Systems and methods for forming a layer onto a surface of a solid substrate and products formed thereby
A method for forming a vehicular brake rotor involving loading a shaped metal substrate with a mixture of metal alloying components and ceramic particles in a dieheating the contents of the die while applying pressure to melt at least one of the metal components of the alloying mixture whereby to densify the contents of the die and form a ceramic particle-containing metal matrix composite coating on the metallic substrate; and cooling the resulting coated product.
1. A method for-forming a metal/ceramic composite coating friction surface layer bonded to a solid metal or metal alloy substrate in the form of a hub-disc assembly, the method comprising:
loading a mixture of a ceramic particulate and two or more reactive metals in powder form, on a surface of a solid metal or alloy substrate, contained within a mold, wherein at least one of the reactive metals has a melting point lower than a melting point of the solid metal or alloy substrate, and the ceramic particulate comprises silicon carbide particles;
closing the mold, evacuating air from the mold, and raising a temperature within the mold while raising a pressure within the mold, so as to at least partially melt a reactive metal of the mixture in the mold;
enabling a reaction involving the reactive metals while maintaining a pressure within the mold whereby to densify contents of the mold during at least a portion of the reaction; and
cooling the contents of the mold to form a metal/ceramic composite coating friction surface layer on the substrate without any intervening layer between the substrate and the coating, whereby to increase friction and enhance wear resistance of the surface of the metal substrate.
2. The method of claim 1 , wherein the volume of the mixture including the ceramic particulate and the two or more reactive metals in powder form is less than the volume of the substrate in the mold.
3. The method of claim 1 wherein the substrate has a melting temperature that corresponds to a melting point of a metal selected from the group consisting of aluminum, cobalt, copper, iron, nickel, titanium, vanadium, zinc, and an aluminum alloy containing one or more elements selected from the group consisting of cobalt, copper, iron, nickel, titanium, vanadium, zinc, chromium, magnesium, manganese, niobium, and silicon.
4. The method of claim 1 wherein the reaction does not produce products in a gas phase.
5. The method of claim 1 wherein the reaction involves an exothermic reaction of two or more metals selected from the group consisting of aluminum, boron, cobalt, copper, iron, nickel, palladium, titanium, vanadium, zinc, chromium, magnesium, manganese, niobium, and silicon.
6. The method of claim 1 wherein the mixture comprises aluminum alloy particles and silicon carbide particles.
7. The method of claim 1 wherein:
a. the substrate comprises a metal or alloy selected from the group consisting of aluminum an aluminum alloy, titanium, a titanium alloy, and an iron/steel alloy; and
b. the mixture comprises silicon carbide particles, and an alloy selected from the group consisting of an alloy of aluminum and silicon, an alloy of aluminum, silicon, and magnesium, an alloy of aluminum and titanium, and an alloy of aluminum, silicon and titanium, or a prealloyed powder selected from Ti—Al and Ti—Al—Cr—Nb.
8. The method of claim 1 wherein the ceramic particulate comprises from 25% to 65% of an exterior surface of the coated substrate.
9. The method of claim 1 wherein a porosity of an exterior surface of the coated substrate is less than 2% by volume.
10. The method of claim 1 wherein an exterior surface of the coated substrate has a porosity of less than 2% by volume.
11. The method of claim 1 wherein the reaction is enabled under less than ambient atmospheric pressure.
12. The method of claim 1 wherein the substrate comprises a huh-disc assembly.
13. The method of claim 1 wherein the mold comprises a vented assembly.
14. The method of claim 1 wherein the ceramic particulate comprises at least 35% of an exterior surface of the coated substrate.
15. The method of claim 1 wherein a porosity of an exterior surface of the coated substrate is less than 1% by volume.
16. The method of claim 1 wherein a porosity of an exterior surface of the coated substrate is less than 0.25% by volume.
17. The method of claim 1 , wherein the mixture of ceramic particulate and two or more reactive metals in powder form are loaded on two surfaces of the substrate whereupon metal/ceramic composite coating friction surface layers are formed on two surfaces of the substrate.