Fig. 4: Atmospheric alteration experiments of three model glass compositions representative of one or more productions of glass objects since Antiquity, SEM images. | npj Materials Degradation

Fig. 4: Atmospheric alteration experiments of three model glass compositions representative of one or more productions of glass objects since Antiquity, SEM images.

From: Glass alteration in atmospheric conditions: crossing perspectives from cultural heritage, glass industry, and nuclear waste management

Fig. 4

(wt%): Glass A, 71.3 SiO2, 0.8 Al2O3, 0.8 MgO, 5.0 CaO, 11.0 Na2O, 11.0 K2O; Glass P, 75.8 SiO2, 0.3 Al2O3, 0.2 MgO, 2.0 CaO, 1.5 Na2O, 20.2 K2O; Glass SL, 66.8 SiO2, 2.5 Al2O3, 3.0 MgO, 7.5 CaO, 18.0 Na2O, 2.1 K2O. In the field of Cultural Heritage glasses, the compositions A and P are considered as unstable and the composition SL is considered as stable against atmospheric degradation. SEM images (secondary electrons except d back-scattered electrons) of the surface (a, c, e) and of the edge (b, d, f) of glass plates altered at 40 °C, 85% RH for 6 months. The alteration layer thickness is indicated on the images. The salts are mainly Ca carbonates (A, P, and SL), Na, Ca, H-mixed carbonates (A and SL), deliquescent K-carbonates (P), and K, Na, Ca-sulfates (P). Scale bars are a 10 µm, b 1 µm, c 10 µm, d 500 nm, e 1 µm, f 500 nm. Reproduced with permission from ref. 109, Editions Hermann, 2019.

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