Formulations for engineered ceramic matrix composites for high temperature applications
An engineered ceramic matrix is provided to blunt and self-heal matrix cracks to reduce oxygen ingress into a fiber reinforced composite.
1. A process for fabricating engineered ceramic matrix composites (E-CMCs) for high temperature applications, comprising:
combining and attrition milling a mixture of silicon carbide (SiC), silicon nitride, and a component selected from the group consisting of CrMoSi, CrMoSiGe, and CrMoSiY;
wet attrition milling the mixture using ethanol and silicon carbide grinding media, grinding the mixture into particles and homogenously mixing the mixture;
slurry preparing the mixture to generate an engineered CMC slurry;
infiltrating a preform with the engineered CMC slurry either under gravity, vacuum, or high pressure to allow particulates to spread uniformly within cavities of the preform; and
melt infiltrating the preform with CrSi 2 , CrSi, Cr 5 Si 3 , or any combination thereof to fill in voids left behind after the slurry infiltration.
2. The process of claim 1 , wherein the component is a chromium silicide alloy having a melting point less than 1550° C., to prevent the fibers from fusing and reacting with the melt.
3. The process of claim 1 , wherein the wet attrition milling of the mixture is between 48 and 64 hours.
4. The process of claim 1 , further comprising:
after the wet attrition milling of the mixture, decanting the ethanol, air drying the mixture and then placing the mixture in an oven to turn the mixture into a dry cake to be grounded using a mortar and pestle to a fine powder.
5. The process of claim 1 , wherein the slurry preparing of the engineered CMC comprises mixing powders in an aqueous alkaline ammonium hydroxide solution containing a dispersant.
6. The process of claim 1 , wherein the melt infiltrating of the preform comprises
melt infiltrating CrSi 2 , CrSi, Cr 5 Si 3 , or any combination into a slurry infiltrated SiC/SiC preform via external melt infiltration.
7. The process of claim 6 , wherein the melt infiltrated SiC/SiC preform comprises voids between fibers that are filled by molten CrSi2, CrSi, Cr 5 Si 3 , or any combination.
8. The process of claim 1 , wherein the mixture further comprises one or more self-healing additives selected from the group consisting of B 4 C, CrB 2 , Ge, Y, ZrB 2 , and ZrSiO 4 .