Melting point and basic properties of iron, classification of metals
Metals melt, as a rule, at a very high temperature, which can reach more than 3 thousand degrees. Although some of them can be melted at home, such as lead or tin. But mercury is melted at a temperature of minus 39 degrees.
This cannot be achieved at home. Melting point is one of the important indicators of the production of not only the metal itself, but also its alloys. When smelting raw materials, specialists take into account other physical and chemical properties of the ore and metal.
Iron is a chemical element that is number 26 on the periodic table. It is one of the most abundant elements in the entire solar system. According to research materials, the Earth's core contains approximately 79−85% of this substance . There is also a large amount of it in the earth's crust, but it is inferior to aluminum.
In its pure form, the metal is white with a slightly silvery tint. It is plastic, but the impurities present in it can determine its physical properties. Reacts to a magnet.
Iron is present in water. In river waters its concentration is approximately 2 mg/l of metal. In sea water its content can be a hundred or even a thousand times lower.
Iron oxide is the main form that is mined and found in nature. Iron oxide can be located in the uppermost part of the earth's crust and be a component of sedimentary formations.
An element in twenty-sixth place on the periodic table can have several oxidation states. It is they who determine its geochemical feature of being in a certain environment. In the Earth's core, the metal is present in a neutral form.
Mining
There are several ores containing iron. However, the following are mainly used as raw materials for iron production in industry:
- magnesite ore;
- goethite ore;
- hematite ore.
And also the following types of ore are often found:
- lellingitis;
- siderite;
- marcasite;
- ilmenite;
- is violent.
There is also a mineral called melanterite . It is used primarily in the pharmaceutical industry. It consists of green, fragile crystals with a glassy sheen. Medicines containing ferum are produced from it.
The main deposit of this metal is South America, namely Brazil.
The melting point of a metal is the minimum temperature at which it changes from solid to liquid. At the same time, it remains practically unchanged in volume.
Metal can be produced from ore in various ways, but the most basic of them is blast furnace . In addition to blast furnace, iron smelting is also used by roasting crushed ore with an admixture of clay. From the resulting mixture, pellets are formed, which are processed in a furnace followed by reduction with hydrogen. Next, the iron is melted in an electric furnace.
The melting point of iron is very high. For a technically pure element it is +1539 °C. This substance contains an impurity - Sulfur, which can only be extracted in liquid form. Without impurities, pure material is obtained by electrolysis of metal salts.
Classification of metals by melting point
Different metals can turn liquid at different temperatures. As a result, a certain classification is distinguished. They are divided as follows:
- Low-fusibility elements are those elements that can become liquid even at temperatures below 600 degrees. These include zinc, tin, lead, etc. They can be melted even at home - you just need to heat them up using a stove or soldering iron. Such types have found application in technology and electronics. They are used to connect metal elements and move electric current. Tin melts at 232 degrees, and zinc at 419 degrees.
- Medium-melting - elements that begin to melt at temperatures from six hundred to one thousand six hundred degrees. These elements are used mainly for building elements and metal structures, that is, when creating fittings, slabs and building blocks. This group includes: iron, copper, aluminum. The melting point of aluminum is relatively low and is 660 degrees. But iron begins to turn into a liquid state only at a temperature of 1539 degrees. It is one of the most common metals used in industry, especially in the automotive industry. However, iron is susceptible to corrosion, that is, rust, so it requires special surface treatment. It must be coated with paint or drying oil, and moisture must not be allowed to enter.
- Refractory are materials that melt and become liquid at temperatures above 1600 degrees. This group includes tungsten, titanium, platinum, chromium, etc. They are used in the nuclear industry and for some machine parts. They can be used for melting other metals, making high-voltage wires or wire. Platinum can be melted at 1769 degrees, and tungsten at 3420 °C.
The only element that is in a liquid state under normal conditions is mercury. Its melting point is minus 39 degrees and its vapors are poisonous, so it is used only in laboratories and closed containers.
Source: https://tokar.guru/metally/temperatura-plavleniya/zhelezo-himicheskie-svoystva-i-temperatura-plavleniya.html
At what temperature does metal melt?
The table shows the melting point of metals tmelt , their boiling point tk at atmospheric pressure, the density of metals ρ at 25°C and thermal conductivity λ at 27°C.
The melting point of metals, as well as their density and thermal conductivity are given in the table for the following metals: actinium Ac, silver Ag, aluminum Al, gold Au, barium Ba, beryllium Be, bismuth Bi, calcium Ca, cadmium Cd, cobalt Co, chromium Cr, cesium Cs, copper Cu, iron Fe, gallium Ga, hafnium Hf, mercury Hg, indium In, iridium Ir, potassium K, lithium Li, magnesium Mg, manganese Mn, molybdenum Mo, sodium Na, niobium Nb, nickel Ni, neptunium Np , osmium Os, protactinium Pa, lead Pb, palladium Pd, polonium Po, platinum Pt, plutonium Pu, radium Ra, rubidium Pb, rhenium Re, rhodium Rh, ruthenium Ru, antimony Sb, tin Sn, strontium Sr, tantalum Ta, technetium Tc, thorium Th, titanium Ti, thallium Tl, uranium U, vanadium V, tungsten W, zinc Zn, zirconium Zr.
According to the table, it can be seen that the melting point of metals varies over a wide range (from -38.83°C for mercury to 3422°C for tungsten). Metals such as lithium (18.05°C), cesium (28.44°C), rubidium (39.3°C) and other alkali metals have a low positive melting point.
The most refractory metals are the following: hafnium, iridium, molybdenum, niobium, osmium, rhenium, ruthenium, tantalum, technetium, tungsten. The melting point of these metals is above 2000°C.
Here are examples of the melting point of metals widely used in industry and everyday life:
- melting point of aluminum 660.32 °C;
- copper melting point 1084.62 °C;
- melting point of lead 327.46 °C;
- melting point of gold 1064.18 °C;
- melting point of tin 231.93 °C;
- the melting point of silver is 961.78 °C;
- The melting point of mercury is -38.83°C.
