Layer that protects surface of zirconium alloys used in nuclear reactors

摘要

The layer that protects surface of zirconium alloys, which are used as material for nuclear reactors, according to the present invention, is formed by a homogeneous polycrystalline diamond layer being prepared by chemical vapor deposition method. The diamond layer thickness is in the range of 100 nm to 50 microns and the size of the crystal grains in the layer is in the range of 10 to 500 nm. The maximum amount of non-diamond carbon is 25 percent by mole and the total amount of the non-carbonaceous impurities is up to 0.5 percent by mole at the most. Surface roughness of the homogeneous polycrystalline diamond layer has RMS roughness value less than 40 nm and thermal conductivity of the layer is in the range of 1000 to 1900 W∙m.e.-1∙K.e.-1. Surface coating of the zirconium alloys by the above-indicated homogeneous polycrystalline diamond layer serves as protection against undesired changes and processes in the nuclear reactor environment.