What is zinc alloy - Metals and their processing

Zinc alloys: description, structure and properties

Metals and alloys have become so integral to our lives that sometimes we don’t even think about them. Back in the 4-3 millennia BC, man first became acquainted with nuggets. A lot of time has passed since then, and every year metal processing has only improved.

A metal such as zinc played a big role in this. Alloys based on it are used in many industries. In this article we will look at zinc alloys and their role in our lives.

Transition metal

Zinc is known to be a bluish-white, brittle transition metal. It is mined from semi-metallic ores. The process of obtaining pure zinc is quite complex and labor-intensive. First of all, ore containing 1-4% zinc is enriched by selective flotation.

This process produces concentrates (55% Zn). Next, you need to obtain zinc oxide. To do this, the resulting concentrates are fired in fluidized bed furnaces. Only from zinc oxide can this metal be obtained in its pure form, and there are two ways to do this.

Obtaining zinc

The first is electrolytic, based on the treatment of zinc oxide with sulfuric acid. As a result of this reaction, a sulfate solution is formed, which is purified from impurities and subjected to electrolysis. Zinc is deposited on aluminum cathodes, which is then melted in induction furnaces. The purity of zinc obtained in this way is about 99.95%.

The second method, the oldest, is distillation. The concentrates are heated to a very high temperature (about 1000°C), zinc vapors are released, which settle on clay vessels by condensation. But this method does not give such purity as the first. The resulting vapor contains about 3% of various impurities, including such a valuable element as cadmium.

Therefore, Zn is further purified by segregation. It is left to stand at a temperature of 500°C for some time and a purity of 98% is obtained. This is enough for the further production of alloys, because then the zinc is still alloyed with the same elements. If this is not enough, rectification is used and zinc is obtained with a purity of 99.995%.

Thus, both methods make it possible to obtain high-purity zinc.

An inseparable pair of metals

As a rule, lead is present in zinc alloys as an impurity. In nature, this inseparable pair of metals is found quite often. But in fact, high lead content in a zinc alloy degrades its physical properties, creating a tendency to intergranular corrosion if its content exceeds 0.007%. Most often, lead and zinc are found together in tin bronzes and brass.

If we talk about the eutectic of these two elements, it is important to note that up to a temperature of 800°C they do not mix with each other and represent two different liquids. With rapid cooling, Pb is uniformly distributed in the form of rounded inclusions along the grain boundaries. Zinc-lead alloy is used to make printing clichés due to the fact that it dissolves very quickly in acid. Most often, lead impurities are removed from zinc using the distillation method.

Copper-zinc alloy

Brass is an alloy known even before our era. At that time, zinc had not yet been discovered, but the ore was used quite widely. Previously, brass was obtained by alloying smithsonite (zinc ore) and copper. It was only in the 18th century that this alloy was first made using the metal zinc.

Nowadays, there are several types of brass: single-phase and two-phase. The former contain about 35% zinc, and the latter – 50% and 4% lead. Single-phase brass is very ductile, while the second type is characterized by brittleness and hardness.

Having examined the phase diagram of these two elements, we can conclude that they form a series of electronic phases: β, γ, ε. An interesting variety of brass is tombak. It contains only up to 10% zinc and due to this it has very high ductility. Tompak is successfully used for cladding steel and producing bimetals.

Previously, it was used to make coins and imitate gold.

Zinc and steel

In almost every home you can find galvanized things: buckets, pots, boiling pots, etc. All of them are reliably protected from rust thanks to zinc.

Figuratively speaking, of course, this metal is sprayed onto the steel, and logically we are not talking about an alloy. On the other hand, knowing how galvanizing occurs, one can say the opposite.

The fact is that zinc melts at a very low temperature (about 400°C), and when it hits the surface of steel in a liquid state, it diffuses into it.

The atoms of both substances bind very tightly to each other, forming an iron-zinc alloy. For this reason, we can safely say that Zn is not “laid” on the product, but “embedded” in it. This can be observed in ordinary everyday situations. For example, a scratch appears on a galvanized bucket. Is it starting to rust at this point? The answer is clear - no.

This happens because when moisture gets in, the zinc compounds begin to deteriorate, but at the same time they form some kind of protection for the steel. So, in most cases, such zinc alloys are intended to protect products from corrosion.

Of course, other substances, such as chromium or nickel, can be used for these purposes, but the cost of these products will be many times higher.

Tin and zinc

This alloy is no less popular than others we have already discussed earlier. In 1917-1918 in Bulgaria it was widely used for the manufacture of special vessels that held warm liquid for a long time (analogues of modern thermoses). Nowadays, zinc-tin alloy is very widely used in the radio and electrical industries. This is due to the fact that a composition containing 20% Zn solders very well, and the polishing of the deposit lasts for a long time.

Of course, this alloy can also be used as an anti-corrosion coating. Its characteristics are very similar to cadmium coating, but at the same time less expensive.

Properties of zinc alloys

Of course, all compositions with this metal differ from each other in its percentage content. In general, zinc alloys have good casting and mechanical properties. The first and most important thing is corrosion resistance. It is most pronounced in an atmosphere of dry, clean air. Possible manifestations of corrosion can be seen in industrial cities.

This is due to the presence of vapors of hydrochloric acid, chlorine and sulfur oxides in the air, which, condensing with moisture, make it difficult to form a protective film. Copper-tin-zinc is an alloy characterized by high protective properties. It is this composition that is least susceptible to corrosion, especially in an industrial atmosphere.

If we talk about the casting properties of zinc, then, of course, they depend on the alloying elements in its alloys.

For example, aluminum makes their structure homogeneous, fine-grained, refines it, and reduces the negative influence of iron. Another important alloying element is copper. It increases strength characteristics and reduces intercrystalline corrosion. The copper-zinc alloy has high impact strength, but at the same time partially loses its casting properties.

Areas of application of zinc and its alloys

In fact, parts made of zinc alloys are quite common in our time. Despite the fact that plastic is replacing metal products, in some cases it is impossible to do without them. For example, the automotive industry is an industry that cannot do without zinc alloys. Filters, sedimentation tanks, carburetor and fuel pump housings, wheel covers, mufflers - all this and much more is made using compounds of this chemical element.

