Tin alloys, cast iron products, and plastically processed products

Abstract

The present invention provides a tin-gold alloy that has a silvery-white metallic luster, flexibility, oxidation resistance, and corrosion resistance, as well as improved tensile strength. [Solution] A tin-gold alloy consisting of 90% to 99% by mass of tin, 1% to 10% by mass of gold, and the remainder being unavoidable impurities.

Description

Technical Field

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[0001] The present invention relates to a tin-gold alloy, a casting, and a wrought product.

Background Art

[0002] Tin has a silver-white metallic luster, a low melting point, and is resistant to oxidation and corrosion. Therefore, it has been used as a material for ornaments, tableware, etc. since ancient times. However, tin with a purity close to 100% is very soft, and this property has been regarded as a disadvantage in that it is easily deformed and damaged when made into a product. In addition, since high-purity tin is sticky and has poor workability, generally, a tin alloy with improved workability by adding metals such as antimony, lead, and copper is used.

[0003] On the other hand, as a technique using an alloy of gold and tin, a gold-tin alloy solder paste in which a solder powder particle surface is coated with a metal other than a gold-tin alloy, a rust preventive, or a chelating agent has been reported in a gold-tin alloy solder paste obtained by mixing a flux and a gold-tin alloy solder powder (see, for example, Patent Document 1). And it has been reported that as the gold-tin alloy, an alloy blended in a ratio of 70 to 85% by weight of gold content and 15 to 30% by weight of tin content is preferable.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] An object of the present disclosure is to provide a tin-gold alloy having a silver-white metallic luster, flexibility, oxidation resistance, corrosion resistance, and improved tensile strength.

Means for Solving the Problems

[0006] The means to solve the aforementioned problem are as follows: <1> Tin with a mass of 90% to 99% or less, Gold in an amount of 1% to 10% by mass, The remaining unavoidable impurities make up this tin-gold alloy. <2> The tin content is 95% by mass or more and 98% by mass or less. The gold content is 2% by mass or more and 5% by mass or less, <1> It is the tin-gold alloy described in [reference]. <3> The aforementioned tin-gold alloy for decorative purposes. <1> or <2> It is the tin-gold alloy described in [reference]. <4> The aforementioned <1> from <3> It is a casting made of a tin-gold alloy as described in any of the following. <5> The aforementioned <1> from <3> It is a plastically formed product made of a tin-gold alloy as described in any of the above. [Effects of the Invention]

[0007] The tin-gold alloy of this disclosure provides a tin-gold alloy that has a silvery-white metallic luster, flexibility, oxidation resistance, and corrosion resistance, as well as improved tensile strength. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a graph showing the Vickers hardness of the tin-gold alloy in the example. [Figure 2] Figure 2 is a graph showing the tensile strength of the tin-gold alloy in the example. [Modes for carrying out the invention]

[0009] (tin-gold alloy) The tin-gold alloy of this embodiment is a tin-gold alloy consisting of 90% to 99% by mass of tin, 1% to 10% by mass of gold, and the remainder being unavoidable impurities.

[0010] Preferably, the tin content is 93% by mass or more and 99% by mass or less, and the gold content is 1% by mass or more and 7% by mass or less, and more preferably, the tin content is 95% by mass or more and 98% by mass or less, and the gold content is 2% by mass or more and 5% by mass or less.

[0011] As a result of diligent research to solve the above-mentioned objectives, the present inventors have found that a tin-gold alloy consisting of 90% to 99% by mass of tin, 1% to 10% by mass of gold, and the remainder being unavoidable impurities, possesses the advantages of tin and / or gold, such as a silvery-white metallic luster, flexibility, oxidation resistance, and corrosion resistance, and also exhibits unexpectedly improved tensile strength, thus completing the present invention.

[0012] The tin-gold alloy of this embodiment has a silvery-white metallic luster, flexibility, oxidation resistance, and corrosion resistance, as well as improved tensile strength, making it suitable for use as a tin-gold alloy for decorative items. It can also be suitably used as a casting and / or a plastically formed product.

