Tribological properties of Ni3Al matrix self-lubricating composites with a gradient composite structure prepared by laser melt deposition

Abstract

As the contact part of metal-matrix self-lubricating composites during sliding friction, the friction interface layer directly affects the tribological performance of the material. However, the formation of the friction interface layer with outstanding tribological performance is limited by the friction conditions during sliding friction. To address this problem, based on the antifriction and wear resistance mechanisms of the in situ formed friction interface layer of Ni3Al matrix self-lubricating composites (NMSCs) with homogeneous solid lubricant, Ni3Al matrix self-lubricating composites with a gradient composite structure (Ni3Al-GCS) were prepared via laser melt deposition, in which each component layer contained different contents of Sn-Ag-Cu and Ti3SiC2. Dry sliding friction tests of Ni3Al-GCS against GCr15 steel balls were performed under different loading conditions. The results showed that the tribological performances of Ni3Al-GCS in the range of 4–16 N were less affected by the variation of the loading conditions than those of NMSCs. The gradient composite structure of Ni3Al-GCS could reduce the dependence of the tribological behavior on the friction conditions, resulting in excellent antifriction and wear resistance of Ni3Al-GCS in a wide load range. In addition, the gradient composite structure could reduce the sliding contact damage of the friction contact surface of Ni3Al-GCS, and contribute to the formation of friction interface layer rich in the lubrication phase and oxides, thus improving the tribological performance of Ni3Al-GCS during sliding friction. This study provides new approaches for the tribological design of metal-matrix self-lubricating composites in a wide load range.