Detailed Program of the 22nd ISC 2024

Investigation of sealing materials with excellent cold temperature flexibility in hydrogen environments

Summary

Reliable operation is a key requirement for hydrogen technology. Operating conditions of up to 1000bar pressure and temperatures of -40°C and 85°C, which are demanded for hydrogen-powered vehicles, are challenging to be met by sealing materials such as TPEs and rubbers.

In-depth understanding of material behavior is therefore needed to meet the requirement of reliable operation. In this work, the relevant properties for hydrogen applications are studied for two polyurethane grades, one EPDM, and two NBR grades with low ACN-content.

To characterize low temperature properties, results of typical methods to characterize the glass transition of sealing materials are compared to static sealability on a component level test with a T-seal design.

To measure permeation of hydrogen through those materials, a test rig was developed that allows the measurement of hydrogen permeation at temperatures up to 75°C and pressures of up to 800 bar within research project funded by the European Union.

Samples of the mentioned sealing materials were placed in an autoclave and exposed to temperatures at the upper service temperature at a pressure of 1000bar. Mechanical properties were tested accordingly before and shortly after the exposure. The tests after exposure were repeated 48 hours after the pressurized hydrogen exposure in order to quantify the reversibility of effects such as swelling.

As another dimension to compatibility, material samples were exposed to pressurized hydrogen at room temperature and tribological properties (wear, coefficient of friction) were characterized in-situ with a linear tribometer in ball-on-plate configuration.

Results show that all selected materials meet the demand of cold-temperature flexibility and compatibility to hydrogen, however distinguish in their swelling behavior, wear resistance and permeability.