Functionally gradient SiC/SiC ceramic matrix composites with tailored properties for turbine engine applications

A method of manufacturing a ceramic fiber preform for use in a ceramic matrix composite, the method comprising:

• providing a fiber preform having a plurality of ceramic fibers;
• defining a plurality of regions of the fiber preform on the basis of variations in the desired level of resistance to in-plane stress and variations in the desired level of resistance to interlaminar stress among corresponding regions of the ceramic matrix composite, the plurality of regions including a first region and a second region;
• applying BN to the first region, yielding a first BN layer having a thickness in the range of about 0.3 micron to about 1.0 micron;
• applying BN to the second region, yielding a second BN layer having a thickness of less than or equal to about 0.3 micron;
• applying Si-doped BN to the first BN layer, yielding a first Si-doped BN layer having a thickness in the range of about 0.4 micron to about 0.6 micron;
• applying Si-doped BN to the second BN layer, yielding a second Si-doped BN layer having a thickness of less than or equal to about 0.3 micron;
• applying SiN to the first Si-doped BN layer, yielding a first SiN layer having a thickness in the range of about 0.75 micron to about 1.25 micron, thereby forming a first multilayer fiber coating corresponding to the first region;
• and
• applying SiN to the second Si-doped BN layer, yielding a second SiN layer having a thickness of about 0.5 micron, thereby forming a second multilayer fiber coating corresponding to the second region.