Characterisation of thin α-Al₂O₃ tribo-coating deposited by low-power gas tunnel plasma spray

Abstract

This study used a unique, low-power (2.8 kW) gas tunnel plasma spray and γ-Al₂O₃ feedstock powder to deposit a thin Al₂O₃ coating (<2 µm) on mild steel substrate. By optimising the plasma gas flow rate, powder feed rate, spraying time, and distance, a dense and homogeneous Al₂O₃ coating was obtained at a very high deposition rate (150 nm/s). During plasma coating, the high energy density plasma transforms the γ-Al₂O₃ powder into a highly crystalline α-Al₂O₃ as the predominant microstructure of the coating. The performance of the Al₂O₃ coating on mild steel was then evaluated preliminary using a linear sliding wear test against a chrome-steel ball, with the results indicating an 18–26% reduction in wear when compared to the uncoated substrate.

KEYWORDS:

• Ceramics
• Thin films
• Alumina
• Plasma spray

Acknowledgements

This project was supported by Universiti Teknologi Malaysia through Collaborative Research Grant National (CRG 26.3 4B537) and Professional Development Research University (PDRU 06E17).

Disclosure statement

The authors have no conflicts of interest to declare.

Additional information

Funding

This project was supported by Universiti Teknologi Malaysia through Collaborative Research Grant National [CRG 26.3 4B537] and Professional Development Research University [PDRU 06E17].