[0013] [Vickers hardness] The Vickers hardness (HV) of the aforementioned tin-gold alloy is preferably 10 HV or higher, and more preferably 12 HV or higher. Compared to 100% by mass of tin (Vickers hardness approximately 7.8 HV), the Vickers hardness increases as the amount of gold added increases. Here, the Vickers hardness of gold (literature value) is approximately 22 HV. When the Vickers hardness is 10 HV or higher, the flexibility of the tin can be maintained while preventing scratches and deformation caused by external forces when processed or used in decorative items.

[0014] The Vickers hardness of the tin-gold alloy can be measured in accordance with JIS Z 2244-1:2020, "Vickers hardness test - Part 1: Test method". Specifically, using a hardness tester (for example, HM-103 manufactured by Mitutoyo Corporation), a diamond pyramid indenter is pressed against a test piece made of the tin-gold alloy of the present embodiment, the formed indentation is observed with a microscope, and the diagonal length (surface area) of the indentation is measured to obtain the Vickers hardness.

[0015] [Tensile strength] As the tensile strength of the tin-gold alloy, 29 MPa or more is preferable, 35 MPa or more is more preferable, and 40 MPa or more is still more preferable. When gold is blended with 100% by mass of tin (tensile strength of about 17.3 MPa), it was unexpectedly found that the tensile strength improves with a peak content of 3% by mass of gold. When the tensile strength is 29 MPa or more, when processed or used as an ornament, it is possible to suppress damage and deformation due to external force while maintaining the flexibility of tin.

[0016] [[ID=🔟]]The tensile strength of the tin-gold alloy can be measured in accordance with JIS Z 2241:2011, "Tensile test method for metallic materials". Specifically, using a fatigue measuring machine (for example, INSTRON-8801 manufactured by Instron Corporation), a tensile load is applied to a test piece made of the tin-gold alloy of the present embodiment, and the maximum stress generated until it breaks is measured to obtain the tensile strength.

[0017] There are no particular limitations on the method for identifying the components constituting the tin-gold alloy and the method for measuring the metal content ratio, and they can be appropriately selected according to the purpose. Examples include fluorescence spectrometry, inductively coupled plasma mass spectrometry (ICP-MS), and the like. [[ID=🔟🔟]]

[0018] Here, inevitable impurities are elements contained in the raw materials or elements inevitably mixed in the manufacturing process. Examples include Ag, Cu, Fe, Pd, Pt, Mg, Al, Si, Ge, Zr, Ru, Rh, Ir, Na, Ca, etc. The content of inevitable impurities in the tin-gold alloy may be within a range that does not impair the effects of the present invention. The lower the content, the better. Specifically, 0.01% by mass or less is preferable, 0.001% by mass or less is more preferable, and it is even more preferable to be below the detection limit of the measuring device.

[0019] The tin-gold alloy is preferably a tin-gold alloy for ornaments. According to the tin-gold alloy of the present embodiment, it has a silver-white metallic luster and has the advantages of tin and / or gold, such as flexibility, oxidation resistance, and corrosion resistance, and can provide a tin-gold alloy with improved tensile strength. Therefore, when processed or used as an ornament, it is possible to suppress damage and deformation caused by external forces. In addition, both tin and gold are known to be safe for the human body, and the tin-gold alloy has also been confirmed to have low allergenicity through patch tests and is suitable for use as an ornament.

[0020] There are no particular restrictions on the ornaments, and they can be appropriately selected according to the purpose. Examples include rings, piercings, earrings, necklaces, bangles, bracelets, ear cuffs, anklets, hair accessories, brooches, etc.

[0021] As another embodiment, the tin-gold alloy may be used for tableware, for flower vases or objet d'art, or for medical instruments. In addition, it is not limited to these uses and can be used in any manner.

[0022] The casting of the present embodiment is made of the tin-gold alloy of the present embodiment.

