Wk 10 Glass

What are the 5 major forms of flat glass?

• Spun

• Blown

• Drawn sheet glass - from furnace and passed through metal rollers

• Plate glass - glass that is ground and polished after manufacture

• Float glass - molten glass poured from the furnace continuously and floats along the surface of a bath of molten tin

What is glass made of?

• sand

• sometimes cullet(scrap glass), limestone, dolomite and soda ash are added

• other additives (lead or borax) added

lead - adds surface lustre/ resistance to x-ray

borax - will produce a glass of very low thermal movement (resistant to thermal shock)

What is the procedure of making glass?

• 1800 C furnace

• 1600 C furnace

• 1100 C furnace

• coating added after

• 600 C - room temp cooling

What are the main desirable material properties of glass?

• appearance

• transparency

• strength (resists wind/loads/thermal stresses)

• solar heat transmission (will transmit short wavelength solar radiation and the objects in the building will absorb and reradiate it out as much longer wavelengths - can’t escape (greenhouse effect)

• durability

• thermal insulation/movement (double glazing)

• sound insulation

• non-combustible (breaks/melts)

How is toughened glass made?

• heating it uniformly to its softening point + cooling rapidly

• chemical treatment