Study On The Corrosion Behavior Of The New Type Of Te- Ni-Cr Alloy

The New Type of Te- Ni-Cr Alloy is an excellent corrosion resistant and wear resistance alloy which was developed by the researchers in our laboratory. This article probes into the influence of Te on the corrosion resistance and corrosion behavior of the New Type of Te- Ni-Cr Alloy.Microstructure and mechanical properties of New Type of Te- Ni-Cr Alloy samples with different mass fraction of Te were observed and analyzed by MEF3,X-ray diffraction, backscatter observation, microhardness testing and wear resistance,etc. The results indicated that:there is black protuberant phase in microstructure of the alloy with tellurium, , which are firmly embedded in the surface of the matrix. The New Type of Te- Ni-Cr Alloy phases compriseα-Ni3CrFe as matrix phase,β-Cr₅Ni₂FeB phase,γ-C₁₉Cr₇Mo₂₄phase,adding Te elements prompted alloy exhalationβphase,γphase.And micro hardness of material has been greatly improved,wear resistance,friction coefficient to strengthen stable over time.The Microscropic structure of the alloy with tellurium has been changed,mechanical properties have been greatly improved.The corrosion resistance and behavior of the New Type of Te- Ni-Cr Alloy with different mass fraction of Te element in seawater(3.5%NaCl solution)and 5%H₂SO₄ solution were investigated by using Static Immersing Corrosion test,scanning electron microscope (SEM), XRD,EPMA,etc. The results show that the corrosion resistance of New Type of Te- Ni-Cr Alloy is very good in seawater and 5%H₂SO₄ solution. Because of anding tellurium, the corrosion resistance becomes strengthened. When anding 0.8% Te, the corrosion resistance is the best in seawater, 5% H₂SO₄ solution. Te - Ni - Cr alloy happenes electrochemical corrosion in solution, corrosion form a pit, pitting corrosion, the corrosion pit of adding tellurium alloy is smaller,wall is smoother and organizations are denser than didn't add tellurium alloy. The ability to resist materials suffering further corrosion becomes stronger. In seawater, the corrosion products are nickel and iron oxide mixture. In 5% H₂SO₄ solution, the corrosion products are nickel ferrochrome sulfide and their oxides.High temperature molten salt corrosion experiment is that Te- Ni-Cr Alloy samples with mass fraction of Te 0.8% are corroded in 750℃Na2SO4- 25%NaCl, the corrosion time is 3 h, 6 h, 12 h, 18 h, 24 h, 30 h. The experimental results show that, at the start stage, Te- Ni-Cr Alloy is corrosion resistant , with the extension of time, the corrosion intensify, the corrosion resistance failure. In 3 h, 18 h, 30 h three stages, Ni₂S₃, Fe₂O₃, Cr₂O₃ corrosion products are generated in alloy surface. After 18 h, NiS,CrS occur. When 30 h, NiS₂, Cr₂S₃ occur. Alloy heat corrosion is a vulcanizing - oxidation coexistence process. In the starte corrosion stage in plasma-nitriding on Te- Ni-Cr Alloy, the corrosion products can fairly solid connected together with substrate,with the corrosion time extension, increased corrosion layer formed product, time continue to increase, the corrosion layer off from substrate.