Internal Friction and Dynamic Modulus in Metaphosphate Glasses
Masahiro Sakamura, Masakuni Ozawa and Suguru Suzuki
Abstract:Internal frictions and dynamic moduli were measured by a forced torsional vibration method at 0.5`5Hz in the temperature range of ?120`300Ž on the metaphosphate glasses such as 50CaOE50P2O5(CaP), 50Na2OE50P2O5(NaP) and 25CaOE25Na2OE50P2O5(CaNaP). Three peaks of internal friction were shown in the results measured as a function of temperature on both the glasses of CaP and NaP. The three peaks appeared at `-50Ž, `80Ž and `210Ž on the CaP, and at `-50Ž, `55Ž and `170Ž on the NaP. For the CaNaP, two peaks were obtained at `-50Ž and `75Ž although the third peak was missed because of the rise of the base line. As those peak temperatures(T) depended on the vibration frequency(f), apparent activation energies(ƒ¢E) to the relaxation were calculated from the equation, lnƒÖ=(ƒ¢E/RT),where ƒÖ=2ƒÎf, R;gas constant. ƒ¢E obtained from the first peaks (low temperature range) were `120kJ/mol with the CaP, `70kJ/mol with the NaP and `75kJ/mol with the CaNaP. From the second peaks at the intermediate temperature range, ƒ¢E were `180kJ/mol with the CaP, `200kJ/mol with the NaP and `170kJ/mol with the CaNaP. ƒ¢E obtained from the third peaks in the high temperature range were the high values with `640kJ/mol on the CaP and `530kJ/mol on the NaP. The dynamic moduli (Gf)gradually decreased a little with increasing temperature in the present range on all specimens. Key Words:Internal friction, Dynamic modulus, Metaphosphate glass, Activation energy