Preparation Of Layered Organic-templated Aluminosilicates And Characterization For Its Use As Thickener Agent For Lubricant Applications

Greases has the advantages of good lubricating performance,good sealing,long operation age and so on,which can enhance service life of mechanical equipments by reducing the friction and wear.Lubricating grease is a semisolid non-Newtonian fluid,it consists of base oils,thickening agents and additives.The thickening agent makes up basic skeleton of the grease,it is about 5.0?25 wt.%in grease formulation,the structure of the thickener has a crucial effect on the properties of the grease.Lithium grease is the most applicable grease,but the rapid development of lithium ion battery industry has made lithium resources increasingly scarce,it has serious impacts on the development of lithium grease.So it is very important to research new thickener for greases.Traditional fatty acid metallic thickener is obtained by long chain fatty acid metal salt thickening base oils.The basic structure of fatty acid metal salt is that one end is a lipophilic alkyl chain,the other end is carboxylate.Based on the concept of"Salt-like Compound",using layered organic-templated aluminosilicates as thickener,polyolefin PAO8 as base oil,we study the basic properties of the new type thickener.The main content and conclusions are as follows:(1)Layered octadecyltrimethylammonium-templated silicates(LS)was synthesized by using octadecyltrimethylammonium bromide,sodium hydroxide,silica sol as raw materials.The obtained sample was flake aggregate with a grain size of 6?m?12?m.CHN element analysis showed that the content of quaternary ammonium salt was 52.47%.(2)LS gel was prepared by using the LS sample as thickening agent and polyolefin PAO8as base oil.Three methods were used in this experiment,these were room temperature and normal pressure method,high-temperature method,high-temperature and high-pressure method,respectively.Rheological tests indicated that LS gel had relatively low viscoelasticity.Although thickening time,temperature,pressure,stirring modes and aging time had been changed,there was almost no increase of the viscoelasticity of LS gel.The performance of LS gel can not meet the basic requirements of lubricating grease.The tribological properties of LS gel were evaluated by a SRV tester,LS gel had good lubricating property,LS acted as a solid additive.(3)Layered octadecyltrimethylammonium-templated alumino silicates(LAS)with Al/Si molar radio of 0.05,0.10,0.15,0.20 were synthesized by using sodium aluminate,octadecyltrimethylammonium bromide,sodium hydroxide,silica sol as raw materials.²⁷Al MAS NMR showed that the Al atom were tetrahedrally-coordinated,the particle size of LAS was about 250 nm?350 nm×40 nm.According to CHN element analysis,the content of quaternary ammonium salt of LAS samples with differernt Al/Si molar radio were 51.91%,51.34%,49.48%and 48.92%,respectively.(4)LAS gels were prepared under room temperature and normal pressure method.Rheological tests showed that the viscoelasticity and structural strength of the gel were enhanced with increase of the molar radio of Al/Si,the viscoelasticity of LAS_(0.20)gel was the highest.The viscoelasticity of LAS_(0.20)gel also rised with the increase of the amount of LAS_(0.20).As the molar radio of Al/Si and thickener amount increased,the dropping point of the gel increased gradually and the oil seperation decreased.The initial oxidation temperature of LAS_(0.20)gel was close to that of base oil.Slight corrosion of LAS_(0.20)gel to copper strip was observed.LAS gels possessed typical characteristics of grease.(5)The tribological properties of LAS_(0.20)gel were evaluated by using a SRV tester.The maximum applied load of LAS_(0.20)gel was 700 N,and the 20 wt.%LAS_(0.20)gel exhibited excellent anti-wear and friction-reducing properties.