Fluorescence Analysis On Degradation Process Of Lubricant Base Oils

Lubrication is the most effective way to reduce friction and wear in mechanical system,which provides an important guarantee for the normal operation of mechanical equipment.Lubricants are known as "industrial blood" as the most important lubricating materials.The actual applications show that the working state of lubricants directly affect its performance.To ensure the efficiency and stability of the mechanical equipment,it is very important to master the real-time state of lubricants.Considering the advantages of rapidity,sensitivity,easy operation,easy integration online and visualization,lubricants have been widely used in biology,medicine,chemistry and industry fields in recent years.Therefore,to evaluate the degradation degree rapidly and effectively through the fluorescence signal shifting in the process of the lubricants' degradation,this dissertation reports a series of relevant research about the pyrolysis of base oils.Detailed results are shown below:1.Taking the Poly ?-olefin(PAO)synthetic base oils as the research object.A series of lubricants with different degradation degree were obtained by high temperature oxidation in artificial atmosphere of 200?.The prepared oil samples were characterized in detail by Fourier transform infrared spectroscopy(FTIR),ultraviolet spectroscopy(UV-Vis),Excitation-emission matrix fluorescence spectroscopy(EEM),viscosity measurement and acid value potential determination measurements.In the process of high temperature oxidation,a series of chemical changes occurred in PAO base oils,resulting in a amounts of oxidation products such as alcohols,aldehydes,ketones and carboxylic acids.The correlation between the modulus of florescence peak vector (?) defined by the maximum value of the EEM spectra and degradation time of lubricants shows that the module ?(?)? of oil sample increases with the increase of degradation time.At the same time,it was also positively correlated with the viscosity and acid value of lubricants.It illustrates that ?(?)? is a feasible parameter for monitoring the degradation of lubricants.2.Taking several common ester base oils as the research object,the diester(DA 51),pentaerythritol ester(PE 451)and trimethyl-olpropane ester(TMP 108A)oil samples with different degradation degrees were prepared by high temperature oxidation simulation.And using FTIR,UV-Vis,EEM,acid value potentiometric titration,viscosity determination and other techniques to characterized in detail.Compared with PAO base oils,ester base oils have richer functional groups and better high temperature resistance.Fluorescence analysis showed that with the increase of oxidation time,the fluorescence intensity and emission wavelength of the oil samples changed,the fluorescence intensity increased first and then decreased,and the emission wavelength of the oil samples showed different degrees of red shift.By EEM spectra of defines two vectors (?) and 9)(?).Calculated vector modules and set up the correlation of the degradation time.The fluorescence shifting vector 9)(?) presents a better correlation between degradation time.At the same time,the correlation between the viscosity and acid value of lubricants and fluorescence parameters was also analyzed.