Copper-nickel alloys, properties, and applications
The basic copper-nickel alloying system is relatively simple,
improving the overall characteristics of copper in terms of strength and
corrosion resistance while maintaining high inherent resistance to biofouling. The
addition of nickel to copper increases strength and many corrosion resistance
characteristics.
Alloys with a nickel content greater than 10% and those which are
more highly alloyed with chromium, aluminum, and tin are used where greater
resistance to flow conditions, sand abrasion, wear, and seizure, as well as
higher mechanical properties, are required.
v
Features of Copper-Nickel Alloys-
·
Corrosion Resistance- 90-10 and 70-30 Copper Nickel Alloy Flanges were originally developed for naval condensers and piping. Their corrosion resistance is obtained by forming a
complex surface film which develops by interaction with the seawater itself,
thus protecting the underlying metal.
·
Biofouling – the adhesion of
slime algae, sea mosses, sea anemones, barnacles, and mollusks (oysters and
mussels) on surfaces of marine structures – can have a strong negative effect
on system performance.
·
Mechanical Properties- The addition of nickel to
copper improves the alloy's strength and durability. The mechanical properties
of copper-nickel alloys combine good tensile strength and excellent ductility
during annealing. As solid solution alloys, alloys 9010 and 7030 cannot be age-hardened. Higher tensile strength and hardness can only be achieved when the
alloys are cold worked.
·
Cryogenic Properties- Cu-Ni alloys were the first
metals used in the fabrication of low-temperature equipment for the
liquefaction and storage of cryogenic fluids. Copper and many copper alloys
retain ductility at low temperatures. Their unusual properties of retaining
ductility at low temperatures and exhibiting
good thermal conductivity are advantageous for heat exchangers and other
components in cryogenic plants and low-temperature processing and storage
equipment.
· Environmental Properties
§ 90-10
Cu-Ni is a single-phase alloy with a melting point above 1100C.
§ In the
case of a hydrocarbon fire, copper-nickel does not generate toxic fumes. It
will not show degradation in an uncontrolled manner.
§ Cu-Ni has
inherent high resistance to biofouling. Chlorination can be reduced or, in some
instances, avoided.
§ Cu-Ni can
be recycled. It can be 100% remelted and reused.
v
Application of Cu-Ni Alloy
·
Applications for
copper-nickel alloys can include condensers, coolers and other heat exchangers,
onboard seawater desalination plants, systems for compressed air, sanitary
systems, bilge, ballast water, brine, fire mains and sprinklers, fuel oil, lube
oil, warm water heating, grey and black water, hydraulic lines and tank
heating.
Comments
Post a Comment