Tribological evaluation on Ni3Al-based alloy and its composites under unlubricated wear condition

Abstract

Friction coefficients and specific wear rates of an existed Ni3Al-based NAC-alloy with composition of Ni-18.8Al-10.7Fe-0.5Mn-0.5Ti-0.2B (at.%) and its composites reinforced by 6 vol.% Cr3C2- and 6 vol.% MnS-particles, respectively were investigated for the initial understanding of sliding wear behaviors of the materials under unlubricated condition. The testing materials were prepared by hot isostatic pressing (HIP) process. Pin-on-Disk (POD) measurements were carried out under room temperature condition. A commercial vermicular graphite cast iron was selected as a reference material. The disks used in this study were made of a grey cast iron as cylinder liner materials of ship engines. The contact pressure of 2.83 MPa and 5.66 MPa were applied in POD tests. The experimental results revealed that the monolithic NAC- alloy has the almost same values of friction coefficient and specific wear rate under the testing condition as compared to a commercial vermicular cast iron. The wear mechanism is probably conducted to its intrinsic deformation mechanism of the Ni3Al-type of intermetallics. For the composite with 6 vol.% hard Cr3C2-particle, wear rate was reduced on both sides of pin and disk up to 50%, comparing to the single phase NAC-alloy at a high load of 5.66 MPa. By an addition of 6 vol.% soft MnS-particle, wear rate of the disk was dramatically decreased and friction coefficient also slightly reduced on the test. But, the wear rate of pin is maintaining as the same level as the monolithic NAC-alloy and the reference vermicular cast iron. The present investigation recognized that it will be potential to develop Ni3Al-matrix composites reinforced by hard Cr3C2- and/or soft MnS-particles for a certain tribological applications, especially other excellent physical, chemical and mechanical properties of the Ni3Al-based intermetallic materials were considered.