Thermophysical properties, composition and thermal conductivity of aluminum alloys

Heat capacity of materials - table

In construction, a very important characteristic is the heat capacity of building materials. The thermal insulation characteristics of the walls of the building depend on it, and, accordingly, the possibility of a comfortable stay inside the building

The thermal insulation characteristics of the walls of the building depend on it, and, accordingly, the possibility of a comfortable stay inside the building.

Before you begin to familiarize yourself with the thermal insulation characteristics of individual building materials, you need to understand what heat capacity is and how it is determined.

Specific heat capacity of materials

Heat capacity is a physical quantity that describes the ability of a material to accumulate temperature from a heated environment.

Quantitatively, specific heat capacity is equal to the amount of energy, measured in J, required to heat a body weighing 1 kg by 1 degree.

Below is a table of the specific heat capacity of the most common materials in construction.

In order to calculate the heat capacity of a particular material, you must have the following data:

• type and volume of heated material (V);
• the specific heat capacity of this material (Sud);
• specific gravity (msp);
• initial and final temperatures of the material.

Heat capacity of building materials

The heat capacity of materials, the table for which is given above, depends on the density and thermal conductivity of the material.

And the thermal conductivity coefficient, in turn, depends on the size and closedness of the pores. A fine-porous material, which has a closed pore system, has greater thermal insulation and, accordingly, lower thermal conductivity than a large-porous one.

This is very easy to see using the most common materials in construction as an example. The figure below shows how the thermal conductivity coefficient and the thickness of the material influence the thermal insulation qualities of external fences.

The figure shows that building materials with lower density have a lower thermal conductivity coefficient.

However, this is not always the case. For example, there are fibrous types of thermal insulation for which the opposite pattern applies: the lower the density of the material, the higher the thermal conductivity coefficient will be.

Therefore, you cannot rely solely on the indicator of the relative density of the material, but it is worth taking into account its other characteristics.

Comparative characteristics of the heat capacity of basic building materials

In order to compare the heat capacity of the most popular building materials, such as wood, brick and concrete, it is necessary to calculate the heat capacity for each of them.

First of all, you need to decide on the specific gravity of wood, brick and concrete. It is known that 1 m3 of wood weighs 500 kg, brick - 1700 kg, and concrete - 2300 kg. If we take a wall whose thickness is 35 cm, then through simple calculations we find that the specific gravity is 1 sq.

m of wood will be 175 kg, brick – 595 kg, and concrete – 805 kg. Next, we will select the temperature value at which thermal energy will accumulate in the walls. For example, this will happen on a hot summer day with an air temperature of 270C.

For the selected conditions, we calculate the heat capacity of the selected materials:

1. Wall made of wood: C=SudhmuddhΔT; Sder=2.3x175x27=10867.5 (kJ);
2. Concrete wall: C=SudhmuddhΔT; Cbet = 0.84x805x27 = 18257.4 (kJ);
3. Brick wall: C=SudhmuddhΔT; Skirp = 0.88x595x27 = 14137.2 (kJ).

From the calculations made, it is clear that with the same wall thickness, concrete has the highest heat capacity, and wood has the least. What does this mean? This suggests that on a hot summer day, the maximum amount of heat will accumulate in a house made of concrete, and the least amount of heat will accumulate in a house made of concrete.

This explains the fact that in a wooden house it is cool in hot weather and warm in cold weather. Brick and concrete easily accumulate a fairly large amount of heat from the environment, but just as easily part with it.

Heat capacity and thermal conductivity of materials

Thermal conductivity is a physical quantity of materials that describes the ability of temperature to penetrate from one wall surface to another.

To create comfortable indoor conditions, it is necessary that the walls have a high heat capacity and a low thermal conductivity coefficient. In this case, the walls of the house will be able to accumulate thermal energy from the environment, but at the same time prevent the penetration of thermal radiation into the room.

