Topics Lecture (h)

Introduction: Development and Scope of powder metallurgy 1Production of metals and ceramic powder: Mechanical, Physico-chemical and advanced methods.

Microstructure control in powders – Conventional (Alloying, Kinetics, etc) and advanced technology (Rapid solidification, nano-scale, etc)

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2

Characterization of powders: Chemical composition, structure, morphology, size and their determination, Powder flow, compressibility, porosity, apparent and tap density mearurements.

Treatments of powders/tailoring powders for shaping and consolidations – Mechanical, thermal and chemical processes.

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3

Modern methods of powder consolidations – Conventional pressing, CIP, Injection molding, Binder assisted processing. Theory of compaction: parametric relationship, characteristics and compaction technology, compact characterizations. Tooling: Types of presses, die design and alternative pressing technologies.

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Sintering: Fundamental theory – solid state, liquid phase and related sintering processes, Sintering furnaces, atmospheres and practical operations.

Full density processing – enhanced sintering, infiltrations, hot and cold consolidations, spray forming.

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Finishing operations – Repressing, Machining, Heat treatment, Joining, Surface treatments, Inspections.

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Sintered Products – Properties and their applications : Structural, Controlled porosity, Refractory materials, Electrical, Hard materials, Bearing, filters, Friction applications, Magnetic, Thermal, High temperature, Wear, High and low density applications, Composites.

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TOTAL 46

PROCESSING BY POWDER METALLURGY TECHNIQUES

In Addition: Some tutorial classes

Recommended Books:1.Powder Metallurgy Science – R. M. German2.Fundamentals of Ceramic Powder Processing and Synthesis – Terry. A. Ring3. Powder Metallurgy: Science, Technology and Materials – A. Upadhyaya and G. S. Upadhyaya

POWDER METALLURGYPOWDER METALLURGY

. . . is a forming techniqueEssentially, Powder Metallurgy is an art & science of producing metal or metallic/alloys/ceramic powders,

and using them to make finished or semi-finished

products for engineering/other applications.

Particle Size ≤ 1µmNano-powder < 100 nm

Science and Engineeringof Metal

. . . particulate technology is probably the oldest forming technique known to man

There are archeological evidences to prove that the ancient man knew something about it . . .

POWDER METALLURGYPOWDER METALLURGY

History of it

How did Men make iron in 3000 BC?

Did they have furnaces to melt iron?

IRON Metallurgy >

Quite unlikely, then how ???

Crushed iron ore with charcoal were heated together in a furnace, with air blasts,

and the reduced material, which would then be spongy, used to be hammered to a solid or to a near solid mass. STILL USED TODAY — DRI

Example: The IRON PILLER at Delhi

POWDER METALLURGYPOWDER METALLURGY

The art of pottery, (terracotta), was known to the pre-historic man (Upper Paleolithic period, around 30,000 years ago)!

Going further back in Time . . .

Dough for making bread is also a powder material, bound together by water and the inherent starch in it. Baked bread, in all its variety, is perhaps one of the first few types of processed food man ate.

(Roti is a form of bread.)

History of itPOWDER METALLURGYPOWDER METALLURGY

An important point that comes out :

The entire material need not be melted to fuse it.

The working temperature is well below the melting point of the major constituent,

It began with Platinum technology about 4 centuries ago (La Tolita, an ancient archaeological site showed the presence of Pt metallurgy in ~ 100-200 AD) … in those days, Platinum, [mp = 1774°C], was "refractory", and could not be melted.

Making it a very suitable method to work with refractory materials, such as: W, Mo, Ta, Nb, oxides, carbides, Nitrides, silicides, etc.

POWDER METALLURGYPOWDER METALLURGY

Renaissance of P/MThe modern renaissance of powder metallurgy began in the early part of last century, when technologists tried to replace the carbon filament in the Edison lamp. Franjo Hanaman and Aleksandar Just made world's first applied electric light-bulb with a metal filament (tungsten) in 1904 (Hungarian Patent #34541).

The commercially successful method was the one developed by William Coolidge. He described it in 1910, and got a patent (US#1,082,933) for it in 1913.

This method is still being used for manufacturing filaments.

Renaissance of P/MThe Wars and the post-war era brought about huge leaps in science, technology and engineering.

New methods of melting and casting were perfected, thereby slowly changing the metallurgy of refractory materials.

P/M techniques have thereafter been used only when their special properties were needed.

P/M Applications► Electrical Contact materials► Heavy-duty Friction materials► Self-Lubricating Porous bearings► P/M filters► Carbide, Alumina, Diamond cutting tools ► Structural parts► P/M magnets► Cermets

► and many more . . . such as Hi-Tech parts…

Hi-Tech Applications of P/MHi-Tech Applications of P/M Anti-friction products Friction products Filters Make-Break Electrical Contacts Sliding Electrical Contacts Very Hard Magnets Very Soft Magnets Refractory Material Products

Hard and Wear Resistant Tools Ferrous & Non-ferrous Structural

parts Etc . . .

THESE COMPONENTS ARE USED IN AIR & SPACE CRAFTS, HEAVY MACHINERY, COMPUTERS, AUTOMOBILES, etc…

P/M Merits :o The main constituent need not be meltedo The product is porous - [ note : the porosity can be controlled]o Constituents that do not mix can be used to make composites,

each constituent retaining its individual propertyo Near Nett Shape is possible, thereby reducing the post-

production costs,therefore, precision parts can be produced

o The production can be fully automated,therefore, Mass production is possible

Production rate is high Over-head costs are low Break even point is not too large Material loss is small

and Control can be exercised at every stage

P/M Disadvantages :o Porous !! Not always desired.

o Large components cannot be produced on a large scale [Why?]

o Some shapes [such as?] are difficult to be produced by the conventional p/m route.

WHATEVER, THE MERITS ARE SO MANY THAT P/M, AS A FORMING TECHNIQUE, IS GAINING POPULARITY

P/M Summarizing :Powder Metallurgy is sought when -

a) It is impossible to form the metal or material by any other technique

b) When p/m gives unique properties which can be put to good use

c) When the p/m route is economical

There may be over-lapping of these three points.