How to Identify Copper Wire or Aluminum Determination by Color

How to distinguish aluminum from other metals

Business July 24, 2018
We welcome everyone who, being a real owner, draws knowledge and experience from our website. This suggests that today for some reason you are interested in the question of how to distinguish aluminum from stainless steel. But really, it’s not that simple.

Features of aluminum

Why is aluminum so valuable? This is a pure metal classified as non-ferrous. It is lightweight, durable, has a good degree of deformation, and is resistant to aggressive environments and corrosion.

All of the listed advantages allow it to be used in a variety of areas from industry and construction (except for industries where high-strength structures are manufactured) to domestic use.

The demand for the valuable metal is great, so it is important to know how to accurately distinguish it from other similar metal alloys.

Aluminum or stainless steel: methods of determination

There are several ways to help you do simple research on your own at home. Find out how to distinguish aluminum from stainless steel - advice from forum members and experts.

1. Using a magnet. Aluminum of any grade will not stick to a magnet. Stainless steel also has this property. But there is an exception to the rule. If it contains nickel in sufficient quantities, the tested products will have some attraction. If there is a lot of chromium or copper in a stainless metal, it will not have any effect on the magnet.
2. Marking on stainless steel. Some stainless steel products have identification markings. This already gives a hint on how to distinguish aluminum from stainless steel. If there are markings, for example, “STAINLESS” and the like, this is not aluminum.
3. Plain paper won't lie. The method is very simple. Experiment conditions: you need white, as thick paper as possible (printer paper will also work). Use a thick cloth to remove dirt from the edges of the products being tested. Move the cleaned areas one by one with some pressure across the sheet. There will be no traces left of the stainless steel. Aluminum will draw gray stripes.
4. How to distinguish aluminum from stainless steel by the color of the metal? The surface of the object has a shiny, colorless hue that does not change over time - it is stainless steel. The matte surface of a product that has a grayish or whitish color is aluminum. It will not be polished with sandpaper to a high gloss finish. Check it out.
5. Under mechanical load. Another simple way will help you understand how to distinguish aluminum from stainless steel. Hit the product against the surface of any hard metal in the dark. Aluminum will never spark, unlike stainless steel.
6. Thermal conductivity, melting. Compare where the water heats up faster. Of course, in an aluminum container. This metal has much better thermal conductivity. But it is not used on the burner of a gas furnace; the melting point is 660 °C. Stainless steel cannot be melted in the usual way (melting index is above 1800 °C).
7. Testing for copper sulfate. An option available to everyone. Copper sulfate, after exposure to aluminum, will leave cloudy stains and traces on it, but will not appear on stainless steel.
8. Alkaline solutions. Any housewife knows that it is impossible to boil aluminum cookware in alkaline solutions. It will darken and lose its appearance. Conclusion: aluminum products are afraid of alkali, both sodium and potassium. The same cannot be said about stainless steel.
9. Acid test. All acids, starting with the usual citric acid and ending with more aggressive ones, will leave marks when they get on the aluminum surface. You won’t see them on stainless steel; it doesn’t react with acids.

Duralumin – an alloy of aluminum with transition metals

The industry is not able to provide itself only with pure metal, and duralumin comes to the rescue here - various combinations of manganese, copper and magnesium in an alloy with aluminum.

In addition to all the above properties of its older brother, the transition metal has:

• high degree of strength;
• long service life;
• plasticity;
• high hardness.

It accumulates fatigue properties more slowly and is resistant to cracking.

The disadvantage of products made of duralumin is susceptibility to corrosion, which can be prevented by anodizing, applying a thin layer of paints and varnishes, aluminum.

The choice between the two metals depends on the end use. We pay tribute to their advantages, but also foresee their disadvantages. The domestic sector leaves the choice to aluminum, while the industrial sector votes for the strength that duralumin has.

Naturally, the question arises of how to distinguish aluminum from duralumin. It is almost impossible to determine by eye which metal is which. The chemical laboratory will give you the exact answer. But experts on the forums have their own opinion on this matter.

1. Follow the markings.
2. The color of the alloy is steel gray.
3. Scratches leave clear marks.
4. A ringing sound is heard from the impact.
5. During processing, the chips will break without ductility.
6. The structure of the alloy is fine-crystalline.

You can determine the type of material by conducting an experiment. Apply a drop of sodium hydroxide to duralumin and aluminum samples for 10 minutes. After removing the substance, we learn about the metal from the resulting stains: the dark one is duralumin.

If you place a piece of aluminum in an acid with added alkali, it will dissolve, forming a white powdery precipitate. In the experiment with duralumin, blue copper granules will be present.

Unlike aluminum, the main characteristics of the alloy are lack of ductility, brittleness and hardness.

Everything can be learned by comparison; examine the parts of two samples several times, pick them up and compare the weight. Such familiarity will help you subsequently simply recognize metals.

Silumin - a twofold relationship

Products made from silumin, an aluminum-based alloy with the addition of silicon, literally flooded the market. Why does it attract the buyer and how to distinguish aluminum from silumin?

