Microstructural characterization of plasma nitriding surface of sintered steels containing Si

Maliska, A.M.; Klein, Aloı́sio Nelmo; Souza, A. R. de

doi:10.1016/0257-8972(94)02269-v

Cited by 16 publications

(8 citation statements)

References 3 publications

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“…This route is a way to expand the range of applications of these materials, which are today dominated by the chemical, petrochemical, pharmaceutical, and food industries [1][2][3][4][5][6][7]. Low-temperature plasma-assisted nitriding and nitrocarburizing are diffusion treatments that minimize the detrimental effects of the generally unwelcome porosity in powder metallurgy (P/M) austenitic stainless steels and iron [8][9][10]. The surface porosity of P/M steels promotes a faster growth of the nitrided layer in comparison with the fully dense steels [10].…”

Section: Introductionmentioning

confidence: 99%

Scratch Response of Hollow Cathode Radiofrequency Plasma-Nitrided and Sintered 316L Austenitic Stainless Steel

Broch,

Fontoura,

Lima

et al. 2024

Coatings

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Low-temperature plasma nitriding is a thermochemical surface treatment that promotes surface hardening and wear resistance enhancement without compromising the corrosion resistance of sintered austenitic stainless steels. Hollow cathode radiofrequency (RF) plasma nitriding was conducted to evaluate the influence of the working pressure and nitriding time on the microstructure and thickness of the nitrided layers. A group of samples of sintered 316L austenitic stainless steel were plasma-nitrided at 400 °C for 4 h, varying the working pressure from 160 to 25 Pa, and the other group was treated at the same temperature, varying the nitriding time (2 h and 4 h) while keeping the pressure at 25 Pa. A higher pressure resulted in a thinner, non-homogeneous nitrided layer with an edge effect. Regardless of the nitriding duration, the lowest pressure (25 Pa) promoted the formation of a homogenously nitrided layer composed of nitrogen-expanded austenite that was free of iron or chromium nitride and harder and more scratching-wear-resistant than the soft steel substrate.

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Section: Introductionmentioning

confidence: 99%

Scratch Response of Hollow Cathode Radiofrequency Plasma-Nitrided and Sintered 316L Austenitic Stainless Steel

Broch,

Fontoura,

Lima

et al. 2024

Coatings

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“…Si is known to affect the hardness and thickness of the compound layer, [5,30,31] and the hardness of the diffusion zone. [23,32] It is also known that Si might affect the nitriding conditions, under which the main iron nitrides e and c¢ form as compared to nitriding of pure iron.…”

Section: Introductionmentioning

confidence: 99%

Fe Nitride Formation in Fe–Si Alloys: Crystallographic and Thermodynamic Aspects

Kante

Leineweber

2021

Metall Mater Trans A

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A Fe–3wt pctSi alloy was gas nitrided to study the effect of Si on the Fe nitride formation. Both ε-Fe3N1+x and γ′-Fe4N were observed at nitriding conditions only allowing to form single-phase γ′ layers in pure α-Fe. During short nitriding times, ε and γ′ simultaneously grow in contact with Si-supersaturated α-Fe(Si). Both nitrides almost invariably exhibit crystallographic orientation relationships with α-Fe, which are indicative of a partially displacive transformation of α-Fe being involved in the initial formation of ε and γ′. Due to Si constraining the Fe nitride growth, such transformation mechanism becomes highly important to the nitride layer formation, causing α-Fe-grain-dependent variations in the nitride layer morphology and thickness, as well as microstructure refinement within the nitride layer. After prolonged nitriding, α-Fe is depleted in Si due the pronounced precipitation of Si-rich nitride in α-Fe. The growth mode of the compound layer changes, now advancing by conventional planar-type growth. During nitriding times of 1 to 48 hours, ε exists in contact with the NH3/H2-containing nitriding atmosphere at a nitriding potential of 1 atm−1/2 and 540 °C, only allowing for the formation of γ′ in pure Fe, indicating that Si affects the thermodynamic stability ranges of ε and γ′.

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“…More elaborated protection methods as steam treatment [3][4] and dacronizing 5 are also sometimes recommended. In addition, plasma-nitriding techniques [6][7][8][9][10] are being used with success for superficial treatment aiming to improve the mechanical properties [11][12][13][14][15] and the corrosion resistance of stainless steels [16][17][18][19][20] and low alloy steels [21][22][23][24][25][26][27] manufactured through powder metallurgy.…”

Section: Introductionmentioning

confidence: 99%

Characterization of Sintered and Sintered/Plasma-Nitrided Fe-1.5% Mo Alloy by SEM, X-Ray Diffraction and Electrochemical Techniques

et al. 2002

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Electrochemical experiments together with SEM and X-Ray techniques were carried out in order to evaluate the corrosion resistance, to analyze the surface condition and to characterize the nitride layer of the sintered and sintered/plasma-nitrided Fe-1.5% Mo alloy in Mg(NO3)2 0.5mol.L-1 solution (pH 7.0). The sintered/plasma-nitrided samples presented a higher corrosion resistance, indicating that the surface treatment improved the electrochemical properties of the sintered material. In addition, the nitride layer formed at 500 °C showed better corrosion resistance that the layers formed at higher temperatures. This difference can be ascribed to the nitrogen content in the nitride layer, which at 500°C is higher due to the formation of a phase rich in nitrogen (epsilon phase) while at higher temperatures a phase poor in nitrogen (gamma' phase) is formed

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Microstructural characterization of plasma nitriding surface of sintered steels containing Si

Cited by 16 publications

References 3 publications

Scratch Response of Hollow Cathode Radiofrequency Plasma-Nitrided and Sintered 316L Austenitic Stainless Steel

Scratch Response of Hollow Cathode Radiofrequency Plasma-Nitrided and Sintered 316L Austenitic Stainless Steel

Fe Nitride Formation in Fe–Si Alloys: Crystallographic and Thermodynamic Aspects

Characterization of Sintered and Sintered/Plasma-Nitrided Fe-1.5% Mo Alloy by SEM, X-Ray Diffraction and Electrochemical Techniques

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