Nowadays, you need to know and be able to distinguish silver from other metals. Silver is a noble natural white metal, which is widely used both in industry and in everyday life. Most often, cutlery, dishes, heirlooms, jewelry, candlesticks, frames are made from it. It is very difficult to distinguish silver from other cheap, but similar metals, which is often used by scammers and pawnshops with a dubious reputation.

Defining real metal

To understand how to distinguish silver from other metals, you need to clearly understand the basic characteristics of imitations that are so often charged for silver. It becomes clear that modern jewelry factories and industrial factories are careful control and do not allow silver of dubious quality to enter the market. All of them work in accordance with certain norms and GOSTs, so you should not worry about the quality when purchasing silver items in reliable places and trusted jewelry stores.

Forging silver began in ancient times, when the price of silver was significantly higher than in our time. Sometimes it exceeded even pure gold in value. To replace or counterfeit this white metal, various analogs were used or alloys were made from them. Ornamental metals were lead, zinc and aluminum. Often pseudo - jewelry was made from them, and covered on top thin layer silver to divert the eyes of inexperienced buyers. But after a while, such products begin to lose their aesthetic appearance, turn black, become covered with bloom, the places of the test and hallmarks are erased. If, after thorough cleaning, these signs only worsened, then the products really turned out to be a fake.

Methods for determining silver

There are many ways to distinguish silver from other metals. This can be done at a simple home, by finding it at hand necessary substances and simple devices.

Such simple methods will help you easily recognize a real noble metal at home in a few minutes. In order not to fall for the tricks of scammers, it is imperative to purchase the product at trusted points of sale. The client always has the right to request a quality certificate for the purchased products.

Differences between silver and similar metals

Silver is very similar in appearance to other metals that can hardly be called cheap and of poor quality. To be able to distinguish between them is not so easy, but still real. Most often, silver is confused with white gold and cupronickel, and sometimes even with aluminum.

To understand how to distinguish silver from white gold, you need to be a highly professional and well know the specifics of these metals. Doing this at home is impossible and dangerous. The wrong approach can ruin the jewelry. These two metals are very confused due to the fact that the basic composition of the white gold alloy has a high percentage of silver. Outwardly, these products can only differ in a more pronounced luster of white gold. But due to decorative special coatings, this distinction has lost its relevance in our days. Only an experienced specialist, a jeweler, can distinguish between these silver and white gold, who can calculate the original by its density. In jewelry stores, you can only calculate the difference between them by looking at the price. White gold will be an order of magnitude 5-10 times more expensive than silver.

Silver is often confused with cupronickel, which is an alloy of lead, nickel and copper. Cupronickel is often a production component of silver of various technical samples. To understand how to distinguish silver from cupronickel, you first need to carefully consider the product. On cupronickel, you will not find a test mark, there will only be the “MSC” mark, which deciphers its basic composition (copper, lead, nickel). You can also distinguish a silver product and cupronickel with the help of water. When diving to the bottom cupronickel products a light will appear on the surface of the water greenish tint, and when interacting with lapis pencil dark spots form on it.

It is possible to determine the authenticity of silver from an alloy using density and weight. This can be done with the help of real jewelry specialists who will determine real authenticity metal by its own technical methods. Cupronickel also gives out a very subtle specific smell of copper, which is not so easy to identify to an unknowing person.

If you still want to use home methods, then you can use an iodine solution, which will leave a slight dark spot... There will be no such trace on cupronickel. However, then you will have to additionally clean the silver from the resulting dark spots.

Silver is one of the scarce elements. But as one of the noble metals, silver is the most widespread in nature. The average silver content in the earth's crust is 7 * 10-6% (by weight), which is 20 times higher than the gold content and is approximately equal to the content of platinum group metals.

In the biosphere, silver is mainly scattered, in sea ​​water its content is 3 * 10-8%.

Basic properties of silver.

Physical and mechanical properties of silver.

Silver is a metal of white shiny color, soft and ductile, it lends itself well to pressure processing. Has a fcc lattice, density at 20 ° C is 10.49 g / cm. cubic meters, melting point 961 ° C (960.8 ° C). The differences in the melting point are explained by the high solubility of oxygen in silver.

Silver is very well polished, has the highest reflectivity, it reflects 94% of light rays, is the most electrically and thermally conductive metal.

