• J Li

      Articles written in Bulletin of Materials Science

    • Nano-tribological characteristics of TiO2 films on 3-mercaptopropyl trimethoxysilane sulfonated self-assembled monolayer

      J Li X H Sheng

      More Details Abstract Fulltext PDF

      Silane coupling reagent (3-mercaptopropyl trimethoxysilane (MPTS)) was used to prepare twodimensional self-assembled monolayer (SAM) on silicon substrate. The terminal –SH group was in situ oxidized to –SO3H group to endow the film with good chemisorption ability. Then TiO2 thin films were deposited on the oxidized MPTS–SAM to form composite thin films, making use of the chemisorption ability of the –SO3H group. Atomic force microscope (AFM) and contact angle measurements were used to characterize TiO2 films. Adhesive force and friction force of TiO2 thin films and silicon substrate were measured under various applied normal loads and scanning speed of AFM tip. Results showed that the friction force increased with applied normal loads and scanning speed of AFM tip. In order to study the effect of capillary force, tests were performed in various relative humidities. Results showed that the adhesive force of silicon substrate increases with relative humidities and the adhesive force of TiO2 thin films only increases slightly with relative humidity. Research showed that surfaces with more hydrophobic property revealed the lower adhesive and friction forces.

    • Tribological characteristics of self-assembled nanometer film deposited on phosphorylated 3-aminopropyltriethoxysilane

      J Li X Z Li

      More Details Abstract Fulltext PDF

      Thin films deposited on the phosphonate 3-aminopropyltriethoxysilane (APTES) self-assembled monolayer (SAM) were prepared on the hydroxylated silicon substrate by a self-assembling process from specially formulated solution. Chemical compositions of the films and chemical state of the elements were detected by X-ray photoelectron spectrometry (XPS). The thickness of the films was determined with an ellipsometer, while the morphologies and nanotribological properties of the samples were analyzed by means of atomic force microscopy (AFM). As the results, the target film was obtained and reaction might have taken place between the thin films and the silicon substrate. It was also found that the thin films showed the lowest friction and adhesion followed by APTESSAM and phosphorylated APTES-SAM, whereas silicon substrate showed high friction and adhesion. Microscale scratch/wear studies clearly showed that thin films were much more scratch/wear-resistant than the other samples. The superior friction reduction and scratch/wear resistance of thin films may be attributed to low work of adhesion of nonpolar terminal groups and the strong bonding strength between the films and the substrate.

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    • Dr Shanti Swarup Bhatnagar for Science and Technology

      Posted on October 12, 2020

      Prof. Subi Jacob George — Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru
      Chemical Sciences 2020

      Prof. Surajit Dhara — School of Physics, University of Hyderabad, Hyderabad
      Physical Sciences 2020

    • Editorial Note on Continuous Article Publication

      Posted on July 25, 2019

      Click here for Editorial Note on CAP Mode

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