Advantages of silumin

Of course, this alloy of two materials has its “fans”. They call the following positive features of silumin:

• light in weight;
• highly durable;
• resistant to wear and corrosion;
• cheap price.

Cons of silumin

Silumin products should be treated with caution, unlike aluminum ones. in silumin, aluminum production waste, silumin-containing alloys, and metal powder do not have an exact proportion. It cannot be called high quality, since the manufacturer produces cheap products under the name of some brand.

The disadvantages of the alloy include:

• design flaws;
• they are unsuitable for food products;
• dangerous to health.

You can distinguish silumin from aluminum visually. The products have a glossy smooth gray surface.

Today, public dissatisfaction with plumbing products continues to grow due to the heterogeneous structure of the material with numerous internal stresses and voids. After 3-5 months, the water tap turns into dust, and the rotary steel ball rusts.

Bimetal and aluminum using radiators as an example

When replacing heating radiators, many are faced with the choice of which material to choose for the new design. Cast iron batteries are a thing of the past; manufacturers offer aluminum, steel and bimetallic ones.

While steel is easily recognizable in appearance, the problem with aluminum and bimetallic structures is that you can’t tell the difference by eye. Moreover, the latter option is in greatest demand.

In the store there is a chance not to buy a fake, but how to distinguish bimetal from aluminum at the market?

Visual recognition will not provide accurate results to the consumer. Both the aluminum and bimetallic systems have external fins made of aluminum. And it’s impossible to visually determine the weight of one section.

For reference: the aluminum section weighs 1–1.6 kg, the bimetallic radiator “compartment” weighs 1.5–2 kg.

You can use the “old-fashioned” method and arm yourself with a neodymium magnet, which has greater power.

Preliminary test. Place the magnet first on the steel, then on the aluminum radiator. The magnetic tester will attract the first option to the surface. The effect will be weaker for a bimetallic radiator. Its steel tubes are located under a diamagnetic material - aluminum. With a powerful neodymium magnet, it is possible to catch the attraction.

It is more difficult when the coolant tubes are made of copper, which, like aluminum, is impervious to the magnetic field.

Difference from other non-ferrous metals

It is known that metals have largely identical properties. But each element has its own distinctive characteristics. They allow you to understand how to distinguish metal from aluminum:

• copper is recognized by its bright reddish hue;
• iron and its alloys have high magnetic properties;
• You can recognize gold by its yellow color;
• Lead has high fragility and density;
• silver has a bright shine;
• Tin has high ductility.

The above methods are only estimates and approximate. More reliable information is available on the pages of special reference literature.

Table

The difference between aluminum and copper can be seen in the table below.

How to distinguish copper from other metals - Metals, equipment, instructions

Business July 24, 2018

We welcome everyone who, being a real owner, draws knowledge and experience from our site. This suggests that today for some reason you are interested in the question of how to distinguish aluminum from stainless steel. But really, it’s not that simple.

How to distinguish copper from brass, bronze, aluminum

23.10.2017

Copper, as a metal, has pronounced ductility. The color of copper has a golden pink hue with the presence of a characteristic metallic sheen.

As an element of the periodic table, it is designated Cu. The name comes from the Latin Cuprum, which is associated with the name of the island of Cyprus.

There is scientific evidence that in ancient times there were mines where this metal was mined and then smelted.

Iodine test

You can check the authenticity of the metal using an iodine solution purchased at a pharmacy. A drop of iodine is applied to the surface and left for several seconds. Iodine will not harm noble metals - gold, platinum, silver. If the color of a drop of iodine does not change, and after removing it with a napkin, no traces or stains remain, this indicates the authenticity of the metal. If darkening is visible at the place of the drop, then this is a low-quality alloy or an outright fake.

Iodine testing of gold

How to distinguish copper from brass, bronze, aluminum

Copper, as a metal, has pronounced ductility. The color of copper has a golden pink hue with the presence of a characteristic metallic sheen.

As an element of the periodic table, it is designated Cu. The name comes from the Latin Cuprum, which is associated with the name of the island of Cyprus.

There is scientific evidence that in ancient times there were mines where this metal was mined and then smelted.

Ancient culture is associated with the manufacture of jewelry, dishes, and other household items from it. But the main achievement of ancient metallurgy was the circumstance in which bronze was obtained - an alloy based on it.

Basic properties and parameters of copper

The following points are characteristic:

1. In contact with atmospheric oxygen, it is capable of forming an oxide film, which is due to the appearance of a yellowish-red tint. This can answer the question, what color is copper? If you hold the thin plate up to the light, it will have a greenish-blue hue.
2. In its pure form it has quite pronounced softness and plasticity. It is easy to roll and stretch. With the addition of impurities, the hardness increases.
3. The breadth of application is due to its ability of excellent electrical conductivity.
4. Has good thermal conductivity. According to this characteristic, only silver is ahead of it.
5. It is characterized by high density, melting and boiling points.
6. With the addition of impurities, the properties of thermal conductivity and electrical conductivity decrease.
7. Resistance to processes associated with corrosion. In water, for example, iron will oxidize much faster.
8. The material is easy to stretch into a fairly thin wire.
9. The metal has diamagnetic properties.

