Research Of Cu-Fe Series Metastable Liquid-liquid Phase Speration Coating With Mo Added By Plasma Transferred Arc Process

Tin bronze is a kind of copper-base alloy with good stain resistence,wear resistence and toughness,which has been widely used as bearing component in engine and other elastic partings.In order to further improve the wear resistance of tin bronze, there are many trddition methods such as add alloying element or dispersion strengthen element.In recent years,the metastable liquid phase sperate in immiscible alloy under the condition of nonequilibrium freezing shows the new ideal to improve the property of alloy.Based on the previous theory, Mo-free Fe based alloy powder(Fe50) was used to strengthen tin-bronze alloy powder(Cu150) by clad mixed powder coating on the surface of 45# steel.In expectation,the phenomenon of liquid sparate of Cu-Fe series would make contribution to strength the coating.Base on this suitation,add 4% and 10%Mo powder into the coating respectively to further improve the properties of the clad coating.The result of analyze microstructure showed that Cu150 coating consist of α(Cu,Sn) solid solution and Cu10Sn3 which mainly located in α(Cu,Sn) solid solution.The coating with 15%Fe50 added had no Cu10Sn3 phase,and new phase was Cu81Sn22、γ(Fe,Ni) and(Cr,Fe)7C3,structure had obvious charastic of liquid-liquid separate,the Fe-rich separate phase was consist of γ(Fe,Ni)(Cr,Fe)7C3 which located in γ(Fe,Ni) phase,mainly formate the nodular and stripped Fe rich phase.The nodular Fe rich phase mainly located in the area which was near the surface, the distribution of Fe rich phase was seriously nonuniform;the number and bulk of phase in this area was much larger than that in other areas;stripped Fe rich phase located in near the fusion line,with larger average thickness.In the coating with Mo added, the condition of nodular Fe rich phase gathered seriously was relieved,the number of nodular was increased; average thickness of stripped Fe rich phase was decreased.The addition of Mo could increase the stagnation temperature,increase the critical radius of nodular Fe rich phase,which result to the distribute uniformity of Fe rich phase.The addition of 15%Fe50 alloy powder increased the hardness of Cu150 coating.The addition of Mo furher increase the hardness,minished the fluctuation.The more Mo added,the higher of average hardness.The friction and wear properties under normal and 250℃ temperature was increased by adding Fe50 and Mo powder,while in the condition of 600℃,the relationship of content and property was not clear.Adding Fe50 alloy powder would increase the stain resistance,while adding Mo powder would decrease the stain resistance.