UNIT 6 B
8. With the help
of neat sketch explain
atomization process for powder production.
A.Atomization
•
Produces a liquid-metal
stream by injecting
molten metal through small orifice.
The stream is broken up
by jets of inert gas, air, or water
• The particle
shape is controlled by
rate of solidification of
metal droplets
• Gas
atomization gives spheroidal
• Water
atomized gives a more irregular shape
• Produce a liquid-metal stream by injecting molten metal
through a small orifice • Stream is broken by jets of inert gas, air, or water
• The size of the
particle formed depends on the temperature of the metal, metal flow rate
through the orifice, nozzle size and jet characteristics.
9. Briefly explain
electrolysis process for
powder production.
A.
A.
Water atomization
Water jet is used instead of inertgas
Fit for high volume and low cost production Powders of average size from 150 micronto 400micron; coolingratesfrom 103 to105 K/s.Rapid exraction of heat results inirregular particle shape =>less time to spheroidizein comparison to gas atomization Waterpressure of 70MP a for fine powder sin 10 micronrange. |
Air atomization Production of high grade metal powders with spherical shape, high bulk density,
flow ability along with low oxygen content and highpurity Eg.Ni based super alloys
Controlling parameters:
(1)viscosity,surfacetension,temperature,flow rateof molten metal;(2)flowrate,velocity,viscosity of atomizing medium;(3)jetangle,
jetdistanceoftheatomizingsystem;(4)natureofquenchingmedia
|
14. Briefly explain
powder rolling process.
A.
0 comments:
Post a Comment