[0023] In the above-mentioned casting, it is preferable that the tin content is 93% by mass or more and 99% by mass or less, and the gold content is 1% by mass or more and 7% by mass or less, and it is more preferable that the tin content is 95% by mass or more and 98% by mass or less, and the gold content is 2% by mass or more and 5% by mass or less.

[0024] The aforementioned casting preferably has a tensile strength of 29 MPa or more, more preferably 35 MPa or more, and even more preferably 40 MPa or more. A tensile strength of 29 MPa or more makes it possible to obtain a casting that maintains the flexibility of tin while suppressing damage and deformation due to external forces when processed or used as a decorative item.

[0025] The plastically formed product of this embodiment is made of the tin-gold alloy of this embodiment.

[0026] In the plastically deformed product, it is preferable that the tin content is 95% by mass or more and 98% by mass or less, and the gold content is 2% by mass or more and 5% by mass or less.

[0027] The plastically deformed product preferably has a tensile strength of 29 MPa or more, more preferably 35 MPa or more, and even more preferably 40 MPa or more. A tensile strength of 29 MPa or more makes it possible to obtain a plastically deformed product that maintains the flexibility of tin while suppressing damage and deformation due to external forces during processing or when used as a decorative item. [Examples]

[0028] The present invention will be described more specifically below based on examples, but the present invention is not limited to the following examples.

[0029] (Example 1) <Manufacturing of tin-gold alloys> To achieve a composition of 99% tin by mass and 1% gold by mass, the masses of tin (purity 99.995% or higher) and gold (purity 99.99% or higher) were measured. These were melted in a pot at approximately 250°C, and the mixture was poured into a mold to produce a tin-gold alloy of size 5mm thick x 20mm in diameter, thereby producing the tin-gold alloy of Example 1.

[0030] (Examples 2-5) <Manufacturing of tin-gold alloys> Except for changing the mass ratio (composition) of tin and gold in Example 1 to the mass ratio shown in Table 1, the tin-gold alloys of Examples 2 to 5 were manufactured in the same manner as in Example 1.

[0031] [Table 1]

[0032] (Comparative Example 1) <Manufacturing of tin-gold alloys> In Example 1, the tin-gold alloy of Comparative Example 1 was manufactured in the same manner as in Example 1, except that the tin content was changed to 100% by mass, as shown in Table 1.

[0033] The following evaluations were performed on each of the obtained tin-gold alloys.

[0034] [Vickers hardness] The Vickers hardness of each tin-gold alloy obtained was measured according to JIS Z 2244-1:2020 "Vickers hardness test - Part 1: Test method". Specifically, a hardness tester (Mitutoyo Corporation, HM-103) was used to press a diamond pyramidal indenter against each tin-gold alloy specimen. The resulting indentation was observed under a microscope, and the Vickers hardness was determined by measuring the length of the diagonal of the indentation (surface area). Measurements were performed on five specimens, and the mean value ± standard deviation was calculated. Figure 1 shows the Vickers hardness measurement results for the tin-gold alloys of the example.

[0035] [Tensile strength] For the tin-gold alloys of Examples 1-3 and Comparative Example 1, specimens with dimensions of 4 mm thickness x 170 mm length x 20 mm width were prepared as samples for tensile strength measurement. The tensile strength of each tin-gold alloy was measured according to JIS Z 2241:2011 "Method for Tensile Testing of Metallic Materials". Specifically, using a fatigue testing machine (INSTRON-8801, manufactured by Instron), the tensile load was applied to each tin-gold alloy specimen, and the maximum stress generated before fracture was measured to determine the tensile strength. Figure 2 shows the measurement results of the tensile strength of the tin-gold alloys in the examples.

[0036] [Specific gravity test] The specific gravity of each tin-gold alloy obtained was measured in accordance with JIS Z 8807:2012 "Method for measuring the density and specific gravity of solids". Specifically, the specific gravity of each tin-gold alloy was determined using an electronic hydrometer (EDM6102, manufactured by AS ONE Corporation).

