Which of the following components can be made by powder metallurgy technique?

1. Porous bearing

2. Filters

3. Gears

4. Turbine blades

Explanation: 

Powder metallurgy: 

• The powder metallurgy process consists of mixing elemental or alloy powder, compacting the mixture in a die and then sintering or heating the resultant shape in a controlled atmosphere.
• The powder metallurgy process enables to produce parts in final shape, thus eliminating the need for any additional machining. 

Basic steps of Powder metallurgy process:

• Production of metal powders.
• Blending and mixing of powders.
• Compaction
• Sintering
• Finishing operation

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Uses of Powder Metallurgy:

• Used for Porous bearings or self-lubrication bearings.
• Used for making filters used in the casting process.
• It is used to produce complex shaped parts which require machining when produced by other methods e.g. gears.
• Used for cutting tool and grinding wheel.
• Some components of tungsten employed in jet engines are made by powder metallurgy. 
• • Many types of hard and soft magnetic components.