5:15 PM - 6:30 PM
[SIT08-P08] Doping effect on high-temperature creep of olivine aggregates
Keywords:olivine aggregates, rheology, doping effect
The inconsistency in strength can be resulted from a small difference in chemical composition because it has been observed that a small amount of impurities such as CaO, Al2O3, TiO2 were segregated at grain boundaries in naturally derived olivine aggregates (Hiraga et al. 2003), and because such impurities segregated at grain boundaries have been found to have a large effect on the strength of polycrystalline oxides such as alumina and zirconia (Yoshida et al. 1997).
In this study, we synthesized olivine aggregates by using a new technique and conducted high-temperature creep experiment on such synthesized olivine aggregates. Also we introduced small amount of impurities on such aggregates to investigate the effect of chemical composition on the creep properties of olivine aggregates.
The aggregates were prepared by applying vacuum sintering to nano-sized olivine powder synthesized from highly pure and fine-grained (<100 nm) raw powders (Koizumi et al 2010). Olivine aggregates with and without dopants of <1 wt% Al2O3, CaO, TiO2 were prepared. Deformation tests on these samples showed that non-doped samples were deformed under grain boundary diffusion creep and that there was no major difference in strength between non-doped and impurity-doped samples. Further, the strength was essentially identical to the aggregates by Faul and Jackson (2007). The similar strength of synthesized olivine aggregates used in our study and Faul and Jackson (2007) strongly suggested the presence of unknown chemicals that control creep properties of polycrystalline olivine.