Solid carbon active screen plasma nitrocarburizing of AISI 316L stainless steel: Influence of N2-H2 gas composition on structure and properties of expanded austenite

Dalke, Anke; Burlacov, I.; Hamann, S.; Puth, Alexander; Böcker, Jan; Spies, H.‐J.; Röpcke, J.; Biermann, Horst

doi:10.1016/j.surfcoat.2018.10.095

Cited by 37 publications

(28 citation statements)

References 45 publications

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“…In previous studies conducted at a similar setup, CH 4 , C 2 H 2 , HCN, and NH 3 were found to be the predominant species in an ASPNC plasma [19,29]. Accordingly, the column-averaged absolute concentrations of the four species were monitored using two spectral windows of an infrared external-cavity quantum cascade laser (EC-QCL) at approximately 1356.3 and 1387.8 cm −1 .…”

Section: Methodsmentioning

confidence: 99%

“…A commercially available austenitic stainless steel AISI 316L (chemical composition in wt.%: C0.05, Cr16.98, Ni11.39, Mo1.92, Mn1.54, Si0.33, and Fe balance [29]) was used for the investigations. Specimens of 20 mm in diameter and 4.5 mm in thickness machined from a cylindrical bar were wet ground up to a 800 SiC paper grid.…”

Section: Methodsmentioning

confidence: 99%

“…As can be seen in Table 1, the N 2 -H 2 feed gas mixture had a significant influence on the resulting screen power. In the case of excess nitrogen in the N 2 -H 2 gas mixture, a lower screen power was required to maintain the process temperature of 733 K. According to a previous study, a difference in AS power resulting from the composition of the N 2 -H 2 feed gas corresponded to a significant change in the concentration of reactive species in the resulting process gas [29].…”

Section: Influence Of An Ohmic Heatermentioning

confidence: 99%

“…In an industrial-scale reactor, the effect of the precursor gas composition at a constant bias power [29] and variations of the bias at a fixed gas composition [30] on AISI 316L steel have been investigated. It was found that the thickness ratios of γ N to γ C can be modified by the variation of the ratio of the N 2 -H 2 feed gas composition.…”

Section: Introductionmentioning

confidence: 99%

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Influence of the Active Screen Plasma Power during Afterglow Nitrocarburizing on the Surface Modification of AISI 316L

et al. 2020

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Active screen plasma nitrocarburizing (ASPNC) increases the surface hardness and lifetime of austenitic stainless steel without deteriorating its corrosion resistance. Using an active screen made of carbon opens up new technological possibilities that have not been exploited to date. In this study, the effect of screen power variation without bias application on resulting concentrations of process gas species and surface modification of AISI 316L steel was studied. The concentrations of gas species (e.g., HCN, NH3, CH4, C2H2) were measured as functions of the active screen power and the feed gas composition at constant temperature using in situ infrared laser absorption spectroscopy. At constant precursor gas composition, the decrease in active screen power led to a decrease in both the concentrations of the detected molecules and the diffusion depths of nitrogen and carbon. Depending on the gas mixture, a threshold of the active screen power was found above which no changes in the expanded austenite layer thickness were measured. The use of a heating independent of the screen power offers an additional parameter for optimizing the ASPNC process in addition to changes in the feed gas composition and the bias power. In this way, an advanced process control can be established.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Influence Of An Ohmic Heatermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Influence of the Active Screen Plasma Power during Afterglow Nitrocarburizing on the Surface Modification of AISI 316L

et al. 2020

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“…Active screen plasma nitriding (ASPN) is an excellent method for the further utilization of active species and the generation of uniform heating regions. The screen suppresses the edge effect by increasing the supply of active species such as N + , N 2 + and H + and by heating the sample surface uniformly [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32]. However, nitriding on small-diameter thin pipes has not been reported yet [30].…”

Section: Introductionmentioning

confidence: 99%

Application of Active-Screen Plasma Nitriding to an Austenitic Stainless Steel Small-Diameter Thin Pipe

Sumiya¹,

Tokuyama²,

Nishimoto

et al. 2021

Metals

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Low-temperature active-screen plasma nitriding (ASPN) was applied in this study to improve the bending rigidity and corrosion resistance of a small-diameter thin pipe composed of austenitic stainless steel (SUS 304). The inner and outer diameters of the pipe were ϕ0.3 and ϕ0.4 mm, respectively, and the pipe length was 50 mm. The jig temperature was measured using a thermocouple and was adopted as the nitriding temperature because measuring the temperature of a small-diameter pipe is difficult. The nitriding temperature was varied from 578 to 638 K to investigate the effect of temperature on the nitriding layer and mechanical property. The nitriding layer thickness increased with an increase in nitriding temperature, reaching 15 μm at 638 K. The existence of expanded austenite (S phase) in this nitriding layer was revealed using the X-ray diffraction pattern. Moreover, the surface hardness increased with the nitriding temperature and took a maximum value of 1100 HV above 598 K. The bending load increased with an increase in the nitriding temperature in relation to the thicker nitriding layer and increased surface hardness. The nitrided samples did not corrode near the center, and corrosion was noted only near the tip at high nitriding temperatures of 618 and 638 K in a salt spray test. These results indicated that the bending rigidity of the small-diameter thin pipe composed of austenitic stainless steel was successfully improved using low-temperature ASPN while ensuring corrosion resistance.

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New Approach for Plasma Nitrocarburizing of Stainless Steels by a Modified Reactor Configuration Using a Plasma‐Activated Solid Carbon Precursor

M. Jafarpour,

Dalke,

Biermann

2024

steel research int.

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Stainless steel surfaces can be modified using plasma‐assisted thermochemical treatments to improve properties like hardness, wear, and pitting corrosion resistance. To specifically adjust the desired properties, a precise control of the produced treatment‐relevant gas species with regard to their type and concentration is essential. This requires the adjustment of the parameters for the generation of the gas species, being independent from heating parameters, as well as their real‐time measurement. Therefore, this study presents the use of a plasma‐activated solid carbon precursor in a cold‐wall reactor using active screen technology and in a modified hot‐wall reactor during plasma nitrocarburizing of austenitic stainless steel. In addition, the modified hot‐wall reactor combined with a compact laser‐based absorption spectroscopy sensor for real‐time monitoring and concentration evaluation of in‐site generated gas species. It is shown that implementing a plasma‐activated solid carbon precursor in a modified hot‐wall reactor enables adjustable generation of C‐containing gas species, particularly HCN, with high production yield by an independent power management. Therefore, HCN is produced independent from heating while the limitations arising during active screen technology using a carbon screen are avoided. The presented technological development thus opens up new possibilities for better control of the plasma nitrocarburizing treatments of steels.

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Solid carbon active screen plasma nitrocarburizing of AISI 316L stainless steel: Influence of N2-H2 gas composition on structure and properties of expanded austenite

Cited by 37 publications

References 45 publications

Influence of the Active Screen Plasma Power during Afterglow Nitrocarburizing on the Surface Modification of AISI 316L

Influence of the Active Screen Plasma Power during Afterglow Nitrocarburizing on the Surface Modification of AISI 316L

Application of Active-Screen Plasma Nitriding to an Austenitic Stainless Steel Small-Diameter Thin Pipe

New Approach for Plasma Nitrocarburizing of Stainless Steels by a Modified Reactor Configuration Using a Plasma‐Activated Solid Carbon Precursor

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