Rhenium Re has the maximum boiling point of the metals presented in the table - it is 5596°C. Also, metals belonging to the group with a high melting point have high boiling points.
The density of the metals in the table ranges from 0.534 to 22.59 g/cm 3 , that is, the lightest metal is lithium, and the heaviest metal is osmium. It should be noted that osmium has a density greater than that of uranium and even plutonium at room temperature.
The thermal conductivity of metals in the table varies from 6.3 to 427 W/(m deg), thus the worst conductor of heat is a metal such as neptunium, and the best heat-conducting metal is silver.
Melting point of steel
A table of melting temperature values for common grades of steel is presented. Steels for castings, structural, heat-resistant, carbon and other classes of steels are considered.
The melting point of steel ranges from 1350 to 1535°C. The steels in the table are arranged in order of increasing melting point.
Melting point of steel - table- Volkov A.I., Zharsky I.M. Large chemical reference book. - M: Soviet School, 2005. - 608 p.
- Kazantsev E.I. Industrial furnaces. Reference manual for calculations and design.
- Physical quantities. Directory. A. P. Babichev, N. A. Babushkina, A. M. Bratkovsky and others; Ed. I. S. Grigorieva, E. Z. Meilikhova. - M.: Energoatomizdat, 1991. - 1232 p.
Source: https://ostwest.su/instrumenty/pri-kakoj-temperature-rasplavljaetsja-metall.php/
Table of melting temperatures of various metals, and at how many degrees they melt
Each metal and alloy has its own unique set of physical and chemical properties, not least of which is the melting point. The process itself means the transition of a body from one state of aggregation to another, in this case, from a solid crystalline state to a liquid one.
To melt a metal, it is necessary to apply heat to it until the melting temperature is reached. With it, it can still remain in a solid state, but with further exposure and increased heat, the metal begins to melt. If the temperature is lowered, that is, some of the heat is removed, the element will harden.
The highest melting point among metals belongs to tungsten : it is 3422Co, the lowest is mercury: the element melts at - 39Co. As a rule, it is not possible to determine the exact value for alloys: it can vary significantly depending on the percentage of components. They are usually written as a number interval.
How it happens
Melting of all metals occurs approximately the same way - using external or internal heating. The first is carried out in a thermal furnace; for the second, resistive heating is used by passing an electric current or induction heating in a high-frequency electromagnetic field. Both options affect the metal approximately equally.
As the temperature increases the amplitude of thermal vibrations of molecules , and structural defects in the lattice arise, expressed in the growth of dislocations, jumping of atoms and other disturbances. This is accompanied by the rupture of interatomic bonds and requires a certain amount of energy. At the same time, a quasi-liquid layer forms on the surface of the body. The period of lattice destruction and defect accumulation is called melting.
Metal separation
Depending on their melting point, metals are divided into:
- Low-melting: they need no more than 600Co. This is zinc, lead, hang, tin.
- Medium-melting: melting point ranges from 600Со to 1600Со. These are gold, copper, aluminum, magnesium, iron, nickel and more than half of all elements.
- Refractory: requires temperatures above 1600°C to make the metal liquid. These include chromium, tungsten, molybdenum, titanium.
Depending on the melting temperature, the melting apparatus is also selected . The higher the indicator, the stronger it should be. You can find out the temperature of the element you need from the table.
Another important quantity is the boiling point. This is the value at which the process of boiling liquids begins; it corresponds to the temperature of saturated steam that forms above the flat surface of the boiling liquid. It is usually almost twice the melting point.
Both values are usually given at normal pressure. directly proportional to each other .
- As the pressure increases, the amount of melting increases.
- As the pressure decreases, the amount of melting decreases.
Table of refractory metals and alloys (over 1600C o)
Source: https://stanok.guru/stanki/metallorezhuschiy-stanok/temperatura-plavleniya-raznyh-metallov-v-tablice.html
Which metal is considered the most refractory?
Metal has been used by humans in various fields of activity since ancient times. To obtain a high-quality metal product, it is important to choose a good material, while assessing its characteristics. An important parameter is refractoriness. For the manufacture of some products, only the most refractory metals are suitable.
Historical information
Before studying the characteristics of the most refractory metals in the world, you should familiarize yourself with their discovery history. Metalworking has been known to man for several thousand years. However, active production of refractory metals began only in the second half of the 19th century.
Initially they were used only in electrical engineering. With the advent of new technologies in the construction of airplanes, cars, trains and rockets, parts with a high melting rate began to be used more actively. The peak popularity of blanks that can withstand temperatures of more than 1000 degrees occurred in the mid-20th century.
Definition
Refractory metal is a separate class that includes metal blanks that can withstand exposure to critically high temperatures. Typically, members of this class have a melting point of more than 1600 degrees, which is considered the melting point of iron. These include noble alloys. They are also called representatives of the platinum group.
Kinds
Types of metals and alloys that are resistant to elevated temperatures:
- Tungsten. They first learned about it in 1781. To melt it, it needed to be heated to 3380 degrees. Tungsten is considered the most refractory. It is made from powder, which is processed chemically. First, the mixture is heated and then subjected to pressure. The output is compressed blanks.
- Niobium. Melts at 2500 degrees. It has high thermal conductivity and is not as difficult to process as tungsten. It is made from powder that is baked and processed using high pressure. Niobium is used to make wire, pipes and tape.
- Molybdenum. Visually, it can be confused with tungsten. It is made from powder by baking and applying pressure. Like tungsten, it has paramagnetic properties. Used in radio electronics, manufacturing of industrial equipment, furnaces and electrodes.
- Tantalum. Melts at 3000 degrees. To make tantalum wire or harden the material, it does not need to be heated to critical temperatures. Used for the manufacture of elements in radio electronics (capacitors, film resistors). Popular in the nuclear industry.
- Rhenium. Material that scientists discovered later than others. You can find it in copper and platinum ore. Used in industrial production as an alloying additive.
Chromium is also a material with high melting points. Due to its unique characteristics, it is used in various industries. It has increased resistance to critical temperatures and corrosive processes. However, it is worth considering its fragility.
Properties
To understand where it is best to use a material, you need to know the properties of refractory metals. They are used to make parts for industrial equipment, machinery and electronics. The characteristics of heavy refractory metals will be described below.
Physical properties
Characteristics:
- Density - up to 10000 kg/m3. For tungsten this figure reaches 19,000 kg/m3.
- The average melting point is 2500 degrees Celsius. Tungsten has the highest metal melting point - 3390 degrees.
- Specific heat capacity - 400 J.
Refractory objects cannot withstand impacts and falls.
Chemical properties
Chemical properties:
- These are solid substances with high chemical activity.
- Strong interatomic structure.
- Resistance to long-term exposure to acids and alkalis.
- High paramagnetic index.
These materials have some disadvantages. The main one is the difficult process of processing and manufacturing products from it.
Application
Initially, refractory metals were used in the manufacture of capacitors and transistors for radio electronics. The number of their areas of application increased only by the middle of the 20th century. The industrial complex expanded to produce parts for machine tools, cars, airplanes and missiles.
Alloys that can withstand exposure to critical temperatures began to be used to make tableware. Refractory metals are used in the production of building and connecting materials. They are used to make parts for household appliances and electronics.
Tungsten is considered the most refractory. Its melting point of 3390 degrees exceeds other materials. However, we must not forget that if a tungsten part falls from a height, it will crack or break into separate parts.
Tungsten is the most refractory metal on earth!
Other materials with a high melting index are little different from tungsten. They are used in mechanical engineering, shipbuilding, nuclear energy, and the manufacture of industrial equipment.
Their development and research continues to this day.
Which metal is considered the most refractory? Link to main publication
Source: https://metalloy.ru/obrabotka/termo/samyj-tugoplavkij-metall
Melting point of metals. The most refractory and fusible metal:
Almost all metals are solids under normal conditions. But at certain temperatures they can change their state of aggregation and become liquid. Let's find out what is the highest melting point of metal? Which is the lowest?
Melting point of metals
Most of the elements in the periodic table are metals. There are currently approximately 96 of them. They all require different conditions to turn into liquid.
The heating threshold of solid crystalline substances, above which they become liquid, is called the melting point. For metals it varies within several thousand degrees. Many of them turn into liquid with relatively high heat. This makes them a common material for making pots, pans and other kitchen utensils.
Silver (962 °C), aluminum (660.32 °C), gold (1064.18 °C), nickel (1455 °C), platinum (1772 °C), etc. have average melting points. There is also a group of refractory and low-melting metals. The first need more than 2000 degrees Celsius to turn into liquid, the second need less than 500 degrees.
Low-melting metals usually include tin (232 °C), zinc (419 °C), and lead (327 °C). However, some of them may have even lower temperatures. For example, francium and gallium melt in the hand, but cesium can only be heated in an ampoule, because it ignites with oxygen.
The lowest and highest melting temperatures of metals are presented in the table:
| Refractory | Low-melting | ||
| Tungsten | 3422 °C | Mercury | -38.87 °C |
| Rhenium | 3186 °C | Gallium | 26.79 °C |
| Tantalum | 3017 °C | France | 27 °C |
| Osmium | 3033 °C | Cesium | 28.5 °C |
| Molybdenum | 2623 °C | Rubidium | 39.31 °C |
| Niobium | 2477°C | Potassium | 63.5 °C |
| Iridium | 2466 °C | Sodium | 97.8 °C |
Tungsten
Tungsten metal has the highest melting point. Only the nonmetal carbon ranks higher in this indicator. Tungsten is a light gray shiny substance, very dense and heavy. It boils at 5555 °C, which is almost equal to the temperature of the Sun's photosphere.
At room conditions, it reacts weakly with oxygen and does not corrode. Despite its refractoriness, it is quite ductile and can be forged even when heated to 1600 °C. These properties of tungsten are used for incandescent filaments in lamps and picture tubes and electrodes for welding. Most of the mined metal is alloyed with steel to increase its strength and hardness.
Tungsten is widely used in the military sphere and technology. It is indispensable for the manufacture of ammunition, armor, engines and the most important parts of military vehicles and aircraft. It is also used to make surgical instruments and boxes for storing radioactive substances.
Mercury
Mercury is the only metal whose melting point is minus. In addition, it is one of two chemical elements whose simple substances, under normal conditions, exist in the form of liquids. Interestingly, the metal boils when heated to 356.73 °C, and this is much higher than its melting point.
It has a silvery-white color and a pronounced shine. It evaporates already at room conditions, condensing into small balls. The metal is very toxic. It can accumulate in human internal organs, causing diseases of the brain, spleen, kidneys and liver.
Mercury is one of the seven first metals that man learned about. In the Middle Ages it was considered the main alchemical element. Despite its toxicity, it was once used in medicine as part of dental fillings, and also as a cure for syphilis. Now mercury has been almost completely eliminated from medical preparations, but it is widely used in measuring instruments (barometers, pressure gauges), for the manufacture of lamps, switches, and doorbells.
Alloys
To change the properties of a particular metal, it is alloyed with other substances. Thus, it can not only acquire greater density and strength, but also reduce or increase the melting point.
An alloy can consist of two or more chemical elements, but at least one of them must be a metal. Such “mixtures” are very often used in industry, because they make it possible to obtain exactly the qualities of materials that are needed.
The melting point of metals and alloys depends on the purity of the former, as well as on the proportions and composition of the latter. To obtain low-melting alloys, lead, mercury, thallium, tin, cadmium, and indium are most often used.
Those containing mercury are called amalgams. A compound of sodium, potassium and cesium in a ratio of 12%/47%/41% becomes a liquid already at minus 78 ° C, an amalgam of mercury and thallium - at minus 61 ° C.
The most refractory material is an alloy of tantalum and hafnium carbides in 1:1 proportions with a melting point of 4115 °C.
Source: https://www.syl.ru/article/374078/temperatura-plavleniya-metallov-samyiy-tugoplavkiy-i-legkoplavkiy-metall
The most fusible metals: properties, features, physical characteristics
Melting point is an important characteristic that is most often applied specifically to metals. It depends on many physical properties of substances - their purity and crystal structure. Which metal is the most fusible: Li, Al, Hg, Cu? Let's find out which of them can really be called such.
The most fusible metals
Melting is the process of transition from a solid to a liquid state. It occurs under the influence of heat, but also depends on a number of physical factors, such as pressure. An important role in how easily and hard a substance can be melted is also played by its composition, the size of the crystals in the lattice, and the strength of the bonds between the atoms.
The melting point of metals varies greatly and can even have sub-zero values. It ranges from -39 to +3410 degrees Celsius. Molybdenum, tungsten, chromium, and titanium are the hardest to transform into liquid. For this process they need to be heated to a temperature of at least 2000 degrees.
The most fusible metals are gallium, mercury, lithium, tin, lead, zinc, indium, bismuth, and thallium. Read more about some of them below.
Gallium
The second most fusible metal is gallium. It becomes liquid at temperatures above 29.5 degrees Celsius, and can be softened simply by holding it in your hands for a while. Under normal conditions, gallium is very brittle, easily amenable to mechanical action, and has a light silver, somewhat bluish tint.
The metal is very dispersed in the earth's crust and is not found in the form of nuggets. In nature, it is found in various minerals, such as garnet, muscovite, tourmaline, chlorite, and feldspar. In addition, it is found in sea water. Gallium is used in high-frequency electronics, for the manufacture of mirrors and various alloys.
Indium
As a simple substance, indium is very light, malleable and soft, so much so that it even leaves a mark if it is passed over paper. It is also one of the most fusible metals, but is only affected by temperatures above 157°C. It boils at 2072 degrees.
Like gallium, indium does not form its own deposits, but is found in various ores. Due to its dispersion in nature, the metal is quite expensive. It is used in microelectronics, for the manufacture of low-melting alloys, solders, and liquid crystal screens for equipment.
Tin
Tin melts at temperatures above 231 degrees Celsius. It is a ductile and soft metal, light silver in color. It exists in four allotropic modifications, two of which appear only at high pressure.
Tin is fairly dispersed in nature, but can form its own minerals, such as stannine and cassiterite. It is used as a coating for metals to enhance their resistance to corrosion, as well as for the production of tin, foil, various alloys, tableware and parts for musical instruments.
Lithium
Lithium is the most fusible metal, becoming a liquid at a temperature of 180 degrees. It is soft, easily forged and machined. It belongs to the alkali metals, but is much less active than other members of the group. It reacts slowly with moist air, and remains practically stable in a dry atmosphere
The metal is found in spodumene, lepidolite, in deposits with tin, bismuth and tungsten, found in sea water and in stellar space objects. Lithium is often used for the manufacture of galvanic cells, batteries, as an oxidizer, and also in pyrotechnics. In alloys with cadmium, copper and aluminum it is used in space, military and aviation technology.
Source: https://FB.ru/article/425120/naibolee-legkoplavkie-metallyi-svoystva-osobennosti-fizicheskie-harakteristiki
At what temperature can iron be melted?
Can gold melt at room temperature?
In an unusual experiment, researchers managed to melt gold at room temperature. They applied a strong electric field to change the surface state of the metal and observed the process using transmission electron microscopy.
As a precious metal, gold has been used for several thousand years throughout the world for jewelry, coinage, and even art. As of 2015, over 186,000 tons of gold exist above ground, of which about 50% is used in jewelry, 20% in private investments, 20% in formal sectors, and 10% in industries.
Gold is known for its high ductility, ductility, corrosion resistance and electrical conductivity. Due to these special properties, it is widely used in almost all types of computing devices. It is also used in dental restoration, colored glass production and infrared protection.
The melting point of gold is 1064°C, and the boiling point is higher: 2970°C. However, researchers from Chalmers University of Technology, Sweden, conducted an unusual experiment in which they were able to melt gold at room temperature (25°C).
Experiment
In addition to high temperatures, an electric field of sufficient strength can change the state of the metal surface. Field ionization and evaporation techniques have been extensively studied using transmission electron microscopy (TEM), a technique that allows simultaneous excitation and observation (at the atomic level).
In this work, the researchers used TEM to demonstrate how strong electric fields induce reversible switching between crystalline and disordered phases of gold surfaces at room temperature.
They placed a small piece of gold under a TEM and applied the electric field step by step to intensely high levels. They wanted to observe how high levels of magnification affected gold atoms.
They then analyzed the microscope recordings and discovered something interesting. The surface layer of the element literally melted at room temperature. This provides both new fundamental information about gold and opens up exciting opportunities in the field of materials science.
How did it happen?
When exposed to a strong electric field, the gold atoms became excited, losing their perfect crystalline ordered structure and breaking their bonds (bonds) with each other. Molecular dynamics simulations show that this structural change occurs primarily due to the vanishing energy cost of creating surface defects in high electric fields.
The researchers further studied the process and found that it was possible to turn the molten structure back into solid gold. They demonstrated (on an atomic scale) how changes in the surface layer can be controlled by applying an external electric field that separates the topmost layer from the main volume.
Applicability
The ability to smelt gold in this way provides many possible applications. For example, it can be used in various types of transistors, catalysts and sensors. It could also aid research into low-dimensional phases of matter and fundamental aspects of surface physics.
Source: https://new-science.ru/mozhet-li-zoloto-plavitsya-pri-komnatnoj-temperature/
At what temperatures do various metals and non-metals melt?
Metals have a number of original properties that are unique to these materials. There is a melting point for metals at which the crystal lattice is destroyed. The substance retains its volume, but it is no longer possible to talk about the constancy of its shape.
