DM308 Exam Materials Part 5

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Questions and Answers

What role does Na2O play in soda-lime glass?

Network former

Network modifier (correct)

Chemical stabilizer

Intermediate behavior

Which type of glass has a glass transition temperature of approximately 570°C?

No information provided

Borosilicate glass

Soda-lime glass (correct)

Lead glass

What is the purpose of adding lime (CaO) to soda-lime glass?

To improve the chemical stability (correct)

To make the glass soluble in water

To increase the glass transition temperature

To improve thermal shock resistance

Which type of glass is known for its high thermal shock resistance?

Borosilicate glass Signup and view all the answers

What is another name for lead glass?

"Lead crystal" Signup and view all the answers

What type of structure does glassy silica lack compared to quartz?

Long-range order Signup and view all the answers

Which type of glass is designed for medical applications involving repair of damaged bone tissue?

Bioglass Signup and view all the answers

Which term is used for glassy silica without additives?

Fused Silica Signup and view all the answers

What is the main mineral in bone that bioglass is chemically similar to?

Hydroxyapatite Signup and view all the answers

What characteristic makes Fused Silica suitable for high-temperature lamp envelopes?

Near zero thermal expansion Signup and view all the answers

Which type of glass can be made transparent to infra-red radiation?

Glass ceramics Signup and view all the answers

What is the purpose of network modifiers in glass?

Break up the molecular network Signup and view all the answers

What is the benefit of using bioglasses in the body for bone repair?

Low thermal conductivity Signup and view all the answers

Why are additives frequently introduced to alter the properties of glasses?

To facilitate processing and alter properties Signup and view all the answers

Which glass composition has a negative thermal expansion coefficient?

Glass ceramics Signup and view all the answers

What is the primary use of LAS, MAS, and ZAS glass ceramic systems?

High temperature applications Signup and view all the answers

Why was glass made with uranium oxide mainly used before the nuclear age?

For artistic glass-blowing Signup and view all the answers

What is the purpose of vitrification in relation to highly radioactive nuclear waste?

To store waste permanently Signup and view all the answers

In the Pilkington float glass process, what does the molten glass float on top of to produce flat glass sheets?

Molten tin Signup and view all the answers

What is the purpose of adding water during the float glass process?

To improve mixing and minimize dust hazards Signup and view all the answers

What is the purpose of rod drawing in optical communication fibre production?

To manufacture high-quality optical communication fibres Signup and view all the answers

What is the role of the glass gob in precision glass forming?

To produce optical lenses with complex profiles Signup and view all the answers

Why is it important for die materials to have high surface smoothness in precision glass forming?

To achieve high-quality surface finish on glass products Signup and view all the answers

What is the purpose of thermally toughening glass?

To heat and rapidly quench the glass for increased strength Signup and view all the answers

How does the process of rod drawing contribute to optical communication fibre production?

By forming optical fibre cladding with outer preform material Signup and view all the answers

Study Notes

Silica-based glasses can incorporate oxides of other elements as network formers or modifiers, with soda-lime glass being a common type consisting of silica, soda as a network modifier, and lime for chemical stability.
Borosilicate glass, used for lab-ware and cookware, has boric oxide as a network former, higher thermal shock resistance than soda-lime glass, and a glass transition temperature of ~820°C.
Lead glass, also known as "lead crystal," contains lead oxide and is used in various applications like glassware and radiation shielding due to its high refractive index and light dispersal properties.
Bioglass is designed for medical applications to repair damaged bone tissue, with a composition similar to hydroxyapatite, a mineral in bone, and the ability to dissolve in the body to aid in new bone tissue growth.
Glass ceramics, produced through controlled crystallization, have both crystalline and amorphous phases, negative thermal expansion coefficient, low thermal conductivity, and can be transparent to infra-red radiation.
The Pilkington float glass process is used to produce flat glass sheets by floating molten glass on molten tin, with key stages including melting raw materials, homogenizing the glass, and cooling it to the correct viscosity.
The structure of glass lacks long-range order like crystalline silica, leading to a gradual glass transition from a stiff brittle state to a soft rubbery state without a defined melting point.

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Description

Test your knowledge on alloying for stabilizing polymorphs and the structure of glass, including the differences between glassy silica, quartz, and fused silica. Explore topics like thermal expansion, thermal shock resistance, chemical inertness, and more.