Powder metallurgy

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/