| SM ISO690:2012|
POPA, Mihaela; SHIKIMAKA, Olga A.; GRABCO, Daria; SAVA, Bogdan Alexandru; BOROICA, Lucica; ELIŞA, Mihail; PYRTSAC, Constantin; BARBOS(DĂNIŢĂ), Zinaida; RĂZLOG (BELEI), Ina. Fracture toughness and hardness at micro- and nanoindentation of phosphate glasses depending on their composition. In: Materials Science and Condensed Matter Physics. Editia a 8-a, 12-16 septembrie 2016, Chişinău. Chişinău: Institutul de Fizică Aplicată, 2016, p. 179. ISBN 978-9975-9787-1-2.
|Materials Science and Condensed Matter Physics
Editia a 8-a, 2016
Conferința "International Conference on Materials Science and Condensed Matter Physics" |
8-th Edition, Chişinău, Moldova, 12-16 septembrie 2016
Phosphate glasses are promising candidates for fast ion conductors, waveguides, optical switches, fibers, etc. However their applications are often hindered by their low chemical durability, therefore the seeking of new improved composition is a key point. At the same time, the new composition should not affect the mechanical durability, which along with chemical stability, optical and magneto-optical properties of phosphate glasses, is an important issue for a reliable and durable function of the systems and devices on their base. Two groups of glasses of a basic aluminophosphate (Al2O3–P2O5–Li2O–BaO–La2O3) composition (APG) doped with Dy2O3, Tb2O3 and Fe2O3, and borophosphate (B2O3–P2O5–Li2O–Al2O3–ZnO) composition (BPG) codoped with Dy2O3–Tb2O3, Bi2O3–PbO and CoO were investigated for hardness (H), Young’s modulus (E) and fracture toughness (KIC) and the comparative analysis was carried out. The dynamic nanoindentation and quasistatic microindentation technique within the load range of 0.02–2.0 N were used in this study. As a whole, BPGs show improved mechanical properties in comparison with APGs. This is manifested by higher values of H, E and KIC for undoped glass (Fig. 1, a, b, c). The smaller ionic radius of B3+ and Zn2+ in BPG in comparison with those ones of Ba2+ and La3+ in APG is expected to strengthen the glass structure, which explains higher values of H and E. It is important that increase of H does not affect the values of KIC, which has usually a decreasing tendency for harder materials. The addition of dopants for optical and magneto-optical properties induces some changes in the values of H, E and KIC (Fig. 1, a, b, c). It is suggested that these changes may be connected with ionic radius and concentration of dopants. Indentation size effect, manifested by decrease of hardness with load increase, observed for all investigated glasses, was explained by the decreasing contribution of permanent densification, intensification of plastic flow and crack initiation (Fig. 1, d, e) resulting in the relaxation of internal stresses and softening of material.