We all know that argon is used to weld various metals, but not everyone thought about what this chemical element is. Meanwhile, its history is rich in events. Tellingly, argon is an exceptional copy of the periodic table of Mendeleev, which has no analogues. The scientist himself was surprised at the time how he could even get here.
Approximately 0.9% of this gas is present in the atmosphere. Like nitrogen, it is neutral in nature, colorless and odorless. It is not suitable for sustaining life, but it is simply irreplaceable in some areas of human activity.
A little digression into history
For the first time it was discovered by an Englishman and physicist by education G. Cavendish, who noticed the presence in the air of something new, resistant to chemical attack. Unfortunately, Cavendish never learned the nature of the new gas. A little over a hundred years later, another scientist, John William Strath, noticed this. He came to the conclusion that the nitrogen from the air contained some gas of unknown origin, but he could not figure out whether it was argon or something else.
At the same time, the gas did not react with various metals, chlorine, acids, alkalis. That is, from a chemical point of view, it was inert in nature. Another surprise was the discovery that a molecule of a new gas includes only one atom. And at that time, a similar composition of gases was still unknown.
The public announcement of the new gas shocked many scientists from all over the world - how could you overlook the new gas in the air for many scientific studies and experiments?! But not all scientists, including Mendeleev, believed in the discovery. Judging by the atomic mass of the new gas (39, 9), it should be located between potassium (39, 1) and calcium (40, 1), but the position has already been taken.
As mentioned, argon is a gas with a rich and detective history. For some time it was forgotten, but after the discovery of helium, the new gas was officially recognized. It was decided to assign a separate zero position for it, located in between halogens and alkali metals.
Properties
Among other inert gases that are included in the heavy group, argon is considered the lightest. Its mass exceeds the weight of air by 1.38 times. The gas passes into a liquid state at a temperature of -185.9 °С, and at -189.4 °С and normal pressure it solidifies.
Argon differs from helium and neon in that it can dissolve in water - at a temperature of 20 degrees in the amount of 3.3 ml per hundred grams of liquid. But in a number of organic solutions, the gas dissolves better. The impact of an electric current causes it to glow, due to which it has become widelyapply to lighting equipment.
Biologists have discovered another useful property that argon has. This is a kind of environment where the plant feels great, as proven by experiments. So, being in a gas atmosphere, the planted seeds of rice, corn, cucumbers and rye gave their sprouts. In a different atmosphere, where 98% argon and 2% oxygen, vegetables such as carrots, lettuce and onions sprout well.
What is especially characteristic, the content of this gas in the earth's crust is much greater than other elements in its group. Its approximate content is 0.04 g per ton. This is 14 times the amount of helium and 57 times the amount of neon. As for the universe around us, there is even more of it, especially on different stars and in nebulae. According to some estimates, there is more argon in space than chlorine, phosphorus, calcium or potassium, which are abundant on Earth.
Getting gas
The argon in cylinders, in which we often meet it, is an inexhaustible source. In addition, in any case, it returns to the atmosphere due to the fact that during use it does not change in physical or chemical terms. An exception may be cases of consumption of a small amount of argon isotopes to obtain new isotopes and elements in the course of nuclear reactions.
In industry, gas is obtained by separating air into oxygen and nitrogen. As a result, gas is born as a by-product. For this, special industrial equipment for double rectification with two columns is used.high and low pressure and an intermediate condenser-evaporator. In addition, waste from ammonia production can be used to produce argon.
Scope of application
The scope of argon has several areas:
- food industry;
- metallurgy;
- scientific research and experiments;
- welding;
- electronics;
- automotive industry.
This neutral gas is inside the electric paws, which slows down the evaporation of the tungsten coil inside. Due to this property, the welding machine based on this gas is widely used. Argon allows you to reliably connect parts made of aluminum and duralumin.
Gas was widely used when creating a protective and inert atmosphere. This is usually necessary for the heat treatment of those metals that are easily subject to oxidation. Crystals grow well in an argon atmosphere to produce semiconductor elements or ultrapure materials.
Advantages and disadvantages of using argon in welding
Regarding the area of welding, argon gives certain advantages. First of all, metal parts do not heat up so much during welding. This avoids deformation. Other benefits include:
- reliable weld protection;
- argon welding speed is an order of magnitude higher;
- process is easy to control;
- welding can be mechanized or fully automated;
- opportunityconnect parts from dissimilar metals.
At the same time, welding argon also implies a number of disadvantages:
- Welding generates ultraviolet radiation;
- high-amperage arc requires high-quality cooling;
- hard work outdoors or drafty.
Nevertheless, with so many advantages, it is difficult to underestimate the importance of argon welding.
Precautions
Be careful when using argon. Although the gas is non-toxic, it can cause asphyxiation by replacing oxygen or liquefying it. Therefore, it is extremely important to control the volume of O2in the air (at least 19%) using special instruments, manual or automatic.
Working with liquid gas requires extreme caution, since the low temperature of argon can cause severe frostbite of the skin and damage to the eye shell. Goggles and protective clothing must be used. Persons who need to work in an argon atmosphere should wear gas masks or other insulating oxygen devices.
