specific weight of aluminium. Density of mercury and its properties Bulk density 30 2 kg m3

All metals have certain physical and mechanical properties, which, in fact, determine their specific gravity. To determine how one or another alloy of black or stainless steel is suitable for production, the specific weight of rolled metal is calculated. Everything hardware, having the same volume, but produced from various metals, for example, made of iron, brass or aluminum, have a different mass, which is directly dependent on its volume. In other words, the ratio of the volume of the alloy to its mass - specific gravity (kg / m3), is a constant value that will be characteristic for given substance. The density of the alloy is calculated from special formula and is directly related to the calculation of the specific gravity of the metal.

The specific gravity of a metal is the ratio of the weight of a homogeneous body of this substance to the volume of the metal, i.e. this is the density, in reference books it is measured in kg / m3 or g / cm3. From here you can calculate the formula for how to find out the weight of the metal. To find this, you need to multiply the reference value of the density by the volume.

The table gives the density of non-ferrous and black iron metals. The table is divided into groups of metals and alloys, where under each name the grade according to GOST and the corresponding density in g / cm3 are indicated, depending on the melting temperature. To determine the physical value of the specific density in kg / m3, you need to multiply the tabular value in g / cm3 by 1000. For example, this way you can find out what is the density of iron - 7850 kg / m3.

The most typical ferrous metal is iron. The density value - 7.85 g/cm3 can be considered as the specific gravity of ferrous metal based on iron. Ferrous metals in the table include iron, manganese, titanium, nickel, chromium, vanadium, tungsten, molybdenum, and ferrous alloys based on them, for example, stainless steels (density 7.7-8.0 g / cm3), ferrous steels ( density 7.85 g/cm3) cast iron (density 7.0-7.3 g/cm3) is mainly used. The remaining metals are considered non-ferrous, as well as alloys based on them. Non-ferrous metals in the table include the following types:

− light - magnesium, aluminum;

− noble metals (precious) - platinum, gold, silver and semi-precious copper;

− fusible metals- zinc, tin, lead.

Specific gravity of non-ferrous metals

When rolling blanks from non-ferrous metals, it is still necessary to know them exactly chemical composition, since their physical properties depend on it.
For example, if aluminum contains impurities (at least within 1%) of silicon or iron, then the plastic characteristics of such a metal will be much worse.
Another requirement for hot rolling of non-ferrous metals is the extremely accurate temperature control of the metal. For example, zinc requires a temperature of strictly 180 degrees during rolling - if it is slightly higher or slightly lower, the capricious metal will sharply lose its plasticity.
Copper is more "loyal" to temperature (it can be rolled at 850 - 900 degrees), but it requires an oxidizing (with a high oxygen content) atmosphere in the melting furnace - otherwise it becomes brittle.

Table of specific gravity of metal alloys

The specific gravity of metals is most often determined in the laboratory, but in its pure form they are very rarely used in construction. The use of non-ferrous metal alloys and ferrous metal alloys is much more common, which are divided into light and heavy according to their specific gravity.

Light alloys are actively used by modern industry due to their high strength and good high-temperature mechanical properties. The main metals of such alloys are titanium, aluminum, magnesium and beryllium. But alloys based on magnesium and aluminum cannot be used in aggressive environments and under high temperature conditions.

Heavy alloys are based on copper, tin, zinc, and lead. Among the heavy alloys in many industries, bronze is used (an alloy of copper with aluminum, an alloy of copper with tin, manganese or iron) and brass (an alloy of zinc and copper). Architectural details and sanitary fittings are produced from these grades of alloys.

The reference table below shows the main quality characteristics and specific gravity of the most common metal alloys. The list contains data on the density of the main metal alloys at an ambient temperature of 20°C.