Silver is perfectly deformed both in cold and hot state. It is easily rolled into the thinnest sheets up to 0.00025 mm. and stretched into a very thin wire. Ag can be used to make foil with a thickness of 2.5 µm. Light passing through the foil takes on a bluish-green tint.

During cold deformation, pure silver and its alloys are subject to work hardening. The area of ​​the highest plasticity and the lowest strength of cast and hot-worked silver is in the temperature range 680-800 ° C. The minimum plasticity value for cast silver is in the range of 600-650 ° С, the plasticity of silver after hot pressing is much higher than that of cast silver.

Silver is harder than gold but softer than copper. Due to its softness, pure silver (used as an alloy with copper).

Thanks to its unique properties- high electrical and thermal conductivity, reflectivity, light sensitivity - silver has a very wide range of applications. Dissolving in a gold alloy, silver gives it plasticity, shine and facilitates soldering, however, it changes the color of the alloy and significantly increases its price.

Chemical properties of silver.

The normal electrode potential of silver is 0.798 V. Pure polished silver practically does not change its color in air.

At normal temperature Ag does not interact with O2, N2 and H2. Under the action of free halogens and sulfur, a protective film of poorly soluble halides and Ag2S sulfide (gray-black crystals) is formed on the silver surface. Ozone forms a black coating on the Ag surface. Chlorine, bromine, iodine react with it even when room temperature.

Of the silver oxides, Ag2O oxide and AgO oxide are stable. Nitrous oxide forms on the surface of silver in the form of a thin film as a result of oxygen adsorption, which increases with increasing temperature and pressure. Molten silver can absorb oxygen in very large quantities, during cooling, the solubility of oxygen decreases, and porosity is formed, which degrades the quality of the surface. Silver is resistant to corrosion in most mineral and organic acids, in aqueous solutions halogens. Silver is also stable in distilled, natural and drinking water, in ethyl and methyl alcohol of any concentration.

Compared to gold and platinum, silver is less stable in acids and alkalis. At room temperature, silver dissolves in nitric acid to form AgNO 3.

Hot concentrated sulfuric acid dissolves silver to form Ag2SO4 sulfate (sulfate solubility in water 0.79% by weight at 20 ° C). Silver easily combines with mercury to form a silver amalgam. Silver does not dissolve in aqua regia due to the formation of a protective AgCl film. In the absence of oxidizing agents at ordinary temperatures, HCl, HBr, HI do not interact with silver due to the formation of a protective film of poorly soluble halides on the metal surface.

Boiling caustic alkalis have no effect on silver. Silver is also resistant to cold sulfuric acid at a concentration of no more than 80%.

The corrosive ability of silver is determined by its high thermodynamic stability, the formation of protected films on the surface and the ability to form complex compounds. Four resistance groups are used to assess the corrosion resistance of silver.

Sulfur vapors present in industrial atmospheres cause darkening of silver. The film on the surface of silver, resulting from atmospheric corrosion, is dense and viscous, consists mainly of silver sulfide and 20-25% of silver sulfate, silver chloride, or combinations thereof.

To increase the corrosion resistance of silver, the alloys are alloyed with aluminum, beryllium and silicon. To clean the surface of Ag-Cu alloys from corrosion products, cyanide solutions or dilute solutions of alkali metals are used.

Alloying elements and impurities in silver alloys.

Silver alloys for jewelry contain two components - silver and copper.

Copper. With an increase in the copper content to 28%, the hardness and strength of Ag-Cu alloys increases, and the ductility decreases.

The color of silver becomes more and more yellowish with increasing copper content. Silver alloy with 50% copper turns reddish, and with 70% copper it turns red. When other metals are added to the Ag-Cu alloy, it becomes three- or multicomponent, which can significantly change its properties: make it more versatile in application, or, conversely, completely unusable.

Gold. Ag-Au alloys have high casting properties and resistance to oxidation. The relative elongation of Ag-Au alloys is 40-45%, which allows forging or rolling the alloys into foil with a thickness of 1-1.25 * 10-4 mm.

Nickel. In silver alloys used in the manufacture of jewelry, with a nickel content of up to 1%, grain growth is slowed down, and thereby their mechanical properties are improved. With an increase in the nickel content to 2.5%, the machinability of the alloy deteriorates. With an even higher nickel content, it does not dissolve in the alloy and becomes harmful when mixed.