Chemically, the activity is insignificant in magnitude. If the air is dry, then oxidation will not occur. The process takes place only in air with sufficient moisture content. Resistant to acids without oxidizing properties. From a chemical point of view, it is characterized by pronounced amphotericity. Depending on the conditions, its characteristics differ and take on the character of an acid or base.

Differences between copper and brass

The question often arises of how to distinguish copper from brass. Brass is an alloy containing 30% zinc.

In half of the cases, technical zinc is used to produce brass, where only 50% is present. The rest consists of lead and other impurities.

In order to distinguish these representatives, you need to know their characteristics. In this regard, the relevant question is how to determine copper?

To distinguish brass from copper, you need to perform a number of actions with which you can recognize copper at home:

• Clean the item that needs to be checked. To remove dirt, use an aqueous solution of vinegar. In this way, oxides are also removed.
• It is better to carry out the determination under white light. Copper products are characterized by a red-brown color. The brass surface shimmers in several colors. This is due to the presence of several representatives in its composition.
• Copper objects are soft and the impact on a hard surface is accompanied by a muffled sound. Brass doesn't have this. The sound is more sonorous in its characteristics.
• Items can contain marks in the form of the letter “M” or “L”. On this basis, these two species may also differ.
• You can also find out what exactly is in front of you by looking at the area of ​​application of the product. Copper products are quite rare, but it is widely used for the production of wires.

Using the methods listed above, copper determination is carried out right at home.

Differences between copper and bronze

The two species are similar in color. Therefore, sometimes it is necessary to make distinctions. This is not so difficult to do if you know the features of the bronze composition. You can find out what exactly is in front of you using the following characteristics.

• Things made of more plastic material are characterized by the presence of a reddish-brown color. But bronze is characterized by a yellow-pink tint. Even by this feature you can distinguish copper from bronze.
• Products can also be distinguished by the nature of their interaction with the saline solution. If it is spilled on a copper object, a color change will be observed. The color of bronze will remain unchanged. This is also a characteristic difference.
• Both types differ in elasticity properties. If copper wire is easily bent with one hand, then bending a bronze product is very problematic.
• Copper items are subject to a natural patination process. With prolonged interaction with air, they become covered with a greenish coating. Bronze items do not have this feature.

Differences between copper and aluminum

The question of how to distinguish copper from aluminum often becomes relevant.

In terms of electrical conductivity properties, it is 1.5 times higher than that of aluminum. Such items are stronger than aluminum items.

If you bend the aluminum wire several times, it will break, but the red wire rod will remain unharmed. You can even distinguish these species by weight. Aluminum products are much lighter. Aluminum has a much lower melting point.

If at a temperature of 660 degrees it begins to melt, then this temperature is clearly not enough to melt copper.

The red wire is easy to solder and the contact will be very reliable. But soldering an aluminum wire using the usual method is very problematic.

He is a younger representative in terms of receiving it. It does not occur in nature in its pure form, but when interacting with oxygen in the air, it is capable of forming a stable compound.

They began to obtain it only in 1825, while copper was smelted already in ancient times. Since it is much lighter, it is actively used in the production of aircraft. That is why it received the name “winged metal”.

By adding copper to aluminum, an alloy called duralumin is obtained, which has higher strength characteristics.

We also recommend reading:

How to clean copper

How to distinguish copper from brass, bronze, aluminum Link to main publication

Magnet check

Bringing a magnet close to the item being tested is a good way to perform initial testing. By the reaction of the magnet you can determine which group the metal belongs to:

1. Ferromagnets. The magnet is clearly attracted to the object, which means that the product may contain iron, steel or nickel.
2. Paramagnetic materials. The interaction with the magnet is very weak. This group includes aluminum and chrome. Precious metals that are paramagnetic are platinum, palladium and silver.
3. Diamagnets. In general, they do not react to magnets. Copper and zinc have these properties. Precious metals - gold.

Checking with a magnet
Of course, such a check will not allow you to accurately determine the material from which the item is made. After all, a non-magnetic metal may not be in its pure form, but in the form of an alloy with a ferromagnet. But it can confirm or refute the assumption. For example, if it is checked whether it is gold or not, but the item is clearly magnetic, then it can be argued that it is a fake.

When checking jewelry, you should take into account that, in addition to precious metals, they may contain clasps, built-in springs, made of another material. You need to check the metal itself.

How to distinguish copper from aluminum

21.03.2017

Which is better - copper or aluminum wiring? This question is often raised among specialists and ordinary people who are planning to change old wires in a house, apartment or office. But in order to make the right decision, it is important to know the advantages and disadvantages, operating rules, as well as the main differences between copper and aluminum switching.

Advantages and disadvantages

Aluminum wiring has the following advantages:

• Small mass. This feature is important when installing power lines, the length of which can reach tens or even hundreds of kilometers.
• Affordability. When choosing a material for wiring, many are guided by the cost of the metal. Aluminum has a correspondingly lower value, which explains the lower price of products made from this metal.
• Resistance to oxidative processes (relevant in the absence of contact with open air).
• Availability of protective film. During operation, a thin coating forms on aluminum wiring, protecting the metal from oxidative processes.

