Abstract
Internal frictions and dynamic moduli were measured by a forced torsional vibration method at 0.5-5Hz in the temperature range of -120-300°C on the metaphosphate glasses such as 50CaO·50P2O5 (CaP), 50Na2O·50P2O5 (NaP) and 25CaO·25Na2O·50P2O5 (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 --50°C, -80°C and -210°C on the CaP, and at --50°C, -55°C and -170°C on the NaP. For the CaNaP, two peaks were obtained at --50°C and -75°C 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 (ΔE) to the relaxation were calculated from the equation, Inω=(ΔE/RT), where ω=2πf, R; gas constant. ΔE 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, ΔE were -180kJ/mol with the CaP, -200kJ/mol with the NaP and -170kJ/mol with the CaNaP. ΔE 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 (G') gradually decreased a little with increasing temperature in the present range on all specimens.
