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Nickel:
Hidden in Plain Sight
Unknown source of strength
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Humans have
been using nickel for about as long as they have been producing
metal wares. A relatively plentiful element — the 24th
most abundant on earth — nickel is found in metal ore
deposits throughout the world. The ancients prized these ores
as a source of metals with desirable properties, such as strength
and flexibility, and used them to make everything from coins
to knives, axes and weapons. However, the desirable traits
of these metal alloys were often attributed to the presence
of copper or iron. In fact, archaeologists have discerned
from ancient metal artifacts that the ‘iron’ of
early metal-using societies was actually a mixture containing
from 5 to 26 percent nickel.
Long before nickel was isolated, the ancient Chinese developed
a material called paitung (also called paktong or tutenag)
that was prized for its silvery luster and strength. According
to Chinese manuscripts, paitung was used as early as the third
century A.D. in weapons, coins and works of art. Paitung is
believed to have contained mainly copper and nickel with small
amounts of zinc and tin.
In Europe as well, nickel found its way into alloys unbeknownst
to the blacksmiths and smelters of the time. Nickel alloys
were used to produce plate and chain armors during the Middle
Ages, and the relative abundance of nickel-containing ores
made it an inexpensive way to add a fine sheen to coin currency.
But it wasn’t until nickel’s discovery in 1750
that this common metal additive was isolated and understood.
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Saxony, Germany |
Devil
of a metal
Mining activity in the Saxony region of Germany eventually
led to nickel’s discovery. In 1750 copper smelters in
Saxony uncovered a peculiar copper ore that was slightly lighter
in color than usual. When processed and refined, this ore
yielded an unusual form of copper that was particularly bright
and silvery. This strange form of copper was also found to
have distinctly different material properties. It was extremely
hard and could not be made malleable despite the repeated
attempts of the smelters. The new metal became known as Kupfernickel
which roughly translates to “copper with the Devil in
it.” The composition of this alloy was in fact very
similar to the paitung of ancient China.
Nickel — the mysterious component of Kupfernickel that
gave it these distinctive properties — was finally “discovered”
and isolated from a mineral called niccolite by the Swedish
mineralogist Baron Axel Frederik Cronstedt in 1751. The Baron,
like the Saxon smelters, had first expected to extract copper
from this mineral, but instead his procedure yielded a strong,
white metal. Unable to compare the material with any known
metal, the Baron determined that he had isolated the enigmatic
component of Kupfernickel and named the new metal “nickel”
after the Devil himself, “Old Nick.”
Nickel and dimed
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Both modern
and ancient societies have used nickel to add luster and to
reduce weight in coins and to increase their resistance to
corrosion and wear. But the practice of adding nickel to coin
alloys became more common as nations began to convert to floating
exchange rate systems in which the value of the physical material
in a coin no longer had to match its face value. As
currency exchange ceased to be linked to the gold and silver
standards, Switzerland became the first of many modern nations
to employ nickel in coins. The first pure nickel coin was
issued by Switzerland in 1881, with Austria and Hungary both
following suit in 1893.
In the late 1850’s the United States added nickel to
both its penny and five-cent piece, which previously contained
mainly copper and zinc (bronze). The word “nickel”
became a popular term for the five-cent piece itself, despite
the fact that the majority of the coin was copper (the U.S.
nickel coin of the 1800s contained 75 percent copper and 25
percent nickel). The coin was in high demand as it was a convenient
denomination for many everyday items such as beer and cigars.
The advent of slot machines and the ubiquity of nickel fares
in buses and subways also helped to spur on the popularity
of this coin. It is estimated that by 1958 the United States
had issued over 4 billion nickels.
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From meteors to machines
Even a century after the element nickel was isolated, scientists
and engineers had not fully exploited its unique material
properties. Nickel is a transition metal that forms alloys
with a host of other transition metals such as copper, zinc,
iron, silver, cadmium and chromium. It is both strong —
it resists fracture under high stress — and ductile
— it bends rather than cracking under stress. This is
a valuable combination of properties. Engineers seek this
combination of properties when designing structures like bridges,
which need to withstand heavy loads but also bend under pressure
rather than cracking.
