The refractory brick which has good thermal shock resistance at high temperature but cracks on cooling below 400°C is
Magnesite
Chrome
Silica
Fireclay
Correct Answer :
C. Silica
Related Questions
In case of simple harmonic motion, displacement is proportional to the
Velocity
Acceleration
Both (A) & (B)
Neither (A) nor (B)
The elastic strain energy of a unit length of an edge dislocation as compared to that of a screw dislocation is
More
Equal
Less
Double
Which of the following fastening devices has its both ends threaded?
Bolt
Stud
Set screw
Split nut
Elimination of brittleness resulting from welding of saw blades is done by __________ of the welded portion.
Annealing
Toughening
Work hardening
Tempering
In the acid Bessemer process, the hot metal should have the following composition.
S < 0.05% and P < 0.05%
S < 0.05% and P < 1.5%
S < 0.05% and P > 1.5%
S > 1.5% and P < 0.05%
Parallel straight line pattern of temperature distribution for both hot and cold fluids is observed in case of heat exchanger of the type
Parallel flow with equal heat capacities
Counter flow with equal heat capacities
Counter flow with unequal heat capacities
Parallel flow with unequal heat capacities
Eutectoid composition of carbon steel at room temperature is
Cementite
Pearlite
Martensite
Ferrite
Depreciation of machines fails under the indirect expenses head. As per income tax regulations, it is calculated by the __________ method.
Diminishing balance
Sinking fund
Multiple straight line
Sum of the years digit
Pick out the wrong statement.
The X-rays cannot be deflected by electric field unlike cathode rays
The intensity of X-rays can be measured by ionisation current produced due to the ionisation of gas by X-rays
The quality of X-rays can be controlled by varying the anode-cathode voltage
Crystal structure of a material can be studied by an electron microscope
Pick out the wrong statement
Processing of thermosetting plastics is ideally done by injection moulding
Processing of thermoplastics is ideally done by compression moulding
Mass production of seamless pipes are done by electrical resistance welding (ERW)
Stretch forming is a process of cold drawing
Isotropic materials have the same __________ in all directions.
Induced stresses
Density
Elastic properties
Thermal properties
As per international norms, the maximum permissible value of noise level in the industrial environment is __________ decibels as measured at a distance of 1.5 metres from the source of noise.
110
85
60
45
Which one can be directly solidified from gaseous state without entering into liquid state?
Helium
Oxygen
Carbon dioxide
None of these
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
The starting of a car takes time in winter, because the
Octane number of fuel is decreased
Fuel supply for ignition is not sufficient
Vaporisation of the fuel is decreased
Pour point of fuel decreases
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
__________ of grey cast iron produces white cast iron.
Tempering
Rapid heating
Rapid cooling
Slow cooling
Which of the following metals is not subjected to electrolytic refining/purification?
Copper
Zinc
Tin
Aluminium
The property of material, by which a given amount of energy is absorbed by it, without plastic deformation, is called
Resilience
Toughness
Ductility
Impact strength
Babbitt lining is used on brass/bronze bearings to increase the
Antifriction properties
Compressive strength
Bearing resistance
Wear resistance
Minimum temperature upto which water can be theoretically cooled down in the cooling tower by evaporative cooling is equal to the __________ temperature of air.
Wet bulb
Dry bulb
Saturation
Dew point
If a nuclear reactor produces more fissile nuclear fuel than it consumes, then it is called a __________ reactor.
Critical
Breeder
Fertile
Heterogeneous
Dephosphorization of molten pig iron is favoured by
Oxidising and basic slag
Reducing and basic slag
High activity co-efficient of phosphorous in metal
Oxidising and neutral slag
With increase in __________ Knocking tendency in a spark ignition petrol engine decreases.
Supercharging
Wall temperature
Compression ratio
Engine speed
Which of the following metals reacts violently with water?
Mercury
Sodium
Calcium
Magnesium
Tumbling is the process of improving the __________ of the materials/parts.
Surface finish
Fatigue limit
Creep limit
Surface cleanliness
The most prominent single cause of corrosion in boiler-tubes, drums, economisers and steam superheaters in a thermal power plant boiler is the
Water alkalinity & leakage
Hydrazine addition during feed water treatment
Release of non-condensable gas from water in the boiler
Scale formation
The pressure drop per unit length for laminar flow of fluid through a long pipe is proportional to (where, A = cross-sectional area of the pipe & D = Diameter of the pipe)
A
D
1/A
1/A2
Midrex process of sponge iron production uses reformed natural gas as the reducing agent, which uses iron ore in the form of
Lumps
Pellets
Briquettes
Sinter
Strain hardening effect in metals subjected to cold working is due to the __________ mechanism.
Slip
Fracture
Winning
Dislocation