6:15 PM - 7:30 PM
[SSS29-P10] Temperature-dependent frictional strength of dolerite in a nitrogen atmosphere
Keywords:Dolerite, Nitrogen atmosphere, Rotary shear experiment, Temperature dependency, Amount of amorphous wear material, Ratio of wear material cover
We therefore have conducted similar friction experiments on dolerite as Noda et al. (2011) in a nitrogen atmosphere with an oxygen concentration of 0.1 %, and investigated the dependence of steady-state frictional strength on temperature and its relation to the amount of amorphous wear material and the ratio of wear material cover on the slip surface. The steady-state friction coefficient was ~0.52 at room temperature, while it was ~0.7 being roughly constant at 100-500 ℃ and ~0.76 at 600 ℃. The amount of amorphous material ranged within 60 ±6 wt% from room temperature to 500 ℃ and ~38 wt% at 600 ℃. The ratio of wear material cover on the slip surface was ~0.78 at room temperature, while it was ~0.9 being roughly constant at 100-600 ℃. The steady-state friction coefficient of dolerite in a nitrogen atmosphere is significantly lower than that in air (~0.77) at room temperature, while it is larger than the latter (0.61 ±0.03) at temperatures from 100-600 ℃. It shows a negative correlation with the amount of amorphous material as observed in air at 100-600 ℃, while it also shows a positive correlation with the ratio of wear material cover at room temperature to 500 ℃. However, the former and latter correlations become unclear at room temperature to 100 ℃ and at 500-600 ℃, respectively.
The frictional strength of dolerite at room temperature significantly lower in a nitrogen atmosphere than in air is likely due to the lack of moisture-adsorbed strengthening. However, the reason for higher frictional strength in a nitrogen atmosphere than in air at 100-600 ℃ is unknown at present. It is also unknown at present what are responsible for the correlations among temperature-dependent frictional strength, the amount of amorphous material and the ratio of wear material cover. These are the subjects of our future study.