Individual metals are found extremely rarely in their pure form. In practice, alloys are used. They have certain differences from pure substances. When complex compounds are formed, the crystal lattices combine with each other. Therefore, the properties of alloys may differ markedly from those of their constituent elements. The melting point no longer remains constant; it depends on the concentration of the ingredients included in the alloy.
Concept of temperature scale
Some non-metallic objects also have similar properties. The most common is water. A temperature scale was developed regarding the properties of the liquid that occupies a dominant position on Earth. The reference points are the temperature of changes in the aggregative states of water:
- Transformations from liquid to solid and vice versa are taken to be zero degrees.
- Boiling (vapor formation inside a liquid) at normal atmospheric pressure (760 mm Hg) is taken to be 100 ⁰C.
Attention! In addition to the Celsius scale, in practice temperature is measured in degrees Fahrenheit and on the absolute Kelvin scale. But when studying the properties of metal objects, other scales are used quite rarely.
In its ideal form, it is generally accepted that metals have a cubic lattice (real substances may have flaws). There are equal distances between molecules horizontally and vertically.
A solid substance is characterized by constancy:
- shapes, the object retains linear dimensions in different conditions;
- volume, the object does not change the amount of substance it occupies;
- mass, the amount of a substance expressed in grams (kilograms, tons);
- density, unit volume contains constant mass.
When transitioning into a liquid state, having reached a certain temperature, the crystal lattices are destroyed. Now we can’t talk about constancy of form. The liquid will take the form in which it is poured.
When evaporation occurs, only the mass of the substance remains constant. Gas will take up the entire volume that will be provided to it. Here we cannot say that density is a constant value.
When liquids combine, the following options are possible:
- Liquids completely dissolve in one another, as do water and alcohol. The concentration of substances will be the same throughout the entire volume.
- Liquids are stratified by density, the connection occurs only at the interface. It is only temporarily possible to obtain a mechanical mixture. Mix liquids with different properties. An example is oil and water.
Metals form alloys in the liquid state. To obtain an alloy, each of the components must be in a liquid state. With alloys, phenomena of complete dissolution of one in another are possible. Options cannot be excluded when the alloy will be obtained only as a result of intensive mixing. In this case, the quality of the alloy is not guaranteed, so they try not to mix components that do not allow obtaining stable alloys.
The resulting substances, soluble in each other, when solidified, form crystal lattices of a new type. Define:
- Heliocentered crystal lattices are also called body-centered. In the middle there is a molecule of one substance, and four more molecules of another are located around it. It is customary to call such lattices loose, since the bonds between metal molecules in them are weaker.
- Face-centered crystal lattices form compounds in which the component molecules are located on the faces. Metallurgists call such crystalline alloys dense. In reality, the density of the alloy can be higher than that of each of the components included in the composition (alchemists of the Middle Ages were looking for options for alloys in which the density would correspond to the density of gold).
Wood's alloy
In 1860, American dental technician Barnabas Wood was looking for optimal ratios of components to produce teeth for clients at minimum melting temperatures. He found an alloy that has a melting point of only 60.268.5 ⁰C. Even in hot water, metal melts easily. It includes:
- tin - 12.512.7%;
- lead - 24.525.0%;
- bismuth - 49.550.3%;
- cadmium - 12.512.7%.
The alloy is interesting for its low temperature, but has never found practical application. Attention! Cadmium and lead are heavy metals and contact with them is not recommended. Many people can experience poisoning from contact with cadmium.
In practice, many people experience melting when soldering parts. If the surfaces of the materials to be joined are cleaned of contaminants and oxides, then they can be easily soldered with solders. It is customary to divide solders into hard and soft. Soft ones are most widespread:
- POS-15 - 278282 °C;
- POS-25 - 258262 °C;
- POS-33 - 245249 °C;
- POS-40 - 236241 °C;
- POS-61 - 181185 °C;
- POS-90 - 217222 °C.
They are produced for enterprises manufacturing various radio equipment.
Brazing alloys based on zinc, copper, silver and bismuth have a higher melting point:
- PSr-10 - 825835 °C;
- PSr-12 - 780790 °C;
- PSr-25 - 760770 °C;
- PSr-45 - 715721 °C;
- PSr-65 - 738743 °C;
- PSr-70 - 778783 °C;
- PMC-36 - 823828 °C;
- PMC-42 - 830837 °C;
- PMC-51 - 867884 °C.
The use of hard solders allows you to obtain strong connections.
Attention! Wed means that silver is used in the solder. Such alloys have minimal electrical resistance.
Melting point of non-metals
Non-metallic materials can be presented in solid and liquid form. Inorganic substances are presented in table. 4.
Table 4, melting point of inorganic non-metals:
In practice, organic materials are of greatest interest to users: polyethylene, polypropylene, wax, paraffin and others. The melting points of some substances are shown in table. 5.
Table 5, melting temperature of polymer materials:
Attention! The glass transition temperature refers to the state at which a material becomes brittle.
melting point of known metals.
Conclusion
- The melting point depends on the nature of the substance itself. Most often this is a constant value.
- In practice, it is not pure metals that are used, but their alloys. They usually have much better properties than pure metal.
Source: https://metmastanki.ru/temperatura-plavleniya-metallov-i-nemetallov-tablitsy
6 Surprising Substances That Defy the Laws of Physics
We can laugh at our ancestors, who considered gunpowder to be magic and did not understand what magnets are, however, even in our enlightened age, there are materials created by science, but similar to the result of real witchcraft. These materials are often difficult to obtain, but are worth it.
1. Metal that melts in your hands
The existence of liquid metals such as mercury and the ability of metals to become liquid at a certain temperature are well known. But solid metal melting in your hands like ice cream is an unusual phenomenon. This metal is called gallium.
It melts at room temperature and is unsuitable for practical use. If you place a gallium object in a glass of hot liquid, it will dissolve right before your eyes.
In addition, gallium can make aluminum very brittle - simply placing a drop of gallium on an aluminum surface is enough.
