CN111394607A

CN111394607A - Nickel-free low-silver-content silver-storing alloy with excellent die-casting performance and process thereof

Info

Publication number: CN111394607A
Application number: CN201810912242.6A
Authority: CN
Inventors: 杨长江
Original assignee: Guangzhou Yuzhi Technology Co Ltd
Current assignee: Guangzhou Yuzhi Technology Co Ltd
Priority date: 2018-08-10
Filing date: 2018-08-10
Publication date: 2020-07-10

Abstract

The invention discloses a nickel-free silver-storing alloy with low silver content and excellent die-casting performance and a process thereof. The alloy comprises, by weight, 0.4-0.5wt.% of B, 1.0-1.2wt.% of Ca, 2.0-3.5wt.% of Al, 1.0-1.8wt.% of Si, 0.2-0.3wt.% of Os, 1.0-1.4wt.% of Ge, 6.0-9.0wt.% of Fe, 29.0-31.0wt.% of Ag, and the balance of copper. The patent provides a new alloy for silver-hiding without nickel, which is not available on the market, and the alloy has excellent die casting performance. The industrialization of the alloy can not only solve the difficult problem of the prior Tibetan silver alloy, but also greatly enrich the types of low-silver-content alloys for jewelry in the market.

Description

Nickel-free low-silver-content silver-storing alloy with excellent die-casting performance and process thereof

Technical Field

The invention relates to the technical field of alloys, in particular to a silver alloy.

Background

Silver is widely used as an ornament material since ancient times due to the unique bright white color and physical and chemical properties of silver, and is deeply loved by people. In this year, silver ornaments are more beautiful with the coming of white storm, and the demand is remarkably increased. In the past decade, silver jewelry has become a fast growth point for jewelry in our country. Pure silver has excellent ductility, but low strength, and is easily scratched and deformed. When various alloying elements are added to pure silver and the content thereof is controlled, various silver alloys are produced.

When very small amounts of alloying elements are added, 999 silver, 990 silver, 925 silver, etc. are produced. 925 pure silver is a silver-copper alloy containing 92.5wt% silver. To enhance the hardness of the silver jewelry, about 7.5wt% copper was added so that 925 silver would appear beige rather than the silvery white of conventional silver. The 925 silver jewelry presents beautiful metallic luster after being polished, has certain hardness, and can be embedded with gems to be made into middle-high grade jewelry. The 925-silver ornament which is made of 925-silver design has an European style, is rough, courage and foreward, is fashionable, exquisite and delicate, and is suitable for the taste of the public. However, 925 silver is relatively expensive due to its low content of alloying elements.

When a large amount of alloy elements are added and the appearance of the jewelry with high silver content is achieved but the cost is further reduced, the silver alloy with low silver content, such as Miao silver, Tibetan silver and the like, used by minority is generated. The Miao silver is silver alloy containing 30-60wt% of silver, while the Tibetan silver is an alloy (about 30 wt%) containing less silver produced by Nipol in Tibet of China, and the main components comprise nickel, copper and the like. Its characteristics are fine pattern, but it is not very material-specific. Most of the Tibetan silver on the market contains about 15 percent of silver, and some Tibetan silver contains almost no silver and is only a craft made of cupronickel alloy.

People wear various ornaments no matter in daily life or in pilgrimage. The silver coin can be worn on the head, such as a ballpoint, a substitute, a hairpin and a plait, a large ring on an ear, a necklace, a bracket and a gay bird worn on the neck, a pattern waistband tied on the waist, a suspended sickle box, a hidden knife, a waist buckle and a snuff bottle, and various ring bracelets worn on the hand. Thereby forming a unique style, giving out strong primitive simplicity and original artistic odour, and being full of wild and rough. In Tibetan, men, women, old and young love to decorate themselves. The popularity of Tibetan style jewelry in cities proves that Tibetan jewelry has strong modern significance in definite cases.

Silver ornaments containing nickel are susceptible to allergic reactions. The long-term contact with the silver jewelry containing nickel, especially the silver-storing jewelry with low silver content, can cause severe stimulation to the skin and cause allergic dermatitis. For example, skin wearing nickel silver jewelry begins to develop erythema, pimples, and herpes dunghill, often accompanied by severe itching and pain, commonly known as nickelism. Thereby causing the allergy phenomenon to the wearer of the jewelry containing nickel and silver. In addition, the silver ornament is placed in the air and reacts with hydrogen sulfide or sulfide ions in the air to generate black silver sulfide to cover the surface of the ornament, so that the silver ornament is gradually blackened. Hydrogen sulfide is a natural product. Firstly, human and animal feces are decomposed by bacteria to generate a large amount of hydrogen sulfide, and the protein in the plant body is decayed to generate hydrogen sulfide. In addition, human sweat also contains sulfur, and particularly, hydrogen sulfide generated by sewage and garbage discharge in urban air is more remarkable. Therefore, the problem of blackening and vulcanizing of silver alloy for silver hiding in the using process is a problem to be solved for a long time in the field.