Specific heat values ​​for some substances

The values ​​of specific heat capacity at constant pressure ( Cp

).
Table I: Standard Specific Heat Capacity Values

Table II: Specific Heat Capacity Values ​​for Some Building Materials

Physical properties of kerosene:

Note:

* with increasing temperature, the density of kerosene decreases.

** ignition temperature is the temperature of a flammable substance at which it emits flammable vapors and gases at such a speed that, after ignition from the ignition source, stable combustion occurs;

** flash point - the temperature at which petroleum product vapors form a mixture with the surrounding air that flares up when a fire is brought to it.

Physical properties of metal

Aluminum is a chemical element (atomic number 13). It belongs to the group of light metals and is a common element found in the earth's crust. Paramagnetic metal has a silvery-white color, it is very easy to machine, and it is convenient to cast products from it.

The metal has high thermal and electrical conductivity. It is resistant to air due to the ability to form metal oxide films that protect the surface from the influence of the external environment.

The film is destroyed under the influence of alkaline solutions. To prevent the metal from reacting with aggressive liquids, indium, tin or gallium are added to the alloy.

The specific heat of fusion is 390 kJ/kg, and the specific heat of evaporation is 10.53 MJ/kg. The metal boils at a temperature of 2500°C. The melting gradient depends on the degree of purification of the material and is accordingly:

• for technical raw materials +658°C;
• for metal with highest class cleaning +660 °C.

Aluminum easily forms alloys, among which everyone knows compounds with copper, magnesium, and silicon. In the jewelry industry, this metal is combined with gold, which gives the composition new physical properties.

Aluminum easily forms alloys.

In nature, a chemical element forms natural compounds. It is found in minerals such as:

• nepheline;
• bauxite;
• corundum;
• feldspar;
• kaolinite;
• beryl;
• emerald;
• chrysoberyl.

In some places (volcano vents) native metal can be found in small quantities.

Table of thermal conductivity of materials on Pli-

Production and market

Main article: Aluminum industry

There is no reliable information about the production of aluminum before the 19th century. The assertion, sometimes found with reference to Pliny's Natural History, that aluminum was known under the Emperor Tiberius, is based on an incorrect interpretation of the source.

In 1825, the Danish physicist Hans Christian Oersted obtained several milligrams of metallic aluminum, and in 1827 Friedrich Wöhler was able to isolate grains of aluminum, which, however, were immediately covered in air with a thin film of aluminum oxide.

Until the end of the 19th century, aluminum was not produced on an industrial scale.

Only in 1854, Henri Saint-Clair Deville (his research was funded by Napoleon III, hoping that aluminum would be useful to his army) invented the first method of industrial production of aluminum, based on the displacement of aluminum by metallic sodium from double sodium chloride and aluminum NaCl AlCl3. In 1855, the first metal ingot weighing 6-8 kg was obtained. Over 36 years of use, from 1855 to 1890, 200 tons of aluminum metal were produced using the Saint-Clair Deville method. In 1856, he also obtained aluminum by electrolysis of a molten sodium-aluminum chloride.

In 1885, an aluminum production plant was built in the German city of Gmelingem, using technology proposed by Nikolai Beketov. Beketov’s technology was not much different from Deville’s method, but it was simpler and involved the interaction between cryolite (Na3AlF6) and magnesium. Over five years, this plant produced about 58 tons of aluminum - more than a quarter of the total world production of metal by chemical means in the period from 1854 to 1890.

The method, invented almost simultaneously by Charles Hall in the USA and Paul Héroux in France (1886) and based on the production of aluminum by electrolysis of alumina dissolved in molten cryolite, laid the foundation for the modern method of aluminum production. Since then, due to improvements in electrical engineering, aluminum production has improved. A notable contribution to the development of alumina production was made by Russian scientists K. I. Bayer, D. A. Penyakov, A. N. Kuznetsov, E. I. Zhukovsky, A. A. Yakovkin and others.

