Toward hard and highly crack resistant magnesium aluminosilicate glasses and transparent glass‐ceramics

Abstract

High hardness and high crack resistance are usually mutually exclusive in glass materials. Through the aerodynamic levitation and laser melting technique, we prepared a series of magnesium aluminosilicate glasses with a constant MgO content, and found a striking enhancement of both hardness and crack resistance with increasing Al2O3. The crack resistance of the magnesium aluminosilicate glass is about five times higher than that of the binary alumina‐silica glass for the similar [Al]/([Al] + [Si]) molar ratio (around 0.6). For the selected magnesium aluminosilicate glass with R = 0.32, when subjected to isothermal treatment at 1283K, we observed a further drastic enhancement of both hardness and crack resistance by extending the heating time. Based on the structural analyses, we propose an atomic‐scale model to explain the mechanism of synergetic enhancement in hardness and crack resistance for the magnesium aluminosilicate glasses and glass‐ceramics.

Development of Mg/Al/Si/O ReaxFF Parameters for Magnesium Aluminosilicate Glass Using an Artificial Neural Network-Assisted Genetic Algorithm

“…Binding energy analysis of Table supports this observation: Mg-OAl 2 has the strongest binding energy among Mg-BO and has the binding energy slightly lower than [3] Mg-NBO and greater than [4] Mg-NBO. Experimental observations also pointed out the higher binding energy of network-modifying cations in aluminosilicate glass to Al-connected oxygen and the binding energy of Mg–O increases especially if the Mg 2+ cations behave as a charge compensator. , …”

“…Experimental observations also pointed out the higher binding energy of network-modifying cations in aluminosilicate glass to Al-connected oxygen 17 and the binding energy of Mg−O increases especially if the Mg 2+ cations behave as a charge compensator. 16,121 The strength of Mg-OAlSi is weaker than that of Mg-OAl 2 , but the amount of Mg-OAlSi outnumbers that of Mg-OAl 2 , especially at the glass with low MgO and Al 2 O 3 amounts like MAS7612. The dominance of Mg-OAlSi is reasonable as all MAS glass systems in our study contain a significant quantity of Si-O-Al bridges, as shown in Table 8.…”

Mg and Al mixed effects on thermal properties in aluminosilicate glasses

“…Phase diagram of MgO–Al 2 O 3 –SiO 2 ternary system 15 together with the investigated compositions (red balls; (49 − x )MgO• x Al 2 O 3 •51SiO 2 ) in this work and the compositions (blue balls; 11MgO• x Al 2 O 3 •(89 − x )SiO 2 ) in our previous investigation 14 …”

“…According to our previous studies, 14 upon the addition of constant 11 molar% MgO into the binary Al 2 O 3 –SiO 2 glassy system shown in Figure 1, 15 the 11MgO•38Al 2 O 3 •51SiO 2 glass exhibits a five times enhancement in crack resistance from 9.69 N for the 45Al 2 O 3 •55SiO 2 glass to 50.22 N for the 11MgO•38Al 2 O 3 •51SiO 2 glass with the similar Al/Si ratio. Herein, on the basis of this composition, by using the aerodynamic levitation and laser heating technique, we extend the glass‐forming region of the magnesium aluminosilicate glasses with the compositions (49 − x )MgO• x Al 2 O 3 •51SiO 2 ( x = 7–49) well from Mg‐rich to peraluminous compositions.…”

Tuning the hardness and crack resistance through liquid–liquid phase separation in an aluminosilicate glass

“…By utilizing the laser-heated aerodynamic levitation setup built in our lab described in detail in our previous reports, [14][15][16] we prepared the sample with the molar composition of 30Al 2 O 3 Á 70SiO 2 having spinodal decomposition peculiarity, whose position in the phase diagram is shown in Fig. 1.…”