This set of Engineering Materials & Metallurgy Multiple Choice Questions & Answers (MCQs) focuses on “Glass Wool and Thermocole”.
1. How is glass wool formed?
a) Hot working
b) Direct melting
c) Cold working
d) Extrusion
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Explanation: Glass wool is a material that provides exceptional insulation against heat and cold. It is formed by the direct melting process. Air and steam jets are used in this process.
2. Short fibers of glass wool can be used up to _______
a) 500oC
b) 600oC
c) 700oC
d) 800oC
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Explanation: Short fibers of glass wool have a natural density of 24 kg per cu. m and can be used up to a temperature of 500oC. These can be bonded with a thermosetting resin, due to which they can only be used up to 200oC. Bonding with thermosetting resins is done to achieve any desired density and curing.
3. What are the applications of the unbounded type of glass wool?
a) Space suits
b) Sound insulation in airplanes
c) Air filters
d) House ceiling
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Explanation: The unbonded type of glass wool, with a vapor wall, is used in exterior walls and ceilings of buildings. These, along with bonded type, are used for furnaces, ovens, water heaters ecetera.
4. Which type of glass wool is used in space suits?
a) Bonded type
b) Low-density wool
c) Coarse wool
d) Unbonded type
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Explanation: Extremely low-density wool is used for thermal and sound insulation in airplanes. This is due to its ability to decrease dead load and also acts as a fire retardant. This is also used in space suits and capsule couches.
5. What is known as expandable polystyrene?
a) Glass wool
b) Fiberglass
c) Thermocole
d) Cement
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Explanation: Thermocole is a white-colored and odorless material produced during the Second World War. It is the trademark name for the material known as expandable polystyrene. It is used as heat insulation and for packing or stationary purposes.
6. What is the maximum heat insulation of thermocole?
a) 100oC
b) 200oC
c) 500oC
d) 750oC
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Explanation: Thermocole is a chemically stable and lightweight material. It is a good heat insulator up to 200oC. Although it is generally resistant to salts, alkalies, and acids, it can be attacked by benzene.
7. Which of these is not a standard thickness in which thermocole is available in?
a) 10 mm
b) 37.5 mm
c) 50 mm
d) 75 mm
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Explanation: Thermocole sheets are a lightweight material having air in their pores. Standard sheets are available in sizes of 10, 12.5, 20, 25, 37.5, and 50 mm thickness.
8. Which of these is not a property of thermocole?
a) Heat insulator
b) Lightweight
c) Receptive to fungus
d) Odorless
View Answer
Explanation: Thermocole is a white-colored odorless material that is chemically stable and resistant to fungus. It has a density of 10-25 kg/cu.m which makes it extremely light in weight. Thermocole is a good heat insulator up to 200oC.
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