Iron is always an undesirable impurity in silver alloys. Iron is present in alloys in the form of foreign particles that impair machinability. In addition, iron interacts with the crucible material, coal particles, emery, salts used in smelting, and forms hard and brittle compounds. Getting on the surface of an ingot or product, these compounds break out of the metal during grinding and leave characteristic elongated traces on the surface of the product. In this regard, when remelting waste in the form of sawdust or shavings, it is first necessary to remove iron particles from them with a magnet.

Lead. Silver alloys containing lead become brittle when heated, since lead and silver at a temperature of 304 ° C form a eutectic, which is located along the grain boundaries, which makes the alloy red brittle. Lead can enter the workpiece from the soft solder or from the liners used for deep minting. Lead must be removed prior to heating or remelting operations. The Pb content in silver alloys should not exceed 0.005%.

Tin. Even a small addition of tin lowers the temperature of the alloy, but the alloy is duller, softer and more ductile than the Ag-Cu alloy. At increased content tin, intermetallic compounds with copper Cu4Sn and tin oxide SnO2 are formed in the alloy, which make the alloy brittle.

Aluminum. At a content of up to 4-5%, aluminum does not affect the structure of the alloy; at a higher content, it makes the alloy brittle, since, in this case, a brittle compound Ag3Al is formed. During annealing and melting, the Al2O3 compound is also formed, which, being located along the grain boundaries, makes the alloy brittle and brittle.

Zinc. Despite the fact that in the solid state silver dissolves up to 20% zinc in itself, its content in silver should not exceed 14%. In this case, the alloys do not tarnish in air, they are well polished and have high ductility.

Cadmium. Alloys with cadmium are ductile and resistant to corrosion in air, do not tarnish and work well. The solubility limit of cadmium in silver is about 30%.

Zinc and cadmium are the most important alloying components in the production of solders, although the strength of such solders does not fully meet the requirements of practice. The alloys have a low melting point, but a wide crystallization area; brazed alloys have low mechanical properties, which leads to the limited use of brazing alloys based on this system.

Silver alloys of various grades.

For the manufacture of jewelry, both pure silver and its alloys with copper and platinum are used. The most widely used in the jewelry industry are silver-copper alloys, less often more expensive silver-platinum alloys.

Over time, a number of silver alloys were formed, which are used mainly for the manufacture of jewelry, decorative items and cutlery and have good technological and operational properties.

According to the "Regulations on samples and branding of products made of precious metals in Russian Federation»The following silver alloys are installed in Russia - 800, 830, 875, 925, 950 (for jewelry and household products). According to the standard that applies to alloys intended for electrical conductors and contacts, jewelry, strings of musical instruments, silver alloys are designated by the letters Cp, followed by the alloying elements (ligatures) (Pt - platinum, Pd - palladium, M - copper).

The numbers after letter designation alloy indicate the mass fraction of silver, expressed in ppm (tenths of a percent) for pure silver and silver-copper alloys (for example, Ср 999, СрМ 950, СрМ925, СрМ 916, etc.), or the weight fraction of the main alloying components, expressed in percents:

In accordance with GOST 6836-2002. "Silver and alloys based on it" The designation of alloy grades consists of letters denoting alloy components, followed by numbers indicating the nominal content of the component (s) of noble metals in the alloy (in percent).

The mechanical properties of silver-copper alloys significantly depend on the copper content in them.

Thus, an increase in copper concentration from 5% (СрМ 950) to 20% (СрМ 800) leads to an increase in strength by 30%, and hardness by 60%, while reducing plasticity.

In the Ag 970 alloy, containing 97% silver, the copper content is very low, therefore, in some properties, for example, in color, tarnish resistance, the ability to remain light during annealing (in the worst case, an internal oxidized zone is formed), it is very similar to pure silver.

Thanks to high temperature melting, this alloy is often used for the manufacture of products with enamel (transparent paints are illuminated more intensely). Particularly suitable for forging, deep drawing and delicate filigree work. Considering the tendency of the alloy to age, after annealing, the alloy containing 97% silver is quenched.

Alloy SrM 950 is used for enameling and blackening. Alloy SrM 950 is also used for the manufacture of strings for musical instruments.

The color of this alloy corresponds to that of pure silver.

The alloy lends itself very well to pressure processing. It is also used for deep drawing, embossing, and for the manufacture of very thin wires. The disadvantages of the 950 silver alloy include low mechanical properties.

Products made from this alloy are deformed during operation. It is possible to increase the strength of the alloy from 500 to 1000 MPa by aging, but this leads to a complication and rise in cost. technological process alloy processing.

