Synthesis And Tribological Properties Of Surface Modified Heteropolyoxometallate Nanoparticles

In this thesis, surface modified (NH4)3PMo12O40 nanoparticles were prepared and characterized. The tribological properties and tribochemical reaction of these nanoparticles as oil additives were investigated. The main research work is as follows: 1. Synthesis, Structure and Tribological Properties of Quaternary Ammonium Modified (NH4)3PMo12O40 Nanoparticles Surface-modified (NH4)3PMo12O40 nanoparticles were synthesized in the mixture solvent of water-ethanol with the surface modification agent of quaternary ammonium. The formation mechanism of these particles was proposed. Some analytical tools such as TEM XRD FTIR DSC&TG were used to characterize the structure of surface modified (NH4)3PMonO4o nanoparticles. The results show that the quaternary ammonium modified (NH4)3PMoi2O4o nanoparticles exhibit good dispersity in the organic solvent and base oil. The mean size of these nanopartitcles with Keggin structure is about 20 nm. The decomposition temperature of (NH4)3PMoi2O4o is approximate 300 0C. The tribological properties of nanoparticles as oil additive were investigated with a four-ball tribometer. The result show that they are of good anti-wear and reduce-friction properties at mid-low applied load. They can improve the load-carrying capacity of base oil (Liquid Paraffin) remarkably. The inorganic VI nanoparticle core plays main role to reduce wear. SEM and XPS analyses of the worn steel surface illustrated that the tribological properties are attributed to the chemical reaction boundary film consisting Fe203, (NH4)2Mo2O7 and [P207]抙 2. Synthesis, Structure and Tribological Properties of Stearic Acid Modified (NH43PMo12O40 Nanoparticles Stearic acid modified (NH4)3PMoi2O4o nanoparticles were synthesized in the mixture solvent of water 梕thanol. Some analytical tools such as TEM.. XRD. FTIR~. DSC and TO were used to characterize the structure of the nanoparticles, and their antiwear properties were investigated using a four-ball tribometer. The results show that the modified particles?average size is 15 nm, they have a uniform grain distribution. But the unmodified particles are easy to agglomerate and their average size is above 1 1.~ m. The nanoparticles exhibit good dipersity in the organic solvent, they have very good anti wear and reduce friction properties at the mid-low applied load. Stearic acid can improve the tribological properties of (NH4)3PMo12O4o. The lubricant effect was attributed to the chemical reaction boundary film consisting (NI-Lt)2Mo2O7, MoO3 and Fe203.