Scientists from Russia found out how water behaves in the hardening of steel

© AP Photo / Channi AnandРабочие at a metallurgical plant in IndiaScientists from Russia found out how water behaves in the hardening of steel© AP Photo / Channi AnandПодпишись to daily updates RIA Science

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Physics from Moscow revealed an unusual nature the boiling point of water, which helps steel or other alloys very rapidly cooled during hardening. Their findings are presented in International Journal of Heat and Mass Transfer.

«We first offered clear physical model to explain paradoxical phenomena, which are observed when cooling hot bodies in fluids. This hardening and heat treatment of metals, cooling of nuclear reactor in case of a severe accident – a huge number of real-world applications,» said Arslan Zabirov from the Moscow power engineering Institute, quoted in a press-service of the Russian science Foundation.

Boiling water or many other liquids accompanied by the formation of a large number of vapor bubbles on the surface of the heating elements or the walls of the vessel. Turning into gas and escaping to the outside, the evaporated water carries away heat and cools the remaining liquid.

As a rule, the hotter the heating element, the stronger the boiling water, however this process has one big «enemy», opened by the German physician Johann Leidenfrost in the middle of the 18th century. He found that the drop of water that fell heavily on red-hot metal and evaporates very slowly due to the formation of very thin films from the vapor, insulating the liquid.

This applies not only to water, something similar can be observed by dipping a wet hand into the vessel with liquid nitrogen or molten lead. The opening of the Leidenfrost effect raised a very interesting question – if water behaves in a similar way in all conditions, then work hardening of the metal, during which the temperature of the iron drops to hundreds of degrees for a split second?

How to write Zabirov and his colleagues three decades ago, British physicists found that water can boil, and otherwise, if the difference in temperature between the liquid and the heating element will be higher than the Leidenfrost effect.

In this case, the vapor bubbles become very small and are formed differently, which prevents the appearance of «isolation» of the film and does not inhibit, but accelerates the process of heat transfer. Precisely how occur these bubbles, scientists did not understand until recently.

Physics from Moscow energy Institute found the answer to this riddle by creating a realistic mathematical model of the boiling liquid. To do this, they combined the results of dozens of experiments, the authors studied the formation of bubbles during hardening of the metal and other similar processes. The researchers then tried to find the factors that hindered or promoted this form of cool water, and contact with her subjects.

For example, combining the results of the experiments showed that this manner of boiling is not characteristic of all liquids and metals, which indicated its connection with the two properties of both the material structure of the metal surface and fluid viscosity. As it turned out, on the surface of certain types of alloys and metals present a special roughness that «punch» the film of steam and allow the bubbles to break free.

The set of equations that describes this phenomenon, can be used not only to predict the properties of alloys and how they behave in the hardening, but also for many other things. As scientists hope their discovery will bring a lot of benefit in all fields of science and technology.

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