Cementite is in the lamellar form in the __________ phase of steel.
Martenistic
Bainitic
Pearlitic
Ferritic
Correct Answer :
C. Pearlitic
Related Questions
In a drilling process, the metal is removed by both shearing & extrusion. General purpose drills are made of
Stainless steel
Mild steel
High speed steel
High carbon steel
In the Bayer's process, bauxite is digested under pressure using
H2SO4
NaOH
NH3
HCl
Fibre glass is a composite material of
Glass fibre in a polymer matrix
Glass fibre in a metallic matrix
Polymer fibre in a glassy matrix
Both 'b' & 'c'
The following type of bonding is strongly directional in solids.
Vander Waal's
Ionic
Metallic
Covalent
Thermit welding is categorised as the __________ welding.
Forge
Fusion
Resistance
Arc
Cobalt - 60 is used as a source of __________ in medical therapy & industrial radiography.
X-rays
γ-rays
α-rays
β-rays
Absolute zero pressure can be attained at a temperature of
0°C
50°K
0°R
None of these
Which of the following represents the correct time-temperature curve when a block of metal is heated above room temperature & then left to cool in the room following Newton's law of cooling in which the rate of temperature drop will go on decreasing with the passage of time.
The difference in one unit of Rockwell hardness number corresponds to a difference in the depth of indentation of __________ mm.
0.001
0.01
0.002
0.02
During sensible cooling of air, its wet bulb temperature
Decreases but dew point remains constant
Increases but dew point remains constant
Increases & the dew point decreases
Decreases & the dew point increases
Carbide tipped cutting tools are manufactured by powder metallurgy techniques and have a composition of
90% tungsten carbide and 10% cobalt
70% aluminium oxide & 30% silica
30% nickel, 15% chromium & 55% tungsten
65% tungsten & 35% zirconium
Electrical conductivities of semi-conductors are of the order of __________ ohm/cm.
10-3
103
10-15
1015
Metal cutting by oxy-acetylene flame is accomplished by the __________ of the metal.
Burning
Intensive oxidation
Evaporation
None of these
Carbon is present in the form of __________ in grey cast iron.
Spheroids
Nodular aggregates of graphite
Flakes
Cementite
The mechanism involved in the removal of metal in drilling operation is by
Compression
Extrusion
Shearing
Both 'b' & 'c'
In a boundary layer developed along the flow, the pressure decreases in the downstream direction. The boundary layer thickness in this case will
Decrease gradually
Increase gradually
Increase rapidly
Remain constant
Atomic __________ is a whole number for an element.
Number
Weight
Radius
None of these
In __________ process, there is an increase in entropy with no degradation of energy.
Isothermal expansion
Isochoric heat addition
Polytropic expansion
Isobaric heat addition
A material is capable of resisting softening at high temperature, because of its property termed as
Hot temper
Hot hardness
Fatigue
Creep
Cast iron contains __________ percent carbon.
2.5
3.75
4.75
5.25
Referring to the periodic table of elements, it is found that with increasing atomic number. The atomic size in the same
Period increases
Period decreases
Group increases
Both 'b' & 'c'
Temperature of hot gases flowing in a pipe is measured by a thermocouple inserted in the thermal well. The thermal well made of __________ will facilitate the most accurate measurement of the temperature.
Copper
Steel
Aluminium
Brass
Diameter of the rivet to be provided on a 20 mm. thick boiler plate will be __________ mm.
10
20
30
40
Air/fuel ratio on molar (volume) basis for combustion of methane with theoretical quantity of air with be
9.5 : 1
12.5 : 1
15.5 : 1
18.5 : 1
__________ is the hardest material out of the following.
Boron carbide
Tungsten carbide
Hardened steel
Silicon carbide
In case of compression of one kg of air, the work done will be the least, when the value of polytropic index 'n' is
1
1.4
1.5
Y = Cp/Cv
Projection welding & stud welding is categorised as the __________ welding.
Pressure
Thermit
Resistance
Arc
Name the safety device used to protect the boiler, when the water level falls below a minimum level.
Blow down valve
Blow off cock
Fusible plug
Safety valve
At 100% relative humidity, the dew point temperature of moist air is
Less than the wet bulb temperature
More than the wet bulb temperature
Equal to the wet bulb temperature
Equal to the ambient temperature
The heat of neutralisation remains constant, when there is a reaction between dilute solutions of strong
Base and strong acid
Base and weak acid
Acid and weak base
None of these