The first aluminum smelter in Russia was built in 1932 in the city of Volkhov. The metallurgical industry of the USSR in 1939 produced 47.7 thousand tons of aluminum, another 2.2 thousand tons were imported.

World War II greatly stimulated aluminum production. Thus, in 1939, its global production, excluding the USSR, was 620 thousand tons, but by 1943 it had grown to 1.9 million tons.

By 1956, the world produced 3.4 million tons of primary aluminum, in 1965 - 5.4 million tons, in 1980 - 16.1 million tons, in 1990 - 18 million tons.

In 2007, the world produced 38 million tons of primary aluminum, and in 2008 - 39.7 million tons. The production leaders were:

1. China (produced 12.60 million tons in 2007, and 13.50 million tons in 2008)
2. Russia (3.96/4.20)
3. Canada (3.09/3.10)
4. USA (2.55/2.64)
5. Australia (1.96/1.96)
6. Brazil (1.66/1.66)
7. India (1.22/1.30)
8. Norway (1.30/1.10)
9. UAE (0.89/0.92)
10. Bahrain (0.87/0.87)
11. South Africa (0.90/0.85)
12. Iceland (0.40/0.79)
13. Germany (0.55/0.59)
14. Venezuela (0.61/0.55)
15. Mozambique (0.56/0.55)
16. Tajikistan (0.42/0.42)

59 million tons of aluminum were produced in 2021

See also: List of countries by aluminum smelting

On the world market, the reserve is 2.224 million tons, and the average daily production is 128.6 thousand tons (2013.7).

In Russia, the monopolist in aluminum production is, which accounts for about 13% of the world aluminum market and 16% of alumina.

The world's reserves of bauxite are practically limitless, that is, they are incommensurate with the dynamics of demand. Existing facilities can produce up to 44.3 million tons of primary aluminum per year. It should also be taken into account that in the future some of the applications of aluminum may be reoriented to the use of, for example, composite materials.

Aluminum prices (at trades on international commodity exchanges) from 2007 to 2021 averaged 1253-3291 US dollars per ton.

Melting point of copper and specific heat capacity of the metal.

Copper and its properties.

The relatively low melting point of copper allowed ancient people to be one of the first to use this metal for their needs. They came across iron ore more often, but it was more difficult to smelt iron from it. The reason is that copper melts at a temperature of 1083 °C, and iron - at 1539 °C.

Copper is not the most common element among minerals; it ranks 23rd among the most popular elements in industry. Typically mined in the form of sulfide ores and their varieties: pyrite, malachite ore and copper luster.

Copper is extremely rare in the form of nuggets; their largest deposits are located in Chile.

In Russia and Kazakhstan, copper deposits are found in the form of sedimentary rocks - cuprous sandstones and shales.

A little history

Research by historians allows us to conclude that copper tools were used in the Middle East as early as the beginning of the 4th century. BC e. At the end of this century, in Western Asia, people began to use the first bronze tools. At the same time, copper objects appeared in Iran, which contained an admixture of tin, and in bronze tools found during excavations in the Caucasus and Anatolia and dating back to the 3rd century. BC e., an admixture of arsenic was discovered.

According to other sources, copper began to be mined for the first time at the same time in Cyprus, hence its Latin name Cuprum. Copper became the main metal for the production of tools, hunting, and household utensils.

Copper has been widely used since time immemorial.

Even ancient people noticed that if tin or zinc is added to copper ore, the mixture will begin to melt at a lower temperature. Therefore, copper melt could be obtained directly from the fire.

Our ancestors more often used malachite ore. She didn't need to be burned. The ore was mixed with coals, placed in a clay vessel and lowered into a hole dug in the ground. Then the mixture in the vessel was set on fire. During combustion, carbon monoxide was released, which, being a catalyst, reduced the ore to metal.

Physical characteristics of copper

The specific heat capacity of copper is 390 J/kg. This means that heating 1 kg of copper by 1 °C will require 390 J of energy.

This value is average. Heat capacity depends on temperature: the higher the temperature, the greater the heat capacity. At the melting point it is 514 J/kg*K.