Aluminum also has a number of disadvantages that you need to be aware of:

• High metal resistivity and tendency to heat. For this reason, the use of wires smaller than 16 sq. mm is not allowed (taking into account the requirements of the PUE, 7th edition).
• Loosening of contact connections due to frequent heating when passing a heavy load and subsequent cooling.
• The film that appears on an aluminum wire upon contact with air has poor current conductivity, which creates additional problems at the junction points of cable products.
• Fragility. Aluminum wires break easily, which is especially important when the metal frequently overheats. In practice, the service life of aluminum wiring does not exceed 30 years, after which it must be replaced.

Rules for connecting copper and aluminum

There are situations when you need to replace only part of the wiring or add (move) several outlets in the apartment.

In such a situation, the question arises of how to properly connect wires made of different metals.

To avoid increased heating in places where copper and aluminum wiring are combined, it is worth using the following switching methods:

• A “nut” type connection. In this version, the wires are clamped between special plates (there are three in total). First, the plates are unscrewed at the top and bottom, after which a wire is inserted between the middle and top clamps. At the last stage, the product is tightened. The same manipulation is done on the other side.
• Connection using a bolt. This type of fastening is similar to a “nut” with the only difference being that the two wires are combined and placed on one bolt with a washer installed between them. Next, fixation is done using a nut.
• Spring terminals. If the wiring is completely changed, it is better to use WAGO type terminal blocks. Their feature is ease of installation and convenient fastening of wires, thanks to the spring type of clamps. Before using such terminals, it is important to first strip the cable at a distance of 13-15 mm at the edges. After this, the wire is inserted into the hole and secured with small levers. A special lubricant is provided in the middle part of the terminals to prevent metal oxidation. The use of spring terminals is only permissible in the lighting network. The flow of a large load leads to heating of the terminal block springs, deterioration of the quality of contact and, accordingly, a decrease in conductivity.
• Terminal blocks are one of the best options for combining copper or aluminum wires. The product is a strip made of dielectric material with a metal strip and terminal blocks for clamping. During installation, you need to clean the edges of the cable, insert it into the holes and squeeze it well.

The considered connection methods can be used to combine wires made of various metals (not only copper and aluminum).

This design guarantees a high level of safety and the ability to avoid potentially dangerous twisting.

But it is worth remembering the importance of periodically checking and tightening bolted connections and terminal blocks, because they tend to loosen.

Which wiring material is best?

Now let's look in more detail which wire is better, copper or aluminum. In this regard, many stereotypes and misconceptions have appeared, which we will discuss below:

• Durability. It is believed that the lifespan of copper wire is longer than aluminum. This is a misconception. If you look at a special reference book, you can make sure that the service life of cables made of both types of metal is identical. For products with single insulation it is 15 years, and for products with double insulation - 30.
• Tendency to oxidation. When using an aluminum cable, it is worth remembering its tendency to oxidative processes. Back in school, we were told that Al (aluminum) is a metal that actively interacts with oxygen, which is why a thin film appears on its surface. The latter protects the metal from further decay, but impairs its conductivity. If the wire is isolated from the environment, the risk of oxidation processes is minimized. The best option is to use special terminal blocks with conductive paste. The peculiarity of the latter is to improve the quality of the contact connection between two wires and remove the oxide film from the metal. In addition, a special lubricant prevents aluminum from coming into contact with the surrounding air.
• Strength. Copper wiring is considered more durable and can withstand repeated bending. GOST states that a wire made of copper must withstand 80 kinks, and one made of aluminum - 12. If the wiring runs in the wall, floor, or is hidden under the ceiling, this feature is not so important.
• Price. The price of aluminum wire is 3-4 times lower. But when choosing, it is important to remember that a copper wire with a cross-section of 2.5 sq. mm is designed for a current of 27 Amperes. If you give preference to aluminum wiring, the thickness of the wire should be 4 square meters. mm (rated current 28 Amps).
• Resistance. When deciding whether to choose aluminum or copper wires, it is worth considering different resistivities. For copper, this parameter is about 0.018 Ohm*sq.mm/m, and for aluminum - 0.028. But it is worth considering that the total resistance (R) of the conductor depends not only on the mentioned parameter, but also on the length and area of ​​the conductor. If we take into account that aluminum wires of a larger cross-section are used for the same load, the final R of copper and aluminum products will be approximately identical. The greatest resistance occurs at the joints, but if you follow the tips discussed above, you don’t have to worry about this.
• Ease of installation. It is believed that connecting aluminum wires is a more difficult task. This is only relevant for the usual connection of wiring, by twisting. In the case of using end caps, terminal blocks or bolts, this problem disappears.

A situation involving contact between two different metals deserves special attention.

When copper and aluminum combine at the point of contact, various processes occur, due to which the resistance increases.

As a result, the junction of the two wires overheats, the insulation is destroyed and the risk of fire increases.

The feature discussed above is characteristic of all metals having different resistivities.

In addition, many manufacturers do not use “pure” metals, but their alloys, which also leads to a change in the resistance parameter.