The industrial problem is not solved for a long time, the market sales volume and the use experience of related products are influenced, and the market occupation of the products in the international field is also severely limited. The alloy material can be innovated by the underlying thermodynamics and kinetics means through the advanced material design technology, and the silver alloy has great market value for solving the difficult problems of developing and developing the novel silver alloy for silver hiding and industrialization. In the face of increasingly violent international and domestic market competition, the structural adjustment must be accelerated, which is not only the need of survival and development of the jewelry industry in China, but also the development trend of the related fields in the world at present.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a nickel-free Tibetan silver alloy with low silver content and excellent die casting performance and a process thereof.

In order to achieve the purpose, the invention adopts the following technical scheme:

a nickel-free low-silver-content silver-storing alloy with excellent die-casting performance and a process thereof. The alloy comprises, by weight, 0.4-0.5wt.% of B, 1.0-1.2wt.% of Ca, 2.0-3.5wt.% of Al, 1.0-1.8wt.% of Si, 0.2-0.3wt.% of Os, 1.0-1.4wt.% of Ge, 6.0-9.0wt.% of Fe, 29.0-31.0wt.% of Ag, and the balance of copper.

The nickel-free low-silver-content silver-storing alloy with excellent die casting performance and the process thereof comprise the following steps: the raw materials are added into an induction furnace protected by argon, a graphite crucible is adopted, argon with low flow is adopted for protection after metal is melted, serious burning loss of alloy elements caused by large airflow is avoided, heat preservation is carried out for 10 minutes at 1200 ℃ during melting, electromagnetic stirring is carried out uniformly by a high-frequency induction furnace, heat preservation is carried out for 1 minute at 1200 ℃ after uniform stirring, casting is carried out, and the alloy is cast by a steel die with the diameter of 40-60mm and cooled by a water cooling mode. Rolling the obtained cast ingot at room temperature, wherein the rolling reduction of each pass is 20-30%, the intermediate annealing temperature is 420 ℃ after each two-time rolling, preserving heat for 0.5 hour, finally rolling the material into a plate with the thickness of 10-15mm, and performing intermediate vacuum annealing treatment in the jewelry forming process to eliminate stress in the processing process, wherein the temperature is 400 ℃ and the time is 0.6 hour.

Compared with the prior art, the invention has the following beneficial effects:

(1) although the silver storage alloy has bright performances in the marketing and industrialization, the silver storage alloy for jewelry unfortunately has a phenomenon of adding a large amount of cupronickel or nickel due to low silver content. In recent years there has been considerable interest in the problem of the potential toxicity of nickel to human skin, and in order to protect the interests of consumers, certain european countries have already enacted regulations on the manufacture and sale of Ni-containing jewelry in contact with the skin. The long-term contact with the silver jewelry containing nickel, especially the silver-storing jewelry with low silver content, can cause severe stimulation to the skin and cause allergic dermatitis. For example, skin wearing nickel silver jewelry begins to develop erythema, pimples, and herpes dunghill, often accompanied by severe itching and pain, commonly known as nickelism. Thereby causing the allergy phenomenon to the wearer of the jewelry containing nickel and silver. Therefore, in order to enter the internationalization of silver-hiding jewelry and obtain a large amount of market sales in the world, the traditional silver-hiding alloy must be optimized in materials science, and a novel material which does not contain nickel and has the performance of the silver-hiding alloy is designed. The requirement just reflects the alloy material for the nickel-free silver-storing jewelry and the processing technology thereof.

(2) The alloy can overcome the hard point defect common in the traditional Tibetan silver alloy. The hard spots refer to the appearance of foreign matters with high hardness on the surface or inside of the ornament, which are commonly called gold slag. The ornaments with hard spots are often seriously scratched and are difficult to polish, the problem is often found in the final polishing stage, a large amount of labor has to be consumed for repairing, and for the fine and scattered hard spots, a lot of time is spent, and the ornaments are finally scrapped due to the difficulty in repairing and qualification. The alloy has excellent fluidity and filling performance, and reduces the oxidation air suction and the generation of suspended scum of the alloy. After the traditional casting process is adopted, the surface of a casting is brighter, the shrinkage porosity tendency of the alloy is small, and the integral casting performance of the alloy is improved. Therefore, the jewelry prepared by the alloy completely overcomes the defect of hard spots of the traditional material, and fundamentally provides a scheme of bottom layer properties.