Due to the fact that zinc alloys have good casting properties, complex parts of various shapes with minimal wall thickness are cast from them. Construction is another area where these alloys cannot be avoided.

Rolled zinc is used for roofing, pipes and gutters.

Despite the fact that there is a tendency to reduce the production of zinc alloys, it is not possible to abandon their production due to the relative cheapness and mechanical properties of the material.

Source: https://FB.ru/article/342309/tsinkovyie-splavyi-opisanie-struktura-i-svoystva

Zinc casting alloys | Agency Lite++

Zinc alloys are divided into casting, antifriction and wrought. The properties of zinc alloys for the production of castings are regulated by GOST 25140-93 “Zinc foundry alloys” . The chemical composition of the alloys is presented in table. 1, mechanical properties are given in table. 2.

Marking of alloys : alloys are marked with the letter C and additionally with letters and numbers displaying the name of the alloying element and its content in the alloy, respectively. For example, TsA4M1 is a zinc cast alloy containing in its composition: 3.5-4.5% Al and 0.7-1.3% Cu, Zn - the rest.

Table 1: Grades and chemical composition of zinc casting alloys

Alloy grade	Mass fraction of elements, %
Main components
Al	Cu	Mg	Fe	Zn
ZnAl4A*	3,5-4,5	—	0,02-0,06	—	ost.
CA4o	3,5-4,5	—	0,02-0,06	—	ost.
CA4	3,5-4,5	—	0,02-0,06	—	ost.
ZnA14Cu1A*	3,5-4,5	0,7-1,3	0,02-0,06	—	ost.
TsA4M1o	3,5-4,5	0,7-1,3	0,02-0,06	—	ost.
TsA4M1	3,5-4,5	0,7-1,3	0,02-0,06	—	ost.
TsA4M1v	3,5-4,5	0,6-1,3	0,02-0,1	—	ost.
ZnA14Cu3A*	3,5-4,5	2,5-3,7	0,02-0,06	—	ost.
TsA4M3o	3,5-4,5	2,5-3,7	0,02-0,06	—	ost.
TsA4M3	3,5-4,5	2,5-3,7	0,02-0,06	—	ost.
TsA8M1	7,1-8,9	0,7-1,4	0,01-0,06	—	ost.
TsA30M5	28,5-32,1	3,8-5,6	0,01-0,08	0,01-0,5	ost.

Table 1: continued

Alloy grade	Mass fraction of elements, %
Impurities, no more
Cu	Pb	Cd	Sn	Fe	Si	Pb+Cd+Sn
ZnAl4A*	0,06	0,004	0,003	0,001	0,06	0,015	0,007
CA4o	0,06	0,005	0,003	0,001	0,06	0,015	0,009
CA4	0,06	0,01	0,005	0,002	0,07	0,015	—
ZnA14Cu1A*	—	0,004	0,003	0,001	0,06	0,015	0,007
TsA4M1o	—	0,005	0,003	0,001	0,06	0,015	0,009
TsA4M1	—	0,01	0,005	0,002	0,07	0,015	—
TsA4M1v	—	0,02	0,015	0,005	0,12	0,03	—
ZnA14Cu3A*	—	0,004	0,003	0,001	0,06	0,015	0,007
TsA4M3o	—	0,006	0,003	0,001	0,06	0,015	0,009
TsA4M3	—	0,01	0,005	0,002	0,07	0,015	—
TsA8M1	—	0,01	0,006	0,002	0,10	0,015	—
TsA30M5	—	0,02	0,016	0,01	—	0,075	—

Note: Alloys manufactured by agreement between the consumer and the manufacturer are marked with an asterisk

Influence of the main components

The main alloying elements of zinc casting alloys are aluminum, copper and magnesium. Zn with Al forms a series of solid solutions with a eutectic temperature of 380°C (in the eutectic there are 95% Zn and 5% Al). A eutectic alloy of zinc with aluminum and copper (composition: 89.1% Zn, 7.05% Al and 3.85% Cu) solidifies at 423.5°C.

When the temperature drops to 274°C, the solid solution decomposes and, as a result, the dimensions of the casting change. It should be noted that when the aluminum content in the alloy is up to 10%, it has little effect on changes in product dimensions. The introduction of 0.03-0.1% magnesium into the alloy increases mechanical strength and corrosion resistance, but its content should not exceed 0.1%, because

high concentration causes hot brittleness of castings. When the copper content in the alloy increases from 1 to 5%, the dimensions of the castings during aging increase to 0.15%.

Impact of impurities

The most harmful impurities in cast zinc alloys are tin, lead and cadmium, which contribute to intercrystalline corrosion. With an increase in lead content from 0.003 to 0.006%, the linear dimensions of products during aging increase by 0.1-0.5%. [3]

Table 2: Mechanical properties of zinc alloys

Alloy grade	Casting method	Mechanical properties, no less
Tensile strength, MPa (kgf/mm2)	Relative extension, %	Hardness, HB
ZnAl4ACA4o, TsA4	KD	196 (20)256 (26)	1,21,8	7070
ZnA14Cu1A, TsA4M1o, TsA4M1	KD	215 (22)270 (28)	1,01,7	8080
TsA4M1v	K, D	196 (20)	0,5	65
ZnA14Cu3A, TsA4M3oTsA4M3	PKD	215 (22)235 (24)290 (30)	1,01,01,5	859090
TsA8M1TsA30M5	KDKD	235 (24)270 (28)435 (44)370 (38)	1,51,58,01,0	7090115115

Symbols for casting methods: P – sand casting; K - chill casting; D - injection molding.

