3. GLASS
Glass is a non-crystalline amorphous solid that is often
transparent and has widespread practical,
technological, and decorative usage in, for
example, window panes, tableware,
and optoelectronics
4. HISTORY OF GLASS
._First true glass was made in coastal north Syria
_the story of glass dates back to ancient Egypt where glass-making
became popular during the late bronze age.
_Anglo-Saxon period glass was a luxury material across England.
_in 10th century stained glass came to usage.
_in 1330crwon glass was produced in rouen.
_in 14th and 19th centuries stained glass employed in building
purposes.
_in 1843 henry bessemer invented float glass.
_in 12th century reinfoorced glass and glass bricks came to usage.
6. SILICA(sand)
_silica is another name for the chemical compound SILICON
SiO2))OXIDE
_each unit of silica includes one atom of silicon and two atom
of oxygen
_physical properties of silica are
1.Solid in room temperature
2.Pure silica is colorless but if contaminants are present in a
sample of quartz, it may be colored
3.Silica has very high melting and boiling
points(3,110F)(4,046F)
_silica reacts with hydrofluoric acid, it also reacts with metal
oxide like sodium oxide or lead oxide ,these reactions are
used to produce different types of glass
7. SODIUM and CALCIUM OXIDE
_sodium oxide is added to reduce the melting point of
soda ash))the sand
_calcium oxide is added to prevent glass from being
limestone))soluble in water
9. AMOROHOUS GLASS
_Glass is called an amorphous solid because its atoms
are arranged in a random fashion. because of its
irregular atomic structure , when glass is broken, it
produces a variety of fracture patterns.
10. COLORED GLASS
_colored glasses are due to inclusion of ions of chemical
elements like:
_iron(Fe)
_cobalt(Co)
_nickel(Ni)
_copper(Cu)
_chromium(Cr)
_magnesium(Mg)
11. TYPES and USES Of GLASS
_fused glass
_borosilicate glass
_soda-line glass
_lead crystal glass
12. FUSED GLASS
_the simplest type of glass is fused glass . it consists
mainly of silica.
_fused glass is made by heating silica to a molten liquid .
the liquid is then cooled rapidly to form an amorphous
solid.
13. SODA-LIME GLASS
Soda-lime glass is the most common and earliest used
glass.
It is made by heating silica with calcium oxide and
sodium carbonate at around 1 500 c and cooling it
quickly
14. BOROSILICATE GLASS
_When boron oxide B2O3 is added to soda-lime
glass,borosilicate glass is formed.
_it has a lower thermal expansion coefficient.
_it is about 3 times as heat-resistant as soda-lime glass.
_it is also more resistant to chemical.
15. LEAD CRYSTAL GLASS
_lead crystal glass is soft and easy to melt
_it is more expansive than soda-lime glass
_it is used for the finest tableware,lead crystal glassware
and art objects.
_it is suitable for fine crystal becaouse it is optically
transparent and contain much more lead.
