부산대학교 도서관

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. Nb 2 O 5 , AgNbO 3 and NiNb 2 O 6 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 Nb 2 O 5 was much higher than those of the Ag – O (−0.59 eV) and Ni – O (−0.90 eV) bonds in AgNbO 3 and NiNb 2 O 6 , indicating that the latter Ag – O and Ni – O bonds were much easier to be fractured or broken under the friction force. AgNbO 3 and NiNb 2 O 6 registered better lubrication performances than Nb 2 O 5 , 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. • Lubrication mechanisms of the Nb-contained oxides were revealed by the density functional theory (DFT) computation. • Nb-contained oxides, e.g. Nb 2 O 5 , AgNbO 3 and NiNb 2 O 6 were generated through tribochemistry with the temperature increasing. • The binding energy of Nb – O bond in Nb 2 O 5 was much higher than those of Ag – O and Ni – O bonds in AgNbO 3 and NiNb 2 O 6. • AgNbO 3 and NiNb 2 O 6 registered better lubrication properties than Nb 2 O 5. [ABSTRACT FROM AUTHOR]