Preparation Of Lubricating Grease Containing Nano Silica And Research On Its Properties

Lubricating grease has wide applications in the bearing industry, its amountaccounts for80%of lubricants in rolling bearings, accounting for20%in slid ingbearings.Base oil, thickener and additives are the three components of grease,baseoil accounts for65to95%of total volume,thickener accounts for5²5%, additivesaccount for0¹0%, all of them affect properties of lubricating grease.In the actualproduction, the properties include extreme pressure, anti-fatigue, corrosionresistance, etc. Although the proportion of additives is small, they are various, andhave the greatest effect of changing grease properties, therefore, grease additivesresearch has important theoretical and practical significance.Because of its size effect, nanomaterials have some properties of traditionalmaterials do not, so nanomaterials are hot issue of grease additives research.Nano-SiO₂is tetrahedron-layered structure,easy to produce sliding between layers,hard and sma ll particle size, good properties at high temperature, thixotropy,nontoxic, tasteless, no pollution, hese unique features make it very suitable asadditives to improve the properties of grease.Based on the actual demands of thefie ld of lubrication.This paper used grease containing nano-SiO₂as the object ofresearch to investigate the preparation and properties.Completed the modified of nano-SiO₂and Preparation of lubricating greasecontaining modification nano-SiO₂. This paper use silane coupling agent graft tomodify nano-SiO₂, the purpose is making nano-SiO₂oleophilic and easy to disperse.The modified nano-SiO₂were characterized, the best ratio of quality percentage ofsilane coupling agent is1.5%. Grease containing modified nano-SiO₂is preparedand nano-SiO₂was evenly dispersed.At the same time the grease properties affectedby nano-SiO₂in physical and chemical was analyze.Viscosity-shear rate model involving nano-content and temperature wasestablished. Flow curves of grease containing nano-SiO₂fitted Herschel-Bulkleymodel. In this paper, through regressing experimental data based onHerschel-Bulk ley model, we considered the impact of nano-content andtemperature, establishing new viscosity-shear rate model involving nano-content Wand temperature T.Test results showed the model’s accuracy is higher than theHerschel-Bulk ley model. Viscosity-shear rate model was applicable to situation thatnano-content was less than5%, temperature less than80℃.It expanded the application scope of thixotropic model. Based on the existingmodel, this paper established segmentation using thixotropic model, the modelmatches well with the experimental data. Viscoelastic mechanical model was established. The two models were applicable to3#lithium grease and7014lubricating grease containing nano-SiO₂.Startup characteristics of grease were investigated. First analys is of nano-SiO₂on the impact of friction torque start, nano-SiO₂content is the main factorsaffecting the start friction torque by range analysis of orthogonal experiment. Withthe increased use of nano-additives increase the friction torque start, Yield stress,too. Start friction torques of7014lubricating grease series are all much smallerthan that of3#lithium grease series.The vibration properties of grease were evaluated with spectrum analysismethod, the results showed spectrum intuitively reflected change between peak andfrequency after adding nano-SiO₂. Compared with characteristic frequency of thebearings and system frequency of bearings without grease, by studying peak, mean,and frequency of grease with different nano-content, we found frequency associatedwith nano-SiO₂content.Low frequency part of grease after adding nano-SiO₂hadlittle change, vibration signals of the3#+3wt%SiO₂and7014+1wt%SiO₂at IF partwere relatively stable, vibration signals of high frequency part were amplified afteradding nano-SiO₂.Lubricating properties and anti-contact fatigue properties of grease was investigated with four-ball mate of friction and wear tester and Contact fatigue tester.Analysis results concluded that friction coefficient of3#+3wt%SiO₂and7014+5wt%SiO₂decreased, wear scar diameter declined and wear scar surface was shallowand uniform.Contact fatigue test results showed working life of3#+3wt%SiO₂and7014+1wt%SiO₂was longest.It could be seen from SEM results that wear surface of3#+3wt%SiO₂was smooth, no furrow, no Adhesion loss.It was believed fromanalys is that on the interface, nano-SiO₂formed deposition film,chemical reactionfilm, ball effect and grain size effect.