Preparation Of Water-soluble Molybdenum Disulfide Nanoparticles And Characterization As Well As Investigation Of The Tribological Behavior

This thesis focuses on the preparation of nanoscale MoS2 particulates and characterization as well as evaluation of tribological behavior of the product as water-dispersible lubricant additive. The main research contents and results are as follows:1. Preparation of molybdenum disulfide in the absence of reducing agent and characterization as well as investigation of its tribological behaviorAmmonium tetrathiomolybdate (ATTM) prepared at our lab was used as the starting material to prepare nanoscale molybdenum disulfide in aqueous solution at relatively low temperature in the absence of reducing agent. The microstructure of the product was characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS); and its photo absorption behavior was evaluated by means of ultraviolet-visible light absorption spectrometry (UV-Vis). Moreover, the tribological behavior of the product as water-dispersible lubricant additive was evaluated by using a four-ball friction and wear tester. Results show that molybdenum disulfide prepared by using this route appears as spherical particles with severe agglomeration. It can be well dispersed in water and ethanol, and its dispersion in water shows better friction-reducing and antiwear behavior than pure water.2. Preparation of molybdenum disulfide via reduction of ammonium tetrathiomolybdate by hydrazine hydrate and characterization as well as investigation of tribological behaviorMolybdenum disulfide was prepared via reduction of ammonium tetrathiomolybdate by 80% (mass fraction) hydrazine hydrate. The microstructure of the product was characterized by means of XRD, TEM, and XPS; Besides, the tribological behavior of the product dispersed in distilled water was evaluated by using a four-ball friction and wear tester. It has been found that molybdenum disulfide prepared by using this route is block-shaped and possesses poor dispersibility in water and ethanol; but its dispersion in water shows slightly better tribological properties than pure water. 3. Preparation of molybdenum disulfide via reduction of ammonium tetrathiomolybdate by ethylene glycol and characterization as well as investigation of tribological behaviorNanoscale molybdenum disulfide was prepared via reduction of ammonium tetrathiomolybdate by reducer ethylene glycol. The microstructure of the product was characterized by means of XRD, TEM, and XPS; At the same time, the tribological behavior of the product dispersed in distilled water was evaluated by using a four-ball friction and wear tester. Results indicate that molybdenum disulfide obtained by using this route appears as spherical particles and has good dispersion in water and ethanol. More importantly, it can effectively improve the friction-reducing, antiwear, and extreme pressure properties of distilled water, showing promising potential as a water-dispersible lubricant additive.