| Wear not only lost a lot of energy,but also caused some damage to the machinery.Therefore,it is necessary to add liquid lubricants to improve the service life of mechanical equipment and reduce maintenance costs.Traditional oil-based lubricants can effectively improve the anti-wear performance and reduce the wear rate of friction pairs.However,the high cost,low thermal conductivity,high flammability,low flash point and environmental pollution of oil-based lubricants affect their wide application.Compared with this,water-based additives have the advantages of low cost,fire resistance,good thermal conductivity and environmental protection.However,water can cause serious corrosion of metal surface,and the low viscosity of water makes it difficult to form elastohydrodynamic lubrication film between friction pairs,which increases the wear rate of friction pairs.Ionic liquid is a good lubricating additive with low melting point,excellent thermal stability and good compatibility with organic compounds,which greatly improves the problem of friction and wear.The tribological properties of water can be improved by using ionic liquid as additive.In the past research,the designed ionic liquids as water-based additives are easy to cause environmental pollution,poor lubrication performance,poor stability,lack of solubility and other problems.At the same time,some ionic liquids containing halogen elements such as tetrafluoroborate,hexafluorophosphate and ionic liquids containing chloride ions are easy to corrode the metal substrate.These problems limit the use of ionic liquids as water-based additives.In order to solve these problems,a series of amino acid type ionic liquids were designed and prepared based on the application of lubricating additives in specific conditions.The designed ionic liquids have good water solubility,excellent friction and wear resistance,good corrosion resistance and low toxicity.The main conclusions are as follows:1.Seven novel ILS(P4444-His,P4444-Ser,P4444-Trp,P4444-Phe,P4444-Lys,P4444-Met,P4444-Cys)have been synthesized and characterized as water-based lubricating additives.As expected,the prepared P4444-His,P4444-Ser,P4444-Trp,P4444-Phe,P4444-Lys,P4444-Met,P4444-Cys significantly enhanced the friction reduction and wear resistance of water-based functional lubricants,and the friction coefficient and wear volume decreased in varying degrees.Among them,P4444-Trp showed excellent friction reduction and anti-wear performance,and the average friction coefficient decreased to about 0.1412.Compared with water,the friction coefficient decreases by 54%and the wear volume decreases by 98%.2.The best amino acid type P4444-Trp ionic liquid was selected,and different concentrations(0.3 wt%,0.5 wt%,1 wt%,2 wt%),different loads(50 N,100 N,150n),and different frequencies(10 Hz,25 Hz,50 N)were investigated It is found that the friction coefficient and wear volume of P4444-Trp ionic liquid decrease with the increase of mass concentration.Under the condition of 1%P4444-Trp,when the frequency increases from 10 Hz to 25 Hz,the friction coefficient and wear volume decrease.We speculate that the formation rate of the friction film is greater than the consumption rate of the friction film.When the frequency reaches a certain value(such as 50 Hz in the experiment)The formation rate of friction film is less than the consumption rate of friction film,which makes the wear volume increase.Under the condition of 1%P4444-Trp,the load was changed.With the increase of load,the friction coefficient decreases and the wear volume increases.The results of mechanism analysis show that the polar elements P and N transfer to the friction interface,participate in the tribochemical reaction and form the tribochemical reaction film.In addition,through the synergistic effect of N-P,the antifriction and antiwear properties of water system were improved.3.The corrosion resistance,biocompatibility and bacteriostasis of amino acid P4444-Trp ionic liquid were investigated.Through the bubble test,QCM test,AFM test and Tafel test,we found that the designed ionic liquid has excellent corrosion resistance,which may be due to the adsorption of ionic liquid on the metal surface.There are imidazole and benzene rings in ionic liquids,and there are many isolated pair electrons in the field,and the density of electron cloud is large.The ion liquid can be used to coordinate with the metal in the space d orbit,form coordination bond,block the direct contact between metal and water,improve the corrosion resistance of water-based lubricant.Through bacteriostatic test and biocompatibility test,we found that the designed ionic liquid has very low toxicity to plants,and has played an excellent role in Quaternary phosphorus salt The different germicidal effect and the inhibition effect on bacterial growth are obvious,which can help to eliminate the corrosion of the microorganism to the metal substrate. |
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