Alloy SrM 925 is also called “sterling” or “standard” silver. Due to the high silver content in the alloy and high mechanical properties, this alloy is widely used in many countries. The color of the alloy is the same as that of the 950 silver alloy, but the mechanical properties are higher. The alloy is suitable for enameling and blackening. The most widely used alloy is for jewelry and tableware.

The SrM 925 alloy is the oldest jewelry alloy widely used in coinage and medal production. Pressure treatment and annealing alter the cast structure of the alloy.

Alloy SrM 916 is widely used in the domestic jewelry industry for the manufacture of cutlery and Jewelry Alloy SrM 916 is very similar in properties to the alloy of the SrM 925 grade.

SrM 900 silver alloy is more often used for jewelry making. Suitable for casting, bending, soldering, forging and embossing, but too hard for delicate filigree operations and deep embossing. Its color is somewhat different from that of pure silver. This alloy is less resistant to air than alloys 950 and 925, but it has good casting properties and is well processed by pressure. The copper content in the SrM 900 alloy exceeds the limit of solubility of copper in silver, and therefore the alloy in all cases contains a certain amount of eutectic. Alloy 900, like all eutectic alloys, is unsuitable as a basis for applying enamel.

Silver alloy SrM 875 is used for making jewelry and decorative ornaments... Alloy color and tarnish resistance are almost the same as for SrM900 alloy. Its mechanical properties are higher, and its workability by pressure is worse than that of the SrM 900 alloy.

Alloy Ag 835, containing 83.5% silver, is most often used in the industrial manufacture of jewelry, due to its high hardness, it is more difficult than other alloys to be machined.

The SrM 800 silver alloy is used for making tableware instead of the 925th test alloy, as well as for making jewelry. The disadvantage of the alloy is yellowish color and low chemical resistance in air.

The plasticity of this alloy is much lower than that of the SrM 925 alloy, therefore, during the pressure treatment, it should be subjected to intermediate annealing more often. The casting properties of the SrM 800 alloy are higher than those of higher-grade alloys. The microstructure of the alloy will differ only by a slight increase in the proportion of the eutectic.

In jewelry, alloys with a silver content of over 72% are used. With an increase in the addition of copper, the shiny white silver takes on a yellowish tint:

• - the alloy of the 800th test is already significantly different from pure silver;
• - eutectic alloy containing 71.9% Ag (720th test), has a yellowish-white tint;
• - alloy with 50% copper content looks reddish;
• - alloy with 70% copper content - bright red.

Due to its yellowish color, Ag 720 alloy is almost never used in jewelry. The alloy is difficult to shape, but retains its hardness and elasticity during operation. Therefore, in individual cases springs, pin needles or other highly loaded parts are made from Ag 720 alloy.

Alloy Ag 720 is also used as a solder for alloys having a solid solution structure when they are coated with enamels.

Tarnishing of Ag-Cu alloys is observed when interacting with sulfur compounds contained in the air. In this case, silver forms silver sulfide Ag2S, and copper forms copper sulfide Cu2S and, in addition, copper oxide Cu2O is red and copper oxide CuO is black. This leads to darkening of the items, and a dark coating is formed gradually: at first the item appears yellowish, almost golden, then the surface becomes brownish, then dirty blue, dark blue and finally black. Moreover, the more copper is in the alloy, the more intense and faster it tarnishes and becomes covered with a dark coating.

The following methods are widely used to protect silver alloys from tarnishing.

Rhodium plating. Wear-resistant rhodium plating reliably protects the silver surface, but at the same time the product loses its shine and looks bluish-white. During the repair process (when soldering) the rhodium plating becomes bluish-black, which can only be removed by applying a new coating.

Varnishing. A coating of zaponlak or hot-drying varnish protects the surface of silver for a long time, but provided that jewelry is not worn and table silver is not used.

In the process of using the products, the coating in certain areas is erased, and the surface in this place fades. An object covered with this kind of stains is difficult to clean.

Passivation. The essence of passivation is to apply a thin, invisible layer of wax to the product, which covers the surface well. This method is used when storing items in warehouses (when using items, the coating is quickly erased).

Silver alloys for solders.

To connect various elements silver solders are used for jewelry among themselves when working with the "filigree" and "granulation" technique. The main requirement for a solder alloy is a low melting point; various alloying elements are added to the alloy. Unlike gold solders, silver solders may not match the sample of the products.

