Microstructure, elastic and inelastic properties of partially graphitized biomorphic carbons

• Published in: Physics of the solid state Vol. 57; no. 3; pp. 586 - 591
• Main Authors: Orlova, T. S., Kardashev, B. K., Smirnov, B. I., Gutierrez-Pardo, A., Ramirez-Rico, J., Martinez-Fernandez, J.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01.03.2015; Springer
• Subjects: Analysis; Diffraction; Graphite; Mechanical Properties; Physics; Physics and Astronomy; Physics of Strength; Plasticity; Solid State Physics; X-rays; Carb; Beech Wood; Amplitude Dependence; Carbonization Temperature; Logarithmic Decrement
• ISSN: 1063-7834; 1090-6460
• DOI: 10.1134/S106378341503018X

The microstructural characteristics and amplitude dependences of the Young’s modulus E and internal friction (logarithmic decrement δ) of biocarbon matrices prepared by beech wood carbonization at temperatures T carb = 850–1600°C in the presence of a nickel-containing catalyst have been studied. Using X-ray diffraction and electron microscopy, it has been shown that the use of a nickel catalyst during carbonization results in a partial graphitization of biocarbons at T carb ≥ 1000°C: the graphite phase is formed as 50- to 100-nm globules at T carb = 1000°C and as 0.5- to 3.0-μm globules at T carb = 1600°C. It has been found that the measured dependences E ( T carb ) and δ( T carb ) contain three characteristic ranges of variations in the Young’s modulus and logarithmic decrement with a change in the carbonization temperature: E increases and δ decreases in the ranges T carb < 1000°C and T carb > 1300°C; in the range 1000 < T carb < 1300°C, E sharply decreases and δ increases. The observed behavior of E ( T carb ) and δ( T carb ) for biocarbons carbonized in the presence of nickel correlates with the evolution of their microstructure. The largest values of E are obtained for samples with T carb = 1000 and 1600°C. However, the samples with T carb = 1600°C exhibit a higher susceptibility to microplasticity due to the presence of a globular graphite phase that is significantly larger in size and total volume.