Research On Influencing Mechanism Of Micro/Nano Particles For The Tribology Properties Of Attapulgite Grease

Wear accidents usually start at the early stage of slight injury on the surface.Having the micro damage on the worn surface in-situ online repaired is an effective method to reduce friction and wear.The attapulgite is a kind of silicate material with unique online repairing function.In recent years,it has become a research hotspot in tribology.This study aims to prepare in-situ reparing lubricating grease with high performance.The effect of nano Cu,nano Ni,graphene,MoS₂,WS₂,nano La₂O₃,nano CeO₂ on the tribological properties of the base grease were investigated.The anti-friction and self-repairing mechanism of the lubricating greases was discussed.The influencing mechanism of the micro-nano particles was also disclosed.The above work may present some experimental basis and theoretical support for the practical application of the attapulgite lubricating grease.The attapulgite powder was organically modified by using quaternary ammonium cationic surfactant as modifier through the technology of microwave modification.Finally,the attapulgite lubricating grease with high dropping point and good colloidal stability was successfully prepared by using organic attapulgite powder as thickener.The effects of micro-nano particles on the tribological properties of the base grease were systemically studied under different load,frequency and temperature.It was found that under different lubrication conditions,the improving effect of the micro-nano particles on the friction-reducing and anti-wear properties of the base grease is different.The greases containing MoS₂ and WS₂ exhibit excellent tribological properties under most lubrication conditions.However,the improving effect of the two kinds of rare earth oxides on the the friction-reducing and anti-wear properties of the base grease are not ideal.In the process of friction,tribo-chemical reaction between matrix friction pair and attapulgite occurred to generate a friction protective film.Under the lubrication condition of 50?,the friction protective film is mainly composed of Fe,Fe₃C,iron oxides,Al₂O₃,silicon oxides,attapulgite and organic matters.Under the lubrication condition of 200?,the friction protective film is mainly composed of Fe,iron containing organic compounds,iron oxides,Al₂O₃,silicon oxides,attapulgite and organic matters.During the lubrication process,the micro-nano particles were physical deposited or took chemical reaction.And the product is doped into the friction protective film.Compared with 50?,under the lubrication condition of 200?,on the one hand,the deposition and adsorption of the attapulgite and micro-nano particles was promoted.On the other hand,the tribo-chemical reactions between the attapulgite,the friction pair and the micro-nano particles were also promoted.For the tribo-chemical reaction between the friction pair and attapulgite,Nano Cu,nano Ni,graphene,nano La₂O₃ and nano CeO₂ can play an active role in promoting it,while MoS₂ and WS₂ bring about inhibiting action on it.Under the lubrication of greases,tribo-chemical reactions between the friction pair and attapulgite occurred on the worn surfaces to generate amorphous multiphase ceramic repairing layer.The thickness of the repairing layer is about 10?m.The structure of repairing layer is compact and the thickness of repairing layer is uniform.In the effect of nano Cu,nano Ni,graphene,nano La₂O₃ and nano CeO₂,the thickness of the repair layer increased in different degree.It is analyzed that physical deposition or chemical reaction occurred for the micro-nano particles in the process of friction.And the product is doped into the ceramic repair layer,improving the self-lubrication and anti-wear properties of the repair layer.