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

Posted on:2014-09-04Degree:MasterType:Thesis
Country:ChinaCandidate:L YangFull Text:PDF
GTID:2251330422950969Subject:Materials science
Abstract/Summary:PDF Full Text Request
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.
Keywords/Search Tags:C17200Cu alloy, Ti2N, Intermetallic compounds, Wear property
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