Table 3: Physical characteristics of alloys

Alloy grade	Density, g/cm3	Temperature range of solidification, °C	Specific heat capacity at 20°C, J/kg °C	Thermal conductivity, W/m °C	Temperature coef. linear expansion in the range 20-100°С, α·10-61/°С
CA4	6,7	380-386	410	113	26,0
TsA4M1	6,7	380-386	440	109	26,5
TsA4M3	6,8	379-389	427	105	29,5
TsA8M1	6,3	375-404	—	—	—
TsA30M5	4,8	480-563	—	—	—

Application area

The linear dimensions of products made from zinc cast alloys change slightly; they have a low melting point and high fluidity, which makes it possible to produce castings from them with a minimum wall thickness of up to 0.5 mm.

The disadvantages of alloys include the tendency to form hot cracks and large zones of columnar crystals, as well as the tendency to coarse grains and the formation of increased porosity when casting in sand-clay molds.

The physical properties of zinc alloys are given in table. 3.

Zinc alloys in the foundry industry are widely used for the production of high-pressure castings used for the production of small parts for the automotive industry, tractor manufacturing, household appliances and appliances, furniture fittings, lock cases, etc. The characteristic properties of zinc alloys and recommendations for their use are given in table. 4.

Table 4: Alloy Recommendations

Alloy grade	Characteristic properties	Application area
ZnAl4A	Good fluidity, increased corrosion resistance, dimensional stability	In the automotive, tractor, electrical and other industries for casting parts of devices that require dimensional stability
CA4o	Good fluidity, good corrosion resistance, dimensional stability
CA4	Same as for grade TsA4o, but with less corrosion resistance
ZnA14Cu1A	Good fluidity, increased corrosion resistance, virtually unchanged dimensions in the natural structure	In the automotive, tractor, electrical and other industries for casting housing, reinforcement, and decorative parts that do not require high precision
TsA4M1o	Good fluidity, good corrosion resistance, almost unchanged dimensions in the natural structure
TsA4M1	As for the TsA4M1o brand, but with less dimensional stability
TsA4M1v	In terms of technological and operational properties, it is inferior to previous grades of alloys of this group	In various industries for casting non-critical parts
ZnA14Cu3A	Good fluidity, high strength, good corrosion resistance, dimensional variability up to 0.5%	In automotive and other industries for the manufacture of parts requiring increased precision
TsA4M3o	Good fluidity, high strength, good corrosion resistance, dimensional variability up to 0.5%
TsA4M3	As for grade TsA4M3o, but with reduced corrosion resistance
TsA8M1	As for the TsA4M1 grade, but with higher strength properties	In automotive, tractor, electrical and other industries
TsA30M5	Designed to replace the standard antifriction alloy TsAM10-5, significantly superior to it in mechanical properties and wear resistance	Bearing shells, balanced suspension bushings, worm gears, rolling bearing cages

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Zinc casting manufacturers

Zinc Alloy High Pressure Casting Manufacturers

Literature

Mechanical and technological properties of metals. Directory. Bobylev A.V. M., “Metallurgy”, 1980. 296 p.
Vozdvizhensky V.M. and others. Foundry alloys and technology of their smelting in mechanical engineering. - M.: Mashinostroenie, 1984. - 432 pp., illus.
Mogilev V.K., Lev O.I. Foundryman's Handbook. M. Mechanical Engineering, 1988. - 272 pp.: ill.
Encyclopedia of Inorganic Materials. In two volumes. K.: Higher School, 1977.
GOST 25140-93 “Zinc casting alloys”

Source: https://on-v.com.ua/novosti/texnologii-i-nauka/cinkovye-litejnye-splavy/

Zinc alloy: special properties and main varieties

Thanks to archaeological excavations, it was discovered that zinc products began to be used around the 7th century AD. This metal was very common due to a number of useful properties. Zinc alloy can be made from various substances, which determine its characteristics. This material is used in various industries, including jewelry.

Properties and characteristics of zinc and zinc alloys

The characteristics of zinc alloys are largely determined by the properties of zinc. This metal is bluish in color, is not found in its pure form, and usually contains impurities that change its properties. Pure metal is obtained as a result of several reactions.

Zinc has the following chemical properties:

When heated, it reacts with hydrogen sulfide and water to release hydrogen.
Does not react with nitrogen and carbon.
It reacts with alkalis to form zinc acid salts - zincates.

Zinc is a very durable material. Its ductility increases when heated. If it is heated by more than 210 degrees, this may change its shape. At low temperatures the substance melts.

What does zinc alloy look like?

The amount of impurities depends on the methods of metal extraction, the characteristics of its processing and the zinc grade. Most often you can find impurities in the form of nickel, chlorine, fluorine and lead. Usually, when creating zinc alloys, pure zinc is used, since the presence of impurities degrades the quality of the material:

tin makes the alloy too brittle and brittle;
in the presence of cadmium, the ductility of the material decreases;
lead increases intercrystalline corrosion of the material and promotes its dissolution in acids;
the presence of iron increases the hardness of alloys, but reduces their ductility;
Arsenic causes the alloy to become brittle and non-ductile.

Therefore, to improve the characteristics of zinc alloys, zinc is first purified from impurities. And then they use pure metal, which is alloyed with various components.

Advantages and disadvantages

Most zinc alloys have the following advantages:

they are very durable and are not damaged by mechanical stress;
resistant to corrosion;
have good casting qualities and can be used to create even small elements;
Over time, they practically do not age.

However, even small amounts of impurities worsen the characteristics of the alloy. They lead to a decrease in melting point, swelling, and contribute to the appearance of cracks. Therefore, zinc alloys must be created in compliance with all technologies, and the amount of impurities in them should not exceed 0.005%.

Many people ask whether zinc alloys darken or not? This is another drawback of the material. Zinc alloys may darken over time. Moreover, the darkening usually spreads over the entire surface of the material. This is caused by the formation of an oxide film on the surface of the material. It forms at room temperature after contact with air or water. Therefore, to avoid this, electroplating is required.

Types of zinc alloys

Zinc can be alloyed with various substances, which will determine the properties of the resulting material. Alloying pure zinc with copper, aluminum and tin can improve its performance. The resulting composition will be of higher quality than the pure substance.

Copper and zinc

The copper-zinc alloy is called brass. This alloy has been known for a very long time. It was first made by alloying zinc ore and copper. It was only in the 18th century that an alloy of copper and zinc metal was first created.

