Studies On Preparation And Performance Of Nanometer Layered Mno₂

Oil additive is a kind of material with good antiwear properties, high load-carrying capacity and self-repair of the worn surface. Nanoparticles because of its special nature can improve the oil tribological properties as oil additives. The supercapacitors is a new storage containers whose capability between traditional capacitor and battery capacity. It contains high-power, energy density and long cycle life. The promising application of supercapacitors in the fields such as mobile telecommnication, consumer electronics, electric cehicle, aviation and national defense, has been attention through out the world.Strong oxidant KMnO4 was used to effect the MnCl2 and alkali solution's suspended solids in the redox reaction. Nanometer layered MnO2 was prepared by using hydrothermal method and liquid precipitation method. The effects of reactants, temperature, time and surface chemical treatments on products were investigated. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to determine the crystal structure and morphology of nanoparticles. It was found that the main phase of as synthesized powder was rutile structure ofδ-MnO2—Syn.Birnessite Na0.58Mn204·1.5H2O, KMn2O4·1.4H2O.Sedimentation experiment and four-ball wear testing were used to investigate the tribology properties. And optical microscopy and SEM were used to observed the surface of steel-steel friction pair. The results show that MnO2 nanoparticles had no effect on the carrying capacity of lubricating oil. But it can reduce the wear scar diameter and has good antiwear ability. The modified MnO2 have better tribological properties. When the concentration of MnO2 nanoparticles which was modified by H2SO4 and prepared by aging, is 0.1%, the wear scar diameter decline largest and decreases from 670.3μm to 441.7μm. When the concentration of MnO2 nanoparticles which is modified by SDS and prepared by hydrothermal synthesis, is 0.75%, friction coefficient decreases from 0.0073 to 0.0058.The cyclic voltammetry (CV) testing and BET surface area analysis are used to invest the impact of layered manganese dioxide's microstructure on the electrochemical capacitance. The CV testing shows that the MnO2 electrode material's capacitance in the Na2SO4 solution has excellent capacitance characteristics. The discharge capacity of the MnO2 electrode which is prepared by aging and modified by H2SO4, is 263.6 F/g when the scan speed is 5mV/s. Even the lowest discharge capacity of MnO2 which is prepared by hydrothermal synthesis and modified by H2SO4, is 203.9 F/g at 5mV/s scan speed. The results show that capacitance data shows that the discharge capacity of MnO2 increases with the average adsorption pore diameter.