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Lead used in various part of life
directly and indirectly. It’s biggest use in batteries specially in
Lead acid battery world wide. It is also used in ammunition (bullets
and shot), in pipes, cable, Lead sheet and others. The use of Lead
sheet in construction and Lead cable sheathing in communications
Ammunition and Metallic Lead is consumed in the manufacture of
ammunition, bearing metals, and other Lead products, with subsequent
Lead emissions. Lead used in the manufacture of ammunition is melted
and alloyed before it is cast, sheared, extruded, swaged, or
mechanically worked. Some Lead is also reacted to form Lead aside, a
detonating agent. Lead is used in bearing manufacture by alloying it
with copper, bronze, antimony, and tin, although Lead usage in this
category is relatively small. Other Lead products include terne
metal (a plating alloy), weights and ballasts, caulking Lead,
plumbing supplies, roofing materials, casting metal foil,
collapsible metal tubes, and sheet Lead. Lead is also used for
galvanizing, annealing, and plating. In all of these cases Lead is
usually melted and cast prior to mechanical forming operations.
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Lead-Acid Batteries
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The biggest use of Lead worldwide is
for the Lead-acid battery. The commonest type of Lead-acid battery
consists of a heavy duty plastic box containing Lead alloy pasted
grids. The grids are made from a Lead-antimony together with minor
additions of elements such as copper, arsenic, tin and selenium.
These are added to confer properties such as grain refinement,
fluidity and age-hardening characteristics to the grids. For the new
generation of sealed, maintenance free batteries a range of Lead
calcium-(tin) alloys is used. These contain up to 0.1% calcium and
from zero to 0.5% tin. The tin-containing alloys are used in the
positive grids to protect against corrosion. A rechargeable cell is
known as a secondary cell and provides a means of storing
electricity. Lead is particularly well suited for this application
because of its conductivity and its resistance to corrosion. The
addition of antimony or calcium gives the Lead an increased hardness
to resist the mechanical stresses within the battery caused, for
example, by the natural vibration of road vehicles and by the
chemical reactions taking place.
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Lead Sheet
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The
benefits of Lead sheet are considerable: it is rugged, flexible and
long lasting and has considerable aesthetic appeal. Around 75% of
the Lead sheet consumed by the building industry is used as
flashings or weathering to prevent water penetrating at points such
as the bases of chimney stacks and abutments. The remaining 25% or
so of the Lead sheet is used for roofing and cladding. The use of
Lead for roofing is by no means confined to traditional applications
such as churches and historic buildings; architects have been won
over to the attractive and long lasting properties of Lead sheet for
modern buildings, both for roofing and for the vertical cladding of
external walls.
By virtue of its resistance to
chemical corrosion, Lead sheet also finds use for the lining of
chemical treatment baths, acid Plant and storage vessels. The high
density of Lead sheet and its "limpness" makes it a very effective
material for reducing the transmission of noise through partitions
and doors of comparatively lightweight construction. Often the Lead
sheet is adhesively bonded to plywood or to other building boards
for convenience of handling. A particular advantage of Lead's high
density is that only relatively thin layers are needed to suppress
the transmission of sound. This makes for important space savings in
the design of large modern buildings such as hotels and office
blocks.
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Lead Pipe
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Pipe
made from Lead and Lead alloys is used for its corrosion resistance
and flexibility in the chemical industry and in plumbing and water
distribution systems.
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Cable Sheathing
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An electric cable consists essentially
of three major components:
• conductors
to transmit power or electrical signals;
• insulation surrounding the conductors to protect
users;
a sheath and other layers surrounding
the insulation to exclude moisture and protect it from corrosion and
mechanical damage during the lifetime of the cable.
Due to its excellent proven corrosion resistance when in contact
with a wide range of industrial and marine environments, soils and
chemicals, Lead was one of the first materials to be used to provide
an impervious sheath on electric cables .
Lead has the major advantage that it can be applied to the cable
core in unlimited lengths by extrusion at temperatures which do not
damage even the most sensitive conductors (optical fibers) or
insulating materials (paper or plastics). Lead is pliable and so can
withstand the several coiling, uncoiling, handling and bending
operations involved during the later manufacturing stages and
installation of the cable. A Lead sheath can be readily soldered
(again at low temperatures) when cable lengths need to be jointed or
new cables installed. With modern screw-type continuous extruders,
un jointed lengths of submarine power cables as long as 100
kilometers have been produced.