For comparison:

• specific heat capacity of iron - 460 J/kg*K;
• specific heat capacity of steel - 500 J/kg*K;
• The specific heat capacity of cast iron is 540 J/kg*K.

Therefore, all other things being equal, copper heats up faster and less energy is required.

The specific heat of fusion of copper is 210 kJ/kg. This value means that 210 kJ of energy is required to melt 1 kg of copper.

For comparison:

Melting copper requires less energy than the same mass of iron.

The relatively low melting point and specific heat allowed ancient people to use copper much more widely than iron or other metals.

How to melt copper at home

Copper has a low melting point, which makes it possible to melt it at home.

Sometimes in our time there is a need to obtain copper melt at home. There are several ways to do this.

• If you have a muffle furnace, the copper parts must be placed in a crucible and placed in the furnace. During the melting process, the formation of an oxide film should be observed. It needs to be removed using a steel hook. The oxide film, if not removed, will make the melt poor quality.
• Copper parts can be melted with an autogen, removing the oxide film.
• If the oxide film is formed intensively, the surface of the melt can be sprinkled with crushed charcoal.
• The most fusible copper alloys - some types of bronze and brass can be melted with a regular blowtorch.
• A better result can be achieved by building a small forge. The steel grate must be placed on the bricks so that there is air access from below. Place a layer of charcoal on the grate and set it on fire. A crucible with copper parts is placed on the coals. To increase the combustion temperature, you need to increase the air flow. This is done using an electric fan or vacuum cleaner that blows air.

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ometallah.com

Kerosene as fuel:

Kerosene (English kerosene from ancient Greek κηρός - “wax”) is a flammable mixture of liquid hydrocarbons (from C8 to C15) with a boiling point in the range of 150-250 °C, obtained by direct distillation or rectification of oil.

Externally, kerosene is a transparent, colorless (or slightly yellowish, or light brown), slightly oily liquid to the touch. Has a characteristic smell of petroleum products.

Kerosene is a flammable, flammable liquid. Refers to low-hazard substances and, in terms of the degree of impact on the human body, in accordance with GOST 12.1.007, belongs to the 4th hazard class. Combustible fuel.

Kerosene is lighter than water. Does not dissolve in water.

Kerosene forms explosive mixtures with air.

Thermal conductivity and density of aluminum

The table shows the thermophysical properties of aluminum Al depending on temperature. The properties of aluminum are given over a wide temperature range - from minus 223 to 1527 ° C (from 50 to 1800 K).

As can be seen from the table, the thermal conductivity of aluminum at room temperature is about 236 W/(m deg), which allows this material to be used for the manufacture of radiators and various heat sinks.

In addition to aluminum, copper also has high thermal conductivity. Which metal has the greater thermal conductivity? It is known that the thermal conductivity of aluminum at medium and high temperatures is still less than that of copper, however, when cooled to 50K, the thermal conductivity of aluminum increases significantly and reaches a value of 1350 W/(m deg). For copper, at such a low temperature, the thermal conductivity value becomes lower than for aluminum and amounts to 1250 W/(m deg).

Aluminum begins to melt at a temperature of 933.61 K (about 660 ° C), while some of its properties undergo significant changes. The values ​​of properties such as thermal diffusivity, aluminum density and thermal conductivity are significantly reduced.

The density of aluminum is mainly determined by its temperature and depends on the state of aggregation of this metal. For example, at a temperature of 27°C, the density of aluminum is 2697 kg/m3, and when this metal is heated to the melting point (660°C), its density becomes equal to 2368 kg/m3. The decrease in aluminum density with increasing temperature is due to its expansion when heated.

The table shows the following thermophysical properties of aluminum:

• aluminum density, g/cm3;
• specific (mass) heat capacity, J/(kg deg);
• thermal diffusivity coefficient, m2/s;
• thermal conductivity of aluminum, W/(m deg);
• electrical resistivity, Ohm m;
• Lorentz function.

