Preparation and Tribological Behavior of Ti 2 AlNb/Ag Self-Lubricating Composites
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JMEPEG https://doi.org/10.1007/s11665-020-05075-3
Preparation and Tribological Behavior of Ti2AlNb/Ag Self-Lubricating Composites Wei Wang, Haixiong Zhou, Qingjuan Wang, Ziru Han, and Kuaishe Wang (Submitted January 30, 2020; in revised form July 11, 2020) In this paper, Ti2AlNb-based composites with different concentrations of Ag were fabricated by ball milling and spark plasma sintering (SPS). Microstructural evolution and phase compositions of the composites were further analyzed. The MS-T3001 friction wear tester was used to evaluate the friction performance of the Ag/Ti2AlNb self-lubricating composites. Results showed that the composites exhibit better anti-friction and anti-wear performance comparing with pure Ti2AlNb alloy. As the Ag wt.% increased, the coefficient of friction (COF) and wear rate of the composites were all decreased. Compared with pure Ti2AlNb, the COF and wear rate of Ti2AlNb-15 wt.%Ag self-lubricating composites at room temperature were decreased approximately 42 and 46%, respectively. The self-lubricating mechanisms of the composites were further discussed, and the silver-rich friction film formed on the friction surface under compression stress was regarded as the main anti-friction and anti-wear factors. Keywords
friction and wear, microstructure, self-lubricating mechanism, Ti2AlNb matrix self-lubricating composites
1. Introduction Ti2AlNb-based alloy had become the key materials for using in aero-engines due to its advantages of lightweight, good plasticity at room temperature, high fracture toughness, creep resistance, fatigue and oxidation resistance (Ref 1, 2). However, when Ti-Al-based alloys were used as the high-temperature parts of aero engines, the lubrication and wear resistance were the main factors affecting the reliability and life of the entire system (Ref 3-5). In recent years, a lot of research works have been carried out on the lubrication and wear resistance of Ti-Al based alloys (Ref 6-10). These methods for improving the wear resistance of Ti-Al based alloys mainly contained surface treatment (Ref 11-13) and self-lubricating composite materials (Ref 14-16). However, the surface treatment layer was thin and the life of the lubricating layer was limited. Therefore, the most effective ways to improve the tribological properties of Ti-Al alloys was to develop the metal-based self-lubricating composites. Adding solid lubricants to composite materials can improve the tribological properties of the materials. Muratore et al. (Ref 17) studied the lubrication mechanism of YSZ-Ag-Mo, and the oxidation products between Ag and Mo played an important role in high-temperature lubrication. Shi et al. (Ref 18-21) fabricated a series of self-lubricating composites by SPS including TiAl-Ag-Ti3SiC2, TiAl-Ag-TiB2, TiAl-Ag-Ti2AlC, and TiAl-Ag-BaF2 /CaF2, the results found that Ag has good Wei Wang, Haixiong Zhou, Qingjuan Wang, Ziru Han, and Kuaishe Wang, School of Metallurgy Engineering, XiÕan University of Architecture and Technology, XiÕan 710055, China. Contact e-mails: gackmol@163
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