Study Of Nano-borate Additives Based On Marine Cylineder Oil

Nano-borate additives have excellent tribological properties,receiving more and more attention; The introduction of nano-borate additives into marine cylinder oil has great significance to ensure the normal operation of marine diesel engine and maintain safe navigation of the ships.In this paper, we select lauric acid sodium salt(LASS) and cetyl trimethyl ammonium bromide(CTAB) mixed surface-modifier and solsperse17000 super dispersant as the ball-milling process control agents, and prepare four kinds of surface-modified nano-borate additives by plasma-assisted ball milling method and ordinary ball milling method whcih have different milling time.And then we detect the dispersion, the physical and chemical properties and the tribological performance of nano-borate additives dispersed in the DCA 5040 marine cylinder oil.X-ray diffraction analysis showed that borate crystallinity with the increase in milling time first increase and then decrease, there is no change in the crystal structure of borate.Using laser microscope and scanning electron microscopy(SEM) to observe nano-borate additives find that plasma-assisted ball milling method could efficiently prepare surface-modified nano-borate additives which have smaller and uniform particle size.When use LASS and CTAB as surface-modifier,the plasma can improve the ball milling efficiency of additive particles.When use super dispersant as surface-modifier,the plasma have no obvious effect on the ball milling efficiency of additive particles.Super dispersant can better prevent additive particles reunion than LASS and CTAB.Infrared spectroscopy(IR) anaiysis showed that the nano-borate addtives prepared by plasma-assisted ball milling method are coated uniformly by surface-modifier.The nano-borate addtives are tested by gravity sedimentation method.The results indicated that When use LASS and CTAB as surface-modifier,the nano-borate addtives plasma-assisted ball milling 3h and ordinary ball milling 5h have best dispersion stability,Other additives appear different height stratification because of surface-modifiers’ steric sabilization. When use super dispersant as surface-modifier,the nano-borate addtives plasma-assisted ball milling 3h and ordinary ball milling 5h、8h have best dispersion stability,Other additives don’t appear different height stratification because of steric sabilization and support action of super dispersant,only appear a small amount of floc;This indicates that the super dispersant improves the dispersion stability of additives.Low molecular weight polyisobutylene can also produce support action in the cylinder oil.The nano-borate addtives are tested by the physical and chemical properties and the results conform to Q/SY RH2016-2001 marine system oil standard.The tribological properties are tested on nano-borate additives.The results indicated that nano-borate addtives which are modified by LASS and CTAB plasma-assisted ball milling 3h and are modified by super dispersant plasma-assisted ball milling 5h have the best antifriction performance;The optimum adding amount of the nano-borate additives is 3wt%.The results of energy dispersive microanalysis(EDS) on the worn surfaces show that nano-borate particles adsorbe on the friction surface,deposition, melting, condenses to form a layer of compact borate wrap in the friction condition.At the same time, some borate particles come into being friction chemical reaction in the friction condition.They break down into boron-containing compound, deposite or penetrate in the friction surface, repair and strengthen the wear surface,thus improving the tribological properties of friction surface.