Electrochemical and microstructural studies of sintered and sintered-plasma nitrided steel containing different alloying elements

Pereira, Nilton Cezar; Mittelstädt, F. G.; Spinelli, Almir; Maliska, A.M.; Klein, Aloı́sio Nelmo; Muzart, J.L.R.; Franco, Carlos

doi:10.1007/bf01154489

Cited by 9 publications

(4 citation statements)

References 2 publications

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“…This has been subject of particular interest from several recent investigations. [4][5][6][7][8][9][10][11][12][13][14][15][16] The porosity increases the area of metallic material exposed to the corrosive environment and might eventually induce crevice corrosion, with concentration cells within the pores. This reduces the passivity of the sintered alloy.…”

Section: Corrosion-april 2006mentioning

confidence: 99%

Corrosion Resistance of Injection-Molded 17-4PH Steel in Sodium Chloride Solution

Costa¹,

Franco²,

Kunioshi³

et al. 2006

CORROSION

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The corrosion resistance of 17-4PH powder injection-molded (PIM) martensitic stainless steel (SS) was evaluated in naturally aerated sodium chloride (NaCl) solution (3 wt%) at 25°C. This resistance was investigated by analyzing the curves of the evolution of open-circuit potential with time (E ocp vs. time), electrochemical impedance spectroscopy (EIS), and surface observation by scanning electron microscopy (SEM) at increasing times of immersion. The susceptibility to pitting was investigated using cyclic potentiodynamic polarization curves and SEM observation after polarization. Additionally, the susceptibility to intergranular corrosion was evaluated by a modifi ed procedure described in ASTM A 262 Practice A. The results of the 17-4PH PIM steel were compared to that of a 17-4PH steel produced by conventional metallurgy. The results showed that under steady-state conditions the PIM steel presented a behavior typical of passive metals during the whole test period (60 days of immersion). This was indicated by the E ocp vs. time curves, EIS results, and SEM observation of the surface at increasing periods of immersion. The steel showed a bright metallic surface and no signs of corrosion during the whole period of the test. Cyclic potentiodynamic polarization curves indicated that both 17-4PH steels, conventional and PIM, are susceptible to pitting but the PIM steel showed a slightly increased susceptibility to pitting, which was supported by posttest observation by SEM. In the PIM steel, pits seemed to be related to the porosity that had inner oxide inclusions. The 17-4PH steel, produced by both PIM technology and conventional metallurgy, did not show a susceptibility to intergranular corrosion by ASTM A 262 Practice A.

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Section: Corrosion-april 2006mentioning

confidence: 99%

Corrosion Resistance of Injection-Molded 17-4PH Steel in Sodium Chloride Solution

Costa¹,

Franco²,

Kunioshi³

et al. 2006

CORROSION

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“…It could also be noticed that the film penetrated into open pores coating, an additional area that otherwise would be exposed to corrosion attack. The influence of porosity on the corrosiveness of sintered stainless steel has been extensively documented by previous literature reports [21][22][23][24][25]. The excessive open porosity increases the exposed area to the corrosive environment which induces crevice corrosion with the formation of concentration cells within the pores [26][27].…”

Section: Materials Science Forum Vols 530-531mentioning

confidence: 99%

Studies on the Preparation, Characterization and Corrosion Behaviour of Injection Molded 316L Steel Electrochemically Coated by Poly{trans[dichloro (4-vinylpyridine) ruthenium]}

Sobral

Costa

Franco

2006

MSF

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The present work describes the studies on corrosion of powder injection molded 316L stainless steel potentiostatically coated by poly{trans[RuCl2(vpy)4]} where vpy (4- vinylpyridine) acts as ligand. Scanning Electron Microscopy (SEM) coupled to an Energy Dispersive X-Ray Analysis (EDAX) characterized the coated electrodes. Anodic polarization tests were performed in 3% NaCl to estimate the anodic dissolution current density of the electrode coated by the polymeric material. In addition, the specimens were exposed to salt spray and acid rain simulated environment. The microestrutural analysis indicated that the films were approximately 58 μm thick. Cyclic voltammetry experiments were carried out in 0.1M HTBA/methyl isobutyl ketone solution. The results revealed a scan rate dependent wave corresponding to a Ru2+/Ru3+ redox reaction, thus confirming the presence of ruthenium as metallic center in the polymer backbone. Pitting corrosion was observed in coated specimens only after thirty days of exposure to salt spray and after two days of exposure to acid rain simulated environment.

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“…Several solutions in order to improve the performance of powdered steels in corrosive environments have been investigated. Although both the quality of the starting powders and sintering process can be optimized by aiming at improved chemical stability, post-sintering surface treatments, such as nitriding and nitrocarburizing, are far more efficient [8,9,11,13]. Coating layers capable of improving bulk hardness [2], wear [3,4], fatigue endurance [5], and corrosion resistance [6 -14] can be formed in a single-step process.…”

Section: Introductionmentioning

confidence: 99%

Microstructure and corrosion behaviour of plasma‐nitrocarburized sintered steel

Borges

Martinelli

Franco³

2004

Materials & Corrosion

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Powder characteristics and manufacturing processes determine the microstructure, and therefore, the physical, chemical, and mechanical properties of sintered steels. In particular, porosity and corrosion resistance are intimately related, since the contact area between substrate and electrolyte significantly affects the corrosion resistance of sintered steels. This study addresses the effect of powder characteristics and pressing parameters on the microstructure and corrosion resistance of low-carbon sintered and sintered/plasma-nitrocarburized steel. The results indicated that the corrosion resistance increased with increasing density and decreasing specific surface area. Additionally, plasma-nitrocarburizing was highly effective in coating open pores of the material.

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Electrochemical and microstructural studies of sintered and sintered-plasma nitrided steel containing different alloying elements

Cited by 9 publications

References 2 publications

Corrosion Resistance of Injection-Molded 17-4PH Steel in Sodium Chloride Solution

Corrosion Resistance of Injection-Molded 17-4PH Steel in Sodium Chloride Solution

Studies on the Preparation, Characterization and Corrosion Behaviour of Injection Molded 316L Steel Electrochemically Coated by Poly{trans[dichloro (4-vinylpyridine) ruthenium]}

Microstructure and corrosion behaviour of plasma‐nitrocarburized sintered steel

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