A Royce-enabled collaboration between university scientists and Rolls-Royce is helping to develop the technology to deliver hydrogen-powered systems safely. Researchers at Royce facilities in the Bragg Centre for Materials Research at the University of Leeds and in Cranfield University partnered with Rolls-Royce on a Henry Royce Institute Industrial Collaboration Programme project to evaluate the wear performance of several hydrogen barrier coatings under pressures representative of those in hydrogen-fuelled engines.
Hydrogen is a clean energy source with the potential to help the UK government achieve its net-zero greenhouse gas emission targets. But it is often referred to as the ‘naughty element’ because it behaves in ways that make it difficult to contain and use safely. Its small molecules can infiltrate materials which would easily contain other gases. When it permeates metals, this can cause embrittlement, making tanks, pipes and components more likely to crack.
Because of hydrogen’s ‘naughtiness’, adoption of hydrogen technologies in sectors such as aviation, shipping and heavy-duty transport depends on reliable hydrogen barrier coatings. These protective surface layers prevent hydrogen permeation which can embrittle components and compromise their structural integrity.
Although hydrogen barrier coatings are critical to enabling the safe and efficient production, transport, storage and use of hydrogen, challenges occur at tribological interfaces (rubbing contact zones between surfaces) in high-pressure hydrogen conditions. To date, hydrogen barrier coatings wear testing has been conducted at ambient pressures that do not reflect the high-pressure environments found in components, as well as through high cost and time-consuming field testing.
Professor Ardian Morina, Dr Liuquan Yang, Dr Junfeng Yang, Dr Chun Wang, Dr Aladdin Al Sheikh Omar, Yuyang Yuan and Dr Marjan Homayoonfard from Leeds University worked with Dr Francesco Fanichia, Cameron Davis, Dr Christopher Shaw and Dr Vikesh Kumar from Cranfield University, and Dr Louise Gale and Dr Al Lamborune from Rolls-Royce to develop a wear testing facility to assess the reliability and durability of coated tribological interfaces that operate in high-pressure hydrogen conditions.
Accessing the unique capabilities within the Advanced Coatings Systems Facility and the Institute of Functional Surfaces, the team conducted wear tests at hydrogen pressures up to 10 bar using adapted high-pressure vessels. This replicated realistic running conditions in hydrogen fuel injectors and provided data relevant to actual applications. The team tested titanium aluminium nitride (TiAlN), aluminium oxide (Al2O3) and two types of diamond-like carbon coatings deposited in the National High Temperature Surface Engineering Centre at Cranfield University and the Advanced Coating System at Leeds. They then benchmarked the performance of these coatings against field-tested engine components supplied by Rolls-Royce, comparing laboratory results to real-world wear behaviour.
Addressing a gap in the ability to perform controlled reliable tribological testing under elevated hydrogen pressures, the project team has developed a unique methodology for replication. The project presents a research base for larger studies and technology transfer projects to develop standardised testing protocols to de-risk investments in hydrogen energy technologies and design barrier coatings with superior properties. The study results will directly benefit Rolls-Royce and other manufacturers developing hydrogen-compatible components for next-generation propulsion and energy systems. The ability to screen coatings in high-pressure conditions could accelerate product development cycles and reduce the reliance on costly and time-consuming field testing.
