Presented by:

1. Anas Hanif2. Ahmed Mazher3. Syed Tanveer4. Umair Tariq

Batch: 2012-13

POWDER METALLURGY is

the art of producing metal powders and using them to make serviceable objects.

Importance of Powder Metallurgy

A cost effective method. Source of high performance. For improved product quality Saves valuable raw material Saves natural resources

Advantages of Powder Metallurgy

Elimination/reduction of machining High production rates Complex shapes can be produced Wide composition variations are possible Wide property variations are possible Scrap is eliminated or reduced

History of Powder Metallurgy

Iron powder metallurgy existed in Egypt as early as 3000 B.C, the smiths of India produced the famous “Delhi Iron Pillar", weighing about 6.5 tons, and other objects even larger as early as 300 A.D.

Major historical developments in Powder Metallurgy:

THREE MAJOR STEPS:

Blending and mixing.

Compaction.

Sintering.

Compaction

1. Blending and MixingBlending:

Blending is the process of mixing powder of the same

chemical composition but different sizes.

Mixing:

Mixing is the process of combining powders of

different chemistries.

2- Compaction:Compaction is a pressing process. Blended powders are pressed in

dies under high pressure to form them into the required shape. The

word part after compaction is called a green compactor simply a

green, the word green means not yet fully processed.

Compaction includes the following processes:

Cold Isostatic pressing.

Hot Isostatic pressing.

Continuous compaction.

Forging or extrusion.

Slip casting.

I. Cold Isostatic Pressing:

Placement of powder in flexible rubber mold.

Hydrostatic pressurization in chamber by water.

Most common pressure of 400 MPa.

2- Slip Casting:

It involves the following steps:

Preparation of slip (powder suspended in liquid and additives).

Keeping slip in mold made up of slip absorbing material.

Formation of slip casting.

Removal of slip followed by drying operation.

3. Hot Isostatic Pressing:

In hot isostatic pressing powder container is usually made up of high melting point sheet

metal.

Pressurizing media: Inert gas.

Common condition: 100 MPa, 1100C.Advantages:

compacts of 100% density,

good metallurgical bonding,

good mechanical properties.

Limitations:

wider dimensional tolerances,

greater cost and time.

4-Continuous Compaction :

Applied to simple shapes (rod, plate, sheet, tube).

Flowing loose powder between a set of vertically

oriented rolls at much lower speed.

5-Forging Or Extrusion:

It involves the following steps:

Canning of powder.

Heating or evacuation of sealed container followed by forging or evacuation.

Mechanical or chemical remover of container material.

Sintering is the major process in powder metallurgy. Every product is necessary to be sintered .

It is a process in which small particles of a material are bonded together by solid state

diffusion.

Achieving high strength. Achieving good bonding of powder particles. Producing a dense and compact structure. Producing parts free of oxides. Obtaining desired structure and improved

mechanical properties.

The six common mechanisms are:

1-Surface diffusion – Diffusion of atoms along the surface of a particle

2-Vapor transport – Evaporation of atoms which condense on a different surface

3-Lattice diffusion from surface – atoms from surface diffuse through lattice

4-Lattice diffusion from grain boundary –atom from grain boundary

diffuses through lattice

5-Grain boundary diffusion – atoms diffuse along grain boundary

6-Plastic deformation – dislocation motion causes flow of matter

Sintering Furnace

• Temperature,• Time,• Controlled Atmosphere.

EXTENSIVE USE IN

AUTOMOTIVE & AEROSPACE

INDUSTRY.

THE RESEARCH PAPER NAMED :

Central South University, State Key Lab for Powder Metallurgy, Changsha, Hunan China .

A new Powder Metallurgied Titanium Composite was developed and its mechanical properties were determined. The composite was based of Ti-Al-Mo-Fe. In order to increase the wear resistance and high temperature strength, TiC was reinforced in the matrix. After tests, it was found that Powder Metallurgied Ti-composite superseded the mechanical properties of cast Ti alloy.

A simulated engine valve test revealed thatthe wear resistance properties of composite was higher than cast

Ti-alloy even at a great 800 ℃

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