This presentation provides information about silica. Silica, also known as silicon dioxide, is most commonly found in nature as quartz and in living organisms. It is the second most abundant element in the earth's crust. The presentation discusses the properties, production methods, and various uses of silica. Some key properties covered include its hardness, melting point, and reactivity. Common production methods include mining quartz and precipitating silica from sodium silicate solutions. Silica has a wide variety of uses including in glass, ceramics, cement, food additives, electronics, and more.

1. PRESENTATION
CHEMISTRY
CERAMICS: SILICA
VASU GOEL
ABHINAV SAINI
RAGHAV AGGARWAL

2. CERAMICS: SILICA
 Silicon dioxide, also known as silica, is an oxide of
silicon with the chemical formula SiO₂.
 It is most commonly found in nature as quartz and in
various living organisms.
 In many parts of the world, silica is the major
constituent of sand.
WHAT IS SILICA?

3. CERAMICS: SILICA
 Silicon is the second most abundant element (≈27.6%)
in the earth’s crust.
 Silicon never occurs as a free element in nature. It
always occurs as a compound with oxygen, magnesium,
calcium, phosphorus or other elements.
 The most common minerals are silicates.
 Silicon has been detected in the sun and stars and
meteorites (aerolites), etc.
SILICA: OCCURRENCE

4. CERAMICS: SILICA
 Existence
 Hardness
 Color
 Melting Point
 Boiling Point
 Refractive Index vs Density
 Reactivity
PROPERTIES OF SILICA

5. CERAMICS: SILICA
 Silica mainly occurs in two allotropic forms: crystalline
and non-crystalline.
 Crystalline form is shiny, greyish-black, needle-like or
flat plates.
 Non-crystalline form usually occurs as brown powder.
PROPERTIES OF SILICA: EXISTENCE

6. CERAMICS: SILICA
 Under normal temperature and pressure conditions, it
is a solid, crystallized mineral.
 It is relatively hard, weighing
a “7” on the Mohs Scale.
PROPERTIES OF SILICA: HARDNESS

7. CERAMICS: SILICA
 Pure silica is colorless.
 However, if contaminants are present in quartz, it may
have some color.
e.g., Rose Quartz is silica with trace amounts of iron
PROPERTIES OF SILICA: COLOR

8. CERAMICS: SILICA
 Silica has very high melting and boiling points.
Melting Point = 3110⁰F = 1410⁰C
Boiling Point = 4046⁰F = 2355⁰C
 It takes a big hot furnace to melt silica sand in order to
make glass.
PROPERTIES OF SILICA: MP & BP

9. CERAMICS: SILICA
PROPERTIES OF SILICA: REFRACTIVE INDEX VS DENSITY

10. CERAMICS: SILICA
 Silica reacts with hydrofluoric acid. This reaction is used
to edge quartz in the semiconductor industry.
 Silica also reacts with metal oxides
(like NaO, PbO). These reactions are used
to produce different kinds of glass such as
borosilicate glass, leaded glass, etc.
PROPERTIES OF SILICA: REACTIVITY

11. CERAMICS: SILICA
SILICA IN DIFFERENT FORMS
 Silica Gel  Silica Dust

12. CERAMICS: SILICA
SILICA IN DIFFERENT FORMS
 Silica Sand  Silica Powder

13. CERAMICS: SILICA
 Silicon dioxide is mostly obtained by mining, including
sand mining and purification of quartz.
 Quartz is suitable for many purposes, while chemical
processing maybe required to make a purer and more
suitable (i.e., more reactive or fine-grained) product.
PRODUCTION OF SILICA

14. CERAMICS: SILICA
 Silica fume is obtained as a by product of hot processes
like ferro-silicon production.
 It is less pure than fumed silica and should not be
confused with that product.
PRODUCTION OF SILICA: SILICA FUME

15. CERAMICS: SILICA
 Precipitated silica or amorphous silica is produced by
the acidification of solutions of sodium silicate.
 The gelatinous precipitate or silica gel, is first washed
and then dehydrated to produce colorless micro-porous
silica.
 Idealized equation involving a tri-silicate and sulfuric
acid is shown:
Na2Si3O7 + H2SO4 → 3 SiO2 + Na2SO4 + H2O
PRODUCTION OF SILICA: PRECIPITATED SILICA

16. CERAMICS: SILICA
 It is applied as a coat to create adhesion.
 It is used in the production of chalk boards and marker
boards.
 It is used as non-stick hybrid coatings.
 It is used for jewelry and silk-screening applications.
 It is used as an anti-caking agent in powdered foods
such as spices and non-dairy coffee creamer.
USES OF SILICA

17. CERAMICS: SILICA
 Colloidal silica is also used as a wine, beer and juice
fining agent.
 Hydrated silica is used in toothpaste as a hard abrasive
to remove tooth plaque.
 Hyper-pure silicon is used in transistors and other
electronic devices.
 It is used in grinding and polishing glass and stone.
and many more…maybe!!
USES OF SILICA

18. FINISH