Specific heat capacity of metals at different temperatures. Heat capacity of copper and aluminum

Specific heat capacity of metals at different temperatures

pellete.ru

What is aviation fuel?

Fuel for use in the aviation industry is a flammable substance intended to be supplied mixed with air into the combustion chamber of an aircraft engine. The goal is to obtain thermal energy, which is released at the moment of oxidation of the mixture with oxygen, that is, combustion. The fuel poured into the coffered tanks of aircraft is divided into two types.

Aviation gasoline

This type of fuel is obtained using direct distillation, reforming or catalytic cracking. The main physical and chemical indicators of aviation gasoline are:

• resistance to detonation;
• chemical stability;
• factional composition.

Gasoline is characterized by high volatility and suitability for the formation of fuel-air mixtures necessary for current flight conditions.

This type of combustible mixture is used for combustion in piston internal combustion engines. Airplanes with such engines fly short distances on local airlines and are used for demonstration flights and air shows. The most popular brands in Russian small aviation were the brands of leaded gasoline for normal and lean mixtures, developed in the last quarter of the last century - B91/115 and B95/130. Today, the small aircraft fleet is fully fueled with regular AI-95 gasoline or imported AVGAS 100LL fuel.

Interesting: Why do children suck their thumb? Reasons, what to do, photos and videos

Aviation kerosene

Regular gasoline is not suitable for combustion in the combustion chamber of a turbojet aircraft engine. Piston engines use the effect of sudden ignition of the gasoline-air mixture to create a shock at the cylinder head. A completely different principle is used in jet engines

It is important here that the combustion is smooth. This is exactly what burning aviation kerosene provides

To fill the caissons of jet aircraft, fuel is used, which is obtained from the middle distillate kerosene fraction of oil with a boiling point of 150-280°C. 96-98% of the composition of aviation kerosene is naphthenic, paraffin and aromatic hydrocarbons. The rest of the composition comes from resins, nitrogenous and organometallic compounds.

Main areas of use

In conclusion, we present the most common areas of use of the substance:

• Aviation kerosene. This is the name of motor fuel for gas turbine engines, which are equipped with various aircraft. These are kerosene fractions of direct distillation of oil. They are often hydrotreated and additives are added to improve performance properties. In Russia, five varieties of such fuel are produced for subsonic aviation - TS-1, T-1, T-1S, T-2 and RT, and for supersonic aviation - two (T-6 and T-8V).
• Rocket kerosene. Here this petroleum product acts as a hydrocarbon, environmentally friendly fuel and the working fluid of hydraulic machines. Its use in rocket engines was proposed back in 1914 by Tsiolkovsky. Paired with liquid oxygen, it is used in the lower stages of many launch vehicles.
• Technical kerosene. This is a raw material for the production of aromatic hydrocarbons, ethylene, propylene. In addition, it is the main fuel for firing porcelain and glass, and a solvent for washing parts and mechanisms.
• Lighting kerosene (KO-25, KO-30, KO-20, KO-22). It is used in lighting fixtures and is used as fuel for some kitchen stoves (kerosene stoves, kerosene stoves, kerosene gas). Another use is in heating. This is a solvent, a cleaning agent (widely used to remove residues of thermal pastes, various paints and varnishes), and a degreaser.
• Automotive kerosene. This application was characteristic of the dawn of the development of internal combustion engines. The petroleum product was widely used as fuel for carburetor and diesel internal combustion engines.

Among the non-trivial uses, the following can be distinguished: a folk remedy for getting rid of lice, treating head lice and diphtheria. In addition, kerosene helped get rid of bedbugs when wiping furniture with it.

As you have seen, kerosene immediately determines a complex of characteristics. And this seems natural given its multiple uses.

