| Titanium and its alloys with excellent properties including high strength,well corrosion resistance and low density have been used in medicine,chemistry,energy,aerospace,aviation and so on.In the study,the double glow plasma nitridation was used for the titanium alloy,a nitrided layer with certain thickness was formed on the titanium alloy,and the wear properties and corrosion resistance of the nitrided layer and the sample of before nitriding was studied.The best nitrided layer was formed with certain process parameters:source voltage940V-970V,cathode voltage 610V-640V,working time 4h,working temperature 850?,the distance between auxiliary cathode and the sample was 15mm-18mm,and the thickness of the nitrided layer was about 23?m.The nitrided layer was characterized by XRD,SEM,EDS.Results showed that the nitrided layer mainly consists of TiN,Ti2N,and ZrN.The hardness on the surface of the nitrided layer reached 1000HV due to nitrides forming on the substrate.The tribological tests of the alloy were conducted using a ball-on-disc tribometer?Rtect instruments,MFT 5000,USA?.The weightlessness of the untreated and treated samples are2.5mg and 0.8mg,respectively.The surface morphology of untreated sample shown severe damage with abrasive wear,and the morpholofy of the worn surface of the treated sample had light plowing without the formation of deep grooves.Thus,the wear resistance of the considerably improved after nitridation by the double glow plasma.The electrochemical corrosion tests in different medium and soaking weightlessness were used to characterize the corrosion properties of the nitrided layer and the sample of before nitridation.The electrochemical corrosion was experimented in the quality of 3.5%NaCl solution,5%HCl and 10%H2SO4 solution,and the soaking weightlessness was experimented in 20%HCl solution.According to the elactrochemical corrosion,the self-corrosion current density from 6.390×10-6A/cm2decreases to 1.395×10-6A/cm2in the 3.5%NaCl solution,the self-corrosion current density from 1.146×10-5mg/cm2decreases to 5.278×10-77 A/cm2 in the 5%HCl solution,the self-corrosion current density had not a abvious change in 10%H2SO4 solution.But,the self-corrosion potential from-0.473V decreases to-0.278 V in the 10%H2SO solution.It can been found that the corrosion properties of the nitrided layer has gotten a improvement.In the experiment of soaking weightlessness,morphologies of the surface of the nitrided layer did not had a apparent variation.On the contrary,numerous etching pits appeared on the surface of the substrate with a serious erode situation.Thus,the nitrided layer of the titanium alloy by the double glow plasma can enhance the corrosion resistance. |
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