Synthesis and characterization of Al and Ti co-doped polycarbosilane for Si(Al,Ti)CO and Si(Al,Ti)C ceramic fibers

A novel aluminum and titanium co-doped polycarbosilane (PATCS) was synthesized by the reaction of liquid polycarbosilane (LPCS), Al(acac) 3 , and Ti(Cp) 2 Cl 2 . The thermal polymerization mechanism of the PATCS was that Si-H bonds in LPCS reacted with C=C/Ti-Cl bonds in Ti(Cp) 2 Cl 2 and Al-O-C/Al-O=C groups in Al(acac) 3 to form Si-Ti, Si-C-C, Si-O-Al bonds. The TG-DSC results showed that the synthesized PATCS exhibited greater stability and a higher ceramic yield compared to PACS. A novel type Si(Al,Ti)CO ceramic fibers (AT-11) with tensile strength (2222 MPa) were obtained by melt-spining, curing, pyrolysis of the synthesized PATCS. After sintering, the AT-13 showed excellent electromagnetic wave absorption. When the thickness reached 2.3 mm, the minimum reflection loss (RL min ) vaule and the EAB were -52.02 dB and 5.12 GHz (RL < −10 dB, 10.64-15.76 GHz), respectively. While the AT-18 fibers showed higher high-temperature creep resistance in the range of 1300∼1700 °C than those of Si(Al)C ceramic fibers.