Density

One of the most important characteristics used for all petroleum products. And if we compare the density of kerosene and water, we will see that the latter will be higher. Here are the specific numbers:

• The density of distilled water at an “ideal” temperature of 3.7 °C is 1000 kg/m3.
• The density of sea water at an “ideal” temperature of 3.7 °C is 1030 kg/m3.
• The density of boiling water at 100 °C is 958.4 kg/m3.

To further compare the density of water and kerosene, let’s get acquainted with this characteristic regarding the petroleum product. This is 800 kg/m3.

It must be said that in the early stages of the development of the oil industry, density was the only characteristic of kerosene. Today, in practice, the quantity most often used is relative density. This is a dimensionless indicator equal to the ratio of the true densities of a given petroleum product and distilled water, taken for comparison at certain temperatures.

Thus, the density of kerosene at 20 °C will be from 780 to 850 kg/m3.

Heat capacity table

The specific heat capacity table shows the ability of substances to accumulate thermal energy. The higher the heat capacity coefficient, the more energy is required to heat the body. And, accordingly, the higher the heat capacity coefficient, the more energy the body can give off when cooling. Heat capacity is measured in J/(kg*K). Those. Specific heat capacity is the number of Joules required to heat a 1 kg body by 1 degree Kelvin.

Below is a short table with the most commonly used substances:

As can be seen from the table of heat capacities of substances, hydrogen has the largest coefficient. But ordinary water also has a good indicator.

The heat capacity of substances is used when it is necessary to store heat or cold, for example, in air conditioning and heating systems. The greater the heat capacity of a substance, the more difficult it is to heat it, but it is also difficult to cool it. Substances with low heat capacity are used where rapid heating or cooling is needed.

energy.clcnet.ru

Specific gravity

Due to the fact that copper is not a one-component metal, calculating its specific gravity on your own in everyday conditions is difficult. As a rule, calculations are carried out in appropriate laboratories. But the average range has long been calculated and is from 8.63 to 8.8 g/cm3.

To simplify independent calculations, we provide below a table with data on specific gravity in accordance with units of measurement.

Accurate data is used to calculate the weight required for the production of rolled metal and metal products.

Sequence for determining the specific heat of combustion

The indicator of the specific heat of combustion of kerosene establishes the conditions for its ignition in various devices - from engines to kerosene cutting devices. In the first case, the optimal combination of thermophysical parameters should be determined more carefully. There are usually several schedules for each fuel combination. These graphs can be used to evaluate:

1. Optimal ratio of mixture of combustion products.
2. Adiabatic flame temperature of combustion reaction.
3. Average molecular weight of combustion products.
4. Specific heat ratio of combustion products.

This data is necessary to determine the speed of the exhaust gases emitted from the engine, which in turn determines the engine's thrust.

The optimal fuel mixture ratio gives the highest specific impulse of energy and is a function of the pressure at which the engine will operate. An engine with high combustion chamber pressure and low exhaust pressure will have the highest optimum mixture ratio. In turn, the pressure in the combustion chamber and the energy intensity of kerosene fuel depend on the optimal mixture ratio.

In most engine designs using kerosene as fuel, much attention is paid to the conditions of adiabatic compression, when the pressure and volume occupied by the combustible mixture are in constant relationship - this affects the durability of engine elements. In this case, as is known, there is no external heat transfer, which determines the maximum efficiency

The specific heat of kerosene is the amount of heat required to raise the temperature of one gram of a substance by one degree Celsius. The specific heat coefficient is the ratio of the specific heat capacity at constant pressure to the specific heat capacity at constant volume. The optimal ratio is established at a predetermined fuel pressure in the combustion chamber.

The exact heat indicators for the combustion of kerosene are usually not established, since this petroleum product is a mixture of four hydrocarbons: dodecane (C12H26), tridecane (C13H28), tetradecane (C14H30) and pentadecane (C15H32). Even within one batch of original oil, the percentage of the listed components is not constant. Therefore, the thermophysical characteristics of kerosene are always calculated with known simplifications and assumptions.

