Study On Surface Modification Of C17200Copper Alloy By Depositing Titanium And Nitriding

In order to improve the wear property, titanium-copper-nitrogenthermo-reactive diffus ion coatings were obtained on the surface of C17200copper–beryllium alloy by deposition and nitriding process. The substrates werefirstly deposited with Ti film by magnetron sputtering and then plasma nitrided. Theas-obtained coating was characterized by optical microscope （OM）, scanningelectron microscope （SEM）, energy dispersive spectrometer （EDS）, X-raydiffractometer （XRD）, microhardness tests and pin-on-disk tribometer.High-quality Ti film was obtained by magnetron sputtering and Cu-Ti-Nthermo-reactive diffusion happened during the nitriding process. The modified layermainly consists of Ti₂N、CuTi₂、CuTi、Cu₄Ti₃、Ti₂Cu₃、Cu2Ti、Cu₃Ti and Be₃Ti₂Cuphases.The modified layer nitrided under high temperature （810⁸80℃） has a highroughness and contaminated in some way by oxygen and nitrides. Better surfacelayer was obtained under810℃in plasma hydrogen atmosphere. A6μm thickCu-Ti compound layer mainly comprised of Ti₂Cu₃and Cu₃Ti.Temperature and timeplayed important role during the diffusion process. Ti₂N phase only exsited in thelow-temperature and short-time nitriding process. Ideal titanium-copper-nitrogenthermo-reactive diffusion coatings was obtaind by nitriding process under lowertemperature（650⁷90℃）. A2.54μm thick Ti₂N layer was obtained after nitriding at650℃for2h.9¹7μm thick modified layer was obtained under different nitridingprocess. CuTi₂、CuTi、Cu₄Ti₃and Be₃Ti₂Cu phase presented in the outmost surfacelayer and Cu₃Ti formed easily in the substrate.9.5μm thick Cu₄Ti₃and14μm Cu₃Tilayer was obtained after nitriding for4h and8h under750℃respectively.The presence of nitrides （Ti₂N） and Ti-Cu intermetallic compounds improvedthe hardness and wear resistance significantly.983HV hardness（2.8times of thelimit of the substrate microhardness）,0.3-0.5friction coefficient and rather lowwear rate were obtained at650℃，4h nitrided C17200Cu alloy. The main wearmechanism is oxidation wear instead of adhesive wear.