chemical prperties

The glass is a brittle material. The fracture shows a conchoïdal shape.

There are many mechanical properties allowing to characterize a glass submitted to an external stress:

• the elastic modulus or Young modulus (E), which relates the glass deformation before breaking
• the rupture modulus
• thoughness (K1c)
• the corrosion under stress: the crack alteration by water increases its velocity of propagation
• the glass fatigue when subjected to periodic alternative stress, a glass can broke through modification of the surface flows (size, number)
• the hardness characterize the resistance to scratch. On the Mohs scale (the scale of the mineralogist) the hardness is close to 6 (1 = talc;10 = diamond).