[0037] Table 2 shows the results. As the mass ratio of gold increased, the specific gravity of the tin-gold alloy increased.

[0038] [Constant temperature and humidity test] The constant temperature and humidity tests performed on each tin-gold alloy were evaluated according to JIS C 60068-2-30. Specifically, using a constant temperature and humidity testing apparatus (PSL-2KPH, manufactured by ESPEC Corporation), each tin-gold alloy was subjected to a constant temperature of 25°C to 55°C and a high humidity of 90% as the lower limit, with each cycle lasting 24 hours. After six cycles under these constant temperature and humidity conditions, the alloys were left to stand and observed to evaluate the effects of the constant temperature and humidity test.

[0039] As a result, no corrosion such as rust or discoloration was observed in any of the tin-gold alloys in the examples or comparative examples, confirming that they possess oxidation resistance and corrosion resistance under constant temperature and humidity conditions.

[0040] [Patch test] The resulting tin-gold alloy (95% tin by mass, 5% gold by mass, size: 1.3 mm thick x 15 mm in diameter) was placed on the backs of 21 subjects and left in place for 24 hours. After that, the subjects' skin was observed to evaluate whether any abnormalities such as swelling, itching, or redness occurred.

[0041] As a result, no one showed even minor reactions, and the tin-gold alloy used in the examples was considered safe and non-irritating to the skin.

[0042] [Allergy Test] Each of the obtained tin-gold alloys (95% tin by mass, 5% gold by mass, size: 1.3 mm thick x 15 mm in diameter) was placed on the backs of 50 subjects and covered. The occlusive application was repeated 10 times for 24 hours, and the subjects' skin was observed each time to evaluate whether any abnormalities such as swelling, itching, or redness occurred.

[0043] As a result, although a few subjects showed mild reactions (erythema) (approximately 1 in 50 subjects each time out of 10 checks), it was confirmed that the tin-gold alloy used in the example had extremely low cumulative irritation and skin sensitization potential, and was considered to be very unlikely to cause allergies.

[0044] [Table 2]

[0045] [Manufacturing of decorative items] (Example 6) Using the tin-gold alloy from Example 2 as the base metal, the ring (ornament) from Example 6 was manufactured by pouring it into a mold to a size of 1.5 mm thickness x 20 mm diameter.

[0046] The ring of Example 6 possesses a suitable balance of hardness and the softness of tin, resulting in high workability. It also exhibits a refined luster and excellent texture, conforming gently to the shape of the part being worn and making it suitable for use as an ornament.

[0047] (Example 7) Using the tin-gold alloy from Example 2 as the base metal, the tin-gold alloy was poured into a mold and cast to a size of 42mm thickness x 20mm length x 11mm width, thereby producing the earrings (ornamental item) from Example 7, which are plastically formed products made of tin-gold alloy.

[0048] The earrings of Example 7 possessed a suitable balance of hardness and tin's softness, resulting in high workability. They also exhibited a refined luster and texture, conforming gently to the shape of the wearer's body and making them suitable for use as decorative items.

[0049] Although the present invention has been described above based on various embodiments, the present invention is not limited to the requirements shown in the above embodiments. These points can be modified as long as they do not impair the spirit of the present invention, and can be appropriately determined according to their application.

Claims

1. Tin in an amount of 95% by mass or more and 99% by mass or less, Gold in an amount of 1% by mass or more and 5% by mass or less, The remaining unavoidable impurities make up a tin-gold alloy, A casting having a tensile strength of 29 MPa or higher and a Vickers hardness of 12 HV or higher.

2. Tin in an amount of 95% to 99% by mass, Gold in an amount of 1% to 5% by mass, The remaining unavoidable impurities make up a tin-gold alloy, A plastically deformed product having a tensile strength of 29 MPa or higher and a Vickers hardness of 12 HV or higher.

3. An ornament made from a cast product as described in Claim 1, or a plastically processed product as described in Claim 2.

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