21. Powder metallurgy is used to produce
22. Which of the following has maximum penetrating power?
23. Match the powder production technique given in Group I with the corresponding shape listed in Group II.
Group-I
Group-II
P. reduction
1. Flaky
Q. Gas Atomization
2. Spongy
R. Milling
3. Dendritic
S. Electrolysis
4. Spherical
| Group-I | Group-II |
| P. reduction | 1. Flaky |
| Q. Gas Atomization | 2. Spongy |
| R. Milling | 3. Dendritic |
| S. Electrolysis | 4. Spherical |
24. When load is applied to a material, instantaneous strain develops with
25. Coating of zine over steel is known as
26. What is the theoretical requirement of air (in m3 at STP) for the complete combustion of 100 m3 (at STP) of a fuel consisting of pure CH4? Assume that air contains 21 vol.% of oxygen.
27. The temperature field od a slab is given by T = 400 - 50z exp (-t-x2-y2). The temperature gradient in y-direction is
28. Match the following materials with the method most commonly used for making their powders.
A. Nickel
1. Carbothermic reduction
B. Tungsten
2. Inert gas atomisation
C. Silicon carbide
3. Oxide reduction
D. Super alloys
4. Carbonyl process
| A. Nickel | 1. Carbothermic reduction |
| B. Tungsten | 2. Inert gas atomisation |
| C. Silicon carbide | 3. Oxide reduction |
| D. Super alloys | 4. Carbonyl process |
29. Alloy powders manufactured by the following process have spherical shapes:
30. The steady state temperature profile of a rectangular sheet of metal inside a furnace can be obtained by solving the following partial differential equation;
$$\frac{{{\delta ^2}T}}{{\delta {x^2}}} + \frac{{{\delta ^2}T}}{{\delta {y^2}}} = 0$$
The number of boundary conditions needed to solve this equation are:
$$\frac{{{\delta ^2}T}}{{\delta {x^2}}} + \frac{{{\delta ^2}T}}{{\delta {y^2}}} = 0$$
The number of boundary conditions needed to solve this equation are: