Preparation hyperthermal lithium complex grease高温复合锂基润滑脂的制备.毛大恒; 俸颢; 孙晓亚 2005

Vol.15 .6 Trans.Nonferrous Met.Soc.C hina Dec.2005 Article ID:10036326(2005)06136106Preparation of hyperthermal lithium complex greaseM AO Da heng(毛大恒),FEN G H ao(俸 颢),SU N Xiao ya(孙晓亚)(School of M echanical and Electrical Eng ineer ing,Central So uth U niversity,Changsha410083,China)Abstract:U sing12 hy dr ox ystearat e,nonan edioic acid and lithium hydrox ide as thickener,r efined mineral o il and sy nt hetic o il as base oil,along w ith some str ucture impr ov er,antiox idant and anti w ear ex treme pressure additive, lit hium com plex g rease w as developed.T he dr opping point o f the gr ease is331!,fr iction factor is0.0250.026 under1.0kN,especially abov e220!,its frict ion factor is2/3o f tho se o f urea based gr eases and other high tem peratur e gr eases.A t the same t ime,it has g oo d w at erproo f,anti ox idatio n effect and anti co rr osio n pro pert ies.T he results of the field ex periment prov es t hat its wo rking temperatur e is higher than600!,and it has reasonable wo rking life in800!.Key words:lithium complex g rease;structure impr over;anti w ear ag entC LC number:T G580.21Document code:A1 INTRODUC TIONAlong w ith the development of metallurg y, mine,material process,mechanism,chem ical in dustry,co mmunications and transport,mo re and more equipm ents r un at high or ex traordinarily hig h tem perature,and the equipment need elev ated temperature pro perty of grease.The development and pro duction of high temperature grease in our countr y is behindhand to developed country.At present,abso lute majority of high temperatur e grease is import,so,it is essential to develop a hig h tem perature grease w ith excellent perfo rm ance[1,2].In1962,the first lithium grease passed field ex periment in America[3].Fr om1970s,lithium com plex grease dev elo ped rapidly,and lithium com plex gr ease w ith dibasic acid,stearinic acid and ortho hydrox ybenzo ic are called new g eneratio n lithium g rease[4,5].In China,there are a lot of re search to lithium complex grease[612],but it is not in a cr eative w ay and is based on the formulatio n and technolo gy,so w e have gr eat gap to fo reig n advanced technolog y.This resear ch w ork is on the base lithium com plex g rease,its major factor w hich im pacts the high temperature behavior w as discussed,a new ex traordinarily high temperatur e grease was developed.The developed g rease hav e hig h dr opping po int,lo w fr ictio n factor,w ith w orking tem peratur e hig her than600!,and r ea sonable w or king life in800!.2 EXPERIMENTAL2.1 Prescription modeT he pro perties of g rease ar e affected by thick ener,base o il and additio n ag ent.At present,lith ium complex gr ease,urea based gr ease and alum i num co mplex g rease are very popular in use,espe cially lithium co mplex g rease and urea based g rease,their dropping po int is250270!,the highest w orking temper ature is about240![13,14]. T o get a co mplex gr ease w ith dropping point o ver 310!and w orking temperature abov e600!,the batch formula w as impr oved on the base o f lithium complex g rease.T he prescr iptio n mo de is as fo l low s.1)T hickener12 hydrox ystearate,nonan edio ic acid and lithium hydrox ide w ere used as leading materials,a small quantity of org anic poly mer and inor ganic m atter w ere added as structure improv er.2)Base oilBase oil is the basis of grease,about70% 80%in all.In g rease,base oil is fastened in str uc tur e fram e created by the thickener,affecting the lubricant per for mance of g rease greatly.T he base oil should have pro perty o f low freezing po int and vapor ability,hig h v isco sity temper ature and flash point,and g ood ox idatio n stability,The fo rmula tion adopts unit system of refined mineral oil w hich has hig h flash point and synthetic oil.T he per formance parameter is listed in T able1.3)Anti wear extreme pressure additive and bulking ag entT o improve the abrasio n resistance and ex treme pressure perform ance,and g ain low friction factor,some borate,WS2co lloidal pow der and anti w ear extreme pressure additive w ere added toReceived date:20050303;Accepted date:20050530Correspondence:M AO Da h eng,Professor;T el:+86 731 8876350;E mail:mdh@Table 1 Chief perform ance parameter sof base oilK inemat ical v iscidity (40!)/(mm ∀s -1)V isco sity indexP our pointing /!500600#120∃-20Split cup f lashingpo int/!T hin layer evapor at ion lo ss(230!,3h)/%#290∃6.0this novel g rease.2.2 Preparation processOne step technolog y w as used to pr epare the grease.Added 12 hydrox ystearate,nonan edioic acid,w ater solution of lithium hydrox ide into reac to r in suitable proportion,then added partial base oil,controled the heating v elo city and degr ee of in termix ,the first saponification proceeded.And added the residual base o il,r aised the temperatur e to 220230!.W hen the grease w as coo led dow n to 130!,added WS 2collo idal pow der,structur e impr over and ex tr em e pressure additive,finally ho mog enized and milled.To compare the contr ibutio n o f structure im prov er and WS 2collo idal pow der to the perfo rm ance o f g rease,in the preparation pro cess the gr ea ses w ere divided to tw o gro ups,one g roup (M W 01)is only added extreme pr essure additive,an o ther g roup (M W 02)is added WS 2collo idal pow der ,structure improver and extreme pressure addi tive.3 RESULTS AND DISCUSSION3.1 Influence of structure improver and WS 2colloidal powder bulking agent on dropping point Dropping po int test w as carr ied out in SYD %4929dropping point appar atus accor ding to the standards o f GB/T4929%85.T he dr opping po int of grease w hich is not added w ith str ucture im prover and WS 2collo idal pow der is 282!,while that is added structure im pr over and WS 2collo idal pow der is 331!,w hich is higher than other high temperature greases by 50110!(T able 2).T his result prov es that structure improver and WS 2co l loidal po wder bulking ag ent have remarkable effect on dropping po int.Table 2 Dropping po int o f some hig h tem perature g rease(!)M W 02hy pert her malgr easeBS HT ex tr eme pr essure lithiumco mplex gr ease3312602657029ur ea basedg rease Pr emalube red g rease (U SA )Heat shield g rease (U SA)2202302502652752803.2 Infection of WS 2colloidal powder bulking agent on oil film strength and friction factor T he o il film streng th and friction facto r of M W 01and M W 02w er e tested on MRC %10A four ball ex treme pressure tester at 30,50,100,150,200and 220!,the results are show n in Figs.1 3.Friction factor o f MW 02grease w hich is add ed w ith WS 2co lloidal pow der is low er than that of M W 01.This anti attrition effect is obvious espe cially w hen w orking temperature is at 150!.Fric tion factors of M W 02are 2/3as that o f M W 01at 150and 200!,respectiv ely.For example,the friction factor o f M W 02is 0.027at load of 1.0kN and 150!,w hile that o f MW 01is 0.039.At 200!,the friction facto r o f M W 02is 0.027,Fig.1 Comparison of oil film strength and friction factor betw een M W 01andM W 02at different tem peratures(a)%30!;(b)%50!∀1362∀Trans.Nonf errous M et.Soc.China Dec.2005Fig.2 Comparison of oil film strength and friction factor betw een M W 01andMW 02at different tem peratures(a)%100!;(b)%150!Fig.3 Comparison of oil film strength and friction factor betw een M W 01andM W 02at different tem peratures(a)%200!;(b)%220!that o f M W 01is0.042.At220!,the fr ictio n facto r o f M W 02is0.029,w hile M W 01is seized.At hig h temper ature the oil film streng th o f MW 02grease that is added w ith WS2co lloidal pow der has sig nificant adv antages ov er M W 01 grease that is added w ith nothing.A t150!,the oil film str ength o f M W 01g rease is 1.21kN, w hile that of M W 02is1.14kN.At200!,oil film strength of MW 01grease is1.14kN,w hile that o f MW 02is 1.0kN.At220!,oil film streng th o f M W 01grease is still 1.0kN,but MW 02has lo st its lubricating ability.3.3 Contrast of MW 02grease to other high temperature