posted 06-21-2000 12:37 PM            

Jeff has found a foreign manufacturer of a new composite of sterling silver. The new mix adds in Germanium. This results in a tarnish resistant sterling. To my eye it also seems brighter than regular sterling.

Jeff is testing this new silver's work ability. His test resulted in the following spoon. Which also reminds us that Jeff is an artist.

posted 06-21-2000 12:45 PM            

Germanium is named from a Latin word "Germania" meaning "Germany." Clemens Alexander Winkler discovered germanium in 1885-6 in Freiberg, Germany. He found it in silver ore (argyrodite). It is a brittle, silver-white metal, chemically intermediate between the metals and nonmetals and resembles tin.

Germanium is in the same chemical family as carbon, silicon, tin, and lead, and resembles these elements in forming organic derivatives. In 1871, the Russian chemist Dmitry Mendeleyev predicted Germanium existed. He predicted that the then unknown element germanium should resemble silicon in its properties. He suggested the name ekasilicon (symbol Es) and his predictions for the properties of germanium were remarkably close to the reality.

The element is commercially obtained from the dusts of smelters processing zinc ores, as well as recovered from combustion by-products of certain coals. A large reserve of the elements for future uses is insured in coal sources.

Germanium is used as a superconductor in electronics; window and lens component in equipment to measure infrared radiation; component of camera lenses and microscopes; in transistors; and in the phosphors for fluorescent lamps. The high index of refraction and dispersion properties of its oxide's have made germanium useful as a coating of wide-angle camera lenses and microscope objectives.

The cost of germanium is about $3/g.

posted 03-27-2006 12:14 PM            

quote:

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A FIRESTAIN FREE STERLING SILVER ALLOY
SAFETY: -

This alloy does not contain Nickel or Cadmium.

CASTING: -
For investment casting the following temperatures are recommended: -
Normal items - Flask 600̊C and Metal 1025̊C
Heavy items - Flask 300̊C and Metal 1025̊C
Neutec Users:-
Flask 630̊C, Metal 930̊C and Positive pressure
Adequate sprueing is essential in order to attain the best results. We recommend that sprues be approximately 20% heavier than normal.
Flasks should be allowed to cool for 20 minutes before being quenched.

WORKING: -
Remains fire-stain free during all normal silversmithing processes.
May be remelted for economical use of scrap.
It is softer than standard sterling silver in the annealed state and work hardens to a greater extent.
Solders used with standard sterling silver can be used with Bright Silver 925, however as it does not give the same visual aids when heated care needs to be taken to avoid over heating.
It has a melting range (solidus - liquidus) of 870̊ - 890̊C.
It can be age hardened to 120 HV by:-
Solution treating at 700̊C for 30 minutes then quenching
Ageing for 2 hours at 250̊C
As this alloy approaches its maximum hardness when reduced by 50% care needs to be taken not to overwork the metal.
This alloy also shows good resistance to tarnish.

Apecs Bright Silver 925 is available as:-

• Wire
  
• Plate
  
• Granules
  Castings

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quote:

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Ap ril 24, 2004
US Patent 6,726,877 B1

ABSTRACT
Silver alloys having properties of fire scale resistance, reduced porosity and oxide formation and reduced grain size relative to traditional sterling silver alloys and useful work hardening performance are provided, comprising about 80-99.0% by weight silver, about 0.5-6% by weight copper, about 0.02-7% by weight of a firescale resisting additive selected from one or a mixture of zinc and silicon, and about 0.01-2.5% by weight germanium. Master alloys for production of the above alloys are also provided for, having the general composition comprising, by weight, about 2.5-99.85% copper, about 0.1-35% zinc or silicon or mixtures thereof, and about 0.05-12.5% germanium.

SILVER ALLOY COMPOSITIONS
FIELD OF THE INVENTION
This invention relates to silver alloy compositions. This invention has particular reference to sterling silver alloy compositions of silver content of at least 92.5% for jewelry, flatware, coinage and other applications where a work hardening alloy is required and for illustrative purposes reference will be made to this application. However, it is to be understood that this invention could be used to produce other types of silver alloys suitable for use as for example, electrical contacts or the like.

BACKGROUND OF THE INVENTION
In general, silver as a material for the production of silver jewelry, certain coinage and the like is specified to be sterling silver comprising at least 925 parts per thousand by weight fine silver and is specified as "0.925 silver". 0.925 silver accordingly typically comprises an alloy 92.5% by weight silver, generally alloyed with copper for hardness traces of other metals as additives or impurities.

Conventional silver alloys of the 0.925 type have several disadvantages in a manufacturing jewelry and other materials engineering contexts. Principal limitations include a characteristic firescale formation tendency attributable to oxidation of copper and other metals at the surface of cast or hot worked pieces. Additionally, traditional alloys have exhibited undesirable porosity in the recast metal and less than desirable grain size properties.

Several formulations have been proposed to overcome one or the other of the aforementioned disadvantages. U.S. Pat. Nos. 5,039,479 and 4,973,446 disclose alloys of silver and master alloys for the production of such silver alloys having superior qualities over conventional alloys, and including, in addition to silver, controlled amounts of copper and zinc, together with tin, indium, boron and silicon.

