Investigation of tribological characteristics of nickel alloy-based solid-lubricating composites at elevated temperature
- PDF / 3,024,619 Bytes
- 12 Pages / 595.22 x 790.976 pts Page_size
- 39 Downloads / 192 Views
ISSN 2223-7690 CN 10-1237/TH
RESEARCH ARTICLE
Investigation of tribological characteristics of nickel alloybased solid-lubricating composites at elevated temperatures under vacuum Jinming ZHEN1, 2, Jun CHENG2,*, Hui TAN2, Qichun SUN2, Shengyu ZHU2, Jun YANG2,*, Weimin LIU2 1
College of Materials Science and Engineering, Liaocheng University, Liaocheng 252059, China
2
State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou
730000, China Received: 03 January 2020 / Revised: 11 March 2020 / Accepted: 15 March 2020
© The author(s) 2020. Abstract: The development of a high-performance solid-lubricating composite with excellent self-lubricity over a broad temperature range in vacuum is significant to solve the frictional problems of spatial mechanisms. In this study, the vacuum tribological behaviors of nickel-matrix/Ag/(Ca, Ba)F2/graphite (0–2 wt%) composites were studied from 25 to 800 ˚C. The results show that the synergistic effects of solid lubricants can significantly improve the tribological properties of the composites in vacuum, with the graphite content contributing considerably. For 2 wt% graphite, a low friction coefficient (0.14–0.25) and the lowest wear rate ((0.12–4.78)×105 mm3∙N1∙m1) were observed in vacuum over the entire testing temperature range. Moreover, the wear mechanisms were clarified via analysis of the chemical composition and morphologies of the sliding surfaces. Keywords: metal matrix composite; graphite; solid lubrication; vacuum; high temperature
1
Introduction
With the rapid development of advanced manufacturing systems in the aerospace and automobile industries, high-temperature lubricating materials and technologies are important and have gained much research attention [1–3]. In these systems, various moving components, such as rolling/sliding bearings and gears, operate under extreme conditions, such as high temperatures above 400 °C, high-speed/load, corrosive, and vacuum environments [3–6]. Under such cases, traditional liquid lubricants cannot provide the desired performance because of evaporation, decomposition, coking, and sealing, among other factors [7, 8]. Instead, highperformance solid-lubricating materials show great potential to fulfill the requirements of reducing friction and wear resistance of the moving parts in
these harsh environments [9–13]. As reported, NASA and the Air Force Research Laboratory developed two typical and pioneering solid-lubricating materials, respectively [1, 14–17]. The former is a plasma spray (PS) coating comprising a Ni-based alloy matrix, hardener phase, and Ag+CaF2/BaF2 eutectic solid lubricants, which have been successfully applied in the aerospace industry. The PS coating facilitated low friction and wear for the first time under broad temperatures (room temperature to 900 °C) owing to the synergistic lubricating effect of the Ag and CaF2/BaF2 eutectic. The latter is a chameleon coating that reduces the friction and wear automatically by adjusting the surface chemica
Data Loading...