(3) The existing Miao silver alloy is mainly a wrought alloy, so that the casting fluidity is insufficient when the Miao silver alloy is used for die casting. The general problems are that the yield is low, the appearance quality of the surface is poor, casting defects such as streamline marks, spots, looseness and the like are easy to appear on the surface, the quality requirement of smoothness and smoothness of the surface of a product is difficult to guarantee, a large surface finishing work load is brought, and the production cost is increased. The novel Miao silver alloy for die casting provided by the invention has excellent die casting performance, and can be used for die casting production of thin-walled and long ornaments. The wall thickness of the die casting can reach a casting with the minimum wall thickness of 1mm, and small holes with the diameter of about 0.5mm can be cast. On the premise of greatly simplifying the process, the cost is reduced, the energy consumption is reduced, and the method has a wide market prospect.

(4) The alloy has excellent discoloration resistance. The discoloration resistance (color stability) and corrosion resistance of the alloy are important for the ornament alloy. The traditional Tibetan silver alloy is bleached after being used for 4 months because the surface of the jewelry is completely vulcanized and blackened. Today, with advanced technology, there are many kinds of jewelry cleaning agents (actually chemical agents with considerable reducing power) on the market for blackening and brightening silver jewelry. However, in the years of wearing jewelry, bleaching and cleaning are required for removing sulfur in silver sulfide for many times. Not only the appearance image of the jewelry in the use process is influenced, but also the use experience of the user is greatly reduced. The silver-stored jewelry prepared from the material has no phenomenon of blackening due to vulcanization after being used for 4 years. The reason is that a dense oxide film is formed on the surface of the silver alloy, thereby protecting the alloy from oxidation and sulfidation. If this oxide film is scratched, a new oxide film is formed quickly, thereby keeping the silver alloy from discoloring for a long time. After the alloy is worn daily, no obvious corrosion phenomenon or surface scratch occurs on the surface, and the alloy has good capability of resisting corrosion of artificial sweat.

Detailed Description

Example 1

A nickel-free low-silver-content silver-storing alloy with excellent die-casting performance and a process thereof. The alloy comprises, by weight, 0.4wt.% of B, 1.0wt.% of Ca, 2.0wt.% of Al, 1.0wt.% of Si, 0.2wt.% of Os, 1.0wt.% of Ge, 6.0wt.% of Fe, 29.0wt.% of Ag and the balance of copper. The nickel-free low-silver-content silver-storing alloy with excellent die casting performance and the process thereof comprise the following steps: the raw materials are added into an induction furnace protected by argon, a graphite crucible is adopted, argon with low flow is adopted for protection after metal is melted, serious burning loss of alloy elements caused by large airflow is avoided, heat preservation is carried out for 10 minutes at 1200 ℃ during melting, electromagnetic stirring is carried out uniformly by a high-frequency induction furnace, heat preservation is carried out for 1 minute at 1200 ℃ after uniform stirring, casting is carried out, and the alloy is cast by a steel die with the diameter of 40-60mm and cooled by a water cooling mode. Rolling the obtained cast ingot at room temperature, wherein the rolling reduction of each pass is 20-30%, the intermediate annealing temperature is 420 ℃ after each two-time rolling, preserving heat for 0.5 hour, finally rolling the material into a plate with the thickness of 10-15mm, and performing intermediate vacuum annealing treatment in the jewelry forming process to eliminate stress in the processing process, wherein the temperature is 400 ℃ and the time is 0.6 hour.

The alloy casting has the advantages of brighter surface, small shrinkage porosity tendency of the alloy and improved integral casting performance of the alloy. The alloy has excellent die casting performance and can be used for die casting thin-wall and long and thin ornaments. The wall thickness of the die casting can reach a casting with the minimum wall thickness of 1mm, and small holes with the diameter of about 0.5mm can be cast. After the silver-hidden jewelry prepared from the alloy is worn daily, no obvious corrosion phenomenon or surface scratch occurs on the surface, and the silver-hidden jewelry has good capability of resisting corrosion of artificial sweat. And no vulcanization blackening phenomenon occurs after the use for 4 years. After the traditional Tibetan silver alloy jewelry is used for 4 months, bleaching operation is required to be carried out because the surface of the jewelry is completely vulcanized and blackened.