To avoid problems in the future, it is better to connect the wires correctly and avoid twisting them.

Useful tips

In conclusion, here are a few tips that should be taken into account when organizing wiring:

1. In case of independent design of wiring in a house or apartment, it is better to choose copper wires. With a smaller cross-section, they can withstand greater currents and are more resistant to frequent bending. An equally important point is volume. Copper wires are compact, which simplifies the process of creating grooves. For example, when connecting a receiver with a power of 7-8 kW, the aluminum wire should have a cross-section of about 8 mm. The cable has three cores plus a braid. As a result, the total diameter is about 1.5 centimeters. For comparison, copper can have a cross-section of 4 sq. mm, and the overall diameter is no more than a centimeter.
2. When installing a socket, a three-core cable with a ground wire must be used. The distance of the socket from the floor is 30 cm. When organizing a lighting circuit, it is allowed to use cables with two cores (grounding is not needed here).
3. It is forbidden to hang the entire load on one pair of wires (especially if they are aluminum). The best option is to divide the circuit into several lines. For example, a bathroom is powered through one machine, lighting through another, a kitchen through a third, and so on. The wire cross-section for the kitchen and bathroom should be 4 or 6 sq. mm, and for the lighting circuit - 1.5 or 2.5 mm.

Other cases of fire and acid testing

Exposure to flame is used not only to identify metal relative to aluminum. For these purposes, a gas stove, lighter or fire is sufficient. Heating copper leads to the formation of its oxide, which affects the color change. The surface of the metal gradually becomes dull until it acquires a completely dark shade.

Nitric acid is another identifier for copper at home. It is also important to be careful here. It's better to just drip the liquid onto the metal. Pure copper at the point of contact will turn blue-green.

Video - how to distinguish aluminum from copper:

The main differences between copper scrap metal

If there is a certain amount of copper-like scrap accumulated around the house, the question arises: is it possible to make sure that it is really Cu? Is it worth taking scrap metal to a collection point? Is it possible to sell copper in Moscow at a price that will provide a high income?

Scrap metal collection points willingly accept unlimited quantities of products made from pure copper and its alloys, paying for them at favorable prices.

Our prices for copper intake

Type of medicinePrice per kg, rub

Specialists in the field can quickly and absolutely accurately determine the composition of scrap using spectral analysis using special devices - metal analyzers.

What can you do at home when options for determining the chemical composition of scrap metal are limited?

Some methods may be available to us, in particular:

• using one's own senses;
• use of readily available chemicals;
• exposure to fire;
• use of simple devices.

How to visually distinguish copper from other metals?

First of all, the material is carefully examined to determine the main external distinctive features of copper:

• the color of the metal should be golden pink;
• There is usually an oxide film on the surface, adding a yellowish-red tint.

Only a few metals have a similar color, including gold (Au), cesium (Cs), and osmium (Os). However, since these chemical elements are rare in their pure form and are produced in small quantities, it is almost impossible to make a mistake during visual inspection and identification of Cu among the listed materials.

The material should be viewed in good daylight, as artificial colors tend to be distorted. It is also recommended to get rid of the oxide film. This is done mechanically using a file, which is used to clean the surface, or identification is performed using a fresh cut.

Many copper products are marked. If you try to carefully examine the surface and find the markings, then its presence will allow you to accurately identify the material from the reference book.

How to distinguish copper from brass?

The situation is somewhat more complicated in identifying the copper alloy - brass. Brass scrap is accepted at collection points somewhat cheaper, since in addition to Cu it contains the chemical element zinc (Zn) in an amount of 4 to 45% of the alloy weight.

1. Color. The color of the alloy is lighter than Cu. Moreover, the greater the amount of Zn it contains, the more the color turns yellow. Although in the case of a small amount of alloying additive (up to 10%), it is still difficult to identify the metal visually.
2. Sound. Brass rings when struck, while soft copper produces a muffled sound. This method is good to use with fairly large products as an example.
3. Plastic. When bending Cu, this occurs easily due to its high ductility. In the case of brass, this is much more difficult to do: the hardness of the alloy is higher and, accordingly, the flexibility is less.
4. Weight. The average density of brass is 8.6 g/cu. cm, copper – 9 g/cu.m. see. You can identify metal using precise scales (if you have them in your house).
5. Shape of chips. After processing, copper shavings have a spiral shape, and brass shavings have a straight needle shape.
6. Chemical method. When exposed to hydrochloric acid, a brass alloy forms a white coating on its surface. If you do the same with copper, then nothing will happen.

Methods to distinguish copper from bronze

Simple methods that make it possible to find the differences between Cu and its alloy with tin (Sn):

1. Plastic. If you apply pressure to the copper with something hard, a notch will appear in this place. It will not be possible to deform harder bronze in this way.
2. Oxidation. Over time, the Cu surface becomes covered with an oxide film, which changes the color of the metal. Bronze alloy does not oxidize in air.
3. Chemical method. In a metal container, a saline solution is heated to 50 degrees at the rate of 200 g of table salt per 1 liter of water. If you place copper there for 15 minutes, its color will change. Bronze alloy will not react in any way to such conditions.