grease in oil film strength and friction factorIn o rder to prove the perform ance of M W 02 g rease,w e select ur ea based g rease,high tem pera tur e lithium grease,impo rt high temperature g rease(NCH Premalube heat shield g rease)in the curr ent m arket as reference o bjects.T he result are sho wn in Figs.4 6.T he measurem ent results indicate that w hen w orking temperature is over150!,the oil film str ength o f M W 02g rease is hig her than those of urea based g rease,hig h tem perature lithium com plex g rease and import high tem perature g rease, and the friction factor o f M W 02g rease is the lo w est.Especially w hen the w orking tem perature is o ver200!,the friction factor of M W 02g rease is only2/3of other high temperatur e g reases.So, M W 02g rease has well anti attrition capability∀1363∀Vol 15 6 Preparation of hyperthermal lithium com plex gr easeFig.4 Com parison of oil film str ength and friction factor betw een four g reases at 150!Fig.5 Com parison of oil film str ength and friction factor betw een four g reases at 200!Fig.6 Com parison of oil film str ength and friction factor betw een four g reases at 220!bo th at nor mal atmospheric temperature and hig h temperature.4 MIC ROSTRUC TURE ANALYSIS AND LUBRIC ANT MEC HANIC S RESEARC H Fig.7show s the ster eo scan photograph by JSM 5600LV scanning electro nic micro scopy (SEM ),sample 1is M W 01grease,sample 2is M W 02g rease.It can be seen fro m Fig.7that the soap fiber of MW 01is thin filament,but that of M W 02is thick filament,w hich is obviously fur cated.At the same tim e,filam ent fibrous tissue of M W 02is in hig her propo rtio n,w hich can confine the base oil in fiber framew o rk better.The result proves that M W 02g rease has better framew ork construction than M W 01grease.Fig.7 SEM images of M W 01g rease(a)andMW 02grease(b) In grease,base oil is fixed in the thicker framew ork co nstr uction,w hose streng th and high temperature stability partly determinate the drop ping po int o f grease.It is the base r easo n w hy the dropping point of M W 02grease is obviously hig h er than that o f M W 01g rease,w hich can pr ove that the structur e im pr over has goo d effect,too.T he m icrostructure of WS 2cry stal is layer ed hollo w spher e w ith hex agonal,its surface form hexago nal netw ork w ith S %W %S molecular,lay ers ar e connected by van de w aals fo rce.T his w eak binding force is easy to be shear ed on the middle oflayers,put up low friction factor [15].Because WS 2crystal is so stable at high tem perature,even above 400!,WS 2can create compact WO 3covering lay er by retarded ox idation w hich can stop further ox idation,and W O 3has low frictio n factor ,too,∀1364∀Trans.Nonf errous M et.Soc.China Dec.2005w hich stop g lue on metal surface.The microstr ucture o f WS 2collo idal pow der by JSM 5600LV scanning electro nic microscope is lamellar structure,bedding surface is very smo oth,and the length and w idth are much greater than thickness (Fig.8).A fter m ultiple milling,under scanning electronic m icrosco pe (SEM )w e can see that ther e are a larg e number o f m icro grains w hose length and w idth are resem ble to thickness at platelet (Fig.9).T hese micro gr ains and base g rease form plentiful oil micro poo ls that ar e locally sealed.So ,the antifr ictio n o f WS 2col loidal po wder in lubrication is not rolling bearing effect but shearing effect along w eak bonded bedding plane and oil m icro po oleffect.Fig.8 M icrostructure of WS 2powderFig.9 Microstr ucture o f WS 2pow der afterrepetitious milling T he result proves that the gr ain size of WS 2pow der greatly affects the friction factor.At the grain size of 0.37.6 m,the friction facto r de crease w ith decreasing grain size (T able 3).When WS 2pow der and Mo S 2pow der w ho se grain sizes ar e similar ar e mixed w ith kerosene oil in the sam e pro por tion,their friction facto rs w ere measured.The results show that the friction factor o f WS 2is low er than that of M oS 2(Table 