Silicon carbide particle formation from carbon black -polymethylsilsesquioxane mixtures with melt pressing

Abstract

Precursors for silicon carbide nano particles were prepared from carbon black and polymethylsilsesquioxane (PMSQ). Ceramization process of PMSQ was characterized as preliminary information. The 29 Si NMR study indicated the existence of SiC 3 O (or SiC 4 ) environment even at 1073 K. The chemical composition of pyrolyzed PMSQ was SiO 1.5 C 0.68 . Carbon black (CB) was dispersed in a PMSQ benzene solution and the mixture was freeze-dried to obtain precursor powders. The powders were hot pressed at 573 K for making contacts between CB and PMSQ. The cured precursor sheets were crushed and heat-treated at 1838 K in an inert atmosphere to synthesize SiC particles with a carbothermal reduction process. The conversion process of the CB-PMSQ hybrids to SiC was monitored by thermogravimetric analysis. The influence of the size and content of carbon blacks on conversion rates and the resulting SiC particle morphology was investigated.

Investigation of Curing Process on Melt Spun Polymethylsilsesquioxane Fiber as Precursor for Silicon Oxycarbide Fibers

“…Since various PMSQ with different molecular structure (First PMSQ soluble in organic solvent was synthesized in 1978 [9,10]) is available in industry, molecular structure, ceramization process and viscoelastic properties of the used PMSQ must be characterized in detail. These data have been shown in our previous studies [11,12]. The precursor was melt spun to fiber form at 403-453K.…”

Processing of polysiloxane-derived porous ceramics: a review

“…SiC nanoparticles and Si O C fiber were produced from polymethylsilsesquioxane (PMSQ) precursors [119][120][121] by advanced cross-linking methods. For example, melt spinning on PMSQ at 130-180…”

Effect of filler addition on porosity and strength of polysiloxane-derived porous silicon carbide ceramics

“…21) The composition of SiOC after pyrolysis at 1400°C was SiO 1.50 C 0.68 . 22) The pyrolyzed specimens were further heat-treated in argon to 1450°C for 1 h at a heating rate of 10°C/min and subsequently annealed at 18001950°C for the liquid-phase sintering of SiC using Al 2 O 3 and Y 2 O 3 . The heat-treatment at 1450°C and annealing at 18001950°C were performed in a graphite furnace (1000-3560-FP20, Thermal Technologies Inc., USA).…”