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1 Basic constituent SiO VerresVerres

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(1)

1 Verres

Verres

• Transparent

• Hard and crack resistant

• Inert, resistant to normal atmosphere

• Poor themal insulation

Basic constituent SiO

2

Si

(2)

2

Silicon ion - Si4+

Oxygen ion - O2- silice crystallin – ex. quartz

SiO2group

silice amorphe - verre

Si pur, très difficile d'eviter le crystallisation de SiO

2

Ajout d'autres oxides: AO

x/2

"Network formers"

X= 3, 4, 5 SiO2

B2O3 P2O5

"Network modifiers"

X= 1, 2 Na2O

K2O MgO CaO

"intermediates"

X= 2, 3 Al2O3

BeO

(3)

3 Fabrication

Tradition: souflage

Modern: float glass – late 1950s

Proprietés Mechanique

• Très fragile

• Tougening:

–Cool air jets on surface in hot state –Surface cools quickly while interior is soft –When interior cools puts surface into

compression

–More difficult for flaws to intitiate

Références

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