This project is dedicated toward the development of novel aluminium oxide-graphite (AOG) composite coatings using plasma spraying technology and for the investigation of its tribological properties.
Aluminium oxide coatings owing to their unique physical properties are used for the protection of systemic elements from thermal, chemical or electrical effects. However, their application in the production of moving parts and components (bearing parts, valves, prostheses, spacecraft parts etc.) is limited by a high coefficient of friction and wear rate, considering dry-sliding conditions. The mechanical and tribological properties of the aluminium oxide composite coatings can be controlled upon formation, thereby providing self-lubricative coatings. Plasma spraying is one of the most widely used technologies in manufacturing, because it allows in the formation of coatings from materials that possess a high melting temperature; and is easy to control and relatively cheap. Despite the variety of composite coatings formed by plasma spraying, the scientific knowledge behind the formation of the AOG coatings is quite rare to find, owing to multiple unresolved technological and physical issues. There is an information lack on the optimal process parameters (plasma composition, power etc.) as well. The graphite concentration and phase structure of the composites in deriving the optimal tribological and mechanical properties is not well defined.
The formation of novel tribologically effective Al2O3-graphite coatings by plasma spraying, would be realized herein. The surface morphology, structure and elemental composition of the deposited Al2O3-graphite coatings would be evaluated and the tribological properties determined. The influence of graphite type and concentration on the friction coefficient and wear resistance of the AOG coatings would be studied. Therefore, novel aluminium oxide-graphite coatings possessing self-lubricative properties would be created.
Project funding:
KTU R&D&I Fund
Project results:
Novel self-lubricating aluminium oxide-graphite (AOG) composite coatings were developed. The influence of the graphite content on the surface morphology, structure, elemental composition and the tribological properties of Al2O3-graphite coatings were evaluated. The performed investigations have shown that the selection of proper plasma spraying parameters (plasma flow temperature) and the optimal graphite concentration in the alumina-graphite coatings reduced the friction coefficient by ~30 % and ~18 % compared to steel and the Al2O3 coatings, respectively. The specific wear rates of the alumina-graphite composite coatings were similar to alumina coatings under dry-sliding conditions.
The as-sprayed coatings exhibited a superior wear-resistance; the specific wear rates were reduced up to 20 times compared to steel and mainly, only plastic deformation was observed. The project results were presented in five international, and one Lithuanian conferences.
Period of project implementation: 2019-04-01 - 2019-12-31
Project partners: Lithuanian Energy Institute