4).So,WS 2colloi dal pow der is a stable and low loss lubricant sy s tem,it can make M W 02grease has low fr ictio n facto r,go od anti high temper ature and ex tr em e pressure perform ance w hen added as extreme pressure additiv e.Table 3 Infectio n of different gr ain sizes o f WS 2pow der on friction factor at different lo adsL oad/kN 0.3 m 0.5 m1.7 m4.2 m7.6 m0.880.02030.02030.02320.02560.02661.000.01940.02600.02660.03010.02751.070.02070.02170.02260.02910.0418Table 4 Com pariso n of friction factors betw eenWS 2and M oS 2L oad/kN F rict ion factor W S 2M oS 23800.02690.02694000.03750.04594400.03480.05104800.03750.05115200.03330.05725600.04190.05655 C ONCLUSION1)WS 2co lloidal pow der is a stable and low lo ss lubricant system,it can make M W 02grease has low friction factor and g ood anti hig h tem pera tur e and ex tr em e pressure perform ance w hen added as extreme pressure additive.2)This kind of str ucture im pro ver can obvi ously impr ove the m icrostructur e of soap fiber in lithium co mplex gr ease,turn thin filam ent to thick filam ent,and obv io usly increase the proportion of filam ent fibr ous tissue.3)U sing WS 2co lloidal pow der as bulking a gent,the dropping point of M W 02hyperther mal g rease is 331!.M W 02hy perther mal grease has anti hig h temperature and extreme pressure per formance,and can w ork long tim e at abov e 600!.4)Above 150!,the o il film strength of M W 02gr ease is hig her than those of urea based g rease,high temper ature lithium grease and im ported hig h temper ature grease,w hile the friction factor is the low est.Especially at over 200!,the friction factor of M W 02gr ease is 2/3of tho se of urea based g rease and other high temperatur e lithi um g reases.REFERENCES[1] LI X ue jing,PA N Yuan qing,ZH OU H ui juan.G ener al situatio n of g rease [J].L ubr icant and Fuel,2003,13(4):1014.(in Chinese)[2] LU O Rui bin.U pdat e pr ospect fo r g lobal lubricating∀1365∀Vol 15 6 Preparation of hyperthermal lithium com plex gr easeg rease industr y[J].L ubr ication Eng ineering,1994(2):6368.(in Chinese)[3] Compell I D,Ha rting G I.A new g eneratio n of lithium co mplex g rease[J].NL GI Spokesman,1976,40(6):193200.[4] Ehrlish M,M usili T G.T he develo pment of lithiumcomplex g rease[J].NL G I Spo kesman,1980,12(6):87100.[5] H issa R,Br asil T.Lithium co mplex gr ease w ith anunusually hig h dr opping po int[J].N LG I Spo kesman,1995,59(1):1920.[6] Y I Jian g uo,Y A N G Shu hong.Per formance and application of lithium complex gr ease[J].Synthetic L ubricant M ater ial,2003,13(4):1518.(in Chinese) [7] Y U A N Jun,JIA N G Chao hui.Per formance and application of decanedio ic acid extr eme pressure lithiumcomplex g rease[J].L ubr icant,2003,30(1):4 6.(in Chinese)[8] CU I Jing jie,L I Y an qiu.A pplicatio n o f PA O and ester o il in sy nthetic lubr icant[J].L ubricant,2004,19(1):712.(in Chinese)[9] CH EN H ui qin.A pplication o f M oS2in g rease[J].Sy nthetic L ubr icant M ater ial,2002,29(1):1319.(in Chinese)[10] XU Jian ping.Sense o f technolog y mov ement o fg rease[J].Synthetic Lubricant M ater ial,2004,31(1):2730.(in Chinese)[11] JIA NG M ing jun,G U O Xiao chuan,CH EN G uo x u.Research of lithium complex g rease[J].Lubricationand Seal,2000(5):2528.(in Chinese)[12] JIA NG M ing jun,G U O Xiao chuan,CH EN G uo x u.A pplicatio n o f additive in lit hium complex g rease[J].L ubr ication and Seal,2000(3):17.(in Chinese) [13] ZH A NG Cheng qing.Grease M aking[M].Beijing:China Petro chemical Pr ess,2003.(in Chinese) [14] Y AN G Zheng yu.A survey o n the r ecently researchabout the g rease making in Amer ica,Eur ope and A sia[A].M emo ir of N at ional N inth G rease T echnical Exchange M eeting[C].Beijing:P etro leum Pr ocessingand P etrochemicals,1997,1116.[15] SU N K e hui,W EI Qin,L U O W en dong.P reparation and micr ostr ucture analy sis of nano WS2so lid lubricat ing materia l[J].M ining&M et allur gy,2001(1):4648.(in Chinese)(Edited by LONG Huai zhong)∀1366∀Trans.Nonf errous M et.Soc.China Dec.2005。