Crystal orientation in cell wall and micro-mechanical characteristics of silica crystals inside petrified wood

Abstract

The research on chemical composition and micro- structure of petrified wood has scarcely been reported in China and abroad, and the study about micro-mechanical characteristics has not been carried out. In this paper, the domestic and foreign research progress was summarized at the same time, and the crystal orientation in the cell wall of Pinus tabulaeformis petrified wood was measured according to the method of wood's MFA using x-ray diffraction tech- niques, while micro-mechanical characteristics were further studied using nanoindentation. The results showed that silica crystals in petrified wood cell wall were arranged from 22.19 to 25.98 ° in accordance with the micro fibril angle. The micro-mechanical characteristics of silica crystals in different locations inside the petrified wood were different; the modu- lus and hardness of silica crystals in the lumen region were 89.86 and 9.33 GPa, but 63.07 and 5.20 GPa in the cell wall region. The difference of hardness and modulus of two parts regional were 44.34 and 27.30 %, respectively; this result was supported by A. Kuczumow's study, which showed the vari- ability of the secondary electron signal of Si could be even over 30 %, the easiest way to explain it was by claiming that the porosity is much increased.