In brands of silver solders, silver has the designation PSr, and the code in percentage placed after each component except the last. For example, when singing PSr70M. KBTs means that the alloy consists of 70% Ag, 26% Cu, the rest (4%) - Zn.

TO distinctive properties silver solders include good ductility and strength, high corrosion resistance. They provide the required softening of the joined surfaces of the parts to be brazed, well fill the gaps of the seams.

The melting temperature of silver solders is 650-810 ° C.

Heat treatment of silver-based alloys.

In the manufacturing process silverware(during casting, welding, grinding) residual compressive or tensile stresses arise. Tensile stresses are especially dangerous: when folded with an applied external load, they can cause fracture even with a relatively small load.

The annealing temperature to relieve internal stresses is usually low and for alloys based on silver, gold and copper is 400-500 ° C, for platinum-based alloys - 600-700 ° C.

The mode of hardening heat treatment of alloys of the silver-copper system consists in quenching the alloy at a temperature of 700 ° C in water, followed by aging. By very rapid cooling during quenching, the eutectic transformation in Ag-Cu alloys can be suppressed.

The use of silver and silver alloys.

In the art industry, silver is used for the production of jewelry, expensive art utensils, cutlery, souvenirs, gifts and other items.

Rice. 4. - Jewelry originally designed to magically protect human hand: rings, signet rings - appear in the graves of the ancient Slavs from the 9th century and are widely found starting from the 10th century:

The means of processing silver and decorating items from it are chasing, casting, filigree, embossing, the use of enamels, niello, engraving, gilding.

Pure silver in the form of the finest wire serves as a material for filigree production and cutting on steel.

It is also a material for expensive artistic enamel products, it is used for anodes when silvering. Silver serves as the main component in silver jewelry solders, which are used to solder not only silver, but also copper and brass products. These solders are of the highest quality.

Pure silver has low strength and too high ductility, therefore, in the manufacture of coins and various works of art, non-ferrous metals, most often copper, are added to it. When making art products also used alloys silver - copper - cadmium, silver - copper - titanium and silver - indium.

In art, silver has been used since ancient times due to its beautiful white color and pliability in processing. The high culture of artistic processing of silver is characteristic of the art of the Hellenistic era, Ancient Rome, Ancient Iran and Medieval Europe.

For a long time in the Ancient World, various jewelry items were made from silver, jewelry - beads, rings, rings, including signet rings, vases, vessels, accessories for clothes and even for doors. From silver, like from gold, thin sheets and foil were made, with which some wooden objects were covered. Remains of thin sheet silver. The natural plasticity of silver makes it possible to create products of various shapes from this metal, from symbolist table sculpture to functionally accurate household items. The shine of silver and the possibility of polishing it allow, without covering the surface with ornaments, to demonstrate the textured beauty of the material, its natural aesthetics.

Silver jewelry is often made using the filigree technique - a pattern made of fine wire. Silver is used to make threads for silver embroidery. Currently, more than 70% of Ag is consumed for industrial purposes, that is, from a metal that served mainly for the production of coins, jewelry and household utensils, silver has turned into an "industrial" metal. The main consumers of silver are photography and cinematography, radiography and other industries using photographic materials.

Rice. 5. - Scythian silver amphora from the Chertomlyk mound:

Silver is widely used in electrical engineering, electronics, radio engineering and related engineering industries. Rocket, space and aviation technology is an important consumer of silver. Navy, production of silver-zinc and silver-cadmium batteries, as well as primary current sources. A large amount of silver is used in the manufacture of solders, in the chemical industry and in chemical engineering.

Materials for jewelry Kumanin Vladimir Igorevich

10. Silver and its alloys

10. Silver and its alloys

Silver is a chemical element, a metal. Atomic number 47, atomic weight 107.8. Density 10.5 g / cm3. The crystal lattice is face-centered cubic (FCC). Melting point 963 ° C, boiling point 2865 ° C. Brinell hardness 16.7.

Silver - metal white... It is considered the second noble metal after gold. Polished sterling silver practically does not change color when exposed to air. However, under the influence of hydrogen sulphide in the air, a dark coating forms on the surface over time - silver sulfide Ag2S. Silver compared to gold and platinum is less stable in acids and alkalis.

Silver is perfectly deformed both in cold and hot state. Highly polished and highly reflective.

The widespread use of silver in photography and electrical engineering is due to its unique physical properties- the highest electrical and thermal conductivity among metals.

