Thermal stability and hydrogenation behavior of Zr-1Nb alloy with TiNx and Ti/TiNx coatings

E B Kashkarov,S A Zakharchenko,O V Vilkhivskaya

doi:10.1088/1742-6596/741/1/012192

Abstract

Titanium nitride coatings were deposited by reactive dc magnetron sputtering (dcMS) to protect Zr-1Nb alloys from hydrogen embrittlement. Dense titanium (Ti) interlayer was prepared between TiNx protection film and a Zr substrate to improve thermal stability and adhesion between the TiNx and the substrate at high temperatures. Hydrogen absorption of Zr- 1Nb with TiNx and Ti/TiNx at 623 K was reduced in comparison with uncoated Zr-1Nb. No peeling or cracks of Ti/TiNx coatings is observed after thermal cycling up to 1073 K. The high temperature (1073 K) hydrogenation behaviour differs from the hydrogenation at lower temperature by increasing the amount of dissolved hydrogen in the β-phase of zirconium. The higher rate of hydrogen absorption by Zr-1Nb with TiNx was observed due to the coating delamination as a result of differences in thermal expansion coefficients, while Ti/TiNx demonstrates the lower hydrogen absorption at 1073 K and good adhesion strength.

Highlights

Hypothetical nuclear accidents can create real danger to the zirconium alloys and stability of parts made of these alloys, especially such as loss of coolant accident (LOCA) and reactivity initiated accidents (RIA)
Titanium nitride (TiN) deposited by magnetron sputtering and vacuum arc deposition is promising in protection of zirconium alloys from hydrogen embrittlement [7,8,9]
It can be seen that the orientation in the plane (200) is the reflection of major intensity and it remains as the most intense for both TiNx and Ti/TiNx coatings

Summary

Introduction

Hypothetical nuclear accidents can create real danger to the zirconium alloys and stability of parts made of these alloys, especially such as loss of coolant accident (LOCA) and reactivity initiated accidents (RIA). The magnetron sputtering and vacuum arc deposition are the main methods used for more than 60 years in various industries for coating deposition and surface modification of structural materials [4,5,6]. Titanium nitride (TiN) deposited by magnetron sputtering and vacuum arc deposition is promising in protection of zirconium alloys from hydrogen embrittlement [7,8,9]. The differences between the temperature expansion coefficient of the TiN coating and zirconium alloy lead to the coating degradation. The titanium thermal expansion coefficient of 8.6×10-6 K-1 is in the range between zirconium (5.7×10-6 K-1) and titanium nitride (9.35×10-6 K-1) It suggests that it will sustain the balancing thermal expansion coefficient between the substrate and the coating and improve the adhesion strength.

Methods

Results

Conclusion