| Active magnetic bearing (AMB) system requires auxiliary bearings as temporary supports toprevent damages in the event of the failure of AMB,based on high speed rotor drops in to auxiliarybearings bringing with enormous impact,vibration and frictional heat,and it often leads to bearings’failure.In this thesis,in order to improve the surface characteristics of the rolling bearingmaterial,making use of excellent properties of quasicrystalline materials:high hardness,low frictionand wear, high temperature and oxidation resistance, we have prepared Al-Cu-Fe quasicrystallinecoating on the GCr15,9Cr18substrate material by air plasma spraying and laser remeltingmethods.Respectively, use SEM, XRD, EDS and microhardness tester to observe profiles and surfacemorphology, phase composition and its content of Al-Cu-Fe quasicrystalline coating, some otherperformance tests also have been studied.Research results show that Al70Cu20Fe10quasicrystalline coating prepared by air plasma sprayingmethod under the50V/400A spraying process parameters has maximum microhardness,a highercontent of quasicrystal phase and good binding state with substrate material,even at the same sprayingprocess parameters,coating of9Cr18is more smooth and compact than GCr15′s.After laser remeltingtreatment,the coating microhardness,compact degree have been improved significantly.Quasicrystllinecoating at1000W，240mm/min laser remelting paremeters shows the most superior performance;Thetesting results indicate that the bonding strength between coating and substrate material is up to50MPa,the average friction coefficient of0.18and the lower friction coefficient,wear rate than substratematerial.The results of plasma spraying coating.350℃100h high temperature oxidation and400℃100times thermal shock cycle show that there is no change in coating organizationcomposition.however,there are also some cracks within the coating dueing to internal stress,and howto reduce them remains further research. |
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