In-Situ Carbon Content Adjustment in Polysilazane Derived Amorphous SiCN Bulk Ceramics

Silicon oxycarbide ceramics with reduced carbon by pyrolysis of polysiloxanes in water vapor

“…This is different from the previous pyrolysis work involving other active gases that is mostly conducted in powdered materials. 9,15 The enabling reduction of carbon in the bulk material indicates that water vapor could penetrate into the polysiloxane body. The path for the water penetration should be the pores that were generated at the intermediate stage of pyrolysis due to the decomposition of volatile polysiloxane components in the precursors.…”

“…[8][9][10][11][12] Many studies address the reduction of free-carbon from PDCs through the designs of precursors 9,13,14 and the control of pyrolysis. 9,15 Silicon oxycarbide (SiOC) is a typical kind of PDCs which has been widely studied in recent years because of its enhanced high temperature properties comparing to silica. 9,13,16,17 SiOC ceramics with various compositions have been produced from siloxane based sol-gel reactions and from polysiloxanes by pyrolysis.…”

“…18 The reduction of free-carbon from SiOC has been conducted using (poly)siloxane precursors with less-carbon or carbon-free groups (Si-CH 3 , Si-H or Si-Si), 9,10,13,14,20 introducing active metal fillers or compounds (such as Ti, Al and MoSi) into polysiloxanes to react with the carbon precipitated in the precursor during pyrolysis, 21,22 and using active gases (such as ammonia) during pyrolysis of polysiloxanes or through postannealing of SiOC ceramics. 9,15 These processes show some effects on the adjusting of the amount of carbon in SiOC, but the effect appears limited since the obtained SiOC ceramics are exclusively black. 9,18 In this work, we report a highly efficient and simple way to reduce carbon from SiOC, that is, to pyrolyze a polysiloxane in water vapor.…”

Template‐Free Synthesis of Porous Fe3O4/SiOC(H) Nanocomposites with Enhanced Catalytic Activity

“…Generally, in PDCs, the pores are generated by the evolution of small molecules like CH 4 and H 2 during the pyrolytic conversion process. However, the transient porosity spontaneously closes‐up at temperature above 600°C–800°C . Therefore, it is still challenging to fabricate porous PDCs without the assistance of templates …”

“…However, the transient porosity spontaneously closes-up at temperature above 600°C-800°C. 2,[17][18][19] Therefore, it is still challenging to fabricate porous PDCs without the assistance of templates. 2,3,20 Water pollution with organic dyes is an increasing challenging environmental issue worldwide.…”