Engineering Materials - Study Mode

[#261] Elinvar, an alloy used in precision instruments, hair springs for watches, etc. contains the following element as principal alloying element
Correct Answer

(D) Nickel

Explanation

Solution: Elinvar is a nickel-iron alloy notable for having a modulus of elasticity which does not change much with temperature changes. Elinvar originally consisted of 52% iron, 36% nickel, and 12% chromium. It is almost non-magnetic, and corrosion resistant.

[#262] Which of the following statement is incorrect about duralumin?
Correct Answer

(D) It is lighter than pure aluminium

Explanation

Solution: In addition to aluminum, the main materials in duralumin are copper, manganese and magnesium. Although the addition of copper improves strength, it also makes these alloys susceptible to corrosion. For sheet products, corrosion resistance can be greatly enhanced by metallurgical bonding of a high-purity aluminium surface layer. These sheets are referred to as alclad, and are commonly used by the aircraft industry

[#263] Pearlite is a combination of
Correct Answer

(A) Ferrite and cementite

Explanation

Solution: Pearlite is a combination of Ferrite and cementite

[#264] Austenite is a combination of
Correct Answer

(B) Cementite and gamma iron

Explanation

Solution: Austenite is a combination of Cementite and gamma iron

[#265] If a refractory contains high content of silicon, it means refractory is
Correct Answer

(C) Neutral

Explanation

Solution: Refractory refers to the heat resistant material used in almost all processes involving high temperatures and/or corrosive environment. These are typically used to insulate and protect industrial furnaces and vessels due to their excellent resistance to heat, chemical attack and mechanical damage.