Investigation of nitrogen mass transfer within an industrial plasma nitriding system I: The role of surface deposits

Hubbard, Philip; Partridge, J. G.; Doyle, E.D.; McCulloch, D. G.; Taylor, Matthew; Dowey, S.J.

doi:10.1016/j.surfcoat.2009.08.029

Cited by 75 publications

(31 citation statements)

References 11 publications

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“…These polygonal particles are considered to be surface deposits. 36,37) These particles became coarser with increasing nitriding time. This result indicates that the FeN deposition increased with increasing treatment time, and these deposited particles grew.…”

Section: Resultsmentioning

confidence: 98%

“…9,16,17,33,35) A recent research suggested that a deposited layer was formed on the sample surface during ASPN. [36][37][38] However, little information has been reported on the effect of the surface deposits on the nitriding layer formation during ASPN process. In this study, austenitic stainless steel SUS 316L was nitrided with a oating potential (bias-off) and a cathodic potential (bias-on) of ASPN process to investigate the effect of surface deposits from the screen on the nitriding layer formation.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Surface Deposits on Nitriding Layer Formation of Active Screen Plasma Nitriding

2016

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Austenitic stainless steel SUS 316L was nitrided by active-screen plasma nitriding (ASPN) to investigate the effect of surface deposits from the screen on the nitriding layer formation. ASPN experiments were carried out using a DC plasma-nitriding unit. The sample was placed on the sample stage in a oating potential (bias-off) and a cathodic potential (bias-on). The screen, which was SUS 316L expanded metal with 38% open area ratio, was mounted on the cathodic stage around the sample stage. Nitriding was performed in a nitrogen-hydrogen atmosphere with 25% N 2 + 75% H 2 for 18-180 ks at 673 K under 200 Pa by the ASPN process. After nitriding, the nitrided samples were examined using scanning electron microscopy, X-ray diffraction, Vickers microhardness and glow discharge optical emission spectroscopy. From the surface observation of the nitrided sample, deposits were observed on the top surface of the sample nitrided with bias-off whereas deposits were not on that nitrided with bias-on. The nitrogen-expanded austenite (S phase) was formed on the surface of both samples. Layer thickness of the S phase increased with increasing the nitriding time. Additionally, the degree of an increase of the layer thickness of the S phase nitrided with bias-on was approximately 2.5 times greater than that nitrided with bias-off. This result suggests that the ASPN treatment with bias-on is effective for the increase of the nitriding layer thickness.

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Section: Resultsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Effect of Surface Deposits on Nitriding Layer Formation of Active Screen Plasma Nitriding

2016

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“…Based on through and comprehensive literature review, a lot of related studies on different aspects and affecting parameter of ion nitriding of AISI P20 mould steel were carried out in recent years [18][19][20][21]. Bull et al [18], simulated the wear condition happening on the body of plastic moulding equipments take place in AISI P20 steel and reported the best surface treatment with a combination of nitriding and ion implantation.…”

Section: Introductionmentioning

confidence: 99%

“…Boey et al [20] simulated the temperature effect on abrasive wear on AISI P20 steel after applying a two step surface treatment on samples, namely plasma nitriding and nitrogen ion implantation and got excellent wear property. Hubbard et al [21] also investigated the dominant mechanism of the surface nitride formation taking the advantage of active screen plasma nitriding (ASPN) of AISI P20.…”

Section: Introductionmentioning

confidence: 99%

“…Although there are studies available on parametric study and related phenomena involved in ion nitriding of AISI P20 in the literatures [18][19][20][21] and in other steel categories with difference performances [6,14,22], but the nitrided layer growth and formation mechanism have not been discussed in details. In this study, an attempt was made to investigate the effect of nitriding temperature and time on the formation of nitrided layer, depth of nitrogen diffusion and achieved microstructure of AISI P20.…”

Section: Introductionmentioning

confidence: 99%

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A Study on Formation and Growth Mechanism of Nitride Layers During Plasma Nitriding Process of Plastic Injection Mold Steel

Nayebpashaee

Soltanieh

Kheirandish

2015

Materials and Manufacturing Processes

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Ion nitriding modifies composition of surface layer in steel used in plastic mold application and this consequently improves their lifecycle. In this study, pulsed plasma nitriding technique was used to produce a protecting hard layer on AISI P20 steel at three process temperatures of 450°C, 500°C and 550°C for durations of 2.5, 5, 7.5 and 10 hours at a constant gas mixture of 75% N 2 -25% H 2 . Surface morphology was studied by optical and scanning electron microscope (SEM) and the phases formed on the surface layer were determined by X-Ray diffraction (XRD). Elemental depth profile was measured by techniques including EDS, WDS and GDS and for identifying hardness profile, micro-hardness variations from surface to core of samples were recorded. Results showed that, thickness of compound layer of plastic mould steel AISI P20 was negligible.Moreover in ion nitriding of AISI P20, nitride were formed and grown in some preferred directions and upward diffusion of carbon and downward diffusion of nitrogen occurred during ion nitriding of AISI P20. XRD results showed that, ε-nitride is the dominant phase after plasma nitriding in all strategies. Furthermore, ion nitriding improved Downloaded by [New York University] at 02:06 14 July 2015 2hardness of AISI P20 up to 3 times and as time and temperature increased, hardness and hardness depth of diffusion zone increased considerably.

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Spectroscopic Investigations of Plasma Nitriding and Nitrocarburizing Processes Using an Active Screen: A Comparative Plasma Chemical Study of Two Reactor Types

Hamann

Börner

Burlacov

et al. 2015

Contrib. Plasma Phys.

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Low-pressure pulsed DC N 2-H2 plasmas with admixtures of CH4 were investigated in a comparative study