Study On The Preparation And Properties Of Self Lubricating Micro-Arc Oxidation Coating On The Surface Of Aluminum Alloy

With the use of aluminum alloy and other materials more and more widely,people use various surface treatment methods to improve the wear resistance and antifriction properties of the alloy metal materials,as well as the study of self lubrication mechanism.Self lubricating composites can play a key role in mechanical design and structural simplification,because of their excellent tribological properties,self lubricating composites are one of the focus of tribology and material research.In this paper,LY12 aluminum alloy is used as the sample material,and the self-lubricating ceramic coatings with friction and wear resistance are successfully prepared by micro arc oxidation technology.The properties of the ceramic coating are evaluated by the analysis of the phase composition,the element content,the surface morphology,the surface roughness,the hardness,the friction coefficient and the wear amount.On the basis of the optimum concentration of NaF and??Na PO₃?₆?in the base liquid?Na₂SiO₃and NaOH solution?,the effect of graphite concentration on the tribological properties of the film is studied,and the optimum amount of graphite is obtained,and the corresponding conclusion is obtained.The main contents and conclusions of this paper are as follows:?1?The effects of three main factors such as electrolyte concentration,voltage?forward/negative?and additives on the formation of ceramic membrane are studied in the base fluid.The results show that the process parameters have a great influence on the formation and friction and wear of ceramic membrane.When the concentration of Na₂SiO₃ and NaOH is 15g/L and 3g/L respectively,when 100min is reacted at the voltage of+500V and-60V,the synthesized film has better comprehensive properties,the dry friction coefficient is larger?1.012?,and the surface is relatively rough.?2?The effects of additives NaF and??NaPO₃?₆?on the properties of ceramic coatings are studied respectively.The results show that the optimum addition of NaF is2g/L.The minimum dry friction coefficient of the film is 0.945,the lowest wear rate is1.01mg,the lowest surface roughness is 1.6028?m,and the surface is more flat.The optimum addition amount of?NaPO₃?₆)is 6g/L,and the minimum dry friction coefficient of the film is 0.759,the lowest wear amount is 0.62mg,the lowest surface roughness is 1.095?m,and the whole structure is more compact.?3?The influence of graphite additives with different concentrations on the properties of ceramic coatings in Na₂SiO₃-NaOH-NaF-?NaPO₃?₆)electrolyte is studied.The results show that the optimum addition of graphite is 10g/L,the lowest wear rate is0.69mg,the lowest surface roughness is 1.022?m,and the dry friction coefficient is0.714?less than the intrinsic matrix friction system value 0.812;the friction coefficient of the ceramic film prepared in the base liquid is 1.012,and the reduction rate is29.45%?.?4?The friction and wear mechanism of different ceramic membranes and the working mechanism of self lubrication are analyzed and studied.It is shown that under the dry friction environment,the friction and wear mechanism of the film prepared in the base liquid is mainly adhesive wear and a small amount of abrasive wear.The frictionandwearmechanismsofthefilmspreparedin Na₂SiO₃-NaOH-Na F-?NaPO₃?₆)-Graphite solution are mainly abrasive wear and a small amount of adhesive wear.