This set of Engineering Materials & Metallurgy Multiple Choice Questions & Answers (MCQs) focuses on “Teflon and Fiber Glass”.
1. Teflon is known as the trademark name for ________
c) Fluorinated ether propane
d) Fluoro ethyl propylene
Explanation: Teflon is the trademark name for polytetrafluoroethylene, which is a synthetic fluoropolymer of tetrafluoroethylene (TFE). It can also be called as fluorinated ethylene-propylene (FEP). They are mainly used as coatings due to their ability to reduce friction, wear and tear.
2. Which of the following is not a property of fiberglass?
c) Thermal insulation
d) Reinforcement for plastics
Explanation: Fiberglass is known as the glass that has been drawn into fine fibers. They are inorganic in nature which makes them greatly inert. They also exhibit a high strength to weight ratio, non-flammability, and resistance to heat. For engineering applications, they are used for thermal and acoustic insulation, and as reinforcements for plastics.
3. Staple fibers are ______ cm in length.
a) 10 – 14
b) 15 – 38
c) 40 – 55
d) 62 – 80
Explanation: Fiberglass is made into either continuous fibers or staple fibers. Continuous fibers can be essentially made into any desired length. Staple fibers, on the other hand, range from 15 – 38 cm.
4. Which chemical composition of fiberglass is used when chemical resistance is not essential?
a) Fused quartz steel
d) Soda lime
Explanation: Depending on the ease of melting and chemical durability, several chemical compositions are compared and chosen to make fiberglass. Fused quartz steel and borosilicate compositions provide the necessary resistance. However, when chemical resistance is not a key requirement, ordinary soda lime is used.
5. The melted glass inserted into a second furnace uses a _______ plate at the bottom.
Explanation: The glass is melted and formed into marbles. These are inserted into a second remelting furnace at a constant rate. This furnace contains a platinum plate at the bottom, holding small orifices from which the required fiber is drawn.
6. The diameter of the selected fibers is of the range of _______
a) 0.1 – 0.155
b) 0.01 – 0.1
c) 0.0025 – 0.01
d) 0.00025 – 0.00125
Explanation: For any operation, the fibers used are of uniform size. They range from 0.00025 to 0.00125 cm. This size of the fiber depends on the desired properties and intended use of the drawings.
7. Staple fibers differ from continuous fibers due to the use of ________
a) Air blower
b) Manual force
c) Winding tube
Explanation: Continuous fibers are made from the melting process in a two-stage method. Staple fibers are formed by remelting process but differ due to the use of air or steam blower for tractive forces.
8. Which of the following is not a type of glass insulation?
Explanation: Fiberglass is mainly used as an insulating material and as reinforcement. The various types of glass insulations are – bonded, unbounded, block, blanket, and preformed insulation.
9. What is the operating temperature of borosilicate glass?
a) 200-300 F
b) 350-550 F
c) 600-1000 F
d) 1200-1800 F
Explanation: Fibrous glass can be used at temperatures even as low as -350 F. The borosilicate type is generally operated at a range of 600 to 1000 F.
10. What is the operating temperature of high silica glass?
a) 300 F
b) 550 F
c) 1250 F
d) 1830 F
Explanation: Heat resistance of a fiberglass material depends on the type of glass used. The maximum operating temperature of high silica glass is about 1830 F (1000oC), whereas that of borosilicate glass is 600-1000 F.
11. What is the product obtained when thermosetting resin fiberglass is exposed to heat and pressure?
b) Fiberglass reinforced plastic
c) Fiber reinforced fluoroethylene
d) Fiber induced carbon
Explanation: Fiberglass reinforced plastic is achieved as a product of fiberglass reinforced in a thermosetting resin and exposed to conditions of heat and pressure. These products were used for military and radar applications. In recent usage, it is being applied to swimming pools and roofing.
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