Evolution of holes and cracks in pre-carbonized glassy carbon

Abstract

Being a type of carbonaceous material, glassy carbon possesses thermomechanical properties akin to ceramics, offering both mechanical and chemical stability at high temperatures; therefore, it can be applied in electrochemistry and high-temperature manufacturing. However, the direct pyrolysis of a bulk precursor leads to internal pores and cracks, usually resulting in fracture. Our characterization results show that at temperatures below 400 degrees C, large pores do not form, and pre-carbonized glassy carbon (PGC) formed at 350 degrees C has a dense microstructure without cracks. It exhibits a high compressive strength of similar to 370 MPa and flexural strength of similar to 190 MPa, making it suitable for load-bearing applications. Additionally, the PGC-350 material shows small mass loss (similar to 5%) and reasonably low thermal expansion (2.5 x 10(-6)/degrees C) when heated to 350 degrees C again. These properties suggest the potential of PGC for high-temperature applications. As a demonstration, PGC formed at 350 degrees C was employed to fabricate molds to press chalcogenide glass blanks, which exhibited favorable molding results for various surface morphologies.