DESIGN AND PERFORMANCE ASSESSMENT OF AN EXPERIMENTAL RIG TO CONDUCT MATERIAL NITRIDATION STUDIES AT EXTREME AMMONIA CONDITIONS

This work presents the design and assessment of an experimental rig intended to carry out material sustainability studies in ammonia (NH₃) environments. The designed facility aims at furthering the understanding of the nitridation potential of NH3 under extreme conditions, particularly at both high pressure and high temperature, when interacting with varying materials of interest. Several key factors were considered during the design process, including a system capable of operating at high pressures (up to 30 bar) and temperatures (up to 800 °C), the possibility of maintaining a continuous NH3 flow to increase the nitridation potential of the atmosphere, the flexibility of accommodating between 60 to 70 metal samples, and the design of a suitable system to operate continuously for hundreds of hours (up to 1000 hours in total). A facility achieving those features involved the development and optimization of three main subsystems such as a liquefied NH3 feeding system, a high-pressure/temperature rig, and an abatement system. Altogether these guarantee safe and continuous operation for long periods of time at the desired experimental conditions. Finally, several tests were conducted to assess the reproducibility and stability of the designed facility, including temperature and pressure profiles, and NH3 concentration gradients in the rig.