Pacific Rim Symposium on Surfaces, Coatings and Interfaces (PacSurf 2018)
    Thin Films Tuesday Sessions
       Session TF-TuP

Paper TF-TuP5
Influence of Ag Content on the Tribological Properties of MoNbN-Ag Coatings at Elevated Temperature

Tuesday, December 4, 2018, 4:00 pm, Room Naupaka Salon 1-3

Session: Thin Films Poster Session I
Presenter: Xuan Dai, State Key Laboratory of Superhard Materials, Department of Materials Science, Key Laboratory of Automobile Materials, MOE, and Jilin University, Changchun, People's Republic of China
Authors: K. Zhang, State Key Laboratory of Superhard Materials, Department of Materials Science, Key Laboratory of Automobile Materials, MOE, and Jilin University, Changchun, People's Republic of China
X. Dai, State Key Laboratory of Superhard Materials, Department of Materials Science, Key Laboratory of Automobile Materials, MOE, and Jilin University, Changchun, People's Republic of China
M. Wen, State Key Laboratory of Superhard Materials, School of Materials Science and Engineering and Key Laboratory of Automobile Materials, MOE, Jilin University, Changchun, People's Republic of China
W. Zheng, tate Key Laboratory of Superhard Materials, School of Materials Science and Engineering and Key Laboratory of Automobile Materials, MOE, Jilin University, Changchun, People's Republic of China
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In recent years, with the increasingly fierce and vigorous development of aviation technology, aerospace engine, as the "crown jewel of the aviation industry", has been constantly improving its requirements of technology and performance. Because the aerospace engines always work in high temperature environment, it is necessary for materials to have reliable tribological performance at high temperature. However, high temperature lubrication is still a considerable challenge for the tribology field, and it results that the damage and failure of motor components are always caused by high temperature friction. Here, a reduced friction coefficient from 25 to 800 ℃ was achieved successfully in MoNbN-Ag coating with tailoring Ag content. The deposited MoNbN coating is a ternary fcc-solid solution, and the transformation from solute Ag atoms to precipitate metal Ag can be realized through the increasing of Ag content. The reduced friction coefficient can be ascribed to silver, molybdenum and niobium reacted with oxygen at elevated temperatures and create lubricious phases molybdenum oxide, niobium oxide ,silver molybdate and silver niobite film on the coating. Amusing, compared with Ag in the form of precipitation in MoNbN coating, when silver exists in the form of solid solution, it has a lower friction coefficient at 25-450 ℃ and a similar friction coefficient at 450-800 ℃. In which, it’s attributed to the contribution: solute Ag can activate easier self-oxidation forming Ag2O+ MoO3/Nb2O5 on the surface, which is beneficial for formation of Ag2Mo4O13/AgNbO3 during sliding at medium and low temperatures, thereby reducing friction.