Despite the fact that silver is a relatively rare element (its content in the earth's crust is only 7 x 10-6%, in seawater it is even less - 3 x 10-8%), for many centuries it has been widely used in jewelry production... This is primarily due to the high decorative properties of silver, as well as its unique plasticity. Silver jewelry is often made using the filigree technique - a pattern made of thin wire. Silver is used to make threads for silver embroidery.

For the manufacture of jewelry, as well as in the electronics industry, both pure silver and its alloys with copper and platinum are used.

Silver and silver alloy grades are regulated by GOST 6836-80.

The standard applies to alloys intended for electrical conductors and contacts, jewelry, strings of musical instruments.

According to the specified standard, silver alloys are designated by the letters Cp, followed by ligatures (Pt - platinum, Pd - palladium, M - copper). The numbers after the letter designation of the alloy indicate the mass fraction of silver, expressed in ppm (tenths of a percent) for pure silver and silver-copper alloys (for example, Sr999, SrM91b, SrM950, etc.), or the mass fraction of the main alloying components, expressed in percent (in this case, the number is separated from the letter designation not by a space, but by a hyphen, for example: СрПл-12 (12% Pt, 88% Ag), СрПд-40 (40% Pd, 60% Ag).

All silver alloys (GOST 6836-80) can be used in the electrical industry for the production of contact groups for various purposes. For the manufacture of strings of musical instruments, the SrM 950 alloy is used.

GOST 6836-80 establishes grades of silver and silver alloys with copper, platinum and palladium, intended for the manufacture of semi-finished products by casting, hot and cold deformation. Other silver alloys are regulated by industry standards or technical specifications.

The chemical composition of silver and its alloys must comply with the standards specified in tables 10.1, 10.2, 10.3 (GOST 6836-80). Silver-platinum alloys, being more expensive, are less commonly used in the jewelry industry.

Table 10.1

Table 10.2

Silver-copper alloys

Table 10.3

Silver-platinum alloys.

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Characteristic different alloys silver and copper

Silver was loved and loved all over the world and is often preferred over more valuable gold. Over the centuries, various things have been made from this beautiful light metal: cutlery, candlesticks, boxes, etc. However, it is most widely used in jewelry. Experienced craftsmen used all their imaginations to make intricate rings, earrings, bracelets, necklaces and pendants from precious metal to decorate the bodies of kings, princesses and wealthy citizens. Nowadays, silver is considered a "female" metal, since products made of it are more worn by the fair sex. But often silver chains can also be seen on men's necks.

Not everyone can afford jewelry made of pure silver, as they have a high cost. Besides, metal of the highest standard is impractical. It is soft so it scratches easily. Openwork jewelry made from it, with daily wear, quickly loses its expressiveness of relief and is no longer as beautiful as before. Therefore, in jewelry, silver alloys with other metals (ligatures) are used. Different types of alloys give the precious material hardness and increase its wear resistance. Thanks to ligatures modern jewelers can fulfill silver jewelry v the most complicated technique execution. What are the silver alloys?

Influence of metals on alloy quality

V modern world Copper is added to liquid silver as a common ligature; it is believed that these 2 metals interact well with each other.

Introduced into alloys with or without copper as well a small amount of nickel, cadmium, zinc and other impurities, which not only improve the quality of silver items, but can also worsen them.

So, if the alloy contains 1% nickel, then its strength increases, while at 2.6%, the impurity makes the alloy brittle. If more than 9% of tin is added to alloys of silver with copper, it begins to melt, oxidizes and increases the brittleness of the master alloy. For the same reason, the content of more than 6% aluminum in the alloy is undesirable. Cadmium with zinc reduce the melting point, are resistant to tarnishing in air, are plastic, and work well. If the alloy contains from 15 to 21% zinc, its beneficial features come to naught. Copper in combination with cadmium forms a rather fragile compound. The content of silicon and lead should not exceed more than 1.5% in the combination of silver with copper, since it becomes brittle, and phosphorus, sulfur and lead should not be present at all in the precious metal as ligatures.

Due to the problems described above, jewelers prefer to add the best metal for it - copper - to pure silver. 5 to 50% of this rose gold metal can be added. With a low content of copper in the alloy, the products look great and in appearance are close to pure metal.

