Effect of dry sliding wear conditions on a vacuum induction melted Ni alloy

Abstract

▶ The microstructure of VIM Ni alloys contains γ-Ni, Ni 3 Si, Ni 3 B, Cr 7 C 3 , and CrB. Also, Ni 3 Si particles were scattered inside the γ-Ni solid solution, Ni 3 B and dendrite Ni 3 Si appeared in the lamellar structures, and Cr 7 C 3 and CrB were scattered in the lamellar structures of Ni 3 B and dendrite Ni 3 Si. Cr 7 C 3 and CrB were more wear resistant compared to other phases. ▶ The wear loss of VIM Ni alloys was lower when the sliding velocity was 0.1 m/s compared to when the velocity was 0.7 m/s. This is due to the fact that the ability of wear at 0.1 m/s is already lower than that at 0.7 m/s. ▶ As the sliding distance increases, the worn surface of 0.1 m/s forms a continuous oxidation layer that protects the original surface. On the contrary, tumorous oxides that result in delamination form on the worn surface of 0.7 m/s. Although this also happens in the case of 0.1 m/s when sliding distance reaches 10,000 m, the quantity of wear loss is still smaller than that in the case of 0.7 m/s. The experiment described in this paper used vacuum induction melting (VIM) to coat Ni alloyNi alloy onto AISI 4140 steel. X-ray diffraction (XRD), scanning electron microscope (SEM), electron probe micro analyzer (EPMA), and transmission electron microscope (TEM) were used to identify the different phases of VIM Ni alloyNi alloys. Then, a ball-on-disc system and different dry sliding wear conditions were used to test VIM Ni alloyNi alloys. Results indicate that Ni 3 Si particles were scattered inside the γ-Ni solid solution, Ni 3 B and dendrite Ni 3 Si appeared in the lamellar structures, and Cr 7 C 3 and CrB were scattered in the lamellar structures of Ni 3 B and dendrite Ni 3 Si. Cr 7 C 3 and CrB were more wear resistant compared to other phases. The wear loss of VIM Ni alloys was lower when the sliding velocity was 0.1 m/s compared to when the velocity was 0.7 m/s. In the former case, the formation of a continuous oxidation layer protected the original surface from direct wear. A further increase in sliding distance caused, in both the cases, the formation of tumorous oxides, which led to delamination. Regardless, wear loss at 0.1 m/s was still lower than at 0.7 m/s.