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. This is an important step towards developing next-generation, low-wear components for hydrogen technologies.
The challenge
Hydrogen is a clean energy source with the potential to help the UK government achieve its net-zero greenhouse gas emission targets. The 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, the diffusion of hydrogen atoms through materials, 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 (see the National Materials Innovation Strategy), challenges occur at rubbing contact zones between surfaces (tribological interfaces) in high-pressure hydrogen conditions. When surfaces move against one another in such environments, their adhesion strength and wear resistance can degrade, significantly impairing performance. While barrier coatings are intended to protect tribological interfaces, their long-term durability in high-pressure hydrogen conditions is poorly understood.
To date, hydrogen barrier coatings wear testing has been conducted at ambient pressures that do not reflect the high-pressure environments found in components, such as fuel injectors, valves and seals, as well as high-cost and time-consuming field testing. It is difficult to develop wear tests in high-pressure conditions as standard tribometers are not designed for such environments and experimental setups are complicated by stringent safety requirements. The absence of standardised testing protocols limits data comparability and transferability across different research and industrial applications.
The solution
Professor Ardian Morina, Dr Liuquan Yang, Dr Junfeng Yang, Dr Chun Wang, Dr Alaaeddin Al Sheikh Omar, Yuyang Yuan and Marjan Homayoonfard from Leeds worked with Dr Francesco Fanicchia, Cameron Davis, and Dr Christopher Shaw and Dr Vikesh Kumar from Cranfield University, and Dr Louise Gale and Dr Al Lambourne from Rolls-Royce to develop and deploy a unique wear testing methodology for assessing the reliability and durability of coated tribological interfaces that operate in high-pressure hydrogen conditions.
Accessing the capabilities within Royce’s Advanced Coatings System and Environmental Tribology Facility at the University of Leeds to deposit the coatings, the team developed a wear testing capability at the Institute of Functional Surfaces to conduct 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) deposited in the National High Temperature Surface Engineering Centre facility at Cranfield University and and two types of diamond-like carbon coatings developed at the University of 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.
The project was made possible by grant funding from the Henry Royce Institute’s Industrial Collaboration Programme and Royce funded experimental facilities.
The impact
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 not only highlights the importance of testing in high-pressure hydrogen but presents a research base for larger studies and technology transfer projects to develop standardised testing protocols to derisk investments in hydrogen energy technologies and design barrier coatings with superior properties.
The results of this project 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.
Find out more about Royce’s Industrial Collaboration Programme.
Collaborators
Researchers at Royce facilities in the Bragg Centre for Materials Research at the University of Leeds and in Cranfield University partnered with Rolls-Royce to evaluate the wear performance of several hydrogen barrier coatings under pressures representative of those in hydrogen-fuelled engines.
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