The density of metals and alloys presented in the table will help you calculate the weight of the product. The technique for calculating the mass of a part is to calculate its volume, which is then multiplied by the density of the material from which it is made. Density is the mass of one cubic centimeter or cubic meter of a metal or alloy. The mass values ​​calculated on the calculator using formulas may differ from the real ones by several percent. This is not because the formulas are not exact, but because in life everything is a little more complicated than in mathematics: right angles are not quite right, a circle and a sphere are not ideal, deformation of the workpiece during bending, chasing and punching leads to uneven thickness , and you can list a bunch of other deviations from the ideal. The final blow to our commitment to precision comes from grinding and polishing, which results in unpredictable weight loss. Therefore, the values ​​obtained should be treated as indicative.

unit of measurement

aluminum density and any other material - this is a physical quantity that determines the ratio of the mass of the material to the volume occupied.

• The unit of density measurement in the SI system is kg/m 3 .
• For the density of aluminum, a more descriptive dimension g / cm 3 is often used.

Density of aluminum in kg / m 3a thousand times more than in g / s m 3.

Specific gravity

To assess the amount of material per unit volume, such a non-systemic, but more descriptive unit of measurement as "specific gravity" is often used. Unlike density, specific gravity is not an absolute unit of measurement. The fact is that it depends on the magnitude of the gravitational acceleration g, which varies depending on the location on Earth.

Density versus temperature

The density of the material depends on the temperature. It usually decreases with increasing temperature. On the other hand, specific volume - the volume per unit mass - increases with increasing temperature. This phenomenon is called thermal expansion. It is usually expressed as a coefficient of thermal expansion, which gives a change in length per degree of temperature, for example, mm / mm / ºС. A change in length is easier to measure and apply than a change in volume.

Specific volume

The specific volume of a material is the reciprocal of density. It shows the value of the volume per unit mass and has the dimension of m 3 /kg. According to the specific volume of the material, it is convenient to observe the change in the density of materials during heating-cooling.

The figure below shows the change in the specific volume of various materials (pure metal, alloy and amorphous material) with increasing temperature. The flat sections of the graphs are the thermal expansion for all types of materials in the solid and liquid state. When melting a pure metal, there is a jump in the increase in specific volume (decrease in density), when melting an alloy, it rapidly increases as it melts in the temperature range. Amorphous materials when melted (at the glass transition temperature) increase their coefficient of thermal expansion.

aluminum density

Theoretical density of aluminum

The density of a chemical element is determined by its atomic number and other factors such as atomic radius and the way the atoms are packed. T The theoretical density of aluminum at room temperature (20 °C) based on its atomic lattice parameters is:

• 2698.72 kg / m 3.

Density of aluminum: solid and liquid

A graph of aluminum density versus temperature is shown in the figure below:

• As the temperature rises, the density of aluminum decreases.
• When aluminum passes from a solid to a liquid state, its density decreases abruptly from 2.55 to 2.34 g/cm 3 .

The density of aluminum in the liquid state - molten 99.996% - at various temperatures is presented in the table.

Aluminum alloys

Effect of doping

Differences in the density of different aluminum alloys are due to the fact that they contain different alloying elements and in different quantities. On the other hand, some alloying elements are lighter than aluminum, while others are heavier.

Alloying elements lighter than aluminum:

• silicon (2.33 g/cm³),
• magnesium (1.74 g/cm³),
• lithium (0.533 g/cm³).

Alloying elements heavier than aluminum:

• iron (7.87 g/cm³),
• manganese (7.40 g/cm³),
• copper (8.96 g/cm³),
• zinc (7.13 g/cm³).

The effect of alloying elements on the density of aluminum alloys shows the graph in the figure below.

Density of industrial aluminum alloys

The density of aluminum and aluminum alloys that are used in industry are presented in the table below for the annealed state (0). To a certain extent, it depends on the state of the alloy, especially for heat-hardenable aluminum alloys.

Aluminum-lithium alloys

The famous aluminum-lithium alloys have the smallest density.