Moreover, both components can be taken in different proportions. As a result, several types of brass are distinguished:

Green. Contains 60% copper and 40% zinc.
Golden. It contains 75% copper and 25% zinc.
Yellow. Contains 67% copper and 33% zinc.

Brass is an alloy of copper and zinc

Brass lends itself well to pressure processing. It is characterized by high mechanical properties and good corrosion resistance. But in air, in salt water and carbon dioxide solutions, brass is unstable and quickly becomes covered with a dark oxygen film.

Externally, brass looks more beautiful than copper and is characterized by better corrosion resistance. But as the temperature rises, the intensity of corrosion also increases. It can be triggered by high air humidity, the presence of ammonia or sulfur dioxide. Therefore, to prevent corrosion, the material is subjected to low-temperature firing.

Brasses do not lose their properties when the temperature drops. This allows them to be used as a structural material. But at high temperatures (more than 200 degrees), phenomena of brittleness of brass can be observed.

Aluminum and zinc

Most often, an alloy of zinc, aluminum and copper is created, which is called TsAM. It also contains a small amount of magnesium.

This alloy has a low melting point and is easy to cast. Products made from it are very durable and resistant to the environment.

There are several high-quality zinc-aluminum alloys, which are designated TsAM 4-1, TsAM 4-3, TsAM 10-5 and others. They contain approximately the same amount of aluminum, but different amounts of magnesium, nickel and copper. The cost of an alloy of aluminum and zinc is lower than that of tin and zinc. Therefore, products made from it are much cheaper.

Scope of application

Zinc alloys are widely used. They are used in the following industries:

In the automotive industry. Door handles, mirrors, and parts for car interior decoration are made from zinc alloys.
When creating jewelry. Zinc is alloyed with gold, thereby increasing its ductility and malleability. This makes it easy to connect small parts to each other.
In medicine. Zinc alloys are used to make medical furniture and devices. And zinc oxide is a good antiseptic, so it is added to various ointments and medicines.

Zinc alloy is used in automobile manufacturing

Thus, zinc and its compounds are used in many fields. But the substance is most widely used in the automotive industry.

Types of zinc alloys by purpose

According to their intended purpose, zinc alloys can be of several types:

Deformable. 15% - aluminum, 5% - copper, more than 1% - magnesium. It is made in the form of sheets or rods. The properties are similar to brass.
Foundries. They are made by adding 3-4% copper and aluminum to zinc, as well as 0.05% magnesium. They have good fluidity. Therefore, they are manufactured through injection molding or mold casting.
Anti-friction. They contain 10% aluminum, 5% copper and 0.1% magnesium. Manufactured by injection molding. They have a low coefficient of friction and are used in the automotive industry.
Solders. They are used for soldering aluminum parts. Usually include impurities - metals. This increases their strength.
Typographic. They contain 7.5% aluminum, 2% magnesium and approximately 4% copper. Such alloys are very durable and cast well into molds.
Protective. They contain no more than 1% aluminum and a tiny amount of silicon and magnesium. Resistant to corrosion even in damp environments. Therefore, such alloys are used as protective materials.

Zinc alloys have proven themselves well and are widely used. But when creating them, proportions must be accurately taken into account, otherwise poor quality material will be obtained.

Zinc alloy in jewelry

Externally, zinc alloys resemble noble metals. Therefore, they are used in costume jewelry to create inexpensive jewelry. Zinc alloy jewelry looks expensive but is easy to create.

Is zinc alloy harmful? In fact, it has no effect on the human body. But, nevertheless, it is better to purchase good quality jewelry. Usually, a special alloy is used to create jewelry, which is called costume jewelry. The most commonly used is brass or an alloy with aluminum. Externally, such products resemble gold and silver.

Is zinc alloy harmful in jewelry? No, so you can safely buy products made from it. After all, if it had a negative impact, making jewelry from it would be prohibited.

Thus, zinc and zinc alloys are widely available. They are used in medicine, automotive industry and even in jewelry. These are high-quality and sustainable materials that practically do not change under the influence of environmental conditions.

Source: https://1nerudnyi.ru/tsinkovyj-splav-01/

How to distinguish zinc from other metals

A metal such as zinc played a big role in this. Alloys based on it are used in many industries. In this article we will look at zinc alloys and their role in our lives.

Is zinc alloy harmful in jewelry? – stalevar.net , , , , – News of the computer world

More and more buyers around the world are paying attention to the content of hazardous metals in jewelry - primarily lead and nickel. In some countries, in the USA, in several European countries, costume jewelry is subject to mandatory certification and inspection, and the sale of jewelry containing lead is strictly limited.

Why is lead content in costume jewelry dangerous, and is it possible to buy lead-free jewelry in China?

Why is lead in jewelry dangerous?

Lead is a toxic metal. When it enters the body, it negatively affects the liver, kidneys, brain, and accumulates in bones and teeth - from where it can later be released again. There is no minimum safe level of lead in the body.

It is most dangerous for pregnant women (as it affects the fetus) and for children under six years of age. Children with elevated levels of lead in their bodies may experience developmental delays, behavioral problems, damage to the nervous system, cause seizures, and even death in high concentrations.

The damage caused to a child's nervous system and brain development due to lead poisoning is irreversible. High levels of lead in a pregnant woman's body can lead to miscarriages, premature fetal death and other consequences.

How dangerous is it to wear lead jewelry?

Lead enters the body through inhalation of vapors and microparticles, as well as through water and food (pipes with lead solders, dishes containing lead, etc.).

Lead practically cannot enter the body through the skin. Therefore, the danger of jewelry that comes into contact with the skin is practically zero.

But, when ingested, lead is absorbed into the blood. Some people “chew” jewelry - a bad habit, especially for children - they put everything in their mouth. With such “chewing,” there is a 100% chance that lead from jewelry will enter the body. And then the only question left is how much lead you “ate.”

Are there any special requirements for certification of costume jewelry from China?

In Russia, costume jewelry is not subject to mandatory certification (only voluntary) - therefore, jewelry even entirely made of lead can be safely sold on the Russian market.