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Lead Cams
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Lead cames have long been a feature of
stained glass windows in churches and cathedrals. They consist of
H-shaped sections of Lead which hold together the individual pieces
of glass. They are now being used more widely in modern homes both
in the traditional way and in the form of self-adhesive strips stuck
on to a larger piece of glass to simulate an integral came. The use
of Lead in this manner is attractive and lends a traditional air to
a home.
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Lead-Clad Steel
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This composite material is
manufactured by cold rolling Lead sheet on to sheet steel which has
been pretreated with a thin tin-Lead alloy coating (terne plate).
This forms a strong metallurgical bond between the Lead and the
steel and provides a material that combines the physical and
chemical properties of Lead with the mechanical properties of steel.
Although primarily aimed at the sound insulation market, Lead clad
steel has also found use in radiation shielding and in the cladding
of buildings.
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Lead Powder
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Lead powder incorporated into a
plasticizer is added to plastics to form sheets of Lead loaded
plastic. This material is used to make radiation protective clothing
and aprons for the medical, scientific and nuclear industries. It
also has sound insulating properties. Lead powder is also used as
the basis for some corrosion resistant paints.
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Lead Alloys
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By far the biggest use of
Lead-antimony alloys is in batteries. Lead-antimony alloys with
antimony contents of between 1 and 12% are used widely in the
chemical industry for pumps and valves on chemical Plant and in
radiation shielding both for lining the walls of X-ray rooms and for
bricks to house radioactive sources in the nuclear industry.
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Lead for Radiation Shielding
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Lead and its alloys in metallic form
and Lead compounds are used in various forms of radiation shielding.
Their high densities meet the primary requirement of a shielding
material and in certain shielding applications Lead's high atomic
number is also important. The ease with which Lead can be worked is
of added value. The shielding of containers for radioactive
materials is usually metallic Lead. Radioactive materials in
laboratories and hospitals are usually handled by remote control
from a position of safety behind a wall of Lead bricks and X ray
machines are normally installed in rooms lined with sheet Lead. Lead
compounds are a constituent of the glass used in shielding
partitions to permit safe viewing and Lead powder is incorporated
into plastic and rubber sheeting as a material for protective
clothing.
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Lead in Glass
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Decorative Lead crystal glass is one
of the most attractive forms in which Lead is used. Normally added
in the form of Lead oxide at 24-36%, it adds luster, density and
brilliance to the glass. The glass is further enhanced by its
ability to have decorative patterns cut on it and has the
characteristic ring associated with Lead crystal. There is now a
substantial market for a cheaper form of Lead 'semi-crystal'
containing in the region of 14-24% Lead oxide and glasses are
usually molded with the decorative pattern rather than hand-cut
later.
Lead is also used in optical glasses (e.g.:
telescopes, binoculars), ophthalmic glass (e.g. spectacles),
electrical glass (e.g.: lamp tubing) and radiation protection glasses
(e.g.: for windows for radiation remote handling boxes, TV tubes)
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Lead for Ceramics
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Lead is used in a wide range of glaze
formulations for items such as tableware (earthenware and china),
wall and floor tiles, porcelain and some sanitary ware. The Lead
compounds used are largely litharge, red Lead and Lead silicates.
The advantageous properties offered by Lead compounds are lower
melting points and wider softening ranges, low surface tension, good
electrical properties and a hard wearing and impervious finish.
Considerable research effort has been put into developing glazes
with very low Lead release. Lead compounds are also used in the
formulation of enamels used on metals and glasses.
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Lead Pigments
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The use of white Lead (basic Lead
carbonate) in decorative paints has been phased out but still has
the reputation of making paint with good external weathering
characteristics,
Red Lead is the traditional pigment for rust-inhibiting priming
paints applied direct to iron and steel. Calcium plumbate based
paints are particularly effective on galvanized steel avoiding the
need for etch primers.
Lead chromate (yellow) and Lead
molybdate (red orange) are still used in plastics and to a lesser
extent paints. Lead chromate is used extensively as the yellow
pigment in road markings.
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Lead Wool
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Lead wool is made by scratching fine
strands from the surface of a Lead disc. It is used for the caulking
of joints in large pipes e.g. gas mains and in some specialist
batteries.
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