• Lithium is the lightest metal element.
• The density of lithium at room temperature is 0.533 g/cm³ - this metal can float in water!
• Every 1% lithium in aluminum reduces its density by 3%
• Every 1% lithium increases the elastic modulus of aluminum by 6%. This is very important for aircraft construction and space technology.

Popular industrial aluminum-lithium alloys are alloys 2090, 2091 and 8090:

• The nominal content of lithium in the 2090 alloy is 1.3%, and the nominal density is 2.59 g/cm 3 .
• Alloy 2091 has a nominal lithium content of 2.2% and a nominal density of 2.58 g/cm3.
• Alloy 8090 with a lithium content of 2.0% has a density of 2.55 g/cm3.

Density of metals

The density of aluminum compared to the density of other light metals:

• aluminum: 2.70 g/cm 3
• titanium: 4.51 g/cm3
• magnesium: 1.74 g / cm 3
• beryllium: 1.85 g / cm 3

Sources:
1. Aluminum and Aluminum Alloys, ASM International, 1993.
2. FUNDAMENTALS OF MODERN MANUFACTURING – Materials, Processes, and Systems /Mikell P. Groover – JOHN WILEY & SONS, INC., 2010

The table shows the density (specific gravity), thermal conductivity, specific heat capacity and other thermophysical properties of Hg mercury depending on temperature. The following properties of this metal are given: density, mass specific heat capacity, thermal conductivity coefficient, thermal diffusivity, kinematic viscosity, thermal expansion coefficient (CTE), electrical resistivity. The properties of mercury are indicated in the temperature range from 100 to 1100 K.

The density of mercury is 13540 kg / m 3 at room temperature- this is a rather high value, it is 13.5 times more. Mercury is the heaviest of. The density of mercury decreases when it is heated, mercury becomes less dense. For example, at 1000K (727°C), the specific gravity of mercury decreases to 11830 kg/m 3 .

Specific the heat capacity of mercury is 139 J/(kg deg) at 300 K and weakly depends on temperature - when mercury is heated, its heat capacity decreases.

Thermal conductivity of mercury at low negative temperatures it has a high value, at a temperature of 250 K the thermal conductivity of mercury is minimal, with its subsequent increase as this metal is heated.

The dependence of the viscosity, Prandtl number, and electrical resistivity of mercury is such that with increasing temperature, the values ​​of these properties of mercury decrease. Thermal diffusivity of mercury increases when it is heated.

It should be noted that mercury is very great importance of KTR, compared with , in other words, when heated, mercury expands very much. This property of mercury is used in the manufacture of mercury thermometers.

Mercury density

The density of mercury is so high that metals such as, rhodium and others float in it. heavy metals. As the temperature rises, the density of mercury decreases. Below is table of mercury density values ​​depending on temperature at atmospheric pressure to the fifth decimal place. The density is indicated in the temperature range from 0 to 800°C. The density in the table is expressed in terms of t/m 3 . For example, at a temperature of 0 ° C, the density of mercury is 13.59503 t / m 3 or 13595.03 kg / m 3.

Table of mercury vapor pressure

The table shows the pressure values ​​of saturated mercury vapor in the temperature range from -30 to 800°C. Mercury has a relatively high vapor pressure, the dependence of which on temperature is quite strong. For example, at 100°C, the saturation vapor pressure of mercury, according to the table, is 37.45 Pa, and at 200°C it rises to 2315 Pa.

Today, many complex structures and devices have been developed that use metals and their alloys with different properties. In order to apply the most suitable alloy in a certain design, designers select it in accordance with the requirements of strength, fluidity, elasticity, etc., as well as the stability of these characteristics in the required temperature range. Next, the required amount of metal is calculated, which is required for the production of products from it. To do this, you need to calculate based on its specific gravity. This value is constant - this is one of the main characteristics of metals and alloys, which practically coincides with density. Calculating it is simple: you need to divide the weight (P) of a piece of metal in solid form by its volume (V). The resulting value is denoted γ, and it is measured in Newtons per cubic meter.

