Browsing by Author "Kong, Fanlin"
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- Deciphering the mechanical strengthening mechanism: Soft metal doping in ceramic matrices: A case study of TiN-Ag filmsPublication . Luan, Jing; Kong, Fanlin; Xu, Junhua; Fernandes, Filipe; Evaristo, Manuel; Dong, Songtao; Cavaleiro, Albano; Ju, Hongbo; Fernandes, FilipeSoft metals have been widely added into ceramic-based films for fully meeting the demanding requirements of green tribological applications. However, the resulting considerable increase of the mechanical strength by adding a soft metal below 5 at.%, which reversed the rule-of-mixture, was still not fully revealed. In this paper, a case study of TiN-Ag films was carried out to investigate the strengthening mechanism induced by adding soft metal in TiN-Ag composite/multilayered films deposited by magnetron sputtering. The results showed that dual-phases of fcc-TiN and fcc-Ag co-existed in the composite films with the Ag particles embedded in the matrix. In some areas of the Ag particles, with a size below 4 nm, epitaxial growth with the TiN template was detected, which obliged the lattice to be distorted and shrunken. Consequently, both hardness and elastic modulus were enhanced from 21 and 236 GPa, for the reference TiN film, to 26 and 323 GPa for the TiN-Ag composite film with 2.4 at.% Ag. The possibility of having the epitaxial growth of Ag within TiN were also confirmed by designing a TiN/Ag multilayered film with an Ag layer thickness of ∼3 nm.
- Design and magnetron sputtering of nanomultilayered W2N/Ag-SiNx films: Microstructural insights and optimized self-lubricant properties from room temperature to 500 ◦CPublication . Luan, Jing; Kong, Fanlin; Evaristo, Manuel; Fernandes, Filipe; Zhou, Yazhou; Cavaleiro, Albano; Ju, Hongbo; Fernandes, FilipeNovel multilayered films were engineered by integrating W2N and Ag-SiNx layers in a multilayer structure to obtain improved hardness and tribological properties. The films were fabricated by alternating magnetron sputtering, depositing 40 nm layers of W2N with varying thickness of Ag-SiNx layers varying in thickness from 4 to 20 nm. The effect of the increase thickness of the Ag-SiNx layers in the films microstructure and tribological properties were accessed. Tribological experiments were conducted at room temperature (RT), 500 °C, and RT-500 °C cycling conditions. The results revealed the production of a multilayered structure comprising single fcc-W2N layers interspersed with dual-phase layers consisting of fcc-Ag and amorphous SiNx phases. Tribological results indicated an improvement in the tribological performance with increase thickness of the Ag-SiNx layer up to 12 nm. The tribo-synergistic/combined action of both W2N and Ag-SiNx layers, along with the presence of layered lubricant tribo-phases of WO3 and Ag2WO4, showcased the pivot role in reducing friction and enhancing wear resistance. The optimized multilayered film, featuring a 12 nm Ag-SiNx layer, demonstrated exceptional tribological properties under temperature-cycling from RT to 500 °C.