Zirconium alloy for improving resistance to oxidation at very high temperature and fabrication method thereof

摘要

A zirconium alloy for use in nuclear fuel assemblies is provided, which provides increased resistance against oxidation and corrosion and also improved bonding with parent material, because pure metallic material such as silicon (Si) or chromium (Cr) is evenly coated on the surface of the parent material by plasma spraying. Because the plasma spray coating used to coat the pure metallic material on the zirconium alloy does not require vacuum equipment and also is not limited due to the shape of the coated product, this is particularly useful when evenly treating the surface of the component such as 4 m-long tube or spacer grip arrangement which is very complicated in shape. Furthermore, because the coated zirconium alloy confers excellent resistance to oxidation and corrosion under emergency such as accident as well as normal service condition, both the economic and safety aspects of nuclear fuel are improved.

主权项

1. A method for fabricating a coated zirconium alloy article, the method comprising steps of:
pre-treating a surface of a zirconium alloy parent material (step 1); providing a pure metallic material of silicon (Si) or chromium (Cr) in powder form (step 2); maintaining a distance between a plasma gun and the parent material at 10 cm and plasma spraying only the pure metallic material of Si or Cr on the surface of the pre-treated parent material of step 1 with the plasma gun (step 3) to form a coating layer on the pre-treated parent material; and thermally-treating the coated parent material coated in step 3 in an inert atmosphere (step 4) to create a diffusion layer comprising zirconium and the pure metallic material of Si or Cr between the parent material and the coating layer, wherein the pure metallic material of Si or Cr is coated on the parent material to a thickness ranging between 20 μm and 500 μm to form the coating layer, and the thermal treatment of step 4 is performed at 350° C. for 4 hours.