Lubrication mechanisms of Nb-contained oxides characterizing tribochemistry of NiAl/Nb/Ag composites coatings revealed by the density functional theory (DFT) computation. (April 2023)

• Record Type: Journal Article
• Authors: Guo, Hongjian; Yan, Pengxun; Wu, Zhiguo; Li, Bo; Li, Fuli; Hu, Jun; Chen, Zhong
• Is Part Of: Tribology international. Volume 182(2023)
• Publication Date: 2023-04
• Subjects: Nb-contained oxides -- Tribological performance -- Density functional theory (DFT) computation -- Lubrication mechanism -- Tribochemistry; Tribology -- Periodicals; 621.89
• DOI: 10.1016/j.triboint.2023.108352
• Languages: English
• ISSNs: 0301-679X

Abstract

Abstract: In this work, the lubrication mechanisms of Nb-contained oxides were revealed by using the density functional theory (DFT) computation. Concretely, a series of Nb-contained oxides, e.g. Nb2 O5, AgNbO3 and NiNb2 O6 were generated through tribochemistry during the friction process of the fabricated NiAl/Nb/Ag coatings as the temperature was increased, and the friction coefficients decreased from 0.51 to 0.54 at low temperatures to 0.24 – 0.27 at elevated temperature. Computational results showed that the binding energy of the Nb – O bond (−15.3 eV) in Nb2 O5 was much higher than those of the Ag – O (−0.59 eV) and Ni – O (−0.90 eV) bonds in AgNbO3 and NiNb2 O6, indicating that the latter Ag – O and Ni – O bonds were much easier to be fractured or broken under the friction force. AgNbO3 and NiNb2 O6 registered better lubrication performances than Nb2 O5, which could account for the excellent tribological performance of the coatings at elevated temperatures. This investigation contributes to revealing the high-temperature lubrication mechanisms of Nb-contained oxides. Highlights: Lubrication mechanisms of the Nb-contained oxides were revealed by the density functional theory (DFT) computation. Nb-contained oxides, e.g. Nb2 O5, AgNbO3 and NiNb2 O6 were generated through tribochemistry with the temperature increasing. The binding energy of Nb – O bond in Nb2 O5 was much higher than those of Ag – O and Ni – O bonds in AgNbO3 and NiNb2 O6 . AgNbO3 and NiNb2 O6 registered better lubrication properties than Nb2 O5 .