The Tribological Behaviors of Different Mass Ratio Al₂O₃-TiO₂ Coatings in Water Lubrication Sliding against Si₃N₄

ABSTRACT

The tribopairs of water hydraulic plunger pumps are usually operated under severe conditions, due to the poor lubrication of water and silt suspended in natural water. It is essential to identify the desired engineering materials and material combinations for designing water pumps. As the candidate materials of tribopairs, the tribological characteristics of different Al₂O₃-TiO₂ coatings combined with Si₃N₄ ceramics under silt-laden water and tap water lubrication were investigated. The Al₂O₃-TiO₂ coatings with different weight percentages of TiO₂ in a wide range from 3 to 100% were tested. The tribological characteristics of the various couple pairs were researched using a ring-on-ring test rig. The microstructures of the contact surfaces were analyzed with a scanning electron microscope before and after the test to study the wear mechanism. The experimental results indicate that the friction coefficient of the Al₂O₃-TiO₂/Si₃N₄ tribopairs increases with an increase in the percentage of TiO₂ content in the Al₂O₃-TiO₂ coating. However, the TiO₂ content does not present a clear relationship with the wear rate. Considering the friction and wear properties, Al₂O₃-13%TiO₂ is the preferred coating to use in water hydraulic pumps when sliding against Si₃N₄.

KEYWORDS:

• Piston hydraulic pumps
• ceramics
• water
• abrasive wear
• marine

Acknowledgements

Thanks are given to Master Zhen Yang, Tao Jiang, and Hui Tang for their contributions to this project. Additionally, thanks are given to the Huazhong University of Science and Technology Test Centre for offering necessary assistance.

Funding

This project was supported by the National Natural Science Foundation of China (No. 50975101), China Postdoctoral Science Foundation (No. 2014M560609 and No. 2015T80804), and National High Technology Research and Development Program of China (No. 2009AA090100).