2. Gas capable of holding solid objects
This gas is heavier than air, and if you fill a closed container with it, it will settle to the bottom. Just like water, sulfur hexafluoride can withstand less dense objects, such as a tin foil boat. The colorless gas will hold the object on its surface, and it will appear that the boat is floating. Sulfur hexafluoride can be scooped out of the container with an ordinary glass - then the boat will smoothly sink to the bottom.
In addition, due to its gravity, the gas reduces the frequency of any sound passing through it, and if you inhale a little sulfur hexafluoride, your voice will sound like the ominous baritone of Dr. Evil.
3. Hydrophobic coatings
The green tile in the photo is not jelly at all, but tinted water. It is located on a flat plate, along the edges treated with a hydrophobic coating. The coating repels water and the droplets take on a convex shape. There is a perfect raw square in the middle of the white surface and the water collects there.
A drop placed on the treated area will immediately flow to the untreated area and merge with the rest of the water. If you dip a finger treated with a hydrophobic coating into a glass of water, it will remain completely dry, and a “bubble” will form around it - the water will desperately try to escape from you.
Based on such substances, it is planned to create water-repellent clothing and glass for cars.
4. Spontaneously exploding powder
Triiodine nitride looks like a ball of dirt, but appearances can be deceiving: the material is so unstable that the slightest touch of a pen is enough to cause an explosion. The material is used exclusively for experiments - it is dangerous to even move it from place to place. When the material explodes, it produces a beautiful purple smoke. A similar substance is silver fulminate - it is also not used anywhere and is only suitable for making bombs.
5. Hot ice
Hot ice, also known as sodium acetate, is a liquid that hardens upon slightest contact. With a simple touch, it instantly transforms from a liquid state into an ice-hard crystal.
Patterns are formed on the entire surface, like on windows in frosty weather; the process continues for several seconds until the entire substance “freezes.” When pressed, a crystallization center is formed, from which information about the new state is transmitted to the molecules along the chain.
Of course, the end result is not ice at all - as the name suggests, the substance is quite warm to the touch, cools very slowly and is used to make chemical heating pads.
6. Metal with memory
Nitinol, an alloy of nickel and titanium, has the impressive ability to “remember” its original shape and return to it after deformation. All it takes is a little heat. For example, you can drop warm water on the alloy, and it will return to its original shape, no matter how much it was previously distorted.
Methods for its practical application are currently being developed. For example, it would be wise to make glasses from such material - if they accidentally bend, you just need to put them under a stream of warm water.
Of course, it is unknown whether cars or anything else serious will ever be made from nitinol, but the properties of the alloy are impressive.
Source: https://www.publy.ru/post/2471
Metal that melts at room temperature
It all depends on what is considered room temperature; the temperature in the room can be +18 degrees, or maybe +40 degrees.
The metal alloy sodium -12%, potassium -47%, cesium -41%, called by scientists - “Soviet alloy” melts at a temperature of -79 degrees. Used in rocket engines.
An alloy of metals that has recently been widely used to replace highly toxic mercury - galinstan , consisting of 68% gallium, 22% idium and 10% tin, will melt at a temperature of -19 degrees.
If we consider room temperature to be +18 degrees, then at this temperature, out of pure metals, only one metal will be liquid - mercury . the melting point of which is -39 degrees.
One of the rarest elements on earth is francium . Its melting point is +21 degrees. It is not chemically stable. A highly radioactive metal. It is obtained artificially, using nuclear reactions of uranium minerals. Let's dissolve in water. It has no practical application yet.
The next metal in terms of fusibility is Cesium - its melting point is +28.4 degrees. Radioactive, not used anywhere in its pure form yet.
When combined with zirconium and tin in a vacuum, it is a source of light. In the form of cesium fluoride or chloride, molybdenum is used for welding. As cesium bromide, it is used to make infrared devices.
Cesium isotopes are used in the production of radioisotope power sources.
If we consider the room temperature to be +29.8 gallium also becomes a liquid metal .
Rubidium metal melts at a temperature of +39 degrees. This is a radioactive metal. Flammable in open air and in water. Capable of destroying hard metals. Used in the production of rockets.
Sodium melts at a temperature of +98 degrees. But in the open air, it spontaneously ignites and begins to burn at a temperature of -298 degrees. For this reason, it is always stored in kerosene or oil.
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Mercury
Galium
Some of the alkaline ones melt in your hand.
They can be in a liquid state at room temperature - there are such. But to melt. Discover the secret
I don't know, but it's interesting
Amalgams. (Mercury alloys).
mercury - melting point +18
Gallium is an extremely unusual silver-colored metal: it is as fragile as glass, melts at room temperature, and at the same time is extremely aggressive towards other metals. what's wrong with you this morning? asked questions.
. otherwise. We live in vain.
you yourself is the word.
young man, are you from Ukraine?
tin definitely doesn’t melt, except in a cup of tea. Don't know!
I don't have that one
There is one more? I can't remember.
You are hospitable, however.
mercury liquid metal
it can be frozen.
Gallium. Mercury and cesium are found in liquid form.
—Statistics
Wednesday, March 02, 2011 18:33 + to quote book
Definition
Gallium (lat. Gallium), Ga, chemical element of group III of the periodic system of D. I. Mendeleev Dmitry Ivanovich, serial number 31, atomic mass 69.72; silvery-white soft metal.
Physical properties
Crystalline gallium has several polymorphic modifications, but only one (I) is thermodynamically stable, having an orthorhombic (pseudo-tetragonal) lattice with parameters a = 4.5186 Å, b = 7.6570 Å, c = 4.5256 Å.
Other modifications of gallium (β, γ, δ, ε) crystallize from supercooled dispersed metal and are unstable.
At elevated pressure, two more polymorphic structures of gallium II and III were observed, having, respectively, cubic and tetragonal lattices.
The density of gallium in the solid state at a temperature of T=20°C is 5.904 g/cm3, liquid gallium at T=29.8°C has a density of 6.095 g/cm3, that is, upon solidification, the volume of gallium increases. The melting point of gallium is slightly higher than room temperature and is equal to Tmelt = 29.8 °C; gallium boils at Tbp. = 2230 °C.
