Microstructure, elastic, and inelastic properties of biomorphic carbons carbonized using a Fe-containing catalyst

• Published in: Physics of the solid state Vol. 58; no. 12; pp. 2481 - 2487
• Main Authors: Orlova, T. S., Kardashev, B. K., Smirnov, B. I., Gutierrez-Pardo, A., Ramirez-Rico, J.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01.12.2016; Springer; Springer Nature B.V
• Subjects: Analysis; Catalysts; Concentration (composition); Elastic properties; Graphite; Mechanical Properties; Microplastics; Nanocrystals; Physics; Physics and Astronomy; Physics of Strength; Plasticity; Solid State Physics; Surface area; X-ray diffraction
• ISSN: 1063-7834; 1090-6460
• DOI: 10.1134/S1063783416120234

The microstructure and amplitude dependences of the Young’s modulus E and internal friction (logarithmic decrement δ), and microplastic properties of biocarbon matrices BE-C(Fe) obtained by beech tree carbonization at temperatures T carb = 850–1600°C in the presence of an iron-containing catalyst are studied. By X-ray diffraction analysis and transmission electron microscopy, it is shown that the use of Fe-catalyst during carbonization with T carb ≥ 1000°C leads to the appearance of a bulk graphite phase in the form of nanoscale bulk graphite inclusions in a quasi-amorphous matrix, whose volume fraction and size increase with T carb . The correlation of the obtained dependences E ( Т carb ) and δ( T carb ) with microstructure evolution with increasing Т carb is revealed. It is found that E is mainly defined by a crystalline phase fraction in the amorphous matrix, i.e., a nanocrystalline phase at Т carb < 1150°C and a bulk graphite phase at T carb > 1300°C. Maximum values E = 10–12 GPa are achieved for samples with Т carb ≈ 1150 and 1600°C. It is shown that the microplasticity manifest itself only in biocarbons with T carb ≥ 1300°C (upon reaching a significant volume of the graphite phase); in this case, the conditional microyield stress decreases with increasing total volume of introduced mesoporosity (free surface area).