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Specific heat

Specific heat

- the ratio of heat capacity to mass, the heat capacity of a unit mass of a substance (different for different substances); a physical quantity numerically equal to the amount of heat that must be transferred to a unit mass of a given substance in order for its temperature to change by one. [1] .

In the International System of Units (SI), specific heat capacity is measured in joules per kilogram per kelvin, J/(kg K) [2]. Sometimes non-systemic units are also used: calorie/(kg °C), etc.

Specific heat capacity is usually denoted by the letters c

or
C
, often with subscripts.

The specific heat capacity is affected by the temperature of the substance and other thermodynamic parameters. For example, measuring the specific heat capacity of water will give different results at 20 °C and 60 °C. In addition, specific heat capacity depends on how the thermodynamic parameters of the substance (pressure, volume, etc.) are allowed to change; for example, specific heat capacity at constant pressure ( CP

) and at constant volume (
CV
), generally speaking, are different.

Formula for calculating specific heat capacity:

c = Q m Δ T , >,> where c

- specific heat capacity,
Q
- amount of heat received by a substance during heating (or released during cooling),
m
- mass of the heated (cooled) substance, Δ
T
- difference between the final and initial temperatures of the substance.

Specific heat capacity can depend (and in principle, strictly speaking, always, more or less strongly, depends) on temperature, therefore the following formula with small (formally infinitesimal) δ T and δ Q is more correct:

c ( T ) = 1 m ( δ Q δ T ) . >left(>right).>

Thermal conductivity of aluminum alloys

A summary table of the thermal conductivity of aluminum alloys is presented. It shows the thermal conductivity values ​​of common aluminum alloys (aluminum alloys with silicon, copper, magnesium and zinc, casting alloys, duralumin) at various temperatures in the range from 4 to 700K.

According to the table, it can be seen that the thermal conductivity of aluminum alloys mainly increases with increasing temperature. An alloy such as AD1 has the greatest thermal conductivity at room temperature - its thermal conductivity at this temperature is 210 W/(m deg). Lower thermal conductivity is characteristic mainly of cast aluminum alloys, for example AK4, AL1, AL8 and others.

The temperature in the table is in degrees Kelvin!
Table of thermal conductivity of aluminum alloys

Heat capacity of steel

Romashkin A.N.

Specific heat capacity is the amount of heat required to heat 1 kilogram of a substance by 1 degree on the Kelvin (or Celsius) scale.

Physical dimension of specific heat capacity: J/(kg K) = J kg-1 K-1 = m2 s-2 K-1.

The table shows, in ascending order, the specific heat capacity of various substances, alloys, solutions, and mixtures. Links to this source are given after the table.

When using Table 1, the approximate nature of the data should be taken into account. For all substances, specific heat capacity depends on temperature and state of aggregation. For complex objects (mixtures, composite materials, food products), the specific heat capacity can vary significantly between different samples.

Table 1. Heat capacity of pure substances

Sources:

• ru.wikipedia.org - Wikipedia: Specific heat capacity;
• alhimik.ru - average specific heat capacity of some solid materials at 0...100 °C, kJ/(kg K) according to the manual “Examples and problems in the course of processes and apparatus of chemical technology”, ed. Romankova;
• school.uni-altai.ru - tabular values ​​of the most common liquids;
• school.uni-altai.ru - tabular values ​​of the most common solids;
• dink.ru - specific heat capacity at 20 °C;
• mensh.ru - heat storage capacity of materials;
• vactekh-holod.ru - specific heat capacity of solids and some liquids;
• xiron.ru - data on the heat capacity of food products;
• aircon.ru - heat capacity of all kinds of [food] products;
• masters.donntu.edu.ua - heat capacity of coal;
• nglib.ru - average specific heat capacity of solids at room temperature - table in the book by S.D. Beskova “Technochemical calculations” in the electronic library “Oil and Gas” (registration required). This is the most detailed reference book available on the Internet.

