Synthesis and Characterization of SiC(Ti) Ceramics Derived from a Hybrid Precursor of Titanium-Containing Polycarbosilane

Abstract

A hybrid precursor of titanium-containing polycarbosilane is prepared by blending hyperbranched polycarbosilane (HBPCS) and tetrabutyl titanate (TBT), and then crosslinking at 160 A degrees C, followed by pyrolyzing at high temperatures to afford SiC(Ti) ceramics. The crosslinking reaction of HBPCS-TBT hybrid precursor is investigated by FT-IR, solid state (29)Si MAS NMR, and GPC. The results indicate that the crosslinking reaction takes place via condensation between the Si-H bond of HBPCS and butoxy group in TBT leading to the formation of Si-O-Ti bonds. The thermal properties and structural evolution of crosslinked hybrid precursor and the crystallization behavior and composition of final ceramics are investigated by TGA, FT-IR, Raman spectroscopy, XRD and energy dispersive elemental analysis. The ceramic yield of hybrid precursor is significantly enhanced by introduction of TBT. The ceramic yield at 1,400 A degrees C is 83% for HBPCS-TBT-5 as measured by TGA. The Ti-content in the ceramic is controlled by varying the TBT content in the feed. The SiC(Ti) ceramic is amorphous at 900 A degrees C. The characteristic peaks of beta-SiC and TiC appear until 1,600 A degrees C. The growth of SiC crystals is inhibited by the formation of TiC.National Natural Science Foundation of China[50802079]; Aviation Science Foundation of China[2008ZH68005]; Natural Science Foundation of Fujian Province of China[2008J0165, 2010J01307

Synthesis of ZrC–SiC Powders by a Preceramic Solution Route

“…These properties led us to prepare ZrC-SiC by using zirconium n-Butoxide as Zr source and Poly[(silylene)acetylene)] as both Si source and C source. The Si-H could interact with zirconium n-Butoxide to get Zr, Si-containing polymer at high temperature like in previous works, 6,15 and the further pyrolysis of the precursor would result in the formation of ZrC-SiC via carbothermal reduction.…”

“…The solution‐derived precursor indicates homogeneous atomic distribution among different components, controllable Zr/Si ratios in precursor solution, and the conversion from precursor to ceramic at low temperature in relative short time . In previous studies, metal alkoxides were generally mixed with PCS (Yajima's PCS or HBPSC) to prepare liquid precursors . The Si–H in PCS could react with M–O–R to produce modified polymer containing M, which could be transformed into binary ceramics of SiC, and corresponding metal carbide .…”

“…15,16 The Si-H in PCS could react with M-O-R to produce modified polymer containing M, which could be transformed into binary ceramics of SiC, and corresponding metal carbide. 15,17 Poly [(silylene)acetylene)], which possesses active Si-H and curable alkynyl bonds, can be converted into SiC with high ceramic yield at 1200°C. The C/Si ratio is usually over two and excess carbon exists in final ceramic bulk.…”

High-ceramic-yield precursor to SiC-based ceramic: A hyperbranched polytitaniumcarbosilane bearing self-catalyzing units

“…Our research, therefore, sought efficient cross-linking agents or effective catalysts to improve the degree of cross-linking and enhance the ceramic yield of HBPCSs. [19][20][21][22][23] The incorporation of transition metals such as Ti and Zr into SiC fibers is very attractive as it leads to materials with excellent heat resistance and interesting catalytic and electrical properties. [24][25][26][27] Among those work, [24][25][26][27] Si-Ti-C-O and Si-Zr-C-O fibers were prepared by the use of polytitanocarbosilane and polyzirconocarbosilane, respectively, which were synthesized by the reaction between polycarbosilane and metal alkoxide or acetyl acetonates.…”

Preparation and Properties of Pinacolborane Modified Polycarbosilane as SiC Fiber Precursor

“…In order to promote the high-temperature performance of SiC fibers, many recent studies have focused on introducing heterogeneous elements, like Ti [14,15], Al [16][17][18] into SiC fibers. Boron element is also reported to promote the high-temperature performance of SiC fibers by holding back the growth of SiC crystallites [19,20].…”