One of the features of gallium is the wide temperature range of existence of the liquid state (from 30 to 2230°C), while it has a low vapor pressure at temperatures up to 1100÷1200°C. The specific heat capacity of solid gallium in the temperature range T÷24°C is 376.7 J/kg K (0.09 cal/g deg.
), in the liquid state at T=29÷100°C - 410 J/kg·K (0.098 cal/g·deg).
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Occurrence in nature Gallium is a typical trace element, sometimes it is also classified as rare. Clarke (numerical estimate of the average content in the earth's crust) of gallium in the earth's crust is quite large and amounts to 1.5·10-3% (mass.). Thus, its content is higher than molybdenum, bismuth, tungsten, mercury and some other elements that are not usually classified as rare.
The main source of gallium is bauxite (hydrated aluminum oxide). It is interesting that bauxite ores, regardless of their location and characteristics of origin, are characterized by a constantly uniform distribution of gallium in them - 0.002-0.006%. Nephelines from apatite-nepheline ores of the Khibiny Mountains contain gallium in significant quantities (0.01-0.04.
The world's main gallium reserves are associated with bauxite deposits, the reserves of which are so large that they will not be depleted for many decades.
However, most of the gallium contained in bauxite remains unavailable due to a lack of production capacity, the volume of which is dictated by economic reasons. Actual reserves of gallium are difficult to estimate. According to US experts
Geological Surveys global gallium resources associated with bauxite deposits amount to 1 million tons. China, the USA, Russia, Ukraine, and Kazakhstan have significant reserves of gallium.
Production
Gallium is a trace element that is a constant companion of aluminum and zinc, so its production is always tied to the processing of aluminum or sulfide polymetallic (especially zinc) ores.
Typically, the extraction of gallium from zinc concentrates is associated with many difficulties, causing the high price of the metal, therefore, for several decades, the main source (95) of obtaining gallium has been waste from the aluminum industry, and the share of the so-called
complex waste processing (along with the extraction of zinc, indium, and germanium) accounts for about 5% of production capacity. In addition, there are technologies for extracting gallium from flue dust and ash from coal combustion, as well as their coking waste.
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Application Gallium does not yet have widespread industrial use.
The potential scale of by-products of gallium in aluminum production still significantly exceeds the demand for the metal.
The most promising application of gallium is in the form of chemical compounds such as GaAs, GaP, GaSb, which have semiconductor properties. They can be used in high-temperature rectifiers and transistors, solar batteries and other devices where the photoelectric effect in the blocking layer can be used, as well as in infrared radiation receivers.
Gallium can be used to make optical mirrors that are highly reflective.
Gallium is expensive; in 2005, on the world market, a ton of gallium cost 1.2 million US dollars, and due to the high cost and at the same time great need for this metal, it is very important to establish its complete extraction in aluminum production and processing of hard coals. liquid fuel.
Gallium has a number of alloys that are liquid at room temperature, and one of its alloys has a melting point of 3 °C, but on the other hand, gallium (alloys to a lesser extent) is quite aggressive to most structural materials (cracking and erosion of alloys at high temperature), and As a coolant, it is ineffective and often simply unacceptable.
Gallium is an excellent lubricant. Almost very important metal adhesives have been created on the basis of gallium and nickel, gallium and scandium.
Gallium oxide is part of a number of strategically important laser materials of the garnet group - GSGG, YAG, ISGG, etc.
Gallium thermometers allow, in principle, to measure temperatures from 30 to 2230 ° C. Gallium thermometers are now produced for temperatures up to 1200 ° C.
Element No. 31 is used for the production of low-melting alloys used in signaling devices. The alloy of gallium with indium melts already at 16 ° C. This is the most fusible of all known alloys.
Source: https://morflot.su/metall-kotoryj-plavitsja-pri-komnatnoj-temperature/
The most unusual metals
Details Category: Interesting
Over the centuries, in a person’s life there have constantly been things that surprised him and went beyond the usual understanding of the world around him.
Once upon a time, our ancestors imagined such things as gunpowder, magnets, electricity, and self-propelled mechanisms to be real magic. However, even in our enlightened age, there are many things that were recently discovered or created by science that are similar to the result of real witchcraft.
Many metals and alloys actively used today have such unusual qualities.
Gallium is a metal that melts in your hands
The existence of liquid metals and the ability of metals to take on a liquid state at high temperatures are well-known facts. But a rather unusual phenomenon is a solid metal that melts in your hands like ice cream. This is gallium.
It melts already at room temperature and is unsuitable for ordinary practical use. It will completely dissolve right before your eyes if you place any gallium product in a glass of hot water. This metal can also make aluminum very brittle.
To do this, simply place a small drop of gallium on an aluminum surface.
Nitinol is a metal with memory
Nitinol is an alloy of nickel and titanium. It has the unusual ability to “remember” its original shape and restore it after deformation. All it takes is a little heat.
A few drops of warm water will be enough for this alloy to return to its original state even after very strong distortion of the original shape.
Currently, methods are being developed for the practical use of this material in technology, and it has already been used quite successfully in medicine, in particular, for the treatment of patients with diseases and injuries of the musculoskeletal system.
Mercury is a liquid metal
Mercury is one of the most interesting and unusual metals. After its discovery, mercury received the name “argentum vivum,” which translated means “living silver.” This name is associated with its characteristics: it is a liquid that spreads faster than water, but it is also quite heavy. For example, a bucket filled with mercury will weigh approximately 130 kg!
This metal is quite rare and is most often found in rocks that were formed during an eruption. Mercury can be extracted from ore by heating it.
This metal has been known for thousands of years. It was originally obtained from cinnabar. It was precisely because of the ease of transition of mercury into cinnabar and back that it was given the role of the main element in the creation of the “philosopher’s stone”, which occupied the minds of various alchemists for many generations. It was believed that if mercury could be purified and made solid, then gold would be made from this material.
