Solid carbon active screen plasma nitrocarburizing of AISI 316L stainless steel in cold wall reactor: influence of plasma conditions

Jafarpour, Saeed Motaragheb; Puth, Alexander; Dalke, Anke; Böcker, Jan; Pipa, A. V.; Röpcke, J.; Helden, J. H. van; Biermann, Horst

doi:10.1016/j.jmrt.2020.06.041

Cited by 24 publications

(10 citation statements)

References 41 publications

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“…The analysis of the process gas by IRLAS helped to control the set conditions. The use of a heating independent of the screen power provided an additional parameter to optimize the process of ASPNC, in addition to changes of the feed gas composition and bias power [30]. By this way, a new system with a process control is a reasonable next step of future work.…”

Section: Discussionmentioning

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: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

et al. 2020

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“…The special role of HCN molecules in carburizing and nitriding, as well as in activation of the oxide layer, during ASPNC of austenitic stainless steel was discussed in our previous work [47]. There, a cylindrical substrate holder with side slits was applied, which prohibited the access of charged particles to the back side of the sample.…”

Section: Discussionmentioning

confidence: 99%

“…As the process temperature has been identified as the most important treatment parameter, it was used as the control parameter for the AS plasma power adjustment in an industrialscale cold-wall ASPNC reactor. However, by applying a bias discharge at the samples to be treated, an additional heat influx was introduced, in turn affecting the plasma power at the AS [47]. The described coupling is displayed in Figure 3 for both the steel AS and for the CFC-AS.…”

Section: Interconnection Of the As And Bias Plasma Powersmentioning

confidence: 99%

“…Slight decreases by a factor of approximately 1.5 in the concentrations of HCN and C 2 H 2 were observed when the bias power increased from 0 to 1.25 kW in the case of the CFC-AS (blue and green lines in Figure 8b). This can be explained based on the previously mentioned fact that, due to the application of a high bias discharge to the treated samples, an additional heat influx was introduced into the process, which in turn reduced the plasma power at the AS [47]. Consequently, as also shown by Puth et al [39], a lower concentration of HCN was detected from the reduction of the AS plasma power in the case of the CFC-AS when a relatively high bias power was applied at the samples.…”

Section: Comparison Of Gaseous and Solid-state Carbon Precursors In Aspnc 331 Plasma Diagnostics Using Oes And Las Techniquesmentioning

confidence: 99%

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Effects of Plasma-Chemical Composition on AISI 316L Surface Modification by Active Screen Nitrocarburizing Using Gaseous and Solid Carbon Precursors

Jafarpour

Pipa

Puth

et al. 2021

Metals

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Low-temperature plasma nitrocarburizing treatments are applied to improve the surface properties of austenitic stainless steels by forming an expanded austenite layer without impairing the excellent corrosion resistance of the steel. Here, low-temperature active screen plasma nitrocarburizing (ASPNC) was investigated in an industrial-scale cold-wall reactor to compare the effects of two active screen materials: (i) a steel active screen with the addition of methane as a gaseous carbon-containing precursor and (ii) an active screen made of carbon-fibre-reinforced carbon (CFC) as a solid carbon precursor. By using both active screen materials, ASPNC treatments at variable plasma conditions were conducted using AISI 316L. Moreover, insight into the plasma-chemical composition of the H2-N2 plasma for both active screen materials was gained by laser absorption spectroscopy (LAS) combined with optical emission spectroscopy (OES). It was found that, in the case of a CFC active screen in a biased condition, the thickness of the nitrogen-expanded austenite layer increased, while the thickness of the carbon-expanded austenite layer decreased compared to the non-biased condition, in which the nitrogen- and carbon-expanded austenite layers had comparable thicknesses. Furthermore, the crucial role of biasing the workload to produce a thick and homogeneous expanded austenite layer by using a steel active screen was validated.

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Comparative Plasma Nitrocarburizing of AISI 316L and AISI 304 Steels Using a Solid Carbon Active Screen: Differences in the Developing Microstructures

Jafarpour,

Martin,

Schimpf

et al. 2024

Metall Mater Trans A

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This paper features a direct comparison of the response of AISI 316L and AISI 304 austenitic stainless steels to active screen plasma nitrocarburizing applied for a wide range of treatment temperatures from 380 °C to 480 °C (653 K to 753 K). Thereby, an active screen made of solid carbon was used without applying bias plasma to the treated steel samples. Since it is believed that the result of treatment strongly depends on the concentration of in-situ generated hydrogen cyanide, the conditions of the treatments were adapted to keep this concentration constant. Under such treatment conditions, it was shown that AISI 316L has a lower tendency to form CrN than AISI 304 at comparable treatment temperatures, where the threshold temperature was found below 480 °C (753 K) for the former and below 440 °C (713 K) for the latter. In addition, the decomposition of expanded austenite generated on the treated AISI 316L at high temperatures leads to CrN and (mainly) Cr-depleted austenite phase, which is possibly accompanied by minor amounts of $$\alpha$$ α -ferrite. Instead, for the treated AISI 304, decomposition leads to CrN and transformed $$\alpha$$ α -ferrite phase. The modified layer thicknesses achieved after a given treatment duration and the kinetics of the layer growth showed a characteristic temperature dependence for each steel, which is discussed in accordance with the results of microstructure analysis.

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Solid carbon active screen plasma nitrocarburizing of AISI 316L stainless steel in cold wall reactor: influence of plasma conditions

Cited by 24 publications

References 41 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

Effects of Plasma-Chemical Composition on AISI 316L Surface Modification by Active Screen Nitrocarburizing Using Gaseous and Solid Carbon Precursors

Comparative Plasma Nitrocarburizing of AISI 316L and AISI 304 Steels Using a Solid Carbon Active Screen: Differences in the Developing Microstructures

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