Corning® Fusion5™ Glass introduced the first auto exterior glass designed for windshields lighter in weight, with superior durability and better optical performance, compared to conventional windshields.
A review in MotorTrend magazine says Fusion5 is considered “hard glass,” with much higher melting points (Fusion5’s is 1,650 degrees C, versus soda-lime’s 1,000). Fusion5’s chemistry causes the molecules to densify and harden under impact.
Lacking this property or a rigid crystalline structure, the molecules in most glass separate, cracking, or shattering upon impact.
“The high melting point also gives Fusion5 a coefficient of thermal expansion that’s half that of old-school glass, so it’s much less susceptible to thermal shock of the sort that happens if you defrost an icy windshield with boiling water,” the review says.
Read more here.