Study On Preparation And Tribological Properties Of Serpentine-B/La Composite Powder

The research used the serpentine of Xiuyan in Liaoning as the main material.On the base of researching the phase transformation,the composite powder was synthesized by sol-gel method. The tribological properties of the composite power have been studied.B₂O₃ was prepared with C₁₂H₂₇BO₃ as precursor, C₂H₅OH as solvent, and PEG as disposition by sol-gel method. The nanocrystalline B₂O₃ powders can be obtained with the grain size of 50nm, low aggregates and fine grain distribution after calcinated at 450℃. The density is 1.846g/cm³. La（OH）₃was prepared with C₆H₈O₇and La（NO）3 in the molar ratio of 1:1 and the pH value keeping neutral by citrate sol-gel method. La（NO）3 powders can be obtained with the grain size of 20nm, the density of 1.22g/cm³ after calcinated at 700℃. Serpentine-B/La composite powder was prepared by adding serpentine in the sol-gel process and citric acid sol-gel self-propagating combustion process.The best surface modification of composite powder have been confirmed by testing wetting angle, activation index and sedimentation rate in hexahydrobenzene. The result shows that the best amount of Span60 are 6%,10% and50% for serpentine,serpentine through heat treatment at 450℃and serpentine through heat treatment at 700℃. The surface properties and structure of serpentine was changed and the surface activity was decreased by heat treatment. The amount of Span60 was increase with temperature rise.The tribological properties have been evaluated by four-ball friction tester,gear friction tester, Tim-ken tester and air compressor tester. The result shows that the composite powder have good anti-wear and friction-reducing properties as the additive in lubricating oil.In four-ball friction test compared with base oil the friction coefficient of La（OH）3-serpentine and La（OH）₃-B₂O₃-serpentine reduced by 20.7% and 22.14%. The energy consumption reduced by about 10%, the noise reduced by about 5% in gear friction test. In air compressor test compared with base oil the energy consumption reduced by 3.63%-6.95%, the temperature of oil reduced by 0.76%-5.18% The graphite and diamond-like film were formate on the surface of friction pair. It would be catalysis of rare earth elements. The good abrasion and energy-saving effect coefficient of composite powder are related to microparticles-supporting effects of nanoparticles, interlayer-gliding in serpentine and catalysis of rare earth elements.