Ceramic foams from preceramic polymers

Abstract.

The direct foaming of preceramic polymer mixtures, followed by high temperature pyrolysis in an inert atmosphere, can be employed to fabricate ceramic foams with impressive strength, stiffness, thermomechanical and thermochemical durability, and electromagnetic properties. Flexural strength and stiffness were superior to those of foams produced using conventional replication process technologies. Excellent strength retention and thermal fatigue resistance was exhibited during long term static and cyclic thermal exposure to 1200 °C in air. Further improvements can be realized through judicious selection of the preceramic polymers and pre-pyrolysis process modifications. Fabrication of foams with graded porosity and multifunctionality, via the incorporation of electrically-, thermally-, and magnetically-active fillers was demonstrated. This direct foaming technology offers substantial opportunity for the near-net shape fabrication of lightweight, inorganic foam structures with tailored thermal, elastic, mechanical, electrical and magnetic characteristics for high temperature applications.