Novel Surface Engineering Strategies for Dry-Sliding Contacts

Due to their unique life and service requirements, many aerospace and space devices cannot use conventional liquid lubricants such as oils and greases. Solid lubricant coatings are used instead - in both in-service and future systems.
Solid lubrication has historically consisted of molybdenum disulphide or graphite particles. Modern solid lubricant coatings are deposited using technologically advanced techniques such as Microwave Plasma Enhanced Chemical Vapour Deposition (MWPECVD), Physical Vapour Deposition (PVD), and cathodic arc deposition, amongst others. Coatings have become more sophisticated, employing functional gradient layers, surface patterning and using post deposition processes such as surface activation and termination.

A detailed review of the current literature will be required to determine the current state of the art of solid lubricant coatings, from which a more in depth experimental matrix can be written. Coating design and architecture will be at the forefront of the project; this will draw upon various different deposition methods, coating types and structures. This will be complemented with rigorous post-deposition analysis, which will determine the chemical and mechanical properties of the coatings, ability of the coatings to provide lubrication and the mechanism by which they do this, and how they function in a contact environment. One of the key goals of the project is to characterise the coatings thoroughly in order to gain full understanding of the tribology, mechanical and surface characteristics of the coatings and the relationship of this to the type and recipe of the coating deposition.
The scope of the proposed project encompasses:

The design of solid lubricant coatings: investigating coating architectures such as multiple layers, patterning, coating structure and levels of nanocrystallinity and bonding structure densities. These would be deposited using the unique deposition system at the University of Leeds.
Testing of the coatings: in order to determine whether the coatings are applicable to AWE specified environments, a rigorous tribological test regime must be applied. After this testing, sophisticated electron microscopy and other spectroscopy techniques will be used so that the coatings may be fully characterised pre- and post-testing, and the mechanisms of lubrication can be analysed.
Development of coatings: once the coatings have been tested, improvements can be continually made and further investigations into more novel areas can be carried out.

Deliverables:
The project will aim to deliver novel coating architectures using a hybrid of newly developed deposition techniques with the aim of enhancing friction and wear performance on solid surfaces, without the need for oil or liquid lubrication.
Tests to determine the lubricity, mechanical properties and surface chemistry of the coatings will run alongside and support the coating development. It is key to understand the mechanisms of lubrication and interaction of surfaces.