powder metallurgy
TRANSCRIPT
Powder MetallurgyPresentation by: Nima Namvar
Introduction
•What is powder metallurgy?•What are the applications of powder metallurgy?
P/M processesProducing
Metal Powders
Additives(lubricants or
binders)
Mixing
Compaction
SinteringOptional
secondarymachining
Optional secondary finishing Finished
product
P/M processesProducing metal powders
• Metal powders are produced by mechanical or chemical methods.
• The most common method is atomization.
• Other methods: milling, mechanical alloying, electrolysis and chemical methods including reduction of oxides.
P/M processesProducing metal powders
Atomization : Atomization is perhaps the most versatile method
that produces metal powders over a wide range of production rates.
Atomization is based on breaking up of liquid into fine droplets.
Processes of P/M Producing metal powders
• After atomization the powder is screened to ensure a correct and uniform particle size distribution and then thermally processed.
• Powders can be ‘elemental’ or ‘pre-alloyed’.
P/M processesAdding additives & Mixing
After producing the powder, we add some additives such as graphite, lubricants or binders.
P/M processesAdding additives & Mixing
Porosity: After mixing , some spaces will be created between
particles of powder which are open to outside or not In order these are called open/closed porosities.
P/M processescompaction
There are several methods that range from high-pressure die compaction to pressureless methods such as slip casting.
Die compaction at high pressure is the dominant approach.
Two other common methods are CIP & HIP.
The resulting component termed a ‘green’ compact.
P/M processessintering
During sintering some bonds are created between the particles of metal powders
The temperature is below the melting point of the major constituent.
The atmosphere is protective.
P/M processessecondary mechanical operations
P/M products have a high dimensional accuracy
In some cases secondary mechanical operations are needed to achieve the final product.
P/M advantages & disadvantages
Advantages Disadvantages
1. Elimination/reduction of machining
2. High production rates3. Complex shapes can be
produced4. Wide composition variations
are possible5. Wide property variations are
possible6. Scrap is eliminated or
reduced
1. Inferior strength properties2. Relatively high die cost3. High material cost
Sources
ASM Handbook Volume 07 - Powder Metal Technologies and Applications
thelibraryofmanufacturing.com/powder_processes.html
www.gkn.com/sintermetals/technologyandinnovation/Pages/from-powder-to-part-1-material-manufacture.aspx
www.tpipm.com/powder-metal-process/