Specific Gravity Formula:

Based on the fact that weight is mass times acceleration free fall, we get the following:

Now about the units of measurement of specific gravity. The above Newtons per cubic meter refer to the SI system. If the CGS metric system is used, then this value is measured in dynes per cubic centimeter. In the MKSS system, the following unit is used to designate specific gravity: kilogram-force per cubic meter. Sometimes it is acceptable to use gram-force per cubic centimeter - this unit lies outside all metric systems. The main ratios are obtained as follows:

1 dyne / cm 3 \u003d 1.02 kg / m 3 \u003d 10 n / m 3.

How greater value specific gravity, the heavier the metal. For light aluminum this value is quite small - in SI units it is equal to 2.69808 g / cm 3 (for example, for steel it is 7.9 g / cm3). Aluminum, as well as its alloys, is in high demand today, and its production is constantly growing. After all, this is one of the few metals needed for industry, the supply of which is in the earth's crust. Knowing the specific gravity of aluminum, you can calculate any product from it. To do this, there is a convenient metal calculator, or you can manually calculate by taking the values ​​​​of the specific gravity of the desired aluminum alloy from the table below.

However, it is important to consider that this is the theoretical weight of rolled products, since the content of additives in the alloy is not strictly defined and can vary within small limits, then the weight of rolled products of the same length, but different manufacturers or batches may differ, of course this difference is small, but it exists.

Here are some calculation examples:

Example 1. Calculate the weight of A97 aluminum wire with a diameter of 4 mm and a length of 2100 meters.

Let's determine the cross-sectional area of ​​​​the circle S \u003d πR 2 means S \u003d 3.1415 2 2 \u003d 12.56 cm 2

Let's determine the weight of rolled products knowing that the specific gravity of the brand A97 \u003d 2.71 g / cm 3

M \u003d 12.56 2.71 2100 \u003d 71478.96 grams \u003d 71.47 kg

Total wire weight 71.47 kg

Example 2. We calculate the weight of a circle made of aluminum grade AL8 with a diameter of 60 mm and a length of 150 cm in the amount of 24 pieces.

Let's determine the cross-sectional area of ​​​​the circle S \u003d πR 2 means S \u003d 3.1415 3 2 \u003d 28.26 cm 2

We determine the weight of rolled products knowing that the specific gravity of the brand AL8 \u003d 2.55 g / cm 3

There is no such person who has not seen the yellow metal in his entire life. There are several minerals found in nature that appearance similar to yellow metal. But as they say, "All that glitters is not gold." In order not to confuse the precious metal with other materials, it is necessary to know the density of gold.

Noble metal density

Molecular structure of gold.

One of the important characteristics of a precious metal is its density. The density of gold is measured in kg m3.

Specific gravity is a very significant characteristic for gold. This is usually not taken into account, since jewelry: rings, earrings, pendants are very light in weight. But if you hold a kilogram ingot of real yellow metal in your hands, you can see that it is very heavy. The significant density of gold facilitates its extraction. Thus, flushing at locks ensures a high level of gold recovery from washed rocks.

The density of gold is 19.3 grams per cubic centimeter.

This means that if you take a certain volume of precious metal, it will weigh almost 20 times more than the same volume of plain water. A two-liter plastic bottle of golden sand weighs about 32 kg. From 500 grams of precious metal, you can lay out a cube with a side of 18.85 mm.

Density table of gold of various samples and colors.

The density of the original gold is several units lower than that of the already purified metal and can vary from 18 to 18.5 grams per cubic centimeter.

583 gold is less dense, as this alloy consists of different metals.

At home, you can determine the density of gold yourself. To do this, it is necessary to weigh the precious metal product on ordinary scales, in which the division value should be at least 1 gram. After that, the container with the marking of the volume must be filled with a liquid, in this case water, into which the jewelry should be lowered. Care must be taken to ensure that the liquid does not start to overflow.