Example 2

A nickel-free low-silver-content silver-storing alloy with excellent die-casting performance and a process thereof. The alloy comprises, by weight, 0.5wt.% of B, 1.2wt.% of Ca, 3.5wt.% of Al, 1.8wt.% of Si, 0.3wt.% of Os, 1.4wt.% of Ge, 9.0wt.% of Fe, 31.0wt.% of Ag and the balance of copper. The nickel-free low-silver-content silver-storing alloy with excellent die casting performance and the process thereof comprise the following steps: the raw materials are added into an induction furnace protected by argon, a graphite crucible is adopted, argon with low flow is adopted for protection after metal is melted, serious burning loss of alloy elements caused by large airflow is avoided, heat preservation is carried out for 10 minutes at 1200 ℃ during melting, electromagnetic stirring is carried out uniformly by a high-frequency induction furnace, heat preservation is carried out for 1 minute at 1200 ℃ after uniform stirring, casting is carried out, and the alloy is cast by a steel die with the diameter of 40-60mm and cooled by a water cooling mode. Rolling the obtained cast ingot at room temperature, wherein the rolling reduction of each pass is 20-30%, the intermediate annealing temperature is 420 ℃ after each two-time rolling, preserving heat for 0.5 hour, finally rolling the material into a plate with the thickness of 10-15mm, and performing intermediate vacuum annealing treatment in the jewelry forming process to eliminate stress in the processing process, wherein the temperature is 400 ℃ and the time is 0.6 hour.

Example 3

A nickel-free low-silver-content silver-storing alloy with excellent die-casting performance and a process thereof. The alloy comprises, by weight, 0.4wt.% of B, 1.1wt.% of Ca, 2.4wt.% of Al, 1.5wt.% of Si, 0.2wt.% of Os, 1.2wt.% of Ge, 8.0wt.% of Fe, 29.0wt.% of Ag and the balance of copper. The nickel-free low-silver-content silver-storing alloy with excellent die casting performance and the process thereof comprise the following steps: the raw materials are added into an induction furnace protected by argon, a graphite crucible is adopted, argon with low flow is adopted for protection after metal is melted, serious burning loss of alloy elements caused by large airflow is avoided, heat preservation is carried out for 10 minutes at 1200 ℃ during melting, electromagnetic stirring is carried out uniformly by a high-frequency induction furnace, heat preservation is carried out for 1 minute at 1200 ℃ after uniform stirring, casting is carried out, and the alloy is cast by a steel die with the diameter of 40-60mm and cooled by a water cooling mode. Rolling the obtained cast ingot at room temperature, wherein the rolling reduction of each pass is 20-30%, the intermediate annealing temperature is 420 ℃ after each two-time rolling, preserving heat for 0.5 hour, finally rolling the material into a plate with the thickness of 10-15mm, and performing intermediate vacuum annealing treatment in the jewelry forming process to eliminate stress in the processing process, wherein the temperature is 400 ℃ and the time is 0.6 hour.

Claims

1. A nickel-free low-silver-content silver-storing alloy with excellent die-casting performance and a process thereof; the composition of the alloy is as follows according to weight percentage

Comprises 0.4-0.5wt.% of B, 1.0-1.2wt.% of Ca, 2.0-3.5wt.% of Al, 1.0-1.8wt.% of Si, 0.2-0.3wt.% of Os and 1.0wt.% of Ge-

1.4wt.%, 6.0-9.0wt.% Fe, 29.0-31.0wt.% Ag, and the balance copper.

2. The nickel-free low-silver-content silver-storing alloy with excellent die casting performance and the process thereof in claim 1 are characterized by comprising the following smelting steps: the raw materials are added into an induction furnace protected by argon, a graphite crucible is adopted, argon with low flow is adopted for protection after metal is melted, serious burning loss of alloy elements caused by large airflow is avoided, heat preservation is carried out for 10 minutes at 1200 ℃ during melting, electromagnetic stirring is carried out uniformly by a high-frequency induction furnace, heat preservation is carried out for 1 minute at 1200 ℃ after uniform stirring, casting is carried out, and the alloy is cast by a steel die with the diameter of 40-60mm and cooled by a water cooling mode.

3. The nickel-free low-silver-content silver storage alloy with excellent die casting performance and the process thereof according to claim 1 are characterized by comprising the following steps: rolling the obtained cast ingot at room temperature, wherein the rolling reduction of each pass is 20-30%, the intermediate annealing temperature is 420 ℃ after each two-time rolling, preserving heat for 0.5 hour, finally rolling the material into a plate with the thickness of 10-15mm, and performing intermediate vacuum annealing treatment in the jewelry forming process to eliminate stress in the processing process, wherein the temperature is 400 ℃ and the time is 0.6 hour.