JP5767484B2 - Silver base alloy - Google Patents

Description

  The present invention relates to a silver-based alloy that can be used for tableware, watches, glasses, jewelry, dentistry, machinery, catalysts, and the like.

  For a long time, silver has been used in jewelry and tableware, but it has been mentioned as a disadvantage that it forms a sulfide film and turns black when left in the atmosphere. When corrosion and discoloration occur, the maintenance is complicated, and it takes a lot of labor to maintain the beautiful glitter of silver.

  Thus, in the field of jewelry, nickel has been plated on silver to prevent discoloration when producing a casting. Such jewelry has been one cause of metal allergies caused by nickel. Another problem is that the plating is peeled off.

  On the other hand, silver base alloys are widely used for decorations such as accessories, tableware, dentistry, medical use, etc., for example, those shown in Patent Documents 1 and 2 below are disclosed.

  The following Patent Document 1 discloses one containing 60% by weight or more of one or more metals selected from gold, platinum, palladium, and silver.

  The following Patent Document 2 is based on silver, and at least one of Re, Re and In, Rh and Pt is 0.1 to 3.0% by mass, Cu and / or Pt and / or Ti and / or What contains 0.1-3.0 mass% of Au and / or Al and / or Ta and / or Si is disclosed.

JP-T-2004-505651 JP 2004-244727 A

  However, even the above-described silver-based alloy does not completely eliminate the problems of corrosion and discoloration as described above.

  The present invention has been made to solve the above-mentioned problems, and provides a silver-based alloy that is excellent in mechanical properties such as viscosity, toughness, ductility and aesthetics, and excellent in corrosion resistance and discoloration resistance. Objective.

In order to achieve the above object, the silver base alloy of the present invention is a silver base alloy that can be used for tableware, watches, glasses, jewelry, decoration, dentistry, medicine, machinery, and catalysts. a is indium 1 mass% to 15 mass%, palladium 1% by mass to 15% by mass or less, of gold over 0.1 wt% 5 wt% or less, platinum 0.01 wt% to 10 wt% The gist is that rhenium is 0.01% by mass to 10% by mass , copper is 0.1% by mass to less than 3% by mass, and the balance is silver and inevitable impurities .

  As a result of research to solve the above problems, the strength of the alloy structure, which is the cause of the problematic properties of silver, has been improved by the addition of rhenium and solid solution strengthening by adding gold and platinum. Improved. In addition, indium, palladium, and copper were added to improve corrosion resistance and discoloration resistance.

According to the silver base alloy of the present invention, it has excellent mechanical properties and aesthetics such as viscosity, toughness, ductility, etc., excellent corrosion resistance and discoloration resistance, tableware, watches, glasses, jewelry, dentistry, machinery, catalysts, etc. Can be used for

The discoloration test result of sample 1 is shown. The discoloration test result of sample 2 is shown. The discoloration test result of sample 3 is shown. The discoloration test result of sample 4 is shown. The discoloration test result of Sample 5 is shown.

  Hereinafter, embodiments of the silver base alloy of the present invention will be described in detail.

The silver base alloy of the present invention is based on silver and contains indium, palladium, gold, platinum, rhenium, and copper. In addition to these, including the unavoidable impurities, a spirit Rukoto which can also be allowed to contain other elements.

The content of indium is preferably 1% by mass or more and 15% by mass or less.
Indium is an effective element for imparting flexibility and discoloration resistance.
Exceeding the upper limit results in unnecessary cost increase. Conversely, if the upper limit is not reached, sufficient flexibility and discoloration resistance cannot be obtained.

The palladium content is preferably 1% by mass or more and 15% by mass or less.
Palladium is an effective element for securing mechanical properties such as durability and imparting discoloration resistance.
Exceeding the upper limit results in unnecessary cost increase. Conversely, if the upper limit is exceeded, durability and discoloration resistance cannot be sufficiently obtained.

The content of gold is preferably 0.1% by mass or more and 5% by mass or less.
Gold is an effective element for ensuring mechanical properties.
Exceeding the upper limit results in unnecessary cost increase, and conversely below the lower limit, sufficient mechanical properties cannot be obtained.

