Ice knife
Lasers and currents of abrasive particles are used to cut hard materials, but in some cases the material is damaged rather than cut. Carbon fiber or glass composites, so used today, can not be cut by laser, since they melt with heat and suffer irreversible changes. Magnesium and titanium, on the other hand, suffer a very intense combustion if heated too much. Australian engineer Elijah Siores of the University of Melbourne has studied what happened to the famous Titanic ship and invented a "knife" that uses ice to cut hard materials.
The operation is as follows: water spray freezes and 0.25 mm wide ice particles form. These are injected into the pressurized water stream and both, water and ice, are expelled by a mouth a millimetre wide. The knife body remains cold by a liquid nitrogen cap. The knife is located at 5 mm of the material to be cut, but the current of water and ice is not applied directly; first by a liquid nitrogen current the surface of the material freezes and becomes fragile and then a stream of water and ice is applied.
With the new technique, more precise and fine sections are obtained, in addition to being very clean: nitrogen evaporates and most of the water used is recoverable. According to the inventor, the "ice knife" can be used in surgery or to cut and clean the fuel bars of nuclear reactors. Labana offers great possibilities and is already on the market.
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