Although there are exceptions to this rule:

1) Large retail chains buy only jewelry that has passed voluntary certification and tests. Accordingly, it will be safer to buy jewelry there.

2) If costume jewelry is intended for children, it must be tested by Rospotrebnadzor, which also gives certain guarantees. Unless, of course, it was brought to Russia “in white”.

1. Cheaper

Costume jewelry is mainly made from either zinc or lead alloy. Lead-based alloy is at least 30% cheaper than zinc alloy. The product will be cheaper in the end.

2. Easier to produce

When casting a product from a lead alloy, you can use cheap rubber molds, while when casting a product from a zinc alloy, you can use expensive silicone and metal ones. Rubber molds last longer, the melting point is lower, and in general it is much easier to produce jewelry from lead alloys.

Soldering connections - beads, chains, small jewelry elements. The easiest way to solder is with lead. Which is what many manufacturers do.

3. High quality

Have you seen bubbles on jewelry? When does the top coating of a product peel off? They say it's of poor quality. So, such defects are much less likely to be seen on jewelry made from lead alloys. It will seem like higher quality jewelry.

Plus, products made from lead alloys are heavier and more massive - for buyers they seem more “expensive”, more solid. This adds purchasing value to the product.

Is it possible to guarantee lead-free jewelry in China?

I’ll tell you about the situation in our city of Yiwu, where the largest wholesale jewelry market in the world is located - about 6,000 suppliers.

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As a rule, the question from buyers is “do you have lead-free jewelry?” To which in almost 100% of cases you will receive the answer “yes, lead-free”. Buyers from Europe and the USA have “trained” suppliers to respond in this way - otherwise no one will buy anything.

Therefore, you should not completely trust words. Jewelry may contain some amount of lead, especially for jewelry that consists of many small parts - they will almost always be soldered using lead.

Many manufacturers purchase “parts” for jewelry production from third-party suppliers—they simply cannot guarantee that these parts are lead-free. They don’t know themselves.

The cheaper the product, the higher the chance that it is made of lead alloy. If low price is your main concern, your shipment will likely contain lead.

The only way to avoid such problems is to have the product tested at a laboratory in Yiwu, which your export agent can help you with. Only such a test will give you complete confidence that the jewelry will not contain toxic metals.

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Is zinc alloy harmful? – kissstyle.ru

Very often people wonder if zinc alloy is harmful to health? Modern zinc jewelry alloy does not contain nickel and lead (very often manufacturers specifically indicate that jewelry is made without the addition of nickel and lead), and it is these metals that are harmful to the human body and cause allergies. We carefully select high-quality jewelry from modern and safe materials, so when buying modern zinc alloy jewelry in our online store, you can be sure that it is safe for your health .

Let's take a closer look at what alloys are used in jewelry. In the manufacture of modern jewelry and costume jewelry, a number of alloys of various metals are used with the addition of certain components; all such alloys, as a rule, are designated by manufacturers as “jewelry alloy .

Modern jewelry alloys no longer use nickel - after all, it is its high content in the alloy from which the jewelry is made, or the nickel coating, that causes allergies.

Let's take a closer look at what exactly the beautiful earrings, necklaces, bracelets, rings, pendants, cuffs and other wonderful jewelry and costume jewelry that you can buy in our store are made of.

The second part of our story about jewelry alloys, which are used to make jewelry and costume jewelry that can be purchased in our store, is devoted to zinc-based alloys. Most often, manufacturers indicate “zinc alloy” as the material.

One of the most common alloys of this kind is brass. It is a combination of zinc and copper with the addition of other metals and components.

Sometimes a type of brass called tombac is distinguished as a separate jewelry alloy - this alloy is very ductile and does not corrode, making it very popular for making jewelry.

Manufacturers of jewelry and costume jewelry also use the term “zinc alloy” to refer to a combination of zinc, aluminum and copper. Often this alloy imitates silver in its appearance, which is why it is so widely used in the manufacture of jewelry and costume jewelry that combines beautiful design and affordable cost.

Source: https://delvik.ru/raznoe/vreden-li-cinkovyj-splav-v-bizhuterii-stalevar-net.html

Zinc alloy

Judging by archaeological finds made in India, China and Greece, humanity has been using zinc to produce various products since about the 7th century. Tools, jewelry and even weapons were made using zinc alloys, but people learned to separate zinc from impurities only 300 years ago. The metal ore contains less than 5% zinc.

Dangerous zinc impurities

It is necessary to separate zinc from impurities not only because of their effect on the working qualities of the metal, but also because many of them are harmful to humans.

Most often, zinc-containing ores contain impurities of the following metals:

tin,
cadmium,
lead,
iron,
copper,
arsenic,
antimony.

The presence of most of these impurities makes zinc castings more durable, but negatively affects their ductility, resistance to corrosion and makes them more brittle and brittle.

The presence of tin makes the alloy too brittle;
The presence of cadmium reduces ductility;
Lead promotes dissolution in acids;
Iron inclusions make the alloy harder, but make the alloy less strong and complicate the melting process;
The presence of copper also makes the alloy harder, but on the contrary improves the quality of casting, although it reduces ductility and resistance to corrosion;
The presence of arsenic makes the alloy more brittle and less ductile;
When a zinc alloy with an admixture of antimony is heated, the edges of the casting crack and the ductility decreases.

Types of zinc alloys and their properties

Alloys with various metals: copper, magnesium, aluminum, nickel are easily soldered and welded, have a lower melting point and are better poured into molds. Each of these metals affects the properties of the alloy in its own way and is used in different industries.

