Influence of C content on the structure, mechanical and tribological properties of CrAlCN films in air and water-based c
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Influence of C content on the structure, mechanical and tribological properties of CrAlCN films in air and water‑based cutting fluid Maoda Zhang1 · Fei Zhou1 · Haotian Fang1 · Zhiwei Wu2 Received: 21 April 2020 / Accepted: 30 June 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract CrAlCN films with different C concentrations ranging from 0 to 75.3 at% were deposited on AISI M2 high-speed steels using magnetron sputtering. Besides their structure and mechanical properties, the tribological performances of CrAlCN films in air and water-based cutting fluid were also compared. The results showed that CrAlN film consisted of most fcc-CrN/Cr2N and less fcc-AlN. After C incorporation, the amount of fcc-CrN/Cr2N in CrAlCN films still kept stable relatively in addition to the more formation of amorphous carbon (a-C). As a consequence, the hardness of CrAlCN films increased firstly to the highest value of 1095.2 ± 56.8 HV0.01 at the C content of 50.3 at%, but then declined slightly. However, the critical loads of CrAlCN films decreased gradually from 14.8 ± 2.7 to 7.9 ± 0.9 N as the C content increased from 0 to75.3 at%. High C content in CrAlCN films resulted in the more formation of a-C, thus contributing to a decrease in friction coefficient of CrAlCN/SUS440C tribopairs both in the air (from 1.06 to 0.47) and water-based cutting fluid (from 0.60 to 0.11). In the meantime, the CrAlCN film containing the highest C content (75.3 at%) showed the minimum wear rate because of the lowest friction coefficient in both friction environments. As compared with the tribological performances of CrAlCN films in air, the CrAlCN films were more suitable to be used in water-based cutting fluid condition. Keywords CrAlCN films · C concentration · Mechanical properties · Friction · Wear
1 Introduction As the first-generation protective film, CrN films have been widely used as a wear-resistant protective coating on the surface of molds and cutting tools due to their good mechanical properties and wear resistance [1–5]. However, the medium hardness of CrN films (about 15 GPa) hinders their application in the processing of modern superhard materials. Therefore, to increase the hardness of the CrN film, alloy elements must be doped in the CrN film. For example, a small amount of Al can be added to the CrN film to obtain a CrAlN film with high hardness [6–12]. When the content of Al was 35 at%, the CrAlN thin films presented a hardness of up to 36.4 GPa [13]. In addition, because the * Fei Zhou [email protected] 1
National Key Laboratory of Helicopter Transmission Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
College of Mechanical Engineering, Nanjing Institute of Industry Technology, Nanjing 210023, China
2
high-temperature oxidation temperature of the CrAlN film was as high as 1173 K, the CrAlN film had excellent hightemperature oxidation resistance [14–20]. Ren et al. reported that as compared with the CrN film, the incorporation of Al led to the formation of CrAlN
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