Which of the following phenomenon/ phenomena is/are diffusion controlled?
Dislocation climb
Cross-slip
Twinning
Recrystallisation
Correct Answer :
D. Recrystallisation
Related Questions
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
An approximately __________ process exemplifies the flow of a gas through a very long pipe of uniform cross-section.
Adiabatic
Isothermal
Isentropic
Isochoric
Difference at any instant between the value of the controlled variable and the set point is called the
Deviation
Derivative time
Error ratio
Differential gap
The most economical channel section for the fluid flow is the one for which the discharge is maximum for a given cross-sectional area. Vertical velocity distribution in an open channel for laminar flow can be assumed to be
Parabolic
Hyperbolic
Straight line
None of these
Steel rods are normally used for concrete reinforcement because concrete and steel have almost equal
Tensile strength
Compressive strength
Young's modulus
Thermal co-efficient of expansion
The 'laughing gas' is
Nitrous oxide
Nitric oxide
Nitrogen trioxide
Nitrogen pentoxide
Uniform ramming of sand in green sand moulding process leads to
Reduced chance of gas porosity
Greater dimensional stability of the casting
Uniform flow of molten metal into the mould cavity
Less sand expansion type of casting defect
Euler number is defined as the ratio of inertia force to __________ force.
Pressure
Elastic
Gravity
Viscous
Other parameters remaining same, the recrystallisation temperature of an alloy is lowered, when
Strain rate is increased
Grain size is increased
Prior cold deformation is increased
Not affected by any of the above parameters
When dry bulb temperature & wet bulb temperature of moist air is the same, it means that the
Partial pressure of water vapour is less than the total pressure
Humidity is < 100% & dew point temperature of air has not reached
Dew point temperature of air has not reached & air is not saturated fully
Air is fully saturated
Out of the following __________ iron has the best capability to bear sudden & excessive shocks.
White
Cast
Wrought
Pig
A semi-conductor is damaged & behaves like a conductor, on passing a strong electric current through it, because it heats up the crystals & breaks the covalent bonds resulting in __________ electrons.
Lack of free
Excess of
Decrease in
None of these
The majority charge carriers in p-type silicon are
Free electrons
Ions
Conduction electrons
Holes
If the head is doubled in & centrifugal pump, the power required will increase in the ratio of
23
23/2
25/2
21/3
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
Heating the Hypo-eutectoid steels to 30°C above the upper critical temperature line, soaking at that temperature and then cooling slowly to the room temperature to form a pearlite & ferrite structure is called
Tempering
Hardening
Annealing
Normalising
An ideal material for making cooking vessels should have
High heat capacity
Low heat capacity
High thermal conductivity
Both (B) and (C)
Which of the following does not have a sharp melting point?
Thoria
Glass
Ice
Pig iron
For the irreversible reaction, Ca+ 2C = Ca C2 , Δ H°298 = - 60000 J . mole-1 . If a system initially containing 2 moles of calcium, 3 moles of carbon and 1 mole of calcium carbide is allowed to react to completion, the heat evolved at 298 K will be
30,000 J
60,000 J
90,000 J
2,40,000 J
The function of neutral flux used in the pyrometallurgy of metal extraction is to increase the __________ of the slag.
Fluidity
Basicity
Acidity
Viscosity
The hardenability of steel decreases with
Decrease in dislocation density
Increase in solutionising temperature
Increase in strength
Decrease in grain size
Milk is fat dispersed in water. It is an example of
Suspension
Emulsion
Gel
Solution
Carbon supply in pack carburising process is in the form of
Charcoal
Calcium carbide
Hydrocarbon oil
Graphite
For a small scale toy factory, the fixed cost per month is Rs. 5000/-. The variable cost per toy is Rs. 20 and sales price is Rs. 30 per toy. The break even production per month will be __________ toys.
250
500
1000
3000
Limestone is added in the blast furnace (during pig iron manufacture) to
Form slag by combining with impurities
Supply heat by undergoing exothermic reaction with impurities
Reduce the coke consumption
Reduce slag viscosity
Oxyacetylene reducing flame is used while carrying out welding on
Alloy steel
Grey cast iron
Mild steel
High carbon steel
Sub zero treatment of steel is done to
Suppress martensite transformation
Enhance its working performance in sub zero atmosphere
Reduce the retained austenite in hardened steel
Induce temper brittleness after its hardening
Globular form of cementite is formed during the __________ process.
Spheroidising
Hardening
Annealing
Normalising
Which of the following is an unconventional source of energy?
Thermal power
Hydroelectric power
Nuclear-fusion power
Solar power
Softening of hardened steel is done by its
Normalising
Tempering
Annealing
Carburising