Preparation Of S,N-containing Borate Ester And Study On Tribological Characterisatics

Organic borate ester possesses good anti-wear,friction-reducing properties,nontoxic and degradation easily,so it is a kind of promising green lubricating oil additives in the future.At present,organic borate ester as a new type of green lubricating oil additive has caused wide public concern.However,the hydrolytic stability of borate ester is greatly limits the borate ester as lubricating oil additives used in industrial gears,automotive engine and hydraulic system.Therefore,in the view of improving the tribological performance of borate ester and improving the hydrolytic stability of borate ester has important significance for the development of green lubricating oil additives.In this work,from the perspective of molecular design,On the basis that the benzene ring could share the electrons with the vacant p-orbital of boron to form the P-π conjugate system,two new types of organic borate molecules,SNBP1 and SNBP2 were synthesized.The structures of these three synthesized borate esters were characterized using Fourier infrared spectrometer(IR)and element analyzer.Results show that the synthesized of three kinds of borate esters consistent with the target molecules.The oil-soluble property,hydrolytic stability and copper corrosion level of synthesized of three kinds of organic borate esters contaiong nitrogen and sulfur,SNBP1 and SNBP2were determined respectively.Results show that the synthesized of three organic borate esters as additives in poly alpha olefin(PAO)have good solubility;all these three kinds of organic borate esters havel high hydrolysis stability and copper corrosion property.The maximum non-seizure load(PB),friction coefficient and wear scar diameter(WSD)of the base oil lubricated by the synthesized borate esters,SNBPl and SNBP2 were characterisized by the MRS-10 type four-ball tester respectively.The results showed that the carrying capacity,antiwear additives anti-friction performance decreases with the increase of alkyl structure,and molecules of sulfur content in most of the SNBP1 and SNBP2 showed the best tribological performance.Compared with the base oil,the PB value lubricated by 2%SNBP1 and 2%SNBP2 were respectively increased by 129.6%and 116.8%.and the WSD value and friction coefficient were readuced by 30.4%and 25%respectively,compared with the base oil,the PB value lubricated by 2.5%SNBP1 and 2.5%SNBP2.The worn surfaces of the steel balls were analyzed by scanning electron microscope(SEM/EDS)and X-ray photoelectron spectroscopy(XPS)respectively.Results show that the surfaces of the steel balls lubricated by these three synthesized borate esters are smoother than the steel balls lubricated by base oil.At the same time,during the course of friction,the synthesized borate esters were reacted with the steel surface and formed a complex low shear strength chemical reaction film containing FeSx and FeSO4 on the surface of the steel balls.A novel kind of vulcanized butyl oleate(denoted SBO)was synthesized and used as lubricating additive mixed with synthetic SNBP1 and SNBP2.The tribological properties of the mixed additives in PAO under different mass fraction was evaluated.The results showed that adding 1.0%SBO mixed with 1.5%SNBP1 and SNBP2.Respectively,the WSD value decrease d by 23.4%and 22.0%respectively.Compared with the base oil,the PB value lubricated by 2%addtive were respectively increased by 132%and 124%.