Question

1. Describe the movement of powder particles during compaction in powder-metallurgy process. What features are responsible for the fact that powder does not flow and transmit pressure like a liquid?

Answer 1

Powder metallurgy is a fabricating method , it is a solid state fabricating method . In this we use 2 or more metal powder Their are 4 Basic process that are involved in powder metallurgy process that are listed below :

1. Manufacture of Powder
2. Blending or Mixing of Powder particles
3. Compacting
4. Sintering

In Powder Metallurgy we are required to obtain metal powder with given amount of purity and fineness , then these particles are then treated under high pressure in die with the help of a press (this is called as die compaction) , so as to develop cohesion amongst them which makes them stick to each other .This compacted powder state is termed as green state which needs to be handled carefully .Then comes the process of sintering of particles which are compacted so as to diffuse them with one and another at high temperature which would bring about growth of inter granular grains which would helps them in sticking together and forms a solid block . This is what comes under primary operations , secondary operations consists of sizing , finishing , machining and finally inspection . All these process brings about changes in its strength and mechanical properties . This is done to achieve desired results or configurartions .

POWDER COMPACTION TECHNIQUES :

• Pressure Techniques it involves Forging methods , Die pressing , Extrusion Methods
• Non Pressure Techniques it involves gravity methods , slip casting

FLOW CHART FOR THE COMPLETE PROCESS :

METAL POWDERS BLENDING 1. COLD COMPACTION SINTERING

SECONDARYOPERATIONS

  2. HOT COMPACTION   

FEATURES FOR POWDER METALLURGY WHICH DOES NOT FLOW AND TRANSMIT PRESSURE LIKE LIQUID DOES :

1. Various Metal which can not be processed by other methods are done by powder metallurgy. For Ex Tungsten
2. It helps in producing parts with metals which are hard to metal or it can`t be melt .
3. The metals which don`t make alloys with other metals can use this method .
4. This method can be used for metals having different melting points and varying densities .

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