Chemical structure and mechanical properties of soda lime silica glass surfaces treated by thermal poling in inert and reactive ambient gases

Abstract

This study employed thermal poling at 200°C as a means to modify the surface mechanical properties of soda lime silica (SLS) glass. SLS float glass panels were allowed to react with molecules constituting ambient air (H2O, O2, N2) while sodium ions were depleted from the surface region through diffusion into the bulk under an anodic potential. A sample poled in inert gas (Ar) was used for comparison. Systematic analyses of the chemical composition, thickness, silicate network, trapped molecular species, and hydrous species in the sodium‐depleted layers revealed correlations between subsurface structural changes and mechanical properties such as hardness, elastic modulus, and fracture toughness. A silica‐like structure was created in the inert gas environment through restructuring of Si–O–Si bonds at 200°C in the Na‐depleted zone; this occurred far below Tg. This silica‐like surface also showed enhancement of hardness comparable to that of pure silica glass. The anodic thermal poling condition was found so reactive that O2 and N2 species can be incorporated into the glass, which also alters the glass structure and mechanical properties. In the case of the anodic surfaces prepared in a humid environment, the glass showed an improved resistance against crack formation, which implies that abundant hydrous species incorporated during thermal poling could be beneficial to improve the toughness.

Enhancement of mechanical properties and chemical durability of Soda‐lime silicate glasses treated by DC gas discharges

“…The hardness value is comparable to those of fused silica tabulated between 9 and 10 GPa depending the authors 30,31 . The second group, composed of the reference and non‐contact air‐poled glasses before and after durability tests, shows hardness values around 8 GPa, which is comparable to soda lime silicate's hardness values reported in the literature 15,20 . The non‐contact nitrogen poled glass after two days in saline waters exhibits an intermediate hardness.…”

“…At the glass surface both anions and electrons neutralize positively charged species from the gas discharge avoiding a screening of the applied electric field and preventing arc formation. Such interactions between charge carriers formed in discharges occurring either in the gas or in the poled glass matrix were discussed by Cremoux et al 34 and Luo et al 15 upon observing NO + , NO 2 and N 2 O 4 species trapped below the poled glass surface. Finally, as observe in Figure 7, the evolution of the light emission curve of the (0-1) transition at 357 nm shows similar trend with the current curve, which is relied to the formation of the poled layer that is a reservoir of electrons and anions.…”

“…30,31 The second group, composed of the reference and non-contact air-poled glasses before and after durability tests, shows hardness values around 8 GPa, which is comparable to soda lime silicate's hardness values reported in the literature. 15,20 The non-contact nitrogen poled glass after two days in saline waters exhibits an intermediate hardness. One can see that the hardness decreases with the indentation depth, except for the group where its hardness attains the reference glass' value.…”

Differences in surface failure modes of soda lime silica glass under normal indentation versus tangential shear: A comparative study on Na+/K+‐ion exchange effects

“…The peak near 3700‐3740 cm −1 is the free Si–OH group . The origin of the peaks at >3740 cm −1 are not fully understood, but they appear to be associated with the non‐equilibrium nature of glass since they are not observed in equilibrium systems (such as crystalline phase or bulk liquid) . In Figure C, the spectral changes in the >3700 cm −1 region (highlighted with the light‐yellow background) are negligible.…”

Detection of phases in Fe‐doped YSZ by XRD and Raman spectroscopy

“…Sintering atmosphere has proved to be crucial in tailoring the properties of other important materials, for example; annealing of Co-doped SnO 2 transparent conducting films in N 2 and Ar atmosphere altered its structural, electrical, and optical properties, 25 the magnetic properties of Ni-Cu-Zn and Cu-Zn ferrite nanoparticles were improved when sintered in reducing atmosphere, 26,27 and surface mechanical properties of soda-lime silica glass were altered by thermal poling in inert atmosphere. 28 Sinteribilty of 8YSZ also is found to be enhanced when sintered in argon atmosphere and thus it becomes necessary to explore the structural changes occurring in it due to such sintering conditions. 22 Mechanical properties and ionic conductivity of YSZ ceramics largely depend on the phase/s it consists and hence limits its applications.…”