Tales of such miracle materials have been passed down through
history. The legendary sword blades of ancient Damascus and
Arabia were widely known for their extreme strength and hardness.
Holy stones such as the black stone of the Kaaba at Mecca
were said to have magical properties, probably magnetism.
These famed weapons and holy relics are composed of iron that
fell from the sky in meteors. This meteroic iron often contains
large amounts of nickel. The ancient weapon-makers who crafted
their blades out this had stumbled upon a primitive, high-strength,
rust-resistant stainless steel alloy. It would be centuries
before the science behind these magic materials would be explained.
In the 1700s, as the Industrial Revolution dawned first in
England, and then in continental Europe and the United States,
the development of industrial equipment and steam engines
in particular spawned a search for stronger materials than
those currently available. Early material scientists developed
steel alloys to fuel this need. Steel is produced when iron
is combined with small amounts of carbon, which helps to stabilize
and strengthen iron’s crystal structure. Adding small
amounts of other elements such as zinc, chromium and nickel
increase strength, ductility, corrosion resistance and finish
of steel.
It was half a century after nickel’s discovery that
Michael Faraday — also famous for his discovery of electromagnetic
induction and Faraday’s Law, the foundation of modern
field theory — first proposed that nickel be added to
steel to enhance its material properties. In a letter to Professor
de la Rive of the Royal Institution in 1820 he wrote, “We
have been induced by the popular idea that meteoric iron would
not rust, to try the effect of nickel on steel and iron.”
Despite initial failures, Faraday was able to successfully
alloy small amounts of nickel with steel, producing materials
that were stronger yet still malleable and workable as ordinary
steel. Work continued by Swiss metallurgist J.C. Fischer in
1824 resulted in successful imitations of meteoric iron.
These early discoveries laid the foundation for advanced stainless
and structural steels made of alloys with increased corrosion
resistance and strength. Nickel-fortified steel armor was
soon used in warships during the mid- to late-1800s. Michael
Faraday’s investigations into the electrochemistry of
various metals — their willingness to interact with
electrical currents — increased nickel’s uses.
By the 1840s, metallurgists were able to plate nickel into
other metal surfaces by using an electrical current to attract
dissolved nickel salts and nickel ions to the surface of metal
electrodes. These coatings provided wear and rust resistance
for numerous products ranging from cooking utensils to plumbing
fixtures.
Fanning flames of war
During World War I the value of nickel increased dramatically
due to newfound demands for high-strength stainless steel
for guns, ammunition and vehicles. Nickel was now not only
an important component in currency but also a valuable natural
resource sought by all warring factions. In 1916, a German
submarine ran life-threatening risks while attempting to break
through the British blockade in order to obtain a small load
of Canadian nickel. The successful mission was celebrated
in the same manner as a traditional military victory; such
was the value and importance of nickel to the German war machine.
At the peak of wartime production, Canada, the world’s
premier source of nickel, produced approximately 92 million
pounds of nickel a year.
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The armistice
and later the Great Depression caused the nickel industry
to take a momentary dive between the World Wars. Production
of military equipment was down dramatically as the industrial
world refocused its efforts on consumer goods. Advancements
in the combustion engine during the 1930s, however, helped
to keep demand high for certain nickel steels desired for
their ability to resist failure at high temperatures. This
property was crucial in parts such as cylinder heads and pistons
that experience explosive pressures at very high temperatures.
The onset of World War II increased the demand for steel and
nickel once again. During the conflict the production of nickel
alloys equaled the production total over the previous 54 years.
Canada in conjunction with the British government essentially
regulated the world’s nickel market during World War
II and even placed restrictions on its use in non-essential,
consumer goods. This severely limited the amount of nickel
available to Axis powers, and nickel ore deposits soon became
a strategic concern to the Germans as a result. Military operations
were launched to bring nickel stores under German control.
The Petsamo nickel mine in Finland, previously brought to
a standstill by the invading Soviet army, was captured by
the Germans in 1940 and became a major source of steel-strengthening
nickel for the German war.
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Airplanes, jet engines and beyond
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The Wright Brothers
Biplane |
In 1903 Orville and Wilbur Wright spurred
a transportation revolution with the flight of their self-propelled
biplane, the first of its kind, in Kittihawk, North Carolina.
