Application of Refractory Metals and Alloys

8/12/2019 Application of Refractory Metals and Alloys

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PPLIC TION OF REFR CTORY MET LSND LLOYS

Submitted To: Submitted

By: AJAY KUMAR LAKKAM(101101122)

Mr.Arvind Jaiswal


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CONTENTS

WHAT ARE REFRACTORIES AND REFRACTORY

METALS

APPLICATIONS-IN GENERAL

SPECIFIC APPLICATIONS

1. Molybdenum

2. Tungsten

3. Niobium4. Tantalum

5. Rhenium

PLANSEE (one of the manufacturers of refractoryroducts


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ALUMINO-SILICATE REFRACTORIES

SILICA BRICKS

MAGNESITE-CHROMITE

CARBON

SPECIAL REFRACTORIES

EMERGING TRENDS


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WHAT ARE REFRACTORIES AND REFRACTORY METALS?

Refractories are material having high melting

points, with properties that make them suitable

to act as heat-resisting barriers between high

and low temperature zones.

These are generally manufactured based on one

or more of the following:

1. Process Parameters

2. Quality Characteristics

3. Best technique for engineering and application.


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Refractory metals are a class of metals that areextraordinarily resistant to heat and wear.

The most common definition includes 5 elements :Niobium(Nb),

Molybdenum(Mo),

Tantalum(Ta),

Tungsten(W),

Rhenium(Re).

Another wider definition includes

Titanium(Ti)

Vanadium(V)

Chromium(Cr) etc.


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APPLICATIONS- IN GENERAL

Refractory metals and their alloys are used in :

a) Lighting

b) Toolsc) Lubricants

d) Nuclear reaction control rods(as catalysts)

e) Chemical reaction vessels in corrosiveenvironments

f) High temperature furnace products


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SPECIFIC APPLICATIONS

1. Molybdenum Alloys Mo-based alloys are cheaper than superior W-

alloys. Most widely used alloy of Mo is Titanium-Zirconium-Molybdenum (TZM).

Composition of TZM : 0.5% Ti, 0.08% Zr and the rest

Mo. Major uses include:

a) Die inserts for casting aluminium, magnesium, zinc,and iron

b)

Rocket nozzlesc) Die bodies and punches for hot stamping

d) Tools for metalworking (due to the high abrasion andchatter-resistance of TZM)

e) Heat shields for furnaces, structural parts, and

heating elements


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Its excellent anti-friction properties lead to itsincorporation in greases and oils where reliabilityand performance are critical.

Automotive constant-velocity joints use greasecontaining Molybdenum.

Mo is used in mercury wetted reed relays as itdoesntform amalgams.

It is widely used as a strengthening alloy for steel.The major use for molybdenum is as an alloying

agent for alloy and tool steels, stainless steels, andnickel-base or cobalt-base super-alloys to increasehot strength, toughness and corrosion resistance.


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Molybdenum is important in the missile industry,where it is used for high-temperature structuralparts, such as nozzles, leading edges of controlsurfaces, support vanes, struts, re-entry cones,heat-radiation shields, heat sinks, turbine wheels,and pumps.

In the electrical and electronic industries,

molybdenum is used in cathodes, cathode supportsfor radar devices, current leads for thoriumcathodes, magnetron end hats, and mandrels forwinding tungsten filaments.


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2. Tungsten Alloys

Upto 22% Re is alloyed with W to improve itshigh temperature strength and corrosion

resistance.

Thorium as an alloying element is used when

electric arcs are to be established.

Tungsten wire filaments provide the vastmajority of household incandescent lighting and

are also common in industrial lighting as

electrodes in arc lamps.


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Tungsten high melting point makes tungsten a

good material for applications like rocket

nozzles, for example in the UGM-27 Polaris.

It is used in balance weights for planes and

helicopters or for heads of golf clubs.

In the Gas tungsten arc welding (TIG)equipment

uses a permanent, non-melting electrode. The

high melting point and the wear resistanceagainst the electric arc makes tungsten a

suitable material for the electrode.


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3. Niobium alloys

Niobium is unique in that it can be workedthrough annealing to achieve a wide range of

strength and elasticity, and is the least dense of

the refractory metals.

It can also be found in electrolytic capacitors and

in the most practical superconducting alloys.

Niobium can be found in aircraft gas turbines,

vacuum tubes and nuclear reactors.


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4. Tantalum alloys

Tantalum is one of the most corrosion resistantsubstances available and is widely used in themedical and surgical fields, and also in harshacidic environments.

It is also used to make superior electrolyticcapacitors. Tantalum films provide the secondmost capacitance per volume of any substance

after Aerogel, and allow

miniaturization ofelectronic components and circuitry. Cellularphones and computers contain tantalumcapacitors.


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5. Rhenium alloys

Rhenium is useful as an alloy to other refractorymetals, where it adds ductility and tensile

strength.

