阅读说明：本技术 高硬度抗变色的银合金及其制备方法 (High-hardness anti-tarnishing silver alloy and preparation method thereof ) 是由 江涛 邬治平 钟飞 于 2019-10-23 设计创作，主要内容包括：本发明属于合金技术领域,尤其涉及一种高硬度抗变色的银合金,以所述高硬度抗变色的银合金的总质量为100％计,由如下质量百分含量的原料组分组成：92.5％～97.8％的银,2.0％～6.0％的锌,0.1％～3.0％的镁,0.1％～3.0％的铝。本发明银合金通过少量锌、镁以及铝在银中的自由扩散和组装,既能够提高银合金的硬度,又能够提高银合金的耐腐蚀性能和抗变色性能,同时具有较好的铸造性能。(The invention belongs to the technical field of alloys, and particularly relates to a high-hardness anti-tarnishing silver alloy which comprises the following raw material components in percentage by mass based on 100% of the total mass of the high-hardness anti-tarnishing silver alloy: 92.5 to 97.8 percent of silver, 2.0 to 6.0 percent of zinc, 0.1 to 3.0 percent of magnesium and 0.1 to 3.0 percent of aluminum. The silver alloy can improve the hardness of the silver alloy, can also improve the corrosion resistance and the discoloration resistance of the silver alloy and has better casting performance at the same time through the free diffusion and assembly of a small amount of zinc, magnesium and aluminum in the silver.)

1. The silver alloy with high hardness and tarnish resistance is characterized by comprising the following raw material components in percentage by mass based on 100% of the total mass of the silver alloy with high hardness and tarnish resistance:

2. the silver alloy with high hardness and tarnish resistance according to claim 1, wherein the silver alloy with high hardness and tarnish resistance comprises the following raw material components in percentage by mass based on 100% of the total mass of the silver alloy with high hardness and tarnish resistance:

3. the silver alloy with high hardness and tarnish resistance according to claim 1, wherein the silver alloy with high hardness and tarnish resistance comprises the following raw material components in percentage by mass based on 100% of the total mass of the silver alloy with high hardness and tarnish resistance:

92.5% silver, 4% zinc, 2% magnesium, 1.5% aluminum;

alternatively, 92.9% silver, 6% zinc, 0.1% magnesium, 1% aluminum;

alternatively, 92.6% silver, 5% zinc, 0.4% magnesium, 2% aluminum;

alternatively, 92.7% silver, 5% zinc, 0.8% magnesium, 1.5% aluminum.

4. The silver alloy with high hardness and tarnish resistance according to any one of claims 1 to 3, wherein the silver alloy has a hardness of not less than 130 HV.

5. The silver alloy with high hardness and tarnish resistance according to any one of claims 1 to 3, wherein said silver alloy is free from corrosion discoloration after 24 hours of salt spray test treatment.

6. A method for preparing the silver alloy with high hardness and tarnish resistance according to any one of claims 1 to 5, comprising the steps of: in a vacuum or protective gas atmosphere, melting silver, magnesium, zinc and aluminum with the formula ratio to form uniform alloy liquid, casting the uniform alloy liquid into a mold, solidifying and cooling to obtain a casting; and then carrying out cold deformation treatment on the casting to obtain the high-hardness anti-tarnishing silver alloy.

7. The method for preparing the silver alloy with high hardness and tarnish resistance according to claim 6, wherein the step of cold-deforming the casting comprises: and cold deformation treatment is carried out on the casting by cold rolling and/or cold heading, so that the deformation of the casting reaches 30-70%.

8. A jewelry clock or piece, characterized in that the material of said jewelry clock or piece comprises the silver alloy of high hardness with resistance to discoloration according to any of claims 1 to 5, or the material of said jewelry clock or piece comprises the silver alloy of high hardness with resistance to discoloration prepared by the method according to any of claims 6 to 7.

9. A tableware, characterized in that the material of the tableware comprises the silver alloy with high hardness and tarnish resistance of any one of claims 1 to 5, or the material of the tableware comprises the silver alloy with high hardness and tarnish resistance prepared by the method of any one of claims 6 to 7.

10. A functional material comprising the silver alloy with high hardness and tarnish resistance of any one of claims 1 to 5, or the silver alloy with high hardness and tarnish resistance prepared by the method of any one of claims 6 to 7.

Technical Field

The invention belongs to the technical field of alloys, and particularly relates to a high-hardness anti-tarnishing silver alloy and a preparation method thereof.