The compositions exhibit reduced porosity, grain size and fire scale production, and have acquired wide utilization in silver jewelry production. It is presumed but not established that the addition of zinc to such compositions provides at least a degree of antioxidant properties to the compositions when hot worked and improves colour, thus limiting the formation of principally copper oxide based fire scale, and reducing silver and copper oxide formation resulting in formation of pores in the cast or recast alloys. Silicon appears also to function as an antioxidant, thereby reducing firescale formation.

A disadvantage of the hereinbefore described firescale resisting alloys is that the alloys exhibit poor work hardening qualities thus not achieving the mechanical strength of traditional worked 0.925 silver goods.

DISCLOSURE OF THE INVENTION
The present invention aims to provide silver alloy compositions which substantially alleviate at least one of the foregoing disadvantages. A further object of the present invention is to provide silver alloys having the desirable properties of reduced fire scale, reduced porosity and oxide formation and reduced grain size relative to traditional sterling silver alloys whilst providing improved work hardening performance over the current firescale resistant alloys. Other objects and advantages of this invention will hereinafter become apparent.
0.5-6% by weight copper;
0.02-7% by weight of a firescale resisting additive selected from one or a mixture of zinc and silicon, and
0.01-2.5% by weight germanium.

The silver content of the alloy may be selected to be in the amounts commonly specified for grading silver. For example, the alloy may comprise from about 89 to 95% by weight silver. Preferably, the alloy contains a proportion of silver required for the graded application to which the alloy is to be put, such as 0.925 silver, that is at least 92.5% by weight, for sterling silver applications and at least 90% by weight for coinage.

The copper content of the alloy may be selected according to the hardness required of the cast alloy. For example, for manufacturing jewelers, 0.925 alloy, the copper content may advantageously be in the range of from about 2.0 to 3.0% by weight.

The zinc content of the alloy has a bearing on the colour of the alloy as well as functioning as a reducing agent for silver and copper oxides. Preferably, the amount of zinc used is selected to be between about 2.0 and 4.0% by weight. The silicon content of the alloy is preferably adjusted relative to the proportion of zinc used to provide the desired firescale resistance whilst maintaining a suitable colour commensurate with the zinc content of the alloy, and may for example advantageously fall within the range of about 0.15 to 0.2% by weight.

With the foregoing and other objects in view, this invention in one aspect resides broadly in firescale resistant, work hardenable jewelry silver alloy compositions comprising:
0.5-6% by weight copper;
0.02-7% by weight of a firescale resisting additive selected from one or a mixture of zinc and silicon, and
0.01-2.5% by weight germanium.

The silver content of the alloy may be selected to be in the amounts commonly specified for grading silver. For example, the alloy may comprise from about 89 to 95% by weight silver. Preferably, the alloy contains a proportion of silver required for the graded application to which the alloy is to be put, such as 0.925 silver, that is at least 92.5% by weight, for sterling silver applications and at least 90% by weight for coinage.

The copper content of the alloy may be selected according to the hardness required of the cast alloy. For example, for manufacturing jewelers, 0.925 alloy, the copper content may advantageously be in the range of from about 2.0 to 3.0% by weight.

The zinc content of the alloy has a bearing on the colour of the alloy as well as functioning as a reducing agent for silver and copper oxides. Preferably, the amount of zinc used is selected to be between about 2.0 and 4.0% by weight. The silicon content of the alloy is preferably adjusted relative to the proportion of zinc used to provide the desired firescale resistance whilst maintaining a suitable colour commensurate with the zinc content of the alloy, and may for example advantageously fall within the range of about 0.15 to 0.2% by weight.

The germanium content of the alloy has surprisingly resulted in alloys having work hardening characteristics of a kind with those exhibited by conventional 0.925 silver alloys, together with the firescale resistance of the hereinbefore described firescale resistant alloys. In general, it has been determined that amounts of germanium in the alloy of from about 0.04 to 2.0% by weight provide modified work hardening properties relative to alloys of the firescale resistant kind not including germanium. However, it is noted that the hardening performance is not linear with increasing germanium nor is the hardening linear with degree of work.

Preferably, the alloy also includes rheology modifying and other additives to aid in improving the castability and/or wetting performance of the molten alloy. For example, about 0.0 to 3.5% by weight of a modifying additive selected from one or a mixture of indium and boron may be advantageously added to the alloy to provide grain refinement and/or reduce surface tension, thereby providing greater wettability of the molten alloy. Where used, preferably the amount of boron utilized in the composition is from about 0 to 2% by weight boron and/or about 0 to 1.5% by weight indium. Other alloying elements may be added such as gold, tin or platinum. Where tin is included in the composition, this may be advantageously used up to about 6% by weight, and is preferably utilized in an amount of from about 0.25 to 6%.

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posted 03-27-2006 12:33 PM            

I was reading that among many other uses (i.e., electronics) germanium is also used in optics. This got me to thinking that germanium must have a degree of clarity to be used in optics. And since germanium seems to be the key to making the tarnish resistant silver, could it be electroplated onto 925 silver? I am wondering if this would help the surface of antique silver not to bind with sulfur thereby preventing tarnishing?

I am just wondering....

posted 03-27-2006 07:01 PM            

But personally I would never plate anything onto an antique piece of silver....