| Iron-based powder metallurgy anti-friction materials have the advantages of flexible composition design,low production cost,good comprehensive mechanical and friction and wear performance and are widely used in engineering machinery,transportation and many other fields.With the development of modern industry,the service conditions of mechanical parts become more rigorous.Filling some polymers with good anti-friction property into the pores in the porous ferrous matrix can further improve the anti-friction properties while maintaining the high strength of the materials.However,due to the limitation of polymer composition and porosity in the sintered body,there still have much work to do in terms of achieving uniform filling of polymer and improving the anti-friction property.In this dissertation,porous ferrous sintered bodies were prepared by using pore forming agents and by controlling the pressure during powder compaction.Polymer/iron matrix composite anti-friction material with high strength and good anti-friction performance were obtained by infiltrating polyphenylene sulfide(PPS)into the pores.On this basis,the mechanical,as well as the friction and wear properties of the materials are further improved by infiltrating multicomponent polymers.The main results of this paper are as followings:Using water atomized iron,electrolytic copper,graphite powders as raw materials,added with different amounts of zinc stearate powders to prepare powder mixes,the powder mixes were then pressed and sintered to obtain porous sintered Fe-10Cu-0.6C samples.Effects of the amount of lubricant added and the pressing pressure on the porosity,density and mechanical properties of the sintered bodies were investigated,and friction and wear properties of the porous sintered materials with different porosity were tested.It was found that the addition amount of zinc stearate and the pressing pressure had a significant effect on the porosity of the green compacts and the sintered samples.Porosity in sintered Fe-10Cu-0.6C samples from powder mixture containing 0.6-2 wt.%zinc stearate and pressed at 500-650 MPa are in the range of 16%-22%,and the samples have good mechanical properties.Also the sintered Fe-10Cu-0.6C samples with different porosity show different friction and wear performances.The samples with a porosity of20%has good tribological performance,and the average friction coefficient and linear wear rate are 0.022 and 1.28×10-8,respectively.The porous sintered Fe-10Cu-0.6C bodies prepared were filled with polyphenylene sulfide(PPS)anti-friction agent by infiltration PPS at different temperature and time.Influence of infiltration temperature and time on the infiltration depth of PPS in the porous Fe-10Cu-0.6C bodies was investigated,and microstructure and mechanical properties of the PPS/Fe-10Cu-0.6C anti-friction composites were tested.Friction and wear properties of the composites infiltrated under different temperature and time were also measured under different tested loading and sliding speeds.It was showed that the infiltration temperature and time has obvious influence on the thickness of the PPS infiltration layer.The PPS/Fe-10Cu-0.6C anti-friction composites infiltrated at 350°C for40 min have the largest infiltration thickness of 900?m and the composites show good comprehensive mechanical properties.Hardness and tensile strength of samples reach68.2HRB and 355MPa,respectively.In addition,the friction and wear properties of the PPS/Fe-10Cu-0.6C anti-friction composites vary as the test load and sliding speed.Increasing test load and sliding speed results in the decrease of the friction coefficient of materials,but results in increased wear of the composites.Also,the wear mechanism changed from the abrasive wear to plastic deformation and even adhesive wear.Polyphenylene sulfide(PPS)and polyetheretherketone(PEEK)were used as a composite infiltrant to prepare PPS-PEEK/Fe-10Cu-0.6C anti-friction composites at an infiltration temperature of 350°C and time of 40 min.Influence of PEEK content(5-20wt.%)in PPS-PEEK composite infiltrant on the thickness of the infiltrated layer and the mechanical properties,as well as the friction and wear properties of the PPS-PEEK/Fe-10Cu-0.6C anti-friction composites were investigated.The results showed that when adding 5-20 wt.%PEEK in the PPS infiltrant,the thickness of the infiltrated layer will increase with PEEK content.At PEEK content of 10 wt.%,the PPS-PEEK/Fe-10Cu-0.6C anti-friction composites exhibit good mechanical properties,and the hardness and tensile strength are 65.4HRB and 341MPa,respectively.In addition,wear resistance of the PPS-PEEK/Fe-10Cu-0.6C composites improved by 75%compared with the PPS/Fe-10Cu-0.6C composites under same test conditions.Polyphenylene sulfide(PPS)and polytetrafluoroethylene(PTFE)were used as a composite infiltrant to prepare PPS-PTFE/Fe-10Cu-0.6C anti-friction composites with different amount of PTFE(5-20wt.%).The tested results revealed that thickness of the infiltrated layer increases first and then decreases with the increase of PTFE in the composite PPS-PTFE infiltrant.When the PTFE content was 10 wt.%,the PPS-PTFE/Fe-10Cu-0.6C anti-friction composites have a largest thickness of infiltrated layer of 752?m,and the composites exhibit good mechanical properties.The hardness and tensile strength are 68.6HRB and 370MPa,respectively.In addition,compared with the PPS/Fe-10Cu-0.6C anti-friction material,the friction coefficient of the PPS-PTFE/Fe-10Cu-0.6C composites reduces by 45%under same test conditions. |
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