Background

Silver is an important precious metal, has beautiful color, easy processing and stable physicochemical properties, and has been found and utilized by human beings for thousands of years. Early it was also found that foot silver was too soft and not good in corrosion resistance to withstand normal use, so it was practiced to add a proportion of base metal to improve its hardness, strength and corrosion resistance, etc. In the uk, regulations that have existed since the fourteenth century specify minimum silver contents of articles sold at 92.5% (sterling standard) or 96% (britannia standard), but do not specify base metal compositions. Stirling silver as we speak today generally refers to silver alloys with a silver content of 92.5% and a copper content of 7.5%, whereas for silver alloys with a silver content of 92.5% we refer to pure silver or 925 silver. However, the corrosion resistance and hardness of the sterling silver cannot meet the requirements of people on increasingly growing material culture than other noble metals or noble metal alloys, so that the adjustment of alloy components and manufacturing processes of pure silver to improve the hardness and corrosion resistance of the sterling silver has long been desired.

In real life, the problems of blackened surface, uneven color and the like of the ornament can be caused by the fact that silver and silver alloy are easy to react with corrosive gases such as human sweat, hydrogen sulfide in air and the like when the ornament is worn. On the one hand, due to the insufficient corrosion resistance of silver itself and, on the other hand, due to the copper element in the alloy. Although copper as a base metal can remarkably improve the hardness and strength of the silver alloy in a solid solution strengthening and precipitation strengthening mode and can keep better plasticity and toughness of the silver alloy, the copper in the alloy is mostly precipitated in the form of a copper-rich phase and the copper-rich phase is different from the electrode potential of silver due to low solid solubility of copper in the silver alloy at room temperature, and a primary battery reaction is easy to occur in a humid environment, so that the overall corrosion rate of the silver alloy is accelerated.

Traditionally, in order to improve the corrosion resistance and hardness of silver ornaments, some silver manufacturers adopt alloying methods for improvement, and some silver manufacturers adopt surface coating, surface modification and other processes. Although the surface treatment process somewhat delays the problem of oxidative blackening of the silver alloy and may impart some particular color appearance to the silver alloy, the actual effect is not ideal. These ornaments often lose luster and color after being worn for a period of time because of the abrasion of the coating, so that the obvious contrast is generated between the substrate and the unworn area of the film layer, and the decorative performance is seriously influenced.

Disclosure of Invention

The invention aims to provide a silver alloy with high hardness and tarnish resistance, and aims to solve the technical problems that the existing 925 silver cannot simultaneously have lasting corrosion resistance, tarnish resistance, high hardness, good casting performance and the like.

Another object of the present invention is to provide a method for preparing a silver alloy having high hardness and discoloration resistance.

In order to achieve the purpose of the invention, the technical scheme adopted by the invention is as follows:

the high-hardness anti-tarnishing silver alloy comprises the following raw material components in percentage by mass, based on 100% of the total mass of the high-hardness anti-tarnishing silver alloy:

preferably, the high-hardness and tarnish-resistant silver alloy comprises the following raw material components in percentage by mass based on 100% of the total mass of the high-hardness and tarnish-resistant silver alloy:

preferably, the high-hardness and tarnish-resistant silver alloy comprises the following raw material components in percentage by mass based on 100% of the total mass of the high-hardness and tarnish-resistant silver alloy: 92.5% silver, 4% zinc, 2% magnesium, 15% aluminum;

alternatively, 92.9% silver, 6% zinc, 0.1% magnesium, 1% aluminum;

alternatively, 92.6% silver, 5% zinc, 0.4% magnesium, 2% aluminum;

alternatively, 92.7% silver, 5% zinc, 0.8% magnesium, 1.5% aluminum.

Preferably, the silver alloy has a hardness of not less than 130 HV.

Preferably, the silver alloy does not corrode and discolor after being treated by a 24-hour salt spray test.

A preparation method of a silver alloy with high hardness and tarnish resistance comprises the following steps: in a vacuum or protective gas atmosphere, melting silver, magnesium, zinc and aluminum with the formula ratio to form uniform alloy liquid, casting the uniform alloy liquid into a mold, solidifying and cooling to obtain a casting; and then carrying out cold deformation treatment on the casting to obtain the high-hardness anti-tarnishing silver alloy.

Preferably, the step of cold-deforming the casting comprises: and cold deformation treatment is carried out on the casting by cold rolling and/or cold heading, so that the deformation of the casting reaches 30-70%.

