Strengthening of Borosilicate Glass by Ion Exchange for Lightweight Transparent Bulletproof Windows Materials

Transparent bulletproof windows play an important role in the munitions industry. The thickness of bulletproof windows including soda-lime silicate(SLS) glass, polyvinyl butyral, poly urethane, main defense(200MD), and safety film was reduced from 40mm to 29mm by adjustment of SLS glass laminated array. Borosilicate glasses generally have lower surface density and more excellent mechanical properties than SLS glass. Borosilicate glass was strengthened by ion exchange in the $KNO_3$ powder. The maximum mechanical properties were observed at $550^{\circ}C$ for 10min. The Vickers hardness, fracture toughness and 3-point bending strength of ion exchanged samples were about $775kg/mm^2$, $1.91MPa{\cdot}m^{1/2}$ and 764MPa each, which are about 27%, 149% and 249% higher than parent borosilicate glass, respectively. The penetration depth of K+ ion at $550^{\circ}C$ for 10min was $59.8{\mu}m$. As a result, the transparent bulletproof windows were predicted to be more lightweight by ion exchange of borosilicate glass. If the SLS glass for bulletproof windows is replaced by ion exchanged borosilicate glass, the bulletproof windows can be expected to be lightweight and thinner.

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