In addition to alchemists, mercury was of considerable interest to various magicians, who actively used it in their magical rituals. In those days, cinnabar - red mercury - was very valuable.
It was used as a means to expel spirits or to destroy astral structures by spraying in the air. It was believed that otherworldly entities, afraid of being damaged, left such “mercury” areas that were dangerous for them.
It was also noticed that devices begin to malfunction in places treated in this way, and people gain heightened emotional perception.
Likewise, doctors in the old days considered mercury the best medicine against a number of diseases. By the time it became known that it was poisonous, mercury was already being widely used for the manufacture of medicinal potions and as cosmetics.
The famous traveler Marco Polo, describing the life of yogis, mentioned an unusual drink that was prepared from mercury and sulfur. According to these yogis, they have been drinking this drink since childhood and thereby significantly prolonging their lives.
It was claimed that some of them were up to 200 years old! Another traveler, Francois Bernier, who studied the lifestyle of Indian ascetics and yogis, wrote about their knowledge of the secret of preparing a special potion from mercury, two drops of which, taken in the morning, allowed a person to feel in excellent physical shape all day long.
Interesting moments related to mercury can also be found in Indian epics. There we are talking about vimanas - special flying machines that were used by gods, princes or demons. According to the translation, the fuel for these devices was a mixture of honey, rice infusion, “soma” (a drink resembling beer) and mercury.
Modern technologies do not allow the use of mercury as fuel for engines, but the possibility cannot be ruled out that in ancient texts they were talking about something similar to nuclear fuel, where mercury played the role that water plays in modern nuclear engines, and vimanas were devices for flying in space.
California-252 is the most expensive metal
Californium was produced artificially in 1950 at the University of California at Berkeley. It is extracted from the products of long-term irradiation of plutonium with neutrons in a nuclear reactor. Due to the extremely complex method of production, California-252 is currently the most expensive metal. Its price reaches $10,000,000 per gram.
However, the reserve of californium is only a few grams on our entire planet, since it is produced in only two reactors - in the USA and Russia, 20-40 micrograms per year. But it has very impressive properties. More than millions of neutrons per second are produced by micrograms of California. And for example, one gram of it during the decay period releases as much energy as 200 kilograms of radium.
Currently, this metal is used in medicine as a point source of neutrons in the local treatment of malignant tumors, as well as a powerful source of neutrons in neutron activation analysis and in experiments studying spontaneous nuclear fission.
Source: http://rosta.spb.ru/notes/86-neobychnye-metally.html
What metal can be melted at home?
For a long time, men began to think about how to create their own furnace for melting metal at home. It must be portable and meet all conditions. The production facility has furnaces for melting large quantities of metal. At home, you can assemble a furnace for melting up to five kilograms of aluminum. Let's look at how to make a smelter at home.
Melting metal at home
Equipment and materials you will need
In order to melt metal, you need to buy the following components for manufacturing:
- fire brick;
- nails;
- transformer;
- copper wire;
- graphite;
- mica;
- asbestos and cement tiles;
- gas-burner;
- crucible.
The dimensions will vary depending on the wishes of the person collecting it. It is better to create a small furnace for melting metals if you want to use it only for your needs. You will spend less time making it, and a small amount of kilowatts will be spent heating it. If you do it using diesel fuel or coal, then do not forget about installing thermal insulation and air supply.
Homemade crucibles
Metals such as iron, nickel, tin, and copper are melted in an electric furnace. The output voltage in an electric furnace should be greater, which means the distance between the electrodes will increase. Brushes from an electric motor are suitable instead of electrodes.
Step-by-step instruction
How to make a melting furnace at home - read the following instructions:
- A high-frequency alternating current generator is installed.
- Spiral winding. Made from copper wire.
- Crucible.
All these elements are placed in one housing. The melting cup is placed in the inductor. The winding is connected to the power source. When the current is turned on, an electromagnetic field appears. The resulting eddy currents pass through the metal in the cup and heat it. Melting occurs.
Homemade muffle furnace
The positive properties of an induction furnace are that when melting metals, a homogeneous melt is obtained, alloying components do not evaporate, and melting occurs quite quickly. In addition, the installation of such a stove does not harm the ecosystem and is safe for the user.
Cooling can be done using a fan. Only the latter should be located as far as possible from the furnace, otherwise its winding will serve as an additional closure of the vortex flows. This will reduce the melting quality.
Wheel furnace
Features of melting some metals
In order to melt metal at home, this element must be placed in a small cup or crucible. The cup with the material is inserted into the oven. Then its melting begins. To melt the precious elements, they are placed in a glass ampoule. In order to make an alloy from several components, follow these instructions:
- First, a refractory element - copper or iron - is placed in the melting cup.
- Then a more fusible component is placed - tin, aluminum.
Melting aluminum in a homemade furnace
Steel is a refractory material. Its melting point is one thousand four hundred degrees Celsius. Therefore, to melt steel at home, you must follow the following instructions:
- To melt steel at home, introduce additional regenerators. If the furnace runs on electricity, then electricity is used.
- During induction heating, slags are added. They increase the speed of melting.
- Constantly monitor instrument readings. If necessary, lower the melting temperature by switching to a more moderate mode.
- It is always correct to determine whether the steel is ready for work or melting. Follow all the above steps. Only then will the resulting metal be of high quality.
Metal smelting
To melt iron at home, the furnace must be preheated. First, a large piece is placed, and then small ones. Iron must be turned over in time. A properly molten metal will have a spherical shape.
If you are going to make bronze, you must first place copper in the melting hole. Since this component is more refractory. When the copper is melted, tin is added.
Under no circumstances should elements such as cadmium, lead or zinc be melted. When burned, they produce toxic yellowish smoke.
And when melting aluminum, tin or iron, you must be careful. Rivet slowly and should be done with a small hammer. Heat the material frequently until reddened and cool in cold water. Only then will you get the perfect alloy at the end.
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Source: http://ooo-asteko.ru/kakoy-metall-mozhno-rasplavit-v-domashnih-usloviyah/
