Preparation Of Molybdenum Disulfide-based Nanolubricants And Investigation Of Their Tribological Properties

Molybdenum disulfide has been used as a solid lubricant for a long history. Withexcellent friction and wear properties under inert or vacuum environments, has been widelystudied because of its unique lamellar structure which enables low shear strength and hencelow friction. However, its short life in humid environment andpoor performance at hightemperatures strongly limit its applications. At the same time, most of the traditionalmodifiers can do harm to the environment. Based on the literature and the conditions in ourlaboratory, we first prepared a modifier L, which can be used as a modifier to modifier thenanoparticles. By adjusting the factor impact on the size and structure, oil soluble MoS2andCu/MoS2nanoparticles were prepared via the in-situ technology. The structure, morphology,and the content of the materials were investigation by XRD, XPS, FEI-SEM, EDX and otherinstruments. The tribological performances of the nanoparticles were used as additives indifferent base oils were evaluated by a four-ball tester. The main contents and research resultsof this thesis are as follows:1. Fabrication of the modifier L, and which were used to modifier the MoS2nanoparticlevia a hydrothermal route and evaluated of their tribological propertiesMany papers studies have proved that the Triton X-100can be used as an organiclubricant. Triton by through reduction and grating can be obtained the modifier L, which wereused to modifier molybdenum disulfide nanoparticles. The syntheses of monodispersed MoS2nanoparticles involve hydrothermal decomposition of salt.The phase composition,morphology, size and chemical structure of as-synthesized MoS2nanoparticles werecharacterized by means of Fourier transform infrared spectrometry (FTIR), X-ray diffraction(XRD), X-ray photoelectron spectroscopy (XPS), High resolution transmission electronmicroscopy (HRTEM). The results of chemical analysis indicate that composition of the materials prepared is very close to MoS2. The tribological properties of as-synthesized MoS2based nanoparticles as a lubricant additive in ester oil were investigation with a four-ballfriction and wear tester. Thechemical states of some typical elements on worn steel surfaceswere analyzed by XPS; the tribological action mechanism of the additives was discussed.Themain reason can be indicate that because of the MoS2nanoparticles with a smaller size are ofhigh surface activity and can be readily deposited on contact surfaces to form a stable andcontinuous protective film. As a result, both the boundary lubricating film and the chemicallyadsorbed and deposited MoS2layers contribute to greatly improve the antiwear behavior andload capacityof ester oil.2. Wet chemistryapproach for the synthesis of MoS2nanoparticles and investigation ofits tribological propertiesMoS2nanoparticles were in-situ synthesized via a simple thermal decomposition methodwith (NH4)2MoS4as the precursor, as well as oleylamine and oleic acid as the surface-cappingagents. The tribological properties of as synthesized nano-MoS2nanolubricants wereevaluated by a four ball tester. Synthetic base oils have been developed initially for theindustrial applications with wider liquid ranges and superior resistance to thermal andoxidative degradation. The tribological properties of capped MoS2nanoparticles were testedby disperse nanoparticles in mineral oil LP, polyalphaolefin PAO, synthetic esters. The resultsdemonstrate that the functional group of modifier can form a competitive adsorption withsynthetic esters on rubbed metal surfaces.3. Preparation of oil-soluble Cu/MoS2nanoparticles and investigation of theirtribological propertiesMonodispersed Cu/MoS2nanoparticles were synthesized via a simple thermaldecomposition method with ATTM and Cu(HCOO)2·4H2O as the MoS2and Cu source, in themeanwhile oleylamine and oley acid as the surface capping agents. The phase composition, morphology, size, and chemical structure of the as-synthesized Cu/MoS2nanoparticles werecharacterized by XRD, HRTEM, and FEI-SEM. The shape-dependent tribological propertiesof as-synthesized nanoparticles as additives were evaluated with a four-ball friction and weartester. It has been found that as-synthesized nanoparticles dispersed in base oil can improvethe lubricating performance.