The platinum content is preferably 0.01% by mass or more and 10% by mass or less.
Platinum is an element effective not only for imparting malleability and ductility to prevent embrittlement, but also for improving workability during casting by improving surface tension and further imparting discoloration resistance.
Exceeding the upper limit results in unnecessary cost increase. Conversely, if the upper limit is exceeded, sufficient effects for preventing embrittlement and improving castability cannot be obtained.

The rhenium content is preferably 0.01% by mass or more and 10% by mass or less.
Rhenium is an element effective for reducing the crystal structure density and imparting corrosion resistance and discoloration resistance.
If the upper limit is exceeded, unnecessary cost increases, and it is extremely difficult to obtain a solid solution alloy. On the contrary, if it is lower than the lower limit, sufficient corrosion resistance and discoloration resistance cannot be obtained.

The copper content is preferably 0.1% by mass or more and less than 3% by mass.
Copper is an effective element for ensuring hardness.
Exceeding the upper limit results in unnecessary cost increase. Conversely, if the upper limit is exceeded, sufficient hardness cannot be obtained.

  By preparing each of the above elements, the silver base alloy of the present invention can be produced, for example, as follows.

(1) Powdery rhenium is wrapped in platinum foil, heated, dissolved and cooled.
(2) The metal in (1) is thinned by extending to a thickness of 0.2 mm or less with a roller.
(3) The metal in (2) is cut into 5 mm square, heated with palladium, dissolved and cooled.
(4) The metal in (3) is thinned by extending to a thickness of 0.2 mm or less with a roller.
(5) The metal in (4) is heated and dissolved together with gold and cooled.
(6) The metal (5) is thinned by extending it to a thickness of 0.2 mm or less with a roller.
(7) Add indium and copper to the metal in (6) above, heat, dissolve with mixing with a ceramic rod, and cool.
(8) The alloy of (7) is pressed with a roller and tightened.
(9) The alloy of (8) is heated and melted again.
(10) Pure silver is added to the crucible in which the alloy has been dissolved in (9) above, heated, melted and cooled to obtain the silver-based alloy of the present invention. At this time, a rainbow-colored glitter pattern can be formed on the surface.

  The silver base alloy thus obtained has a melting point of around 800 ° C., excellent handling properties such as melt castability, cutting workability, polishing workability, etc., and corrosion resistance and discoloration resistance compared to conventional silver alloys. Is outstanding.

  When casting the obtained silver base alloy, the melting point is around 800 ° C., but the casting temperature is preferably 10000 to 1600 ° C. Further, if the alloy is rapidly cooled from a temperature of 1500 ° C. or higher, the alloy may be scattered, which is dangerous. Therefore, it is preferable that the cast product after casting is not rapidly cooled. When casting by the lost wax method, the product is taken out in a stage where it is heated to 1050 to 1150 ° C. in advance and gradually cooled after casting.

  Silver base alloys of Samples 1 to 5 having the compositions shown in Table 1 below were prepared. These silver-base alloy ingots were polished with No. 800 water-resistant abrasive paper specified in JIS R6253, and then immersed in a 0.1% sodium sulfide solution for 72 hours at 40 ° C., and the state of discoloration was observed. .

FIGS. 1-5 shows the discoloration state after the test of each sample, The observation result was as follows.
Sample 1: No evidence of discoloration on the surface.
Sample 2: Discolored black after 2 hours.
Sample 3: Discolored after 24 hours.
Sample 4: Discoloration after 24 hours.
Sample 5: Discolored after 1 hour.

Claims (1)

A silver- based alloy based on silver that can be used for tableware, watches, glasses, jewelry, decoration, dentistry, medicine, machinery, and catalysts, and contains indium in an amount of 1 to 15% by weight , palladium 1 to 15% by mass , gold to 0.1 to 5% by mass , platinum to 0.01 to 10% by mass , rhenium to 0.01 to 10% by mass , copper A silver base alloy characterized by comprising 0.1% by mass or more and less than 3% by mass and the balance comprising silver and inevitable impurities .