How more copper contained in the compound, the more its color will differ from silver without impurities. If ready-made decorations have a slight reddish tint, this is the first sign that the alloy contains 50% copper. If the reddening of the product is pronounced, this indicates the presence of more than 50% copper in it. In the markets Arab countries jewelry of this kind is very often found, and sellers assure gullible tourists that they contain at least 60% silver. Although silver items are cheaper in eastern markets, it is better to buy them in specialized stores... This will serve as a guarantor of the quality of jewelry and help to avoid buying fakes.

How to understand silver samples?

Samples help to find out how many percent of copper is added to the precious metal: their number, consisting of 3 digits, indicates how many grams of pure silver is contained in 1 kg of the alloy. In the world jewelry practice, there are specially adopted standards for assaying silver and gold alloys, which must be observed by manufacturers. precious jewelry... Asian countries produce jewelry masterpieces 600, although they are not of high quality and quickly lose their appearance.

According to international standards the lowest fineness is Ag 720. Although this alloy has a slight yellowness, it is used in Russia in jewelry workshops for the manufacture of locks and clasps for chains and necklaces.

Cutlery and crockery are produced from alloys of the 750th and 800th standard. For products from these samples, you need constant care, since they quickly oxidize in air.

Silver of the 830th and 875th assay is suitable as a material for the manufacture of not only cutlery and tableware. It has found application in the production of decorative ornaments for room interiors.

The most famous alloy of silver and copper is sterling. It contains 92.5% precious metal and only 7.5% copper. It is the 925th test that is most in demand in jewelry. Most of all precious jewelry is made from it. Dazzling sterling is similar in color to pure silver, but has greater hardness, resistance to blackening.

For the production of jewelry, metal of the 960th test is also used. However, such jewelry must be worn very carefully and taken care of with great care. Due to the plasticity of the metal, the products do not differ in durability.

Only 1% of the gold-pink metal contains 999 silver. Despite the short life span, such jewelry is eagerly bought by the inhabitants of Japan. They believe that pure silver is closely connected with the Moon, which is the abode of deities merciful to people, and through wearing this precious metal they want to be closer to them.

What can be confused with ligatures?

Often attempts are made to counterfeit silver alloys by replacing them with similar-looking materials. The most common of them are cupronickel and nickel silver copper alloys. Cupronickel was very famous in ancient times under the name "Warsaw silver". Pendants, bracelets were made from it, they were used to put them on guns and daggers. From above, the material was covered with a thin layer of silver, so it was no different from real metal. It cost much less, and not only rich people could purchase products from it.

Nickel silver contains copper, nickel and zinc. In color and bright luster, it is so similar to the precious metal that it is even called “new silver”. Nowadays, nickel silver is used in jewelry for the production of clasps and pins for jewelry, but numerous fraudsters can make rings and brooches from cupronickel and silver silver in order to sell gullible buyers at the price of a precious metal. Often there are no samples on such products, which should already lead to thoughts about the dubious quality of jewelry. Therefore, it is better not to chase after rather cheap "silver", but to buy it in jewelry stores.

Why is shibuichi alloy good?

In addition to the generally recognized probed ligatures, there are silver compounds containing a high percentage of copper (from 30 to 75). They are of little value in jewelry market, but are used in the manufacture interesting decorations... One of these alloys is shibuichi. It is also called “Japanese bronze” in another way, since it was invented by the Japanese, who widely used ligature in the manufacture of handles for daggers and knives. Now beautiful brooches, bracelets, rings and earrings are made from shibuichi.

The word shibuichi means "three quarters" as it contains ¾ copper and only ¼ silver. Natural flowers of this alloy are pale pink and yellowish white. The beauty of "Japanese bronze" is that when patinated, the material takes on a variety of shades from light gray to chocolate brown. Thanks to them, the products look unusual and fantastically beautiful. Whatever alloy of silver men and women choose for themselves, they can be sure that the products will delight them appearance and shine for a long time.

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Replacing silver with dielectric coatings makes it possible to obtain light filters with a transmittance at a maximum of 80 - 90% with a small bandwidth.

To replace silver, it is necessary to take refractory metals, and non-oxidizing ones, since widely used ceramic masses require firing in an oxidizing environment. These metals include platinum and palladium; both of them are scarce and expensive, which increases the cost of monolithic capacitors and limits the development of their production.

To replace silver, oxide catalysts for the oxidative dehydrogenation of methanol have been developed. The most effective of these are the oxides of molybdenum and titanium. To increase the activity, up to 37% iron oxide is added to the molybdenum oxides. Mixed catalysts are more active and selective, the process on them proceeds at more low temperatures(350 - 400 C) and with a large excess of air in the reaction mixture. These catalysts are gradually replacing the previously accepted silver catalysts.