A jewelry clock and piece, the material of which comprises the above-mentioned high hardness tarnish resistant silver alloy, or the material of which comprises the above-mentioned high hardness tarnish resistant silver alloy produced by the above-mentioned method.

The tableware is made of the high-hardness anti-tarnishing silver alloy or the high-hardness anti-tarnishing silver alloy prepared by the method.

A functional material, which comprises the silver alloy with high hardness and tarnish resistance, or comprises the silver alloy with high hardness and tarnish resistance prepared by the method.

The silver alloy with high hardness and tarnish resistance provided by the invention comprises, by taking the total mass of the silver alloy with high hardness and tarnish resistance as 100%, 92.5-97.8% of silver, 2.0-6.0% of zinc, 0.1-3.0% of magnesium and 0.1-3.0% of aluminum, and does not contain other alloy elements. It should be understood that the silver alloy with high hardness and discoloration resistance may contain inevitable trace impurity elements, but the trace impurity elements do not constitute alloy elements of the silver alloy. The silver alloy material with a silver framework doped with a small amount of zinc, magnesium and aluminum is formed by diffusion and free assembly of silver, a small amount of zinc, magnesium and aluminum, wherein the doped small amount of aluminum can form a thin and stable aluminum oxide layer on the surface of the silver alloy, so that the corrosion resistance of the silver alloy can be improved, the migration capability of silver can be inhibited, and the microstructure of the silver alloy is kept from being damaged by high-temperature annealing treatment. A small amount of doped zinc element can generate a synergistic effect with aluminum element, a compact and transparent passivation film layer is formed on the surface of the silver alloy, and the corrosion resistance of the silver alloy is further improved. The doped small amount of magnesium can not only improve the hardness of the silver alloy, but also improve the light reflection capability of the silver alloy, thereby improving the glossiness of the silver alloy, and simultaneously improving the fluidity of the silver alloy, thereby improving the processing performance of the silver alloy. The silver alloy can improve the hardness of the silver alloy, can also improve the corrosion resistance and the discoloration resistance of the silver alloy and has better casting performance at the same time through the free diffusion and assembly of a small amount of zinc, magnesium and aluminum in the silver.

The preparation method of the high-hardness anti-tarnishing silver alloy provided by the invention is carried out in a vacuum or protective gas atmosphere to prevent metal materials from being oxidized in a high-temperature environment, silver, magnesium, zinc and aluminum with the formula amount are melted to form uniform alloy liquid, the uniform alloy liquid is cast into a mold for solidification and cooling, and then the casting is cooled and deformed to obtain the high-hardness anti-tarnishing silver alloy. Meanwhile, the formula of the silver alloy does not contain elements such as copper and the like, such as precipitated phases, eutectic crystals and the like, so that the molten silver alloy has good fluidity and less casting defects in castings. In addition, the hardness of the silver alloy is greatly improved through cold deformation treatment, the preparation method is simple, the process conditions are mild, and the method is suitable for industrial production and application.

The jewelry, clock and jewelry provided by the invention has good color and luster, durable corrosion resistance and wear resistance because the material of the jewelry, clock and jewelry comprises the silver alloy with high hardness, corrosion resistance and tarnish resistance, and can well resist the corrosion of sweat, air and the like in the daily use process and keep the luster and color.

The tableware provided by the invention has good discoloration resistance and corrosion resistance due to the fact that the material of the tableware contains the silver alloy with high hardness, corrosion resistance and discoloration resistance, and the tableware has good discoloration resistance and corrosion resistance no matter the silver alloy is directly adopted as the tableware material or the silver alloy is used as the surface coating of the tableware.

The functional material provided by the invention contains the silver alloy with high hardness, corrosion resistance and tarnish resistance, so that the functional material can be used as a packaging coating or a material of a functional part, and the corrosion resistance, tarnish resistance and other properties of the packaging and the functional part are improved.

Drawings

Fig. 1 is an as-cast metallographic structure diagram of silver alloys provided in example 1 of the present invention and comparative example 1.

Fig. 2 is an image of a microscope image of a silver alloy provided in example 2 of the present invention and comparative example 1 after a salt spray experiment.

Detailed Description

In order to make the purpose, technical solution and technical effect of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention is clearly and completely described, and it is obvious that the described embodiments are a part of the embodiments of the present invention, but not all embodiments. All other embodiments obtained by a person of ordinary skill in the art without any inventive step in connection with the embodiments of the present invention shall fall within the scope of protection of the present invention.

