We all know that argon is used to weld different metals, but not everyone has thought about what this chemical element is. Meanwhile, his story is rich in events. Typically, argon is an exceptional instance of the periodic table, which has no analogues. The scientist himself was surprised at one time how he could even get here.
About 0.9% of this gas is present in the atmosphere. Like nitrogen, it has a neutral character without color and odor. It is not suitable for maintaining life, but it is simply irreplaceable in some areas of human activity.
A small digression into history
He was first discovered by an Englishman and physicist by training G. Cavendish, who noticed the presence in the air of something new, resistant to chemical attack. Unfortunately, Cavendish did not recognize the nature of the new gas. A little over a hundred years later, another scientist noticed this - John William Strat. He came to the conclusion that in nitrogen from the air there is some admixture of gas of unknown origin, but argon, or something else, he still could not understand.
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. Another surprise was the discovery - a new gas molecule 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 see the new gas in the air over 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 already mentioned, argon is a gas with a rich and detective story. It was forgotten for a while, but after the discovery of helium, the new gas was officially recognized. It was decided to set aside for him a separate zero position located between the halogens and alkali metals.
The properties
Among other inert gases that make up the heavy group, argon is considered the lightest. Its mass exceeds the weight of air by 1.38 times. The gas goes into a liquid state at a temperature of -185.9 ° C, and at -189.4 ° C and normal pressure hardens.
Argon differs from helium and neon in that it is capable of dissolving in water - at a temperature of 20 degrees in the amount of 3.3 ml in one hundred grams of liquid. But in a number of organic solutions, gas dissolves better. Exposure to electric current causes it to glow, due to which it has become widely used in lighting equipment.
Biologists have discovered another useful property that argon has. This is a kind of environment where the plant feels great, which is proved by experiments. So, being in a gas atmosphere, planted seeds of rice, corn, cucumbers and rye sprouted. In another atmosphere, where 98% comes from argon and 2% from oxygen, a vegetable crop such as carrots, lettuce and onions sprouts 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 surrounding us, it is even larger there, 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 full on Earth.
Gas production
That argon in cylinders in which we meet it more often is an inexhaustible source. Moreover, in any case, it returns to the atmosphere due to the fact that when used it does not change physically or chemically. An exception may be cases of the consumption of a small amount of argon isotopes to produce 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 produced as a by-product. For this purpose, special industrial equipment for double rectification with two high and low pressure columns and an intermediate condenser-evaporator is used. In addition, ammonia waste can be used to produce argon.
Application area
The scope of argon has several areas:
- food industry;
- metallurgy;
- scientific research and experiments;
- welding work;
- electronics;
- Automotive industry.
This neutral gas is located inside the electric paws, which slows down the evaporation of the tungsten spiral inside. Due to this property, a 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 to create a protective and inert atmosphere. This is usually necessary for the heat treatment of those metals that are easily susceptible to oxidation. Crystals grow well in an argon atmosphere to produce semiconductor elements or ultra-pure materials.
Advantages and disadvantages of using argon in welding
Regarding the welding area, argon offers certain advantages. First of all, metal parts do not heat up so much during welding. This avoids deformation. Other benefits include:
- reliable protection of the weld;
- argon welding speed is an order of magnitude higher;
- the process is easy to control;
- welding can be mechanized or completely transferred to automatic mode;
- the ability to connect parts of dissimilar metals.
At the same time, welding argon implies a number of disadvantages:
- when welding, ultraviolet radiation occurs;
- to use a high-amp arc, high-quality cooling is necessary;
- difficult work outdoors or in a draft.
Nevertheless, with so many advantages, it is difficult to underestimate the importance of argon welding.
Precautionary measures
When using argon, caution should be exercised. Although the gas is non-toxic, it can cause choking, replacing oxygen or liquefying it. Therefore, it is extremely important to control the volume of O 2 in the air (at least 19%) using special instruments, manual or automatic.
Working with liquid gas requires extreme caution, since a low temperature of argon can cause severe frostbite of the skin and damage to the ocular membrane. It is necessary to use glasses and overalls. Persons who need to work in an argon atmosphere should wear gas masks or other insulating oxygen devices.