Load/unload displacement curves at room temperature (humidity 49%) for silica glass have been measured in the penetration range of 0.5-1.2 μm using a Vickers nanoindentation technique (load/unload speed 50 mN/s). Deformation energies have been estimated for the first time. The universal (dynamic) hardness, Hu, and elastic recovery, ER, at the penetration depth, ht, of 1.0 μm are Hu = 4.1 GPa and ER = 0.7. The following energies for total deformation, Ut, elastic deformation, Ue, and plastic deformation (i.e., densification during loading), Up, are obtained: Ut=190, Ue=135 and Up = 55 kJ/mol at ht = 0.5 μm and Ut = 139, Ue = 96 and Up = 43 kJ/mol at ht = 1.0 μm. All these deformation energies increase with decreasing penetration depth. It is found that plastic deformation energies of 38-55 kJ/mol for 0.5 < ht < 1.2 μm are very close to the activation energy (46-54 kJ/mol) for the recovery of densification in silica glass, but are very small compared with the single bond strength (443 kJ/mol for Si-O bond) of SiO2.
|ジャーナル||Journal of the American Ceramic Society|
|出版ステータス||Published - 2002 12|
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