Tribological behavior of double-glow plasma Zirconium-Yttrium alloying on γ-TiAl
Cong Huang, Pingze Zhang*, Dongbo Wei, Xiangfei Wei, Xiaohu Chen and Feng Ding
(College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 211100, China)
* Corresponding author: pzzhang_nuaa@126.com
Abstract: A Zr-Y alloyed layer was prepared onto the surface of γ-TiAl using double-glow plasma surface alloying technique (DG technique). The results showed that the Zr-Y alloyed layer was comprised of deposited sub-layer and diffused sub-layer, with a total layer thickness of about 20μm. The nano-indentation test result showed that the nano-hardness of Zr-Y alloyed layer was 2.35 times that of γ-TiAl. The scratch test …show more content…
2(a). It could be found that the surface demonstrated a dense and homogeneous structure. The fine and closely-packed grains were attributed to the existence of yttrium, which segregated at the boundaries and accelerated the formation of the grain structure. In Fig. 2(b), surface chemical composition of zirconium and yttrium is presented. However, the composition of the coating deviated from that of the sputtering targets. The result not only related to the different sputtering yields of the zirconium and yttrium19, but also to the separate diffusion velocity at γ-TiAl. Zirconium has the same lattice structure and similar to the atomic radius with titanium, which easy to form the substitutional solid solution. It is beneficial to the process of diffusing into the …show more content…
The acoustic emission value varied with the vertical load is shown in Fig. 6(a). At a certain critical load, the coating would start to fail, which was identified as a coating critical failure load. The noise generated in succession with the increase of load since 75 N, which was the critical load for Zr-Y alloyed layer. This strong adhesion was attributed to the existence of the diffusion layer.
3.4 Wear properties
The friction coefficients of γ-TiAl and Zr-Y alloyed layer varied with sliding distance at ambient temperature and 500°C are shown in Fig. 7. It could be seen from Fig.7 that no matter at ambient temperature or 500°C, the friction coefficients of Zr-Y alloyed layer were much smaller and smoother than the γ-TiAl, which was due to the high hardness. However, the friction coefficients increased as the temperature increased27. As shown in Fig. 7(b), the friction coefficient of the Zr-Y alloyed layer became fluctuant but still much smaller compared with the γ-TiAl. Effect of temperature on friction coefficient was closely related to the change in surface layer, which indicated the friction mechanism may change with the change of the
Cong Huang, Pingze Zhang*, Dongbo Wei, Xiangfei Wei, Xiaohu Chen and Feng Ding
(College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 211100, China)
* Corresponding author: pzzhang_nuaa@126.com
Abstract: A Zr-Y alloyed layer was prepared onto the surface of γ-TiAl using double-glow plasma surface alloying technique (DG technique). The results showed that the Zr-Y alloyed layer was comprised of deposited sub-layer and diffused sub-layer, with a total layer thickness of about 20μm. The nano-indentation test result showed that the nano-hardness of Zr-Y alloyed layer was 2.35 times that of γ-TiAl. The scratch test …show more content…
2(a). It could be found that the surface demonstrated a dense and homogeneous structure. The fine and closely-packed grains were attributed to the existence of yttrium, which segregated at the boundaries and accelerated the formation of the grain structure. In Fig. 2(b), surface chemical composition of zirconium and yttrium is presented. However, the composition of the coating deviated from that of the sputtering targets. The result not only related to the different sputtering yields of the zirconium and yttrium19, but also to the separate diffusion velocity at γ-TiAl. Zirconium has the same lattice structure and similar to the atomic radius with titanium, which easy to form the substitutional solid solution. It is beneficial to the process of diffusing into the …show more content…
The acoustic emission value varied with the vertical load is shown in Fig. 6(a). At a certain critical load, the coating would start to fail, which was identified as a coating critical failure load. The noise generated in succession with the increase of load since 75 N, which was the critical load for Zr-Y alloyed layer. This strong adhesion was attributed to the existence of the diffusion layer.
3.4 Wear properties
The friction coefficients of γ-TiAl and Zr-Y alloyed layer varied with sliding distance at ambient temperature and 500°C are shown in Fig. 7. It could be seen from Fig.7 that no matter at ambient temperature or 500°C, the friction coefficients of Zr-Y alloyed layer were much smaller and smoother than the γ-TiAl, which was due to the high hardness. However, the friction coefficients increased as the temperature increased27. As shown in Fig. 7(b), the friction coefficient of the Zr-Y alloyed layer became fluctuant but still much smaller compared with the γ-TiAl. Effect of temperature on friction coefficient was closely related to the change in surface layer, which indicated the friction mechanism may change with the change of the