Ceramic/metal material and method for making same
An improved ceramic/metal composite material is disclosed which is fully reacted with aluminum. The composite is made from a ceramic preform, such as silicon carbide, having a binding agent, such as silica, that is contacted with a metal mixture or alloy, such as aluminum/silicon, that reacts with the binding agent to form a ceramic/metal composite material. Also disclosed is a method of making the improved composite material and articles made incorporating the material.
1. A composite material comprising at least about 50 volume percent boride or carbide, the composite material comprising a ceramic portion having alumina and an aluminum alloy made by:
a. contacting a silica-bonded boride- or carbide-based preform with a molten aluminum alloy comprising between about 18 weight percent and about 95 weight percent silicon;
b. allowing reaction between the aluminum and the silica in the preform to go substantially to completion; and
c. removing the composite material from contact with the molten metal.
2. The composite material of claim 1 , wherein the material is substantially non-reactive with aluminum.
3. The composite material of claim 1 , wherein the ceramic portion comprises silicon carbide, boron carbide, or titanium diboride, or mixtures thereof.
4. The composite material of claim 3 , wherein the ceramic portion comprises particulate silicon carbide having an average diameter of between about 5 micrometers and about 5000 micrometers.
5. The composite material of claim 1 , comprising at least 50 volume percent carbide particles.
6. The composite material of claim 5 , comprising at least 60 volume percent carbide particles.
7. The composite material of claim 1 , comprising between about 50 and 90 volume percent carbide, between about 32 and 7 volume percent aluminum oxide, and between about 18 and 3 volume percent aluminum.
8. The composite material of claim 1 , comprising an essentially continuous ceramic portion.
9. The composite material of claim 1 , comprising less than about five weight percent silica.
10. The composite material of claim 9 , comprising less than about one weight percent silica.
11. The composite material of claim 1 , wherein the density of the preform is at least about 75 volume percent.
12. The composite material of claim 11 , wherein the density of the preform is at least about 85 volume percent.
13. The composite material of claim 1 , wherein the composite material is made from a preform that is sufficiently free of interstitial cavities to promote formation of composite material without travel of reactants through interstitial cavities.
14. The composite material of claim 1 , wherein the composite material is made from a preform that is substantially totally immersed in molten aluminum alloy.
15. An article comprising the composite material of claim 1 .
16. The article of claim 15 , wherein the article is capable of contact with molten aluminum without significant reaction with the aluminum.
17. The article of claim 16 , wherein the article is selected from the group consisting of riser tubes, dies/molds, heater immersion tubes, thermocouple protection tubes, ladles, and stirring devices.
18. The article of claim 15 , wherein the article has one or more surfaces to be exposed to friction or wear.
19. The article of claim 18 , wherein the article is selected from the group consisting of bearings, nozzles, bushings, valve components, liners, brake components, clutches, engine components, and turbine components.
20. The article of claim 15 , wherein the article is an electrical conductor.
21. The article of claim 20 , wherein the article is selected from the group consisting of electric motor brushes, high temperature/hostile environment sensors, high temperature/hostile environment probes, electrodes, and current collectors.
22. The article of claim 15 , wherein the article is a thermal management device.
23. The article of claim 22 , wherein the article is selected from the group consisting of heat spreaders, heat sinks, thermal diffusers, and substrates.
24. The article of claim 15 , wherein the article absorbs and dissipates kinetic energy from high velocity projectiles.
25. The article of claim 15 , wherein the article is in substantially the same shape and size as the preform.
26. The article of claim 15 , wherein the article is selected from the group consisting of riser tubes, molds, heater immersion tubes, thermocouple protection tubes, bearings, nozzles, bushings, valve components, liners, electric motor brushes, high temperature/hostile environment sensors, high temperature/hostile environment probes, electrodes, current collectors, and armor.
27. A ceramic/metal composite material comprising a ceramic portion comprising silicon carbide and boron carbide, and an alumina-aluminum binding phase, wherein the composite material has been substantially fully reacted with aluminum, and wherein the ceramic portion is formed from a preform comprising about 50 volume percent silicon carbide, about 15 volume percent boron carbide, and about 35 volume percent silica.