Process for preparing textured ceramic composites

A method for preparing a green fibrous monolith from at least one green ceramic fiber having a controlled texture comprising

• (a) forming a first ceramic-laden composition comprising a thermoplastic polymer and at least about 40 vol. % of a ceramic particulate into a substantially cylindrical core,
• (b) applying a layer of a second ceramic-laden composition comprising a thermoplastic polymer and at least about 40 vol. % of a ceramic particulate which differs from the particulate contained in the first composition onto the core to form a substantially cylindrical feed rod having an average diameter,
• (c) extruding the feed rod to provide at least one green ceramic fiber which has an average diameter that is less than the average diameter of the feed rod, and
• (d) shaping the at least one green ceramic fiber to provide the green fibrous monolith,
• wherein, during the extrusion step, each ceramic-laden composition has a viscosity which is approximately equivalent to that of each other ceramic-laden composition, and, when the ceramics present in the extruded at least one green ceramic fiber are sintered, a plane of weakness defined by the interface of the core and the layer is provided, the interface being relatively weaker than the core.

A method for preparing a green fibrous monolith from at least one green multifilament ceramic fiber having a controlled texture comprising

• (a) forming a first ceramic-laden composition comprising a thermoplastic polymer and at least about 40 vol. % of a ceramic particulate into a substantially cylindrical core,
• (b) applying a layer of a second ceramic-laden composition comprising a thermoplastic polymer and at least about 40 vol. % of a ceramic particulate which differs from the particulate contained in the first composition onto the core to form a substantially cylindrical feed rod having an average diameter,
• (c) extruding the feed rod to provide at least two green ceramic fibers, each fiber having an average diameter that is less than the average diameter of the feed rod,
• (d) extruding the at least two green ceramic fibers substantially simultaneously to form at least one multifilament green ceramic fiber, and
• (e) shaping the at least one multifilament green ceramic fiber to provide the green fibrous monolith,
• wherein, during each extrusion step, each ceramic-laden composition has a viscosity which is approximately equivalent to that of each other ceramic-laden composition, and, when the ceramics present in the at least one green ceramic fiber are sintered, a plane of weakness defined by the interface of the core and the layer is provided, the interface being relatively weaker than the cores.