In the description of the present invention, it is to be understood that the terms "first", "second" and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

The weight of the related components mentioned in the description of the embodiments of the present invention may not only refer to the specific content of each component, but also represent the proportional relationship of the weight among the components, and therefore, the content of the related components is scaled up or down within the scope disclosed in the description of the embodiments of the present invention as long as it is in accordance with the description of the embodiments of the present invention. Specifically, the weight described in the description of the embodiment of the present invention may be a unit of mass known in the chemical industry field, such as μ g, mg, g, and kg.

The embodiment of the invention provides a high-hardness anti-tarnishing silver alloy, which comprises the following raw material components in percentage by mass based on 100% of the total mass of the high-hardness anti-tarnishing silver alloy:

the silver alloy with high hardness and tarnish resistance provided by the embodiment of the invention comprises 92.5-97.8% of silver, 2.0-6.0% of zinc, 0.1-3.0% of magnesium and 0.1-3.0% of aluminum by taking the total mass of the silver alloy with high hardness and tarnish resistance as 100%, and does not contain other alloy elements. It should be understood that the silver alloy with high hardness and discoloration resistance may contain inevitable trace impurity elements, but the trace impurity elements do not constitute alloy elements of the silver alloy. The silver alloy material with a silver framework doped with a small amount of zinc, magnesium and aluminum is formed by diffusion and free assembly of silver, a small amount of zinc, magnesium and aluminum, wherein the doped small amount of aluminum can form a thin and stable aluminum oxide layer on the surface of the silver alloy, so that the corrosion resistance of the silver alloy can be improved, the migration capability of silver can be inhibited, and the microstructure of the silver alloy is kept from being damaged by high-temperature annealing treatment. A small amount of doped zinc can generate a synergistic effect with aluminum element, a compact and transparent passivation film layer is formed on the surface of the silver alloy, and the corrosion resistance of the silver alloy is further improved. The doped small amount of magnesium can not only improve the hardness of the silver alloy, but also improve the light reflection capability of the silver alloy, thereby improving the glossiness of the silver alloy, and simultaneously improving the melt fluidity of the silver alloy, thereby improving the processing performance of the silver alloy. According to the silver alloy disclosed by the embodiment of the invention, through free diffusion and assembly of a small amount of zinc, magnesium and aluminum in silver, the hardness of the silver alloy can be improved, the corrosion resistance and the discoloration resistance of the silver alloy can be improved, and the silver alloy has better casting performance.

In a further embodiment, the high-hardness and tarnish-resistant silver alloy comprises the following raw material components in percentage by mass based on 100% of the total mass of the high-hardness and tarnish-resistant silver alloy:

the silver alloy with high hardness and discoloration resistance of the embodiment of the invention is characterized in that 3-5% of zinc, 1-3% of magnesium and 1-2% of aluminum are doped in silver, and the doping elements in the proportion not only have better solid solubility in silver, but also can better improve the corrosion resistance, hardness, discoloration resistance and processability of the silver alloy, so that the silver alloy has more durable corrosion resistance, discoloration resistance, high hardness and good casting performance.

In some specific embodiments, the silver alloy with high hardness and tarnish resistance comprises the following raw material components in percentage by mass based on 100% of the total mass of the silver alloy with high hardness and tarnish resistance:

the silver alloy surface of the embodiment of the invention is polished, the microhardness is 132HV, and the silver alloy surface is not corroded and discolored after 24h salt spray experiment.

In some specific embodiments, the silver alloy with high hardness and tarnish resistance comprises the following raw material components in percentage by mass based on 100% of the total mass of the silver alloy with high hardness and tarnish resistance:

the silver alloy surface of the embodiment of the invention is polished, the microhardness is 148HV, and the silver alloy surface is not corroded and discolored after 24h salt spray experiment.

In some specific embodiments, the silver alloy with high hardness and tarnish resistance comprises the following raw material components in percentage by mass based on 100% of the total mass of the silver alloy with high hardness and tarnish resistance:

the silver alloy surface of the embodiment of the invention is ground and polished, the microhardness is 131HV, and the silver alloy surface is not corroded and discolored after 24h salt spray experiment.

In some specific embodiments, the silver alloy with high hardness and tarnish resistance comprises the following raw material components in percentage by mass based on 100% of the total mass of the silver alloy with high hardness and tarnish resistance:

the silver alloy surface of the embodiment of the invention is polished, the microhardness is 136HV, and the silver alloy surface is not corroded and discolored after 24h salt spray experiment.

