selected from the group consisting of PAN based carbon fibers pitch based carbon or graphite fibers, boron doped fibers, silicon carbide fibers, silicon carbonitride fibers, silicon oxycarbide fibers, alumina fibers, and oxide based fibers.  
   
   
       7 . The friction materials of  claim 3  wherein the polymer precursor infused into the preform contains one or more friction modifying powder additives selected from the group consisting of aluminum oxide, iron, iron oxide, iron silicide, iron silicate, magnesium oxide, titanium oxide, zirconium oxide, carbon, and mixtures thereof.  
   
   
       8 . A silicon carbide precursor composition for infusion into a fiber preform comprising a silicon carbide forming polymer resin selected from the group consisting of polycarbosilanes, hydridopolycarbosilanes, polyhydridosiloxanes, polymethylsiloxanes, polyphenylsiloxanes, and polyhydridosilanes and a friction modifying powder additive selected from the group consisting of aluminum oxide, iron, iron oxide, iron silicide, iron silicate, magnesium oxide, titanium oxide, zirconium oxide, carbon, and mixtures thereof.  
   
   
       9 . A composition according to  claim 8  wherein the powder additive are of the size range from about 10 nanometers to about 100 micrometers.  
   
   
       10 . A composition according to  claim 9  wherein the powder additive are of the size range from about 0.6 micrometers to about 45 micrometers.  
   
   
       11 . A composition according to  claim 10  in which the ratio of polymer to additive is from about 25 percent to about 150 percent by mass.  
   
   
       12 . A composition according to  claim 10  in which the ratio of polymer to additive is from about 50 percent to about 95 percent by mass.  
   
   
       13 . A composition according to  claim 8  also comprising a solvent.  
   
   
       14 . A composition according to  claim 8  wherein the fiber is selected from the group consisting of PAN based carbon fibers pitch based carbon or graphite fibers, boron doped fibers, silicon carbide fibers, silicon carbonitride fibers, silicon oxycarbide fibers, alumina fibers, and oxide based fibers.  
   
   
       15 . A composition according to  claim 14  in which the fibers are provided with an interface coating.  
   
   
       16 . A composition according to  claim 15  in which the interface coating has a thickness of about 0.01 to about 1.5 microns.  
   
   
       17 . A process for making fiber reinforced silicon carbide matrix structures which comprises providing a carbon or ceramic fiber preform, applying a fiber interface coating on the surfaces of the preform fibers, infusing the preform with a silicon carbide forming resin composition, and pyrolyzing the resin to a silicon carbide matrix.  
   
   
       18 . A process according to  claim 17  in which the fiber preform is infused with a stoichiometric or near stoichiometric silicon carbide forming resin composition selected from the group consisting of polycarbosilanes, hydridopolycarbosilanes, polyhydridosiloxanes, polymethylsiloxanes, polyphenylsiloxanes, and polyhydridosilanes, a friction modifying powder additive selected from the group consisting of aluminum oxide, iron, iron oxide, iron silicide, iron silicate, magnesium oxide, titanium oxide, zirconium oxide, carbon, and mixtures thereof and optionally a solvent.  
   
   
       19 . A process according to  claim 18  in which multiple infusions each followed by pyrolysis are carried out until the open porosity of the silicon carbide matrix composite is less than 12 percent by volume.  
   
   
       20 . A process according to  claim 19  in which the final porosity is from about 4 to about 10 percent by volume.  
   
   
       21 . The process according to  claim 18  in which the preform is infused with a composition in which the ratio of polymer to powder additive is from about 50 percent to about 95 percent by mass.  
   
   
       22 . A process according to  claim 19  in which the silicon carbide matrix is formed by firing the resin at between 850° C. and about 16500° C. in an inert gas.  
   
   
       23 . A process according to  claim 22  in which the inert gas is nitrogen, argon, or helium and mixtures thereof optionally mix with up to about 5 volume percent hydrogen.