FREISTRAHL-WASSERTURBINE.

摘要

In a nozzle for a free-jet water turbine of the Pelton type, in order to protect the surfaces of the spear and the inner wall of the water discharge nozzle from erosion or material abrasion through entrained sand or stone particles, at least the part of the surface at risk is covered with a mechanically resistant ceramic coating, for example a ceramic coating with a Vickers hardness of at least 1000 kg/mm<2>, preferably above 1200 kg/mm<2>, e.g. in the range between 1600 and 2000 kg/mm<2>. Particularly suitable are ceramic coatings with a thickness of at least 0.1 mm, preferably in the range of 0.35 - 0.5 mm, which can be applied to a roughened surface by a spraying process, in particular the plasma spraying process.