The silver alloy prepared according to the above embodiments of the invention has good anti-discoloration performance, high hardness and good casting performance, and the hardness of the silver alloy is not lower than 130 HV; meanwhile, the silver alloy has better corrosion resistance, and the silver alloy is not corroded and discolored after being treated by a salt spray experiment for 24 hours. The cast structure of the silver alloy does not contain structures such as precipitated phases and eutectic crystals, the alloy has good fluidity when in a liquid state, and casting defects in castings are few. In addition, since the silver alloy does not contain copper, a copper-rich phase does not exist in an as-cast state, and thus the silver alloy has good hot spot (or hot streak) resistance.

The silver alloy with high hardness and tarnish resistance provided by the embodiment of the invention can be prepared by the following method.

Correspondingly, the embodiment of the invention also provides a preparation method of the silver alloy with high hardness and tarnish resistance, which comprises the following steps: in a vacuum or protective gas atmosphere, melting silver, magnesium, zinc and aluminum with the formula ratio to form uniform alloy liquid, casting the uniform alloy liquid into a mold, solidifying and cooling to obtain a casting; and then carrying out cold deformation treatment on the casting to obtain the high-hardness anti-tarnishing silver alloy.

The preparation method of the high-hardness and anti-tarnishing silver alloy provided by the embodiment of the invention is carried out in a vacuum or protective gas atmosphere, prevents metal materials from being oxidized in a high-temperature environment, melts silver, magnesium, zinc and aluminum with the formula amount to form uniform alloy liquid, then casts the uniform alloy liquid into a mould for solidification and cooling, and then carries out cooling deformation treatment on a casting to obtain the high-hardness and anti-tarnishing silver alloy. Meanwhile, the formula of the silver alloy does not contain elements such as copper and the like, such as precipitated phases, eutectic crystals and the like, so that the molten silver alloy has good fluidity and less casting defects in castings. In addition, the hardness of the silver alloy is greatly improved through cold deformation treatment, the preparation method is simple, the process conditions are mild, and the method is suitable for industrial production and application.

The embodiment of the present invention does not specifically limit the manner of the cold deformation treatment, as long as the hardness of the silver alloy can be increased by the cold deformation treatment. In some embodiments, the step of cold-deforming the casting comprises: and cold deformation treatment is carried out on the casting by cold rolling and/or cold heading, so that the deformation of the casting reaches 30-70%.

In some embodiments, the raw materials with the composition ratio are put into a graphite crucible to be smelted in vacuum or protective atmosphere, and the alloy liquid is cast into a mould to be solidified and cooled after the components are uniform; and then carrying out cold deformation treatment on the casting, including but not limited to cold rolling or cold heading, so that the deformation of the casting reaches 30-70%.

Accordingly, embodiments of the present invention also provide a piece of jewelry, clocks and pieces of material comprising the above-described high hardness anti-tarnish silver alloy, or a piece of jewelry, clocks and pieces of material comprising the above-described high hardness anti-tarnish silver alloy produced by the above-described method.

The jewelry, clocks and jewelries provided by the embodiment of the invention have good color and luster, durable corrosion resistance and wear resistance because the materials of the jewelry, clocks and jewelries comprise the silver alloy with high hardness, corrosion resistance and tarnish resistance, and can well resist the corrosion of sweat, air and the like in the daily use process and keep the luster and color.

Accordingly, the embodiment of the invention also provides tableware, and the material of the tableware comprises the silver alloy with high hardness and resistance to color change, or the material of the tableware comprises the silver alloy with high hardness and resistance to color change, which is prepared by the method.

The tableware provided by the embodiment of the invention has the advantages that as the material of the tableware comprises the silver alloy with high hardness, corrosion resistance and tarnish resistance, the tableware has good tarnish resistance and corrosion resistance no matter the silver alloy is directly adopted as the tableware material or the silver alloy is used as the surface coating of the tableware.

Accordingly, the embodiment of the present invention also provides a functional material, wherein the functional material comprises the silver alloy with high hardness and tarnish resistance, or the functional material comprises the silver alloy with high hardness and tarnish resistance prepared by the method.

The functional material provided by the embodiment of the invention contains the silver alloy with high hardness, corrosion resistance and tarnish resistance, so that the functional material can be used as a packaging coating or a material of functional parts, and the performances of corrosion resistance, tarnish resistance and the like of the packaging and the functional parts are improved.

In order to make the above implementation details and operations of the present invention clearly understood by those skilled in the art and to make the advanced performance of the silver alloy with high hardness and color fastness obvious in the embodiments of the present invention, the above technical solution is illustrated by a plurality of examples below.