How to distinguish from aluminum?

Tinned copper and copper-plated aluminum (Al) are often used in cable and wire products. Metals can be identified in this way:

1. Color. Copper-plated aluminum has a yellow tint, and the surface of Cu after tinning becomes silver.
2. Plastic. Copper conductors are several times more stable when bent and unbent, while aluminum conductors break quickly.
3. Resistance measurement. The resistance of copper twisted pair (100 m) ranges from 4 to 8 Ohms, aluminum - from 12 to 20 Ohms.
4. Exposure to flame. Al begins to melt at 600 degrees. The temperature at which signs of Cu melting appear is much higher.

Other cases of fire and acid testing

When copper is exposed to an open flame, it begins to tarnish until it becomes completely dark.

If Cu is exposed to nitric acid, the surface at the point of contact will turn blue-green.

how to distinguish copper from other metals

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For those familiar with electrical engineering

Very often, copper cores from electrical cables are sold as scrap non-ferrous metals, and there are often cases when copper-coated aluminum is used in the production of electrical products. This material has a significantly lower density, but due to its irregular geometric shape, determining the volume to calculate the density is quite difficult. In this case, copper can be determined by electrical resistance (of course, if you have the appropriate instruments - a voltmeter, ammeter, rheostat). We measure the cross-section and length of the core, take instrument readings, and Ohm’s law will help you. Resistivity is a fairly accurate characteristic by which any metal can be identified with a high degree of reliability.

How to distinguish between the main copper alloys

The optimal method for accurate metal identification is spectral analysis. However, it requires complex, expensive instruments. If you need to distinguish copper on your own, you have to make do with improvised means.

Metallic copper has three distinctive features: a characteristic color, high ductility and corrosion resistance. Anti-corrosion properties are due to the thinnest layer of oxide covering the metal surface. This film ensures chemical inertness of the material and changes the light of the product.

How to identify copper by eye?

The visual method is the most accessible, although not always effective. The following metals have a color similar to copper:

• gold with impurities;
• cesium with impurities;
• osmium with impurities;

Others are painted in gray tones, making it easy to distinguish copper from most metals.

Pure copper has a pinkish-red color. The product must be viewed in daylight, otherwise the object may appear yellow-green.

An important point: you must first remove the oxide layer, which has a bluish-green tint.

Some difficulties may arise with copper alloys - brass and bronze, as well as copper-enriched aluminum.

How to distinguish copper from brass

Brass is an alloy of copper and zinc, the content of which ranges from 4 to 45%. With a significant proportion of zinc, the color of brass becomes yellowish. If zinc is less than 10%, the visual method will not help. In this situation, there are 3 solutions:

1. Acoustic method. When struck, copper produces a muffled sound, while brass produces a ringing sound. A keen ear is required. This method is good for large objects.
2. Mechanical method. Copper is ductile and, unlike brass, bends easily.
3. Weighing. Zinc and its alloy are lighter than copper. For low zinc content and for small items, an accurate scale will be required. The density of copper is 9 g/cm3, zinc - 7.1 g/cm3, the density of brass depends on its composition, but is always lower than that of pure metal.

There are other methods. For example, if it is possible to remove chips. In copper it has a spiral shape, while in brass it is straight and needle-shaped.

Another method is somewhat more complicated, since it requires hydrochloric acid. Copper does not react with this reagent, but brass reacts to form zinc chloride, which forms a whitish coating.

How to distinguish copper from bronze

Bronze is an alloy of copper and tin. It is painted almost the same as pure copper. The visual method will be ineffective in such a situation. The most common identification method is based on the high ductility of copper.

Pressing a hard object onto a copper piece will cause a dent to form. Bronze is much stronger. This method is suitable for scrap or technical products.

But it is not always acceptable to leave defects on an item.

Another method will require a solution of table salt, which is always available on the farm. Prepare a solution at the rate of 200 g of salt per 1 liter of water and heat to 50 degrees. or a little higher. Immerse the product under study in it and keep it there for a quarter of an hour. Bronze will remain inert, while copper will change color.

Another technique is patting. This is the process of formation of an oxide film under natural conditions. An old piece of copper is already covered with a bluish-green coating, but a newly minted or cleaned one will inevitably become covered with it for some time. Bronze is not patinated.

How to distinguish copper from aluminum

Pure metals are easily distinguished by color. However, quite often there is a need to identify tinned copper, which has a silvery color, or copper-rich aluminum, which has a yellowish color. Both alloys are used to make the cable, and in some cases it is important to know what it is made of. In such a situation, visual analysis will not yield results.

The easiest way is to measure resistance. For a hundred-meter copper wire this value is 4 - 8 Ohms, while for an aluminum wire it is about 12 - 20 Ohms. The advantage of this technique is that the cable is not damaged.

Another method is based on different bending strengths. If you bend and straighten an aluminum core several times, it will break, but a copper core will withstand such a test.

Finally, you can hold the cable in the fire. Aluminum melts already at 600 degrees, copper - at a much higher temperature. It is necessary to understand that when heated, especially over an open fire, copper will quickly become covered with an oxide film and change color. This can be used to distinguish copper from other alloys.

