Porous SiC and SiC/C_f Ceramic Microspheres Derived from Polyhydromethylsiloxane by Carbothermal Reduction

Area of Science:

• Materials Science
• Ceramic Engineering
• Nanotechnology

Background:

• Porous silicon carbide (SiC) materials are valuable for applications requiring high thermal stability and specific surface area.
• Existing methods for producing porous SiC microspheres can be complex or expensive.
• Controlling the pore structure and composition of SiC is crucial for tailoring its properties.

Purpose of the Study:

• To present a simple and inexpensive method for preparing porous SiC microspheres.
• To demonstrate control over the free carbon content (C_f) within the SiC matrix.
• To investigate the relationship between synthesis parameters and the resulting pore structure.

Main Methods:

• Preparation of polysiloxane microspheres from polyhydromethylsiloxane (PHMS) and divinylbenzene (DVB).
• Ceramization of precursor microspheres under reducing conditions to form SiC.
• Characterization using elemental analysis, solid-state NMR (²⁹Si, ¹³C MAS NMR), SEM/EDS, XRD, Raman spectroscopy, and porosimetry (N₂ adsorption, Hg intrusion).

Main Results:

• A scalable method for producing porous SiC microspheres was successfully developed.
• The free carbon content in SiC/C_f microspheres can be tuned by adjusting the DVB ratio.
• Gaseous byproducts during ceramization create porosity; SiC/C_f exhibits meso/microporosity, while carbon-free SiC shows macroporosity.

Conclusions:

• The presented method offers a cost-effective route to tunable porous SiC microspheres.
• The controlled incorporation of free carbon influences the pore architecture of the SiC microspheres.
• These findings open possibilities for designing SiC-based materials with tailored porosity for advanced applications.