World War I sped the development of powered aircraft, but
pushing engineering barriers would not have been possible
without the development of new aerospace materials for structural
and engine components. To reduce burdens on propeller engines,
increase speeds and boost maneuverability airplane structures
required high-strength, lightweight alloys. The high rotational
speeds and temperatures of aviation engines also depended
on alloys that could resist deformation and failure at high
temperatures with a minimum of additional weight. Aluminum
alloys with nickel additives and traditional nickel steels
fed this need.
New feats in speed and power came from the development of
the first jet engines during World War II and into the 1950s.
These new engines created high-pressure gas jets by using
rapidly spinning turbines to compress air and eject it through
exhaust nozzles. The fast-spinning turbines reached high temperatures
and stresses and once again required new metal alloys to withstand
these forces. Nickel was used as a strengthening agent in
many of these alloys. Similar needs for stress and temperature
resistance prompted the use of nickel-containing alloys in
the burgeoning space race. Rocket engines have similar engineering
demands as jet engines due to the high temperature and pressure
of exhaust gases, and they also must endure extreme vibration
caused by the combustion of rocket fuels. The early space
industry used nickel in conjunction with other high-strength
materials like titanium to create new classes of superalloys
capable of withstanding the turbulence of space flight.
Nickel today
 Recent
studies have shown that nickel processing and refinement can
produce harmful health consequences. Research during the 1960s
showed early indications that nickel compounds such as nickel
carbonyl could cause lung tumors in laboratory rats. Later
studies conducted during the 1980s by the United States Environmental
Protection Agency (EPA) demonstrated that prolonged exposure
to high levels of nickel refinery dust, nickel carbonyl or
nickel subsulfide — all direct byproducts of nickel
refining and metals processing — could cause cancer.
Inhalation of nickel-containing fumes from welding of stainless
steel was also found to be associated with increased cancer
risk. This led to federal regulations limiting the amount
of certain nickel compounds acceptable in the workplace and
the environment.
If inhaled in certain forms at high concentrations over a
long enough period of time, nickel is indeed carcinogenic
to human beings. Modern industrial hygiene practices have
helped to curb these nickel-induced health complications.
By far the most common health-related effect of exposure to
nickel is an allergic reaction. Some people are genetically
predisposed to becoming sensitized to nickel if they directly
handle the metal often enough. Once sensitized, dermatitis
— an allergic reaction on the skin — can occur
at the site of contact, causing rashes and, in extreme cases,
asthma attacks. An estimated 5 to 10 percent of the population
is susceptible to nickel allergies.
Though nickel is used primarily in the steel industry to strengthen
and add corrosion resistance to high-quality steels, it has
found its way into a host of everyday objects. Nickel-containing
household objects include faucets, kitchen utensils, appliances,
rechargeable batteries (nickel-cadmium or Ni-Cad variety),
jewelry and of course coins. Like the ancients, most of us
probably use nickel products without even knowing it.
Peter
Ostendorp
Center
for Environmental Health Sciences
Science Writing Intern
SOURCES INCLUDE:
-Agency for Toxic Substances and Disease Registry (ATSDR). 1997.
Toxicological profile for nickel. Atlanta, GA: U.S. Department
of Health and Human Services, Public Health Service.
-Aitchison, Leslie. A History of Metals. London: MacDonald and
Evans Ltd., 1960.
-Encyclopedia of Toxicology. ed. Philip Wexler. Boston: Academic
Press, 1998.
-Gmelins Handbuch der Inorganischen Chemie. Berlin: Springer-Verlag,
1924.
-Howard-White, F. B. Nickel: an Historical Review. New York:
D. Van Nostrand Company, Inc., 1963.
-John Harte, Holdren, Schneider and Shirley. Toxics A to Z:
a Guide to Everyday Pollution Hazards. Berkley, CA: University
of California Press, 1991.
-Klaasen, Curtis D. Carasett and Doull’s Toxicology: the
Basic Science of Poisons. New York: McGraw-Hill, 2001.
-Nriagu, Jerome O. Nickel in the Environment. New York: Wiley,
1980.
-Winter, Mark. Nickel: Key
Information. 2002. The University of Sheffield. 4 September
2002.
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