Another universal method is exposure to nitric acid. Gently drop the reagent onto the product. The metallic copper in the contact area will turn blue-green.

Grandma's tips

In jewelry, metal is not used in its original, pure form (the same applies to the production of cutlery). Other components are added to the alloy, which give additional strength. The classic option here is copper. To distinguish real silver from a fake, you need to talk not about Ag as such, but about the percentage of its content in the alloy.

of people living today were able to determine the purity of metal without any drugs or devices

Argentum is very thermally conductive - it heats up quickly and cools down quickly. If you hold it in your fist, it will immediately acquire body temperature. You can put it in boiling water (if the decoration does not have stones) and then pick it up. Real metal will burn, but not for long.

• The product can be rubbed in your palms for several minutes. If the skin remains clean, the alloy is good; if dark traces remain, there are excess impurities (most often zinc).
• Silver ringing is not just a stable phrase. When gently tapped, the jewelry rattles; the argentum vibrates lightly and protractedly. The percussion instrument should be something akin to a knitting needle.
• If you place a spoon made of Ag in the sun, it will brightly reflect the rays and shine. A cheap alloy will give a dull glow, or even a barely noticeable one.
• People with a keen sense of smell (and good experience) distinguished silver by smell. They assured that pure metal smelled of freshness and lily of the valley. Now this method is hardly suitable for everyone - modern perfumery will make even iron smell like roses.
• Argentum has a high density. Even a small product made from it should be felt in your hand. And today it is so easy to distinguish silver from much lighter aluminum.
• Previously, the ring was covered with crumbs of rye bread and left there for two days. If the jewelry noticeably turned black during this time, this was a good sign - the alloy was considered to be of high quality. With today's bread this test may not pass.
• You can try to bend the spoon (plate). An object made of normal argentum will yield quite easily and will have almost no spring. But this method will not give a 100% guarantee: you can also bend a steel device. And it will be difficult to return the item to its original appearance.

All these tests were based on knowledge of the properties of Ag. Knowledgeable people could determine the authenticity of the metal by its appearance. This is probably still available to experienced jewelers.

Vinegar test

Household vinegar solution also does not affect precious metals. And it is dangerous for counterfeits. But, unlike the iodine test, acetic acid takes time. To wait for the result, you need to immerse the metal being tested in a container with vinegar for 15–30 minutes. The absence of traces of interaction between metal and vinegar is a sign of nobility.

If, in addition to metal, the product contains precious or semi-precious stones, then it is better not to check them this way; vinegar can ruin them. This is especially true for pearls.

Which wiring is better - comparison of copper and aluminum wiring

When planning electrical installation work in a house or apartment, the question may arise about what is better: copper or aluminum wiring?

In this article we will figure out what material should be used when laying electrical cables in residential premises and consider all the pros and cons of copper and aluminum conductors.

Comparison of aluminum and copper wires by technical characteristics

In order to understand the difference between copper and aluminum, you need to consider and compare their technical characteristics.

Properties of conductors

The main electrical properties of conductor materials are their electrical resistivity, thermal conductivity and temperature coefficient of resistance. Mechanical properties include weight, strength, elongation at break and life under normal operation.

Electrical resistivity

Electrical resistivity is the ability of a material to resist electric current as it flows through a conductor. This characteristic is calculated by the formula:

Ρ = r⋅S/l,

where l is the length of the conductor, S is the cross-sectional area, r is the resistance.

For comparison:

Conductor material Electrical resistivity, Ohm mm²/m

As can be seen from this table, copper has a lower resistivity and, accordingly, it heats up less and conducts electric current better.

Thermal conductivity

Thermal conductivity is a property of a conductor that shows the amount of heat that passes per unit time through a layer of a substance. For calculating an electrical cable, this characteristic is quite important, since the safe operation of electrical wiring depends on it. The higher the thermal conductivity of a material, the less it heats up and the better it gives off excess heat.

For comparison:

Conductor materialThermal conductivity, W/(m K)

Temperature coefficient of resistance

When different materials are heated, their electrical conductivity changes. The characteristic that shows this change is called the temperature coefficient of resistance (TCR). This value is determined using a special TKS meter and the average value of this coefficient is taken.

Note! The temperature coefficient of resistance is the ratio of the relative change in resistance to the change in temperature. Denoted by α.

For comparison:

Conductor material Temperature coefficient of resistance, 10-3/K

The lower the temperature coefficient of resistance, the more stable the conductor is.

Conductor weight and conductivity

Copper is much heavier than aluminum. Its density is 8900 kg/m³, and the density of aluminum is 2700 kg/m³. This means that a copper conductor will be 3.4 times heavier than an aluminum wire of the same size.

It is important to understand that the electrical conductivity of copper is more than 50% higher than that of aluminum and, accordingly, in order for an aluminum conductor to conduct the same current, it must be 50% larger than copper.

Therefore, it is more efficient to use a copper conductor than a cable made of aluminum material.