After that, we measure how much the volume of liquid has changed after lowering the gold product into the container. According to a special formula known from the school bench, we calculate the density: mass divided by volume.

It must be remembered that a precious metal product does not consist of pure gold, so it is necessary to make an adjustment for the density of the alloy sample.

How to distinguish real yellow metal from a fake

On the this moment both in the Russian and foreign markets there is a very large percentage of counterfeit gold. There is a huge risk of acquiring gold jewelry containing up to 5% of the precious metal or without it at all. The basic rules when buying gold will help you not to feel cheated.

To begin with, you should inspect the product well. It must have a sample on it. Moreover, it should not consist of crooked numbers or a smeared brand. Otherwise, this is the first sign of a counterfeit.

An example of a unified state hallmark for gold items.

The next sign of a fake is the wrong side of the precious metal jewelry. It must be as well made as the front side, otherwise it is a low-quality product. It is also possible to determine the quality of a product using such a characteristic as the density of gold, but it is impossible to conduct such an experiment in a store.

There is also such a method of determination as a strength test. True, it is not always possible to scratch a gold item in front of the seller, so this method cannot be implemented.

Iodine check.

The following chemical methods can serve as good ways to determine the quality of a product. You can drop a little iodine on the yellow metal jewelry. If the spot is dark in color, then we can confidently speak about the quality of the offered product. Table vinegar can also help. If, after three minutes spent in it, the precious metal has darkened, then you can safely take the product to a landfill.

Chlorine gold can be of great help in determining the quality. From the course of chemistry, it became known not only the density of gold, but also the fact that it cannot enter into any chemical reactions. Therefore, if, after applying chlorine gold to the precious metal, it began to deteriorate, then this is a real fake and place it in the trash.

One of the most good ways protection against the acquisition of counterfeit goods is the purchase of precious metal products in well-known specialized stores.

In this case, there is a high probability of buying a truly high-quality product. Let the price in them is a little higher than in various shops and markets, but the quality is worth it. Otherwise, you can buy a fake product and very much regret the money saved.

twins of gold

In nature, there are several metals that have the same density as gold. These are uranium, which is radioactive, and tungsten. It is cheaper than the yellow metal, but the density of tungsten and gold is almost the same, the difference is three tenths. What distinguishes tungsten from gold is that it has a different color and is much harder than the yellow metal. Pure gold is very soft and can be easily scratched with a fingernail.

A fake gold bar filled with tungsten from the inside.

The fact that the density of elements such as tungsten and gold is the same is very attractive to counterfeiters. They replace gold bars with tungsten of similar density and weight, and cover with a thin layer of precious metal on top. At the same time, the high cost of the yellow metal makes tungsten more popular among young people. Tungsten products are much cheaper and more scratch resistant.

Lead Density

The purer gold, the less hard it is, so before the yellow metal was bitten to check. This method unreliable. The decoration may be made of lead covered with a very thin layer of gold. And lead also has a soft structure. You can try to scratch the jewelry not from the front side, and base metal can be found under a very thin layer of precious metal.

The density of the element of the periodic table - lead and its counterpart - gold is different. The density of lead is much less than gold and is 11.34 grams per cubic centimeter. Thus, if we take the yellow metal and lead of the same volume, then the mass of gold will be much greater than that of lead.

White gold is an alloy of a yellow precious metal with platinum or other metals that give it a white, or rather dull, silver color. There is an opinion in everyday life that "white gold" is one of the names of platinum, but this is not so. This type of gold costs a little more than usual. In appearance, white metal is similar to silver, which is much cheaper. The density of such elements of the periodic table as gold and silver is different. How to distinguish white gold from silver? These precious metals have different densities.

Silver is the least dense material of all those considered in the article.

The density of gold is greater than the density of silver. Its density is 10.49 grams per cubic centimeter. Silver is much softer than white metal. Therefore, if you hold a silver product on a white sheet, then a trace will remain. If you do the same with white precious metal, then there will be no trace.