Table 2. Specific heat capacity of carbon steel grades Steel 20 and Steel 40 at high temperatures (J/(kg∙ºC)) From 50 ºC to a given temperature

Source: Thermophysical properties of substances, Directory.
Ed. N.B.Vargaftika. Leningrad: State Energy Publishing House. 1956 - 367 p. steelcast.ru

Heat capacity of materials - table

In construction, a very important characteristic is the heat capacity of building materials. The thermal insulation characteristics of the walls of the building depend on it, and, accordingly, the possibility of a comfortable stay inside the building

Before you begin to familiarize yourself with the thermal insulation characteristics of individual building materials, you need to understand what heat capacity is and how it is determined.

Specific heat capacity of materials

Heat capacity is a physical quantity that describes the ability of a material to accumulate temperature from a heated environment. Quantitatively, specific heat capacity is equal to the amount of energy, measured in J, required to heat a body weighing 1 kg by 1 degree. Below is a table of the specific heat capacity of the most common materials in construction.

In order to calculate the heat capacity of a particular material, you must have the following data:

• type and volume of heated material (V);
• the specific heat capacity of this material (Sud);
• specific gravity (msp);
• initial and final temperatures of the material.

Specific heat capacity of steel | Metalworking

The concept of specific heat capacity and characteristics of steel

Specific heat capacity is an important parameter that determines the characteristics of steel. It shows the amount of heat that needs to be spent to heat a kilogram of alloy by 1 degree

The heat capacity is affected by different characteristics of steel, which is especially important in the manufacture of metal structures

The specific heat capacity of steel is the amount of heat required to increase the temperature of one kilogram of a substance by exactly one degree. Both the Celsius and Kelvin scales can be used equally.

Numerous factors influence heat capacity:

• state of aggregation of the heated substance;
• Atmosphere pressure;
• heating method;
• steel type.

In particular, high-alloy steels contain large amounts of carbon and are refractory. Accordingly, to heat one degree, more heat is needed than the standard 460 J/(kg*K). Low alloy steels heat up faster and easier. The maximum amount of heat and energy is required to heat heat-resistant materials with anti-corrosion treatment.

Heat capacity is calculated for each specific case. It is also necessary to take into account that as the temperature of the heated substance increases, its heat capacity changes.

Specific heat capacity is important when carrying out induction hardening or tempering of parts made of steel, cast iron, and composite materials. When the temperature of the product increases by a certain number of degrees, phase changes occur in the structure, and accordingly, the specific heat capacity also changes. Further heating will require larger/smaller volumes of heat.

Specific heat capacity characterizes not only the heating process of steel or composite materials, but also their cooling. Each material releases a certain amount of heat and/or energy when cooled. Specific heat capacity allows you to calculate how much heat will be obtained when one kilogram of metal cools by one degree. Heat transfer is affected by the area of ​​the cooled material and the presence/absence of additional ventilation.

How to calculate specific heat capacity

Specific heat capacity is often calculated using the Kelvin scale. But thanks only to the difference in the reference point, the indicator can be converted to degrees Celsius.

The specific heat capacity parameter determines the amount of fuel required to heat the part to a given point. The type and grade of steel depends on this. A high alloy alloy has a higher parameter value at the same temperature. Low alloy and carbon steels - less.

Example:

For comparison, G13 steel has a heat capacity of 0.520 kJ/(kg*deg) at a temperature of 100°C. This alloy is highly alloyed, meaning it contains more chromium, nickel, silicon and other additional elements. Carbon steel grade 20 at a similar temperature has a specific heat capacity of 0.460 kJ/(kg*deg).

Thus, specific heat capacity depends not only on temperature, but also on the type of steel. High-alloy steels are less resistant to cracking and are less weldable. The refractoriness of such materials is increased. These indicators directly affect the price of metal structures, which are made from different grades of steel. Stability, lightness, strength are the most important criteria that are determined by the quality of such an alloy.

In the tables you can see the specific heat capacity of high-alloy steels G13 and R18, as well as a number of low-alloy alloys. Temperature ranges – 50:650оС.

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