According to their purpose, zinc alloys are divided into the following types:

Deformable. Approximately 15% aluminum, 5% copper and less than 1% magnesium, similar in properties to brass, manufactured using fill or semi-continuous casting and subsequent production of sheet or rod material;
Foundries. They are obtained by adding no more than 3.5-4% copper and aluminum and a small amount (approximately 0.05%) magnesium to the metal, they are characterized by good fluidity and do not interact with the material of the casting mold, they are manufactured using injection molding or casting into molds;
Anti-friction. They contain more than 10% aluminum, about 5% copper and less than 0.1% magnesium, they are widely used in the manufacture of bearings, due to the low coefficient of friction, they are manufactured using injection molding;
Solders. Used for soldering aluminum. Depending on the brand, they may include aluminum, copper, cadmium, silver, lead and other metals, which are characterized by high strength and ductility, but are susceptible to corrosion;
Typographical. They contain up to 7.5% aluminum, slightly less than 2% magnesium and up to 4.5% copper, are durable and pour well into molds, and are used for casting typographic fonts;
Protective. They contain less than 1% aluminum and small amounts of magnesium or silicon, resist corrosion well in humid environments, and are used as protective metals in many industries.

Among the common and well-known zinc alloys are:

Brass. Zinc-copper alloy. Copper is the main component. Depending on the copper content, green, yellow and golden brass are distinguished. At temperatures above 300°C, brass may become deformed. There are also multi-component brasses; they are obtained by adding a number of other metals to the alloy.
TsAM. An alloy of zinc, aluminum and copper with a small amount of magnesium. They have a low melting point, cast well and make stronger products. The group of copper-zinc alloys with the addition of magnesium and aluminum used in industry is designated by the abbreviation TsAM. They melt at a relatively low temperature, and therefore pour well into molds. Products made from TsAM group alloys are much stronger.
Virenium is an alloy of copper and zinc with a small addition of nickel.

The influence of various metals on the properties of the alloy

Copper-zinc alloys are increasingly used in the manufacture of various industrial products, and the presence of metals such as magnesium, aluminum, and nickel improves their performance.

They are easier to process by soldering and welding, have a lower melting point and are better poured into molds. Each of these metals affects its properties in its own way and is used in different industries.

Is zinc alloy in jewelry harmful?

In their appearance, such jewelry resembles precious metals, so they are widely used in the jewelry industry. They are often used to make jewelry. Jewelry made from zinc alloys looks quite expensive, but due to its ease of processing, it is easy to manufacture.

There is a special zinc alloy that is used only for making jewelry; it is called “costume jewelry”; in the passport for jewelry there is even a mark “zinc alloy for costume jewelry.”

Brass or tombak (golden brass) is most often used in the production of costume jewelry; it is less susceptible to corrosion, therefore it is used in the production of more expensive jewelry. Jewelry made from an alloy of copper and zinc with the addition of aluminum looks very similar to silver.

For the manufacture of jewelry, zinc is used, purified from nickel, lead and other metals hazardous to humans. The passport for such jewelry must include a note indicating the absence of harmful impurities in the alloy from which it is made. Therefore, we can talk about the absolute safety of such jewelry for the people wearing them.

Does zinc alloy rust or not?

To prevent rust, jewelry containing zinc is treated with a special protective compound, and such jewelry can last quite a long time.

Is it getting dark or not?

True, zinc, interacting with atmospheric oxygen and various household liquids, including water, is susceptible to oxidation even at normal temperatures, which contributes to the darkening of zinc alloy products. Such jewelry can leave marks on clothing and skin, so they require additional care.

Also, to prevent oxidation, some manufacturers electroplate zinc products with gold or silver, but such treatment significantly increases the cost of jewelry.

Zinc deposits are quite common on earth, and despite its low content in ore and the difficulty of purifying it from impurities, the zinc obtained from it and its alloys with other metals are increasingly used in various industries.

Source: https://prompriem.ru/splavyi/cinkovyj.html

Is zinc alloy dangerous? Jewelry alloy. What it is

What metal is best to choose jewelry from?

Most often, aluminum, copper, zinc, tin, brass, steel and nickel are used to make high-end jewelry. Moreover, products made from only one metal are extremely rare. To create rings, brooches, bracelets or pendants, alloys that consist of two or more metals are mainly used.

Tompak Alloy with high corrosion resistance and increased ductility. It consists of copper and zinc in a ratio of 1 to 9. Copper is found in alloys more often than other metals because it gives the effect of antiquity. However, it quickly oxidizes and over time the jewelry darkens.
Brass is brass, that is, again, an alloy of zinc and copper with an admixture of other metals. It has approximately the same properties as tombak. Does not contain nickel, which, although highly corrosion resistant, quite often causes allergies and irritation. That is why the absence of nickel indicates high quality jewelry.
Stainless steel is perhaps the most practical metal, which is highly resistant to corrosion, but because of this, finished products have a fairly high price. In addition, to protect jewelry from corrosion, a protective coating is applied to alloys and metals, which has a certain color and dullness.

5 types of jewelry coatings

In the modern jewelry industry, there are many different coatings that, in addition to protection, serve as a dye. For example, as a result of their use, jewelry made from the same alloys can be made to resemble silver, gold, bronze, platinum, or be matte black.

Rhodium and palladium As a result of sputtering, jewelry has a silver color. Jewelry with such a coating does not darken over time, but the coating may wear off.
Gold Spraying of precious metals, in particular gold, can make jewelry into an almost eternal piece of jewelry that does not deteriorate over time. However, too thin a layer can lead to scuff marks.
Silver is a metal that oxidizes very easily and quickly, resulting in the formation of a dark and thin layer of plaque on the surface of the metal. You can get rid of it by caring for the product, but over time it will appear again.
Ruthenium allows you to make silver jewelry with a characteristic whitish tint and incredible shine.
Copper This coating can make it possible to make rings, pendants, bracelets in bronze or antique gold. In addition, copper is hypoallergenic and does not cause itching or irritation like other metals can.

Coatings are applied in different ways. This can be foiling, painting, simple and electroplating. The latter method takes place at the interatomic level and is considered the most durable and wear-resistant.

The most common material used in costume jewelry is electroplated jewelry alloy. In fact, most of our beads, rings, toggles, earrings, and so on are made from it.

This is a tin-based jewelry alloy. Tin in its pure form is unsuitable for the manufacture of forged metal products. It is refractory and too brittle for casting. Therefore, alloys have long been made from tin by adding other metals to it.

