miércoles, 16 de febrero de 2011

Azterlan and the cryogenic treatment of materials

When we speak about thermal treatments the first thing that comes to our minds is furnaces and high temperatures. However, we should take into account that the room temperature is about 300 K, still far away from absolute zero. That means that there is a quite big margin for lowering the temperature of a material and for microstructural changes to be triggered.

This possibility has not been explored until relatively recently because the really low temperatures are not available in nature. They could only be reached when, in the late nineteenth century, the liquefying process of the air and its major constituents (nitrogen -196 ºC, oxygen -183 ºC) was discovered. The first experiences concerning the effect of cryogenic temperatures on materials were done in the early twentieth century, but it was not possible to speak about a cryogenic treatment industry until just twenty years ago. Nowadays cryogenic treatments are still hardly known in Europe but their development and implementation are growing in the worldwide.

There are many materials whose properties can be altered by deep low temperatures: metals (steel, carbide, cast iron, copper, aluminium, magnesium, etc.), ceramics and even some polymers. Obviously, the effects depend on the considered material, being the most common ones those related to wear resistance and fatigue life, but also to conductivity, toughness, residual stresses... However, the mechanisms that underlie behind the changes in the materials caused by cryogenic temperatures are still poorly understood. The main explanation can be that this is a quite new technology and many of its applications have been developed empirically.

The most common examples of application of cryogenic treatments are all kind of tools or spare parts that have to be substituted as a result of wear or fatigue: machine tools (drill bits, mills, carbide inserts, reamers, broaches...), cutting knives, punches, dies, moulds, rolls, etc. It is possible to find examples in practically any sector considered (metalworking, automotive, aerospace, timber, mining, electronics ...). If there is a problem related with the durability of a material it may be also an opportunity for this technology.

One of the characteristics of cryogenic treatments is that, like other heat treatments, they permanently affect the entire volume of the treated material. So, they are not surface treatments. This means that, for example, a cryogenically treated knife can be sharpened as many times as necessary without losing its performance.

Furthermore, cryogenic treatments are also compatible with most of the surface treatments and coatings that are commonly used in industry for wear reduction.

This is an environmentally friendly technology and, during the process cryogenic treatments do not produce absolutely any kind of waste or residue.

It is obvious that this technology has a tremendous development potential. Azterlan is aware of it and has created a new department, equipped with adequate human and technical resources, to investigate in depth about the impact of cryogenic treatments in the materials and to develop new industrial applications. Not only that, since Azterlan has installed in its facilities two industrial cryogenic treatment processors, each of them capable for processing up to 600 Kg. per batch. Those equipments are being used for providing cryogenic treatment services to many companies. All of them have in common that they are achieving important benefits from the reduction in manufacturing costs or the improvement of their products’

There is no doubt about the brilliant future that cryogenic treatments have, but fortunately, there is no need to wait because this technology is already available for those companies interested on it. It is a simple, efficient and environmentally friendly way for improving the performance of the materials.

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