Rhenium alloys are being found in electronic

components, gyroscopes and nuclear reactors.

Rhenium finds its most important use as acatalyst. It is used as a catalyst in reactions such

as alkylation, dealkylation, hydrogenation and

oxidation.


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PLANSEE

PLANSEE is the leading manufacturer of powder-

metallurgically processed refractory and special

metals.

Application Fields of PLANSEE Materials:

a) Sintering of metals and ceramics

b) Powder processing (calcining, reduction,

agglomeration)

c) Brazing, high-temperature annealing and heattreatment

d) Metal injection moulding (MIM)


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e) Annealing of stainless and electrical steel in N2/H2

atmospheresf) Aerospace including maintenance, repair and

overhaul (MRO)

g) Medical technology

h) Electronics and semiconductor industries

i) Lighting industry

j) Production of nuclear fuel

k) Thermal waste treatment

l) Research and development


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The unique properties of PLANSEE materials make

them indispensable to many industries such as:

-Lighting Industry

- Electronics- Coating Technology

- Medical Technology

- Power Technology

- Material and Processing Technology


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Spreader for AI wheel casting made

of PLANSEE material


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TZM hot runner nozzles


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High temperature vacuum batch

furnace


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W-Cu plasma spray nozzles and

electrodes


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ALUMINO-SILICATE REFRACTORIES

1) Firebricks

These appear in Blast furnace stack, bosh&

hearth and in ladles. They appear in the open-

hearth wherein they fill the checkers.

They appear in small furnaces in foundaries, non-

ferrous industries and in steam-raising plants.


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2) High Alumina Bricks

Mullite(70-73% alumina) is used to line the bosh ofhe blast furnace.

Sillimanite and andalusite are used in lower stack

of blast furnace.

Mullite and andalusite are incorporated in the upper

course of checker work in regenerators and cowper

stoves.

Non-ferrous metallurgical applications includebrass melting reverberatories, lead drossing

reverberatories and aluminium smelting furnaces.


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SILICA BRICKS

It is used in construction of certain structures suchas roofs of open-hearth steel-making furnaces andwalls of coke-ovens. It can withstand compressive

forces in an arched roof at temperatures up to1873K.

It is used in some small acid electric arc furnaces

and small foundry cupolas.

It is used in the domes and upper checker work ofCowper stoves.


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4) Chromite

It is used as a single neutral course b/w the basic

walls and acid roof of a basic open-hearth furnace.

It also protects firebricks and silica.

5) Magnesite-Chrome

These are the most highly developed basic bricks

and are used in basic open-hearth furnace in gasuptakes and burner zones.

These can also be used in electric steel furnaces

and in hearths of soaking pits.

In non-ferrous extraction they are used in copper

reverberatories.


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CARBON

Both Carbon and Graphite are used as electrodesin arc furnaces and in electrolysis plants such as for

producing aluminium.

Carbon is also used as an electrical resistor in

resistance furnaces, in the form of rods or tubes oras granules.

These bricks are used in iron blast furnaces,

especially in hearth. These are used as linings forfurnaces making Phosphorus, calcium carbide,

aluminium and magnesium.


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SPECIAL REFRACTORIES

Alundum cement is useful mixture of fusedalumina and clay which can be water-tempered and

hand-moulded to any shape for laboratory uses.

Laboratory alumino-silicates Porcelains andmullites are used as insulators e.g. On

thermocouples and electric heating elements.

Laboratory silica available as Vittreosilis used for

replaceable thermocouple sheaths for use up to

steel bath temperatures.


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Magnesia is made into crucibles for melting pure

metals.

Zirconia is particularly useful for containing

refractory alloys and is used as nozzles through

which steel flows in continuous casting equipment.

Zircon is used in glass industry, in foundaries as a

moulding sand, in the re-melting of aluminium. Silicon Carbide or Carborundum is used in form of

tubes in recuperators and in bars or spiral form as

electric resistors.

Beryllia (BeO) is mainly used for crucibles for

obtaining very pure metals. It is also used as

radiation shield in carbon resistance furnaces.


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Refractory lining of a furnace

arch


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Refractory walls of a furnace

interior with burner blocks


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EMERGING TRENDS

Refractory has undergone many changes to meet

the diversified requirements of the industryparticularly steel industry.

The main objective is to increase the lining life atreduced cost by developing:

a) High quality refractory for critical applications insteel making at e.g. slag line, impact area of moltensteel stream, bottom tuyere refractory in hybridblowing, immersion nozzles in continuous costingetc. In this connection mention may be made ofsome refractory like MgOC, Al2O3 Si C C, MgOCa O C, Al,Mg and AlSi alloy stabilized MgO C brick, zircon based refractory, and Al2 O3 C


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b) Repairing methods like slag splashing, slagcoating, hot patching, gunning (flame gunning

involves melting and spraying on hot surface).

c) Monolithic refractory


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THANK YOU

Documents

Application of Refractory Metals and Alloys