Copper is considered one of the most promising materials for replacing silver in fast acting fuse elements. Copper is at least 300 times cheaper than silver and is close to it in its electrical properties. The specific electrical resistance of copper is 5 - 6% higher than that of silver, which is easily compensated by an increase in the cross section of the fusible elements. The modulus of elasticity of copper is 1 to 3 times higher than that of silver, which is unfavorable for the cyclic mode of operation of the fuse. The thermal conductivity of copper is about 6% less than that of silver, and the melting point is more than 120 ° C higher.

The currently emerging tendencies of the increasingly widespread introduction of ceramic materials instead of oil-containing plastics for the manufacture of insulating parts for wiring devices and the replacement of silver and silver-containing metal-ceramic compositions with full-fledged contact materials (alloys) that do not contain precious metals for the manufacture of break contacts for switches and switches will receive the greatest development in the future.

Nowadays nickel silver and its related cupronickel (cupronickel does not contain zinc, but about 1% manganese is present) are used not only and not so much to replace table silver as for engineering purposes: cupronickel is the most resistant (of all known alloys. great stuff for taps, valves and especially condenser tubes.

Pye nickel silver and a related cupronickel (cupronickel does not contain zinc, but about 1% manganese is present) are used not only to replace table silver, but for engineering purposes: cupronickel is the most resistant (of all known alloys.

The S electrons of the alloying metal fill the vacancies of the cf - palladium bands, reducing% A, and the effect of the additive increases with the transition from Ag to Sb and especially sharply when silver is replaced by cadmium.

Toning positive images v different colors, for example, brown, blue, green and others, is based on the transformation of metallic silver in the emulsion layer into some colored compound, as well as by replacing silver with another metal or dye. When toning, only the image itself is colored, and the image in the process of toning may slightly increase or decrease. The composition of the tinting solutions and their amount are determined by the method used.

Large quantities of silver are used for the production of photographic and film materials. Despite persistent attempts to replace silver in these materials with other metals or substances, the problem remains unresolved.

Amplification is used to increase the visual or copy density of the image, as well as to correct its contrast. Strengthening of leather can be carried out by building up on metallic silver present in a layer of some substance, forming a colored silver salt and replacing silver with another substance. The amplification process is carried out in one or more solutions.

In the case of KC1 - Ag phosphors, the curve consists of two maxima at 575 and 450 tp. The latter coincides with the K-band in the spectrum of phosphorus KC1 - Ag and is undoubtedly due to silver, and not to the base, since this peak is not observed when silver is replaced by thallium. Curve a in Fig. 70 shows the absorption spectrum of X-ray phosphorus NaCl - - Ag with a low concentration of activator.

Copper-olo-po alloy coating, or bronzing, is used both for corrosion protection and for decorative finishing surface of products. Plating with a low-tin alloy (10 - 20% of tin) of golden yellow color is also used as sublayers instead of copper and nickel coatings before chrome plating, High-tin alloy (40 - 45% of tin), the so-called white bronze, in some cases can serve as a substitute silver. Despite the fact that the value of the electrical resistivity of the Cu-Sn alloy is much higher than that of silver, in an industrial atmosphere where there are impurities of sulfur compounds, it remains stable, while in silver it increases by tens of ral. For this reason, white bronze coatings are recommended for electrical contacts.

The developer treatment can be replaced by treatment with ammonia or sodium sulphide, which precipitate mercury alone as a black oxide or sulphide. Under the action of ammonia, the simultaneous dissolution of silver chloride occurs. The replacement of silver with the mentioned mercury compounds increases the intensity of blackening. Reinforcement with a mixture of uranium nitrate and potassium iron cyanide is often used. Reacting with silver, this mixture deposits on its grains a dark precipitate from a mixture of ferrous cyanide salts of uranium and silver.

Tantalum can also replace platinum in the manufacture of various chemical glassware. In the artificial silk industry, tantalum is used for the production of mouthpieces, in the chemical industry for the lining of equipment and pump parts that are subject to the greatest corrosion. Tantalum is recommended for replacing silver in spark contact tips and as a cathode in the analysis of metal salts. High strength, thermal conductivity and resistance to the action of acids make it possible to use tantalum as a material for electric heaters for hydrochloric and sulfuric acids.