The composition may include copper, aluminum, antimony or any other hypoallergenic metal that does not oxidize upon prolonged contact with human skin. The addition of copper adds ductility to the alloy. The addition of antimony provides brightness, thanks to which the alloy does not fade over time.

Traditionally, lead was added to tin alloys until the end of the 19th century. Nowadays, there is no such practice, since it can transfer to human skin. The absence of lead in jewelry alloys is regulated by law. Another metal that is never present in high-quality alloys is nickel.

This is primarily due to the fact that it often causes allergies on sensitive skin. The components vary depending on the manufacturer, but any additive adds its own characteristics to the alloy, which is reflected in the use of the final product.

Sometimes manufacturers use zinc as the base alloy, which reduces the cost of the product. Such products differ from pewter ones, since the alloy itself is harder and duller.

THIS IS INTERESTING: What is the name of the alloy of copper and zinc

Jewelry alloy is very plastic and, as a result, is optimal for creating a variety of shapes and designs. Today it is used not only to create jewelry. A similar alloy can be found in the production of exquisite tableware and winners' cups. For example, the famous Oscar figurine is made of just such an alloy with gold plating.

To give a variety of shades, galvanic coatings are used: silver plating, gilding, copper, bronze, brass, chrome, etc. Sometimes products are coated with a thin layer of gold or silver leaf.

But jewelry alloy also has negative sides. First of all, it is quite fragile and cannot withstand repeated bending. Secondly, any, even the most durable coating is subject to wear and does not withstand aggressive environments such as sea water, acid, alcoholic drinks, etc.

Very often people wonder if zinc alloy is harmful to health ? Modern zinc jewelry alloy does not contain nickel and lead (very often manufacturers specifically indicate that jewelry is made without the addition of nickel and lead), and it is these metals that are harmful to the human body and cause allergies. We carefully select high-quality jewelry from modern and safe materials, so when buying modern zinc alloy jewelry in our online store, you can be sure that it is safe for your health .

Let's take a closer look at what alloys are used in jewelry. In manufacturing, a number of alloys of various metals are used with the addition of certain components; all such alloys, as a rule, are designated by manufacturers as “jewelry alloy” .

Modern jewelry alloys no longer use nickel - after all, it is its high content in the alloy from which the jewelry is made, or the nickel coating, that causes allergies.

Let's take a closer look at what exactly the beautiful earrings, necklaces, bracelets, rings, pendants, cuffs and other wonderful jewelry and costume jewelry that you can buy in our store are made of.

One of the most common alloys of this kind is brass. It is a combination of zinc and copper with the addition of other metals and components.

Sometimes a type of brass called tombac is distinguished as a separate jewelry alloy - this alloy is very ductile and does not corrode, making it very popular for making.

Manufacturers of jewelry and costume jewelry also use the term “zinc alloy” to refer to a combination of zinc, aluminum and copper . Often this alloy imitates silver in its appearance, which is why it is so widely used in the manufacture of jewelry and costume jewelry that combines beautiful design and affordable cost.

Jewelry alloy is a macroscopically homogeneous metallic material consisting of a mixture of two or more chemical elements with a predominance of metallic components. As a rule, these are tin, nickel, brass, copper and other metals.

What alloys are jewelry made from?

The higher the quality of the alloy, the more expensive the product will be. Typically, alloys based on nickel, tin, brass and copper, zinc, and aluminum are used.

More expensive jewelry can be made of steel: surgical (medical), stainless and other types.

What kind of jewelry does not darken?

Any jewelry can darken, since jewelry alloys easily come into contact with

Reaction with oxygen and human sebum. Upon contact with the human body, the metal begins to change color and lose some properties. Exceptions may be alloys with a durable galvanic coating.

How to determine what jewelry is made of without chemical testing?

The matte, dull gray color of the product indicates the predominance of tin in the alloy. The decoration is light and brittle.

The aging effect (tarnished, reddish or bronze color) indicates the presence of copper in the alloy. In this case, the process of color change is inevitable, but practically unnoticeable, because the alloy already looks old and darkened in its original design.

If the jewelry is made “bronze” and has a yellow-green or yellow-gray tint, most likely the base of the alloy is brass .

Steel is widely used in the production of costume jewelry. Such jewelry has a gray color, metallic or chrome-plated surfaces “silver”. As a rule, such products last longer than their “golden” counterparts.

The dark, almost black color of the metal indicates a high nickel ; it is these alloys that often cause allergies.

Titanium alloys (mostly silver) are durable and hard materials that do not cause allergies. But their cost is much higher than that of ordinary jewelry.

What are the alloys coated with?

Alloys that require plating (gold or silver) can be thinly coated with gold or silver, or simply painted. Foil foiling is also often used. Expensive products have galvanic coating - this is a more complex process of applying one metal to another, the result is of high quality, the product is wear-resistant.

Also, jewelry coatings are rhodium, osmium, paladium - more expensive.

Less expensive ones are nickel, ruthenium, copper, bronze and brass.

What alloys can cause allergies?

In fact, allergies are quite an individual phenomenon, so it manifests itself in different people under different circumstances, but still, there is a lower chance of developing a rash if you do not wear jewelry with a high nickel . Give preference to steel, titanium alloys or jewelry with galvanic gold and silver plating.

How much does high-quality, allergy-free jewelry cost?

Probably the easiest way to distinguish “elite” alloys from widely used materials is to look at their price.

Thus, jewelry made from medical alloys, steel, and jewelry with galvanic coatings of gold, silver, and rhodium cost tens of times more than regular jewelry. For example, a pendant made of jewelry alloy on aluminum or brass costs on average $4 - $5. While its steel counterpart will cost about $20-30.

How to preserve the original appearance of jewelry longer?

If we are talking about inexpensive jewelry from Chinese and Korean manufacturers, then it is better not to wet it with water, keep the jewelry separately from each other, or better yet, each in a separate bag/package to prevent air from entering as much as possible. Before putting on the jewelry, do not apply perfume and hand/body cream. Never spray cosmetics on your jewelry.

We wish you happy shopping!

