DEVICE AND METHOD FOR THE SURFACE TREATMENT OF A MATERIAL

A device and a method for the surface treatment of a material by a pressurized jet of liquid nitrogen, supercritical cryogenic nitrogen or hypercritical cryogenic nitrogen that may be loaded with particles, use a device that includes a mixing chamber (10) closed by a downstream wall with an outlet orifice, and a diffusion focusing barrel (20) having an inlet and an outlet, the inlet being designed to be fastened to the mixing chamber (10) while being in fluid contact with the outlet orifice of the mixing chamber (10), the pressurized jet of nitrogen having to pass through the focusing barrel from the inlet to the outlet. The diffusion focusing barrel (20) includes a hollow tube having three successive portions placed one after the other, namely a convergent portion (21) located on the side of the inlet opening of the diffusion focusing barrel and whose inner face, considered in the direction of flow of the nitrogen jet, is convergent, a neck (22) whose inner face is cylindrical, and a divergent portion (23) ending in the outlet of the diffusion focusing barrel and whose inner face, considered in the direction of flow of the nitrogen jet, is divergent.