GATE MT year:2019 PYQs & Answers — Page 6

Questions 51–60 of 65. Imported answers require independent review unless marked reviewed.

Topic practice 65 questionsPage 6 of 7

Steady state radial heat conduction through a hollow, infinitely long zirconia cylinder is governed by the following ordinary differential equation:

Here, T is the temperature and r is the radial distance. The inner surface of the hollow cylinder is maintained at 1473 K and the outer surface at 973 K. The rate of heat loss per unit length through the outer surface of the hollow cylinder (in W.m⁻¹, rounded off to the nearest integer) is _____________.

Given: Inner radius of cylinder = 0.05 m; outer radius of cylinder = 0.07 m and thermal conductivity of zirconia (k) = 2 W.m⁻¹.K⁻¹.

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A 50 mm (diameter) sphere of solid nickel is oxidized in a gas mixture containing 60% argon and 40% oxygen by volume. The rate of oxidation of nickel is controlled by the rate of transport of oxygen through the concentration boundary layer. The rate of oxidation (in moles of nickel per minute (mol/min), rounded off to two decimal places) is ________.

Given: Total pressure = 1 atm, Temperature = 1173 K; Concentration of oxygen at the surface of the solid = 0; Boundary layer mass transfer coefficient = 0.03

; Universal gas constant,

= 8.205

. Assume ideal gas behavior.

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Equilibrium concentration of dissolved nitrogen (in wt.%, rounded off to three decimal places) in pure liquid iron, exposed to atmospheric air at 1873 K, is ________.

Given: Sieverts’ law constant as a function of temperature (

; in Kelvin) is

where

has the dimension of

. Assume

, where

is the activity of nitrogen with respect to 1 wt.% Henrian standard state.

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Pressure drop in the granular zone of a blast furnace is 300 mm of water per meter of the bed height. The bed permeability is 0.8

. The volumetric flow rate of gas per unit area through the bed [in

, rounded off to the nearest integer] is ________.

Assume Darcy’s law is applicable and

. Density of water = 1000

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A blast furnace charged with hematite containing 90 wt.% Fe

produces liquid iron with 3.6 wt.% carbon. Coke containing 90 wt.% carbon is charged at a rate of 500 kg per Metric ton of liquid iron produced. The blast furnace top gas contains (by volume), 22% CO, 18% CO

, and balance nitrogen. The volume of the blast furnace top gas [in m

(NP), rounded off to the nearest integer] is ________.

Given: Assume ideal gas behavior, and molar volume of the gas at NP is 22.4 liter.

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100 Metric tons of copper concentrate containing 21 wt.% Cu is to be processed in 6 months with 25 working days per month and 8 working hours per day. The concentrate is leached by sulphuric acid and electrolyzed in 10 cells arranged in series. The minimum current rating (Ampere per month per cell, rounded off to the nearest integer) is ________.

Given: Faraday constant = 96500 Coulomb per gram equivalent. Atomic weight of copper is 63.

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Cold working of iron leads to increase in dislocation density from

. The associated stored energy (in

, rounded off to one decimal place) is ________.

Given: Shear modulus of iron = 82 GPa, Burger’s vector,

nm.

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The critical radius (in nm, rounded off to one decimal place) of nickel nucleus during solidification at 1673 K is ________.

Given: Enthalpy of fusion of nickel =

; Liquid-solid interfacial energy = 0.5

, and Equilibrium melting temperature of nickel = 1728 K.

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A material, made up of alternating layers of metals A and B, is loaded as shown below. If the volume % of B is 25%, the elastic modulus (in GPa, rounded off to one decimal place) of the material is ________.

Diagram for Metallurgical Engineering question 49

Given: Elastic moduli of A and B are 200 GPa and 100 GPa, respectively.

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The S-N curve for a steel is shown below. If the stress ratio, (

) =

, the maximum stress (in MPa, rounded off to the nearest integer) that the steel can withstand for infinite fatigue life is ________.

Diagram for Metallurgical Engineering question 50

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GATE MT year:2019 PYQs

Question 41

Question 42

Question 43

Question 44

Question 45

Question 46

Question 47

Question 48

Question 49

Question 50