Source: https://aprilis.ru/opasen-li-cinkovyi-splav-bizhuternyi-splav-chto-eto-takoe.html

Zinc alloys: GOST, melting point, properties, application:

Zinc is a bluish-white metal, which could not be obtained in its pure form for a long time. Only the Englishman J. Champion acquired a patent for its production in 1738. And five years later the first zinc plant appeared in Europe in Bristol. Its annual productivity was only 200 tons. In terms of use, this popular non-ferrous metal is second only to copper and aluminum. Millions of tons of it are smelted around the world every year.

Properties of zinc

The metal has weak mechanical properties. It is brittle and brittle at normal temperatures, and when it rises to 100–150 degrees Celsius, it becomes malleable and easily deformed: it is forged and rolled into sheets. To increase the strength and melting point, copper, lead, tin, aluminum, and magnesium are added to zinc.

It is a reactive metal. In open air at a temperature of 100 degrees Celsius, a film appears on the surface and the zinc takes on a dull appearance. High humidity and carbon dioxide contribute to the destruction of the element. It is easily corroded by acids and alkalis, so only alloys are used for industrial use.

Types of alloys

According to their intended purpose, zinc alloys are divided into:

Deformable. The basis of these alloys is zinc. Their properties are similar to brass. Ingots are produced using the casting method, and rods, strips, and sheets are made from them.
Foundries. They have high fluidity. Fills the mold perfectly without sticking to it. High-quality castings of complex configurations are obtained by injection molding.
Anti-friction. The alloys have a low coefficient of friction and good wearability of the bearing to the shaft journal.
Solders. They are used for soldering products and have good ductility and strength.
Typographical. Used for casting hand and machine typefaces. Replace toxic lead alloys. Abrasion resistant.
Protective. Protects internal and external parts of sea vessels from corrosion. They are used with a special paint coating.

Characteristics and properties of brass

A copper-zinc alloy in which copper is the main component and zinc is the alloying component is called brass. The color of the metal depends on the composition and varies from light yellow tones to reddish shades. Such alloys are characterized by resistance to corrosion and have high strength. They lend themselves well to various processing methods.

The fluidity of brass allows parts to be manufactured using the casting method. Using plastic deformation of the alloy, wire, sheets, tapes, and various profiles are produced from it by rolling. zinc in the alloy can vary and range from 5 to 45%.

In addition, it also includes additional alloying components that are used to improve the properties of brass:

Nickel. Helps increase corrosion resistance and strength.
Silicon. Improves anti-friction properties.
Tin. Affects strength and resistance to salt water.
Lead. Improves machinability.
Manganese. Affects strength and corrosion resistance.

When various combinations of alloying components are used, brass with the required qualities and characteristics is obtained. Products made from such alloys are not exposed to environmental influences and have high wear resistance.

Application of alloys

Without zinc and its alloys, many industries from mechanical engineering to medicine cannot exist.

Application of zinc alloys in various fields and industries:

mechanical engineering - for the production of gas tanks, trunk lids, carburetor bodies, mufflers, gas pumps, radiators, pumps, accessories;
foundry - weapon bolts;
electrical engineering – production of accumulators and batteries;
printing – for typing texts and printing illustrations;
processing of metal structures - metallization and galvanizing of various surfaces from destruction and corrosion of metal;
medicine – antiseptic and anti-inflammatory drugs, obtaining radionuclides for the diagnosis and treatment of a number of diseases;
paint production – production of zinc white;
construction – for roofing, wall cladding, drainpipes, gutters;
art – coinage, graphics;
jewelry - personal jewelry, boxes, buttons, zippers, decorative overlays;
household – for kitchen equipment, cornices.

Zinc casting alloys

The following requirements apply to alloys for injection molding. They have to:

have excellent fluidity;
do not react or weld to the mold;
have a short crystallization interval;
have strength at high temperatures.

Such alloys are used in the following cases:

For injection molding of parts with complex configurations and thin walls. This is how brake equipment parts and pumps are produced using the properties of alloys, such as resistance to cracking, fluidity, and low melting point.
For the production of cast decorative products. After galvanization, a beautiful and durable coating is installed on the surface. It may not be of very high quality if the surface is porous or contains excessive aluminum.
For the production of antifriction zinc alloys used in mechanical engineering.
For casting typographic fonts. With changes in technology, the need to manufacture them disappears.

Automotive industry

The automotive industry is one of the leading areas of mechanical engineering. Research is steadily being carried out here on the use of the latest materials and alloys, which have significant performance and technological properties. These include zinc alloys in accordance with GOST 21437-75.

It includes four grades of alloys, two of which are casting, and the others are pressure-processable. These materials are used to produce car parts (bushings and bearings) with anti-friction properties.

Cast zinc alloys GOST 19424-74 and 25140-82 are used for the manufacture of carburetors with complex shapes and gasoline pumps by injection molding, using their high fluidity properties.

The disadvantage of alloys is that the parts are practically irreparable.

Instead of a conclusion

Brasses - zinc alloys - are widely used in the engineering industry. They are used to produce highly durable parts where precision castings are required.

Most of the world's zinc is used to make galvanized steel because it forms a protective film, preventing them from corrosion. Alloys are indispensable in the manufacture of various sources of electric current.

As a component in solders, this non-ferrous metal reduces the melting point. Medicines containing zinc oxide have anti-inflammatory and antiseptic properties.

An insufficient amount of zinc microelement in the human body leads to serious diseases: stomach ulcers, liver cirrhosis, atherosclerosis.

Source: https://www.syl.ru/article/371035/tsinkovyie-splavyi-gost-temperatura-plavleniya-svoystva-primenenie

Does zinc alloy rust? — Metals, equipment, instructions

/ Products / Costume jewelry / Lead in jewelry

More and more buyers around the world are paying attention to the content of hazardous metals in jewelry - primarily lead and nickel. In the USA and several European countries, costume jewelry is subject to mandatory certification and inspection, and the sale of jewelry containing lead is strictly limited.

Why is lead content dangerous in jewelry? Is it possible to guarantee lead-free jewelry in China?