Glass and Ceramics
Autor: Maryam • February 22, 2018 • 701 Words (3 Pages) • 789 Views
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Borosilicate glass
[pic 15]
Properties
Chemical composition
Examples
Quite high softening point (800˚C), hence it is heat-resistant
Does not crack easily when sudden change in temperature
Transparent to ultraviolet light
More resistant to chemical reactions
Does not break easily
(80%)[pic 16]
(15%)[pic 17]
(3%)[pic 18]
(1%)[pic 19]
Laboratory apparatus, cooking utensils, electrical-tubes and glass pipelines
Lead glass
[pic 20]
Properties
Chemical composition
Examples
Low softening point (600˚C)
High density
High refractive index
Reflects light rays and appears sparkling
(55%)[pic 21]
(30%)[pic 22]
(10%)[pic 23]
(3%)[pic 24]
(2%)[pic 25]
Decorative items, crystal glass wares, lens, prisms and chandeliers
Improved Glass
Photochromic glass
[pic 26]
Photochromic glass is a type of glass that is sensitive to light intensity. The glass darkens when exposed to sunlight but becomes clear when light intensity decreases
Photochromic glass is produced when a dispersion of silver chloride, or silver bromide, is added to normal glass[pic 29][pic 27][pic 28]
Conducting glass[pic 30]
[pic 31]
Conducting glass is a type of glass that can conduct electricity.
Conducting glass is produced by embedding a thin layer of conducting material in glass.
A type of conducting glass is produced by adding a layer of indium tin(IV) oxide (ITO) that acts as an electrical conductor. This type of glass is used in the making of LCD (liquid crystal display) panel.
Another type of conducting glass is made by embedding thin gold threads in glass.
Example, water condenses as ice on the window panes of aircrafts at high altitudes and this obstructs the vision of the pilot. Hence, windows of aircraft are heated by passing electric current through the gold threads embedded in the glass.
Essay Question
In this modern era, we have many different types of glass that we us for many things. Two of the most common is fused glass and soda-lime glass.
- State the different properties that this two glass possess . ( 10 marks )
Fused glass
- Very high softening point as high as 1700 degrees Celsius hence making it highly heat-resistant
- Transparent to ultraviolet and infrared light
- Difficult to be made into different shapes
- Does not crack when temperature changes ( has very low thermal expansion coefficient )
- Very resistant to chemical reactions
Soda-lime glass
- Low softening point as low as 700 degrees Celsius hence it does not withstand heating
- It breaks easily
- Cracks easily with sudden temperature ( high thermal coefficient of expansion )
- Less resistant to chemical reactions
- Easy to make into different shapes
[pic 32]
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