Corrosion Behavior of Tentative Nickel Binary and Ternary Alloys after Plasma Ion Nitriding Treatment : Studies on Surface Modification of Non Ferrous Metals by means of Plasma Ion Nitriding (PIN) Process (Report 3)(Materials, Metallurgy & Weldability)
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In order to investigate the corrosion properties of Ni alloys after nitriding treatment, tentative Ni binary alloys of Ni-7wt%Ti, -15wt%V, -10wt%Nb, -20wt%Cr and -30wt%Cr and Ni ternary alloys of Ni-7wt%Ti-2wt% (V, Nb, Ta, Cr, Mo or Al) and Ni-20wt%Cr-2wt% (Ti, V, Nb, Ta, Mo or Al) were nitrided by means of plasma ion nitriding (PIN) process under the conditions of 873K (823K at Ni-30wt%Cr), 10.8ks, N_2+H_2 mixed gas atmosphere of 800Pa. Corrosion properties of tentative Ni alloys were determined by means of potentiodynamic polarization methode in an acid solution (30℃, 5%H_2SO_4). Pure nickel and austenitic stainless steel, SUS304 were also used as reference materials. Tentative Ni alloys showed better corrosion resistance than pure nickel before PIN treatment. PIN treatment resulted in a slight deterioration of corrosion resistance of tentative Ni alloys. Comparing of corrosion resistance of Ni alloys with SUS 304 after PIN treatment, deterioration of corrosion resistalnce of Ni alloys were slighter than SUS304. Spalling of nitrided layer occurred in nitrided Ni-Cr binary alloys. On the contrary, Pitting and intergranular corrosion were observed in nitrided Ni binary and ternary alloys except Ni-Cr alloys. Taking into consideration of corrosion resistance and hardenability by PIN treatment, Ni-7wt%Ti binary alloy, Ni-7wt%Ti-X and Ni-20wt%Cr-X ternary alloys were proved to be beneficial alloys as hardenable Ni alloys by PIN treatment.
- Transactions of JWRI
Transactions of JWRI 21(1), 77-83, 1992-06