Elongation before break and strength

An electrical cable can operate in various modes and operating conditions, so when choosing a conductor it is very important to take into account its resistance to mechanical loads. Tensile strength is a characteristic that takes into account the strength of the material and its resistance to destructive load.

For comparison:

Conductor material Tensile strength, kg/m²

Based on the analysis of the table, it is clearly seen that copper has high resistance to mechanical stress and is significantly superior to aluminum in this characteristic.

Life time

The service life of electrical wiring depends on operating conditions and the environment. It is generally accepted that the service life of an aluminum cable under normal operating conditions is 20-30 years. At the same time, copper wiring lasts much longer and its service life can reach up to 50 years.

What material for electrical wiring should you choose for your apartment?

In Soviet times, the use of aluminum electrical wiring in residential premises was common. This was due to the fact that in residential buildings there was no high load on the electrical network due to low power and a small number of electrical appliances.

With the development of technology and the advent of a huge variety of powerful electrical appliances that are used at home, the requirements for the quality and materials for electrical cables have increased significantly.

In modern realities, wiring made of aluminum material is practically not used, since according to the PUE, electrical wiring in residential premises must be made of copper !

Interesting fact! Not many people know, but a little earlier before aluminum wiring, in Stalin’s times, copper wiring was used in apartments.

Advantages and disadvantages of aluminum electrical wiring

The main advantages of aluminum electrical wiring are:

1. Low mass: the density of aluminum is lower and, accordingly, its mass is lower. When laying simple networks with many cables but light loads, this will be a convenient advantage.
2. Low price: aluminum is several times cheaper than copper, so products made from this material are also low in price.
3. Resistance to oxidation: in the absence of contact with the environment, it lasts a long time and is not destroyed by oxidation.

Which wiring is better, copper or aluminum and why?

It is impossible to imagine a house or apartment without electricity in our age; light comes to all apartments and houses. To determine which wiring is better, copper or aluminum, it is necessary to consider the characteristics of the two materials and conduct a comparative analysis.

Aluminum wiring

This type of wiring became widespread in residential buildings and apartments throughout the country back in Soviet times. You can still find aluminum today, in any house older than 15-20 years. This was due to such alloy parameters as:

Since aluminum weighs much less than copper, it is more often used when laying power lines, which reduces the load on the supports and, accordingly, saves on their manufacture and installation. According to the PUE, when installing a new network, aluminum cables with a cross-section of less than 16 mm2 are not used. Don't discount the cheapness either, since copper is more expensive.

Minuses

However, even high-quality aluminum wire has more disadvantages than advantages. Negative points include:

• lower electrical conductivity than copper (2 times difference);
• the ability to oxidize upon contact with air (as a result of oxidation, a layer is formed on the surface of the wire that does not conduct electric current, which reduces the useful cross-section and increases resistance);
• shorter service life (20-25 years, after which the probability of fire increases sharply due to oxidation and subsequent heating of the contacts);
• weak mechanical strength (after several bends, the aluminum cable breaks easily);
• complexity of installation (in this case, you will have to ensure the necessary conductivity by choosing cables with a larger cross-section, which are extremely inconvenient to work with. Such cables are produced only as single-core cables).

Advice! You can check the quality of aluminum for fracture; to do this, when purchasing in a store, try bending the wire 4-6 times; if its surface quickly becomes covered with cracks, then the wire is fragile and will be difficult to work with. It is clear that it is better to refuse such a product.

Copper wiring

When buying or building a house or apartment, it is advisable to use this type of wiring.

However, keep in mind that by replacing the wiring in the apartment you have not yet received a reliable network that can withstand heavy loads.

Do not forget that the input cable from the staircase panel to the apartment in old apartments is always made of aluminum. This section should be replaced, because its conductivity is now the weak point of the new network.

Advantages of copper wiring

Comparing the parameters presented below with the parameters of aluminum will allow you to make the right choice in the future. Copper, as a material for electrical wiring, has a number of advantages, which include:

• good conductivity (even after oxidation, the film on the surface does not interfere with the passage of electric current);
• service life reaches 50 years;
• high mechanical strength (the core can easily withstand bending and twisting up to 10-15 times);
• ease of installation (the industry produces several types of wires with different parameters and cores that are convenient to work with).

There is probably only one downside to a copper home network - its price, however, when it is necessary to perform high-quality wiring, give preference to this material.

In construction stores you can purchase wires made of zinc alloys coated with copper plating. They are cheaper than copper ones, however, the characteristics of the materials are inferior to wires made of pure copper.

If there is a shortage of funds, it is better to carry out combined wiring, power the socket group separately with copper wires designed for high current, and the lighting circuits with aluminum.

However, keep in mind that the connection between aluminum and copper is made only through special clamps or connecting blocks, which prevent direct contact between copper and aluminum, which causes severe oxidation of the latter.

Due to oxidation of the joint, the resistivity of the contact increases, heating and eventually burning occurs.

Having examined the characteristics, it is easy to come to the conclusion that it is better to use copper for installation work, however, if necessary, you can make the network from aluminum, but you will just have to monitor it more carefully. It is necessary to choose one or another type of wiring taking into account electrical safety requirements, because this determines how long the network will last without the need for specialist intervention.

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