Study On Tribological Properties Of Superlubricity Epoxy Resin Composite Coatings Containing Polydimethylsiloxane

Superlubricity has attracted great attention in tribological research.In engineering,superlubricity is a lubrication state of the coefficient of friction <0.01.The large-scale application of superlubricity in engineering will reduce global energy consumption caused by the friction.The development of superlubricity materials and technologies is of great significance to the mechanical equipment of future high-tech field in our country.Epoxy resin(EP)coatings have attracted attention of many researchers in the field of surface protection engineering due to their high adhesion and good corrosion resistance.However,the high friction and low wear resistance of pure EP coatings limit its wide application.Many advances have been made in the study of modification of the tribological properties of EP coatings,but developing superior EP coatings with superlubricity and good antiwear performance remains to be a challenge yet.In this paper.Polydimethylsiloxane/epoxy resin(PDMS/EP)composite coating with superlubricity in high humidity environment was prepared by a simple solvent evaporation method.The effects of PDMS on the chemical composition,microstructure and morphology of EP coating were investigated,and the effects of PDMS on the mechanical properties and tribological properties of EP coating were studied.The friction and wear behavior of PDMS/EP composite coating modified by branched polyethylenimide(PEI)on fluororubber was further studied.The main results of this paper are as follows:(1)Fourier transform infrared spectroscopy(FTIR)results show that EP coating and PDMS/EP composite coating all contain hydroxyl groups,which is derived from the the reaction of epoxy groups in the epoxy resin and the amino groups in the amine curing agent.It was found from scanning transmission electron microscope(STEM)results of PDMS/EP composite coating that PDMS self-aggregated into nanoparticle phase in the epoxy resin matrix.The tensile tests results showed that the tensile toughness and ductility of the PDMS/EP composite coating were enhanced.This may be related to the formation of PDMS nanoparticle phase,and PDMS nanoparticles have an inhibitory effect on the crack extension of epoxy resin materials during the tensile process.(2)Friction test results of PDMS/EP composite coatings in high humidity environments show that the introduction of PDMS can significantly reduce the coefficient of friction(COF)and wear rate of EP coatings.The modified PDMS/EP composite coatings has the best tribological properties when PDMS content is 3 wt.%(Named after 3-PDMS/EP),and the COF can reach an ultra-low level(COF=0.008).The COF of 3-PDMS/EP composite coating sliding against different bearing materials is less than 0.01.The superlubricity of PDMS/EP composite coatings is attributed to the formation of the lubricating film at the friction interface.This is due to the presence of PDMS and EP coating in the lubricating film.PDMS and the hydroxyl groups in EP coating have a synergistic effect on friction and wear reduction.At the same time,the anti-wear performance of the composite coating has been significantly improved due to its increased toughness.In the friction test of 3-PDMS/EP composite coating at different loads and rotational speeds,with the increased of load,the COF of the composite coating decreased first and then increased.The COF is the lowest when the load is 2 N.With the increase of rotational speed,the COF of the composite coating increased.The superlubricity of composite coating disappeared when the rotational speed was ≥1000rpm.The COF of the 3-PDMS/EP composite coating increased with the increase of heating temperature and the superlubricity of 3-PDMS/EP composite coating disappeared when the heating temperature was ≥150 ℃.(3)The tensile test results showed that the introduction of PEI has a good strengthening effect on the mechanical properties of 3-PDMS/EP composite coating.The modified 3-PDMS/EP composite coating has the best mechanical properties when PEI content is 3 wt.%(Named after 3-PEI/3-PDMS/EP).This may be due to the reaction of the epoxy group in the epoxy resin with the amino group in the PEI to form chemical bond,which enhances the interfacial interaction.Therefore,the tensile toughness and ductility of PEI/3-PDMS/EP composite coatings are improved.Friction test results show that the 3-PDMS/EP composite coating on fluororubber surface has the lowest COF when the PEI content is 3 wt.%.The excellent tribological properties of 3-PEI/3-PDMS/EP composite coating on fluororubber surface may benefit from the improvement of the hardness,which reduces the contact area of the friction interface.In the friction test of 3-PEI/3-PDMS/EP composite coating on fluororubber surface at different loads and rotational speeds,with the increase of rotational speed,the COF of composite coating decreases first and then increases.The composite coating has the lowest COF when the rotational speed is 750 rpm.The COF of the composite coating increased with the load.