How metal powder is prepared

How metal powder is prepared

Cu, Fe base are used in powder metallurgy of the stainless steel, tungsten, nickel, silver etc.

1) Atomisation- Forcing molten metal as it comes into the stream here the metal is solidifing in small parts. powder here produced are of spherical in shape and have a layer of oxide on it. High a,mount6 of pressure is used and in water jet system but in air jet the oxidised particles are not acceptable but inert gas can be used that process is called gas atomisation.This metal powder producing is called Rapid solidification technology (RST).

2) Reduction processs- Hydrogen is used in this process, it combine with oxygen and then removed after combination. Iron, tungsten, nickel, cobalt, molybdenum powder are produced here.

3) Electrolysis - This process is applied and the powder part is needed is deposited.

4) Milling and grinding pulverisation method- In this process the small particles are crushed and powder is made in this process. This is also used for making malleable and ductile metals.

5) Shotting - Dropping the molten metal in water producing those particles for further crushing of that particles to produce powder.

6) Machining - Mainly used for producing magnesium, beryllium particles vapour condensation and granulation are also used n this process and this consist of rapid stirring of molten metal while it is cooling.

 Characteristics of metal powders are :-

a) Particle shape

b) Particle size and distribution

c) Apparent density (specific gravity)

d) Flow rate or flowability

e) Compressibility

f) Purity

g) Sintering ability

h) Entering ability

<> Processing of Powder-

These are of two types

: PRIMARY PROCESS

: SECONDARY PROCESS

First of all we will talk about Primary process-

* Blending or mixing - Mixing is done here of some materials and many non  metallic particles are added to some of the materials.

* Briquetting or Compacting - Concerting of the loose powder into green tis is done in steel dies and punches.

* Presintering - Heating the green compact, during blending removal of lubricant to increase green compact.

* Sintering - Strength of particles are increased.

Now talking about Secondary process

* Sizing

* Coining

* Machining

* Infiltration

* Impregnation

* Plating

* Heat treatment