Investigation Of The Alloying And Properties Of Aluminium Base Sintered Oil-impregnated Bearing

As a new type anti-friction material,aluminum base oil-impregnated sintered bearing has wide development and application prospect due to its excellent properties of small density,good anti-corrosion,good heat conduction,good anti-friction,and so on.So it is an ideal substitute of the sintered bronze oil bearing.In this paper,aluminum base oil-impregnated sintered bearing was prepared by powder metallurgy.The property of the sintered sample was tested and analyzed by SWX digital universal strength tester,optical microscopy,SEM,EDS,XRD.The influence of milling time,sintering temperature,the kind and content of alloying element on dimensional change,oil content,crushing strength and microscopic morphology were investigated.Milling time and sintering temperature significantly affect the property of the sintered sample.With the increase of the milling time,the alloying and homogenization process was better,the crushing strength was higher,but the shrinkage of the axial and radial dimension sharply increase,the oil content drastically decrease.With the increase of the sintering temperature,the metallurgical bonding was better,the crushing strength was higher,but the shrinkage of the axial and radial dimension rapidly increase and the oil content gradually decrease.When the milling time is 12 hours,the sintering temperature is 570℃,the oil content and crushing strength of the Al-7.5%Cu sintered sample were 18.4%and 180.8MPa,it has the best comprehensive property.The alloy element copper can significantly improve the crushing strength of the sintered sample,but it will reduce its oil content.With the increase of the copper content,the shrinkage of the axial and radial dimension,the relative density and the crushing strength gradually increase,the oil content gradually decrease.When the copper content is 7.5%,the oil content and crushing strength of the sintered sample were 18.7%and 179.7MPa,it has the best comprehensive property.The alloy element magnesium can make the sintered sample produce expansion and significantly improve the oil content,but the excess of magnesium content will reduce its crushing strength.With the increase of the magnesium content,the expansion of the axial and radial dimension and the oil content gradually increase,the relative density gradually decrease.The crushing strength first increase and then decrease as the magnesium content increase.When the magnesium content is 1.5%,the oil content and crushing strength were 22.3%and 226MPa,it has the best comprehensive property.The alloy element silicon can significantly improve the crushing strength of the sintered sample,but it will reduce its oil content.With the increase of the silicon content,the shrinkage of the axial and radial dimension and the crushing strength gradually increase,the relative density rapidly increase,but the oil content sharply decrease.When the silicon content is 1.0%,the oil content and crushing strength of the sintered sample were 18.7%and 256MPa,it has the best comprehensive property.The optimized composition of aluminum oil-impregnated sintered bearing composition is Al-7.5%Cu-1.5%Mg-1.0%Si.When the rotational speed of ball mill is 1140rpm,the ratio of ball and powder is 5:1,the process control agent of ethanol is 5wt%,the milling time is 12 hours,the sintering temperature is 570 ℃,the oil content and crushing strength of Al-7.5%Cu-1.5%Mg-1.0%Si oil-bearing alloy sintered sample were 18.7%and 256MPa,it has the best comprehensive property.