Argentium silver (originally patented in 1998) is a brand of modern tarnish-resistant
silver
Silver is a chemical element with the symbol Ag (from the Latin ', derived from the Proto-Indo-European ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, white, lustrous transition metal, it exhibits the highest electrical co ...
alloys, containing either 93.5% or 96% silver. Argentium alloys replace some of the
copper (approximately 1% of the copper and other alloys is replaced with germanium) in the traditional
sterling silver
Sterling silver is an alloy of silver containing 92.5% by weight of silver and 7.5% by weight of other metals, usually copper. The sterling silver standard has a minimum millesimal fineness of 925.
''Fine silver'', which is 99.9% pure silver, is ...
alloy (92.5% silver + 7.5% copper) with the
metalloid
A metalloid is a type of chemical element which has a preponderance of properties in between, or that are a mixture of, those of metals and nonmetals. There is no standard definition of a metalloid and no complete agreement on which elements are ...
germanium
Germanium is a chemical element with the symbol Ge and atomic number 32. It is lustrous, hard-brittle, grayish-white and similar in appearance to silicon. It is a metalloid in the carbon group that is chemically similar to its group neighbors si ...
. Argentium's patents refer to percentages of zinc and boron present in Argentium silver. Both Argentium alloys exceed the standard required for
hallmark
A hallmark is an official mark or series of marks struck on items made of metal, mostly to certify the content of noble metals—such as platinum, gold, silver and in some nations, palladium. In a more general sense, the term ''hallmark'' can al ...
ing as sterling silver and Argentium silver 960 meets the standard for hallmarking as
Britannia silver
Britannia silver is an alloy of silver containing 11 ozt 10 dwt (i.e. 11½ troy oz.) silver in the pound troy, equivalent to , or 95.833% by weight (mass) silver, the rest usually being copper.
This standard was introduced in England by Act of ...
(95.84% silver).
Origins and description
Argentium silver is the result of research by Peter Johns at the Art and Design Research Institute (ADRI), School of Art & Design,
Middlesex University
Middlesex University London (legally Middlesex University and abbreviated MDX) is a public research university in Hendon, northwest London, England. The name of the university is taken from its location within the historic county boundaries of ...
. The project began in 1990 with research on the effects of germanium additions to silver
alloy
An alloy is a mixture of chemical elements of which at least one is a metal. Unlike chemical compounds with metallic bases, an alloy will retain all the properties of a metal in the resulting material, such as electrical conductivity, ductility, ...
s. Germanium was discovered to impart the following properties to sterling silver:
*
Firescale
Firestain is a layer of oxides that is visible on the surface of objects made of metal alloys containing copper when the object is heated, as by a jeweler heating a ring to apply solder during a repair. On copper-containing alloys of gold or of sil ...
elimination
* High
tarnish
Tarnish is a thin layer of corrosion that forms over copper, brass, aluminum, magnesium, neodymium and other similar metals as their outermost layer undergoes a chemical reaction. Tarnish does not always result from the sole effects of oxygen in ...
resistance
*
Precipitation hardening
Precipitation hardening, also called age hardening or particle hardening, is a heat treatment technique used to increase the yield strength of malleable materials, including most structural alloys of aluminium, magnesium, nickel, titanium, and so ...
and simple heat-hardening properties
* Increased
ductility
Ductility is a mechanical property commonly described as a material's amenability to drawing (e.g. into wire). In materials science, ductility is defined by the degree to which a material can sustain plastic deformation under tensile stres ...
* Increased thermal and
electrical resistance
The electrical resistance of an object is a measure of its opposition to the flow of electric current. Its reciprocal quantity is , measuring the ease with which an electric current passes. Electrical resistance shares some conceptual parallel ...
(making alloys suitable for
welding
Welding is a fabrication process that joins materials, usually metals or thermoplastics, by using high heat to melt the parts together and allowing them to cool, causing fusion. Welding is distinct from lower temperature techniques such as bra ...
and laser forming)
* Environmental advantages (associated with not having to remove or plate over firescale)
Many of these properties significantly affect the traditional methods of working silver. For instance the absence of firescale eliminates tedious and time-consuming steps required by the silver worker using traditional sterling silver. It also eliminates the need for plating the final product which is often done on manufactured items because of the problems introduced by firescale. Tarnish resistance is of significant importance to both silver workers and the wearer of silver jewellery.
Argentium Silver is patented and trademarked by Argentium Silver Company, UK.
Physical properties
Traditional sterling silver has a
solidus
Solidus (Latin for "solid") may refer to:
* Solidus (coin)
The ''solidus'' (Latin 'solid'; ''solidi'') or nomisma ( grc-gre, νόμισμα, ''nómisma'', 'coin') was a highly pure gold coin issued in the Late Roman Empire and By ...
melting temperature of 802°C (1475°F) and a
liquidus
The liquidus temperature, TL or Tliq, specifies the temperature above which a material is completely liquid, and the maximum temperature at which crystals can co-exist with the melt in thermodynamic equilibrium. It is mostly used for impure subst ...
flow point of 899°C (1650°F). Argentium 935 silver has a solidus of 803°C (1477°F) and a liquidus of 903°C (1657°F), while Argentium 960 has a solidus of 905°C (1661°F) and a liquidus of 925°C (1697°F).
References
Further reading
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External links
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Argentium Silver Guild
{{Jewelry
Silver
Precious metal alloys
Jewellery making