The formation of stable hydrogen impermeable TiN-based coatings on zirconium alloy Zr1%Nb

Abstract

IntroductionThe problem of protection of structural and functional materials operating in hydrogen-containing ambient in nuclear reactors and fuel cells is very important. In Russian Water-Water Energetic Reactor (WWER) and High Power Channel Reactor (RBMK) the Zr1%Nb alloy is used as a cladding material. Zirconium and its alloys are susceptible to hydrogen corrosion and fretting wear. It is known that the certain concentrations of hydrogen in the bulk of the material leads to embrittlement and subsequent degradation of mechanical properties [1][2][3][4][5][6]. Titanium nitride (TiN) deposited by vacuum ion-plasma methods is promising in protection zirconium alloys from hydrogen corrosion [7]. Moreover, TiN coatings have an excellent erosion resistance, which favorably affects the fretting resistance of the coatings [8]. There is no scientific data in information about hydrogen sorption kinetics by TiN coated zirconium alloy by dcMS method. At the same time, such studies are of great practical importance for the development of TiN coating technology, allowing to work in extremal conditions. One of the most important tasks in the development of coating technology is to ensure good adhesion of the coating under thermal cycling. The differences between temperature expansion coefficient of the coating and substrate materials leads to the coating degradation and varios accidents can occur. In this paper the problem of stability of the coatings under thermal cycling was solved by creating a Ti underlayer deposited by AIP between the zirconium alloy Zr1%Nb and magnetron sputtered TiN.The aim of this work is to create a stable hydrogen-impermeable TiN-based protective coating under thermocycling conditions using the AIP and dcMS methods.