Addition of silicon to cast iron
Promotes graphite module formation
Improves its ductility
Does not promote graphite flakes formation
Increases the fluidity of molten metal
Correct Answer :
D. Increases the fluidity of molten metal
Related Questions
The hardenability of steel decreases with
Decrease in dislocation density
Increase in solutionising temperature
Increase in strength
Decrease in grain size
Absolute zero pressure can be attained at a temperature of
0°C
50°K
0°R
None of these
Pick out the wrong statement.
Both annealing and normalising release the internal stresses of the material besides improving the mechanical properties
Low carbon steel does not respond to the heat treatment for hardening of the material, hence it is subjected to case hardening or surface hardening processes like cyaniding, carburising, nitriding etc., which produces high carbon outer layers resulting in increase of surface hardness
Induction hardening and flame hardening techniques are also used for surface hardening
Martempering of a material is a hardening process
Heat flow across a hollow sphere of inner radius 'r1' and outer radius 'r2' is directly proportional to
(r2 - r1)/r1. r2
r1. r2/(r2 - r1)
(r2 + r1)/r1. r2
r1. r2/(r2 + r1)
Minimum thermal efficiency of a steam boiler may be around __________ percent
25
45
65
20
Limestone addition in the blast furnace is done to flux __________ present in the raw materials.
SiO2
Al2O3
MnO2
P
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
Maximum change in the hardness of martensite occurs in the carbon content range of __________ percent in steel.
0.01 to 0.10
0.2 to 0.4
0.5 to 0.7
0.8 to 1.0
__________ furnace is generally used in the non-ferrous foundries.
Direct arc
Indirect arc
Resistance
Induction
Carbon supply in pack carburising process is in the form of
Charcoal
Calcium carbide
Hydrocarbon oil
Graphite
Gage pressure within a spherical droplet of a fluid is 'p'. What will be gage pressure within a bubble of the same size & of the same fluid?
p
2 p
0.5 p
0.25 p
For grinding of softer materials, the grinding wheel should have __________ grain size.
Finer
Coarser
Medium
Any type of
Pick out the wrong statement.
Seam welding, projection welding & spot welding are the classification of electrical resistance welding
Electrode tip in spot welding is of copper and the tip diameter should be equal to t (where, t = plate thickness to be welded)
In spot welding, two pieces to be joined are overlapped and placed between two electrodes
Mild steel sheet cannot be spot welded
Transformer cores are normally made from
Soft ferrites
High purity iron
Grain oriented Fe-Si alloy
Al-Ni-Co alloy
Which of the following properties of a solid is not dependent on crystal imperfection?
Ductility
Semi-conductivity
Melting point
Yield stress
Thermal diffusivity of a substance is proportional to (where, k = Thermal conductivity)
1/k
k
k2
1/k2
In chemical dehumidification of air
Both specific humidity & dry bulb temperature increases
Both specific humidity & dry bulb temperature decreases
Specific humidity decreases & dry bulb temperature increases
Specific humidity increases & dry bulb temperature decreases
Cemented carbide tools are not suitable for cutting
Aluminium
Brass
Cast iron
Steel
Nusselt number/Biot number varies
Inversely with thermal conductivity
Directly with heat transfer co-efficient
Directly with thermal conductivity
Inversely with the dimension of the solid
Exposure to __________ accelerates the degradation of plastics.
Ultraviolet radiation
High atmospheric temperature
High ambient temperature
Damp atmosphere
The underground well of a biogas plant is called the
Septic tank
Oxidation well
Digestor
Lagoon
In case of water (Prandtl number ≈ 6) flowing over a flat plate heated over the entire length, the thermal boundary layer thickness as compared to hydrodynamic boundary layer thickness is
Less
More
Equal
Unpredictable
Young's modulus of a material is the measure of its
Stiffness
Malleability
Creep resistance
Tensile strength
Spark plug is provided in a/an
Engine having carburettor
Diesel engine
Compression ignition engine
Both (B) & (C)
The value of 
for air & most common gases can be safely assumed to be
0.8
1
1.4
1.8
Out of the following, maximum temperature drop for a given heat flow & for the same thickness will be in the case of
Steel
Glass wood
Copper
Fireclay bricks
Which of the following fastening devices has its both ends threaded?
Bolt
Stud
Set screw
Split nut
Brittleness induced due to the presence of sulphur in steel can be reduced by adding
Manganese
Magnesium
Vanadium
Copper
Which of the following phenomenon will exhibit the minimum heat transfer?
Boiling
Forced convection in air
Free convection in air
Conduction in air
Silicon percentage in silicon steel used for electrical equipments is about
1
4.0
8
14