Ultrasonic-assisted top-down preparation of NbSe2 micro/nanoparticles and hybrid material as solid lubricant for sliding electrical contact

Rong Qu; Xiaoqin Wen; Yamei Zhao; Tingmei Wang; Ruiqing Yao; Jinjun Lu

doi:10.1016/j.ultsonch.2021.105491

Ultrasonic-assisted top-down preparation of NbSe₂ micro/nanoparticles and hybrid material as solid lubricant for sliding electrical contact

Ultrason Sonochem. 2021 May:73:105491. doi: 10.1016/j.ultsonch.2021.105491. Epub 2021 Feb 10.

Authors

Rong Qu¹, Xiaoqin Wen¹, Yamei Zhao¹, Tingmei Wang², Ruiqing Yao¹, Jinjun Lu³

Affiliations

¹ Key Laboratory of Synthetic and Natural Functional Molecule of Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an 710127, China.
² State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China.
³ Key Laboratory of Synthetic and Natural Functional Molecule of Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an 710127, China; State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China. Electronic address: jjlu@nwu.edu.cn.

Abstract

2H-NbSe₂ single crystal flake (ca. 2 × 2 × 0.5 mm in size) by chemical vapor transport is employed as the precursor for a top-down preparation of NbSe₂ micro/nanoparticles by two kinds of processes, i.e. (1) mechanical exfoliation; (2) ultrasonic-assisted exfoliation in ethanol without ageing and with ageing for 210 days. NbSe₂ micro/nanoparticles are applied on top of a Cu disk by a drop-casting process and the tribological property in sliding against a Cu pin under sliding electrical contact is investigated at room temperature. Mechanical exfoliation produces NbSe₂ microplatets with typical sizes of 1 μm to 30 μ m with a thickness less than 2 μm. Ultrasonic-assisted exfoliation without aging facilitates the formation of NbSe₂ micro/nanoplatets with sizes of 0.1 μm to 25 μm and nano-whiskers with 100 nm in diameter and 1 ~ 3 μm in length, but Nb₂O₅ and Se are also found on the basis of XPS results. Prolonged aging of the suspensions modifies the morphology by converting platets and whiskers into corrugated floccules (hybrid material), which are composed of Nb₂O₅, Se, NbSe₂, and graphene. Notably, NbSe₂ micro/nanoparticles by ultrasonic-assisted exfoliation without ageing exhibit an excellent lubricating property with low friction coefficient (0.3), mild wear, and longer wear lifetime (120 min) than that of mechanical exfoliated NbSe₂ microplatets (10 min). The wear lifetime for the aged NbSe₂ micro/nanoparticles can be as long as 504 min and are 4.2 times of the sample without aging, which can be a good solid lubricant for sliding electrical contact.

Keywords: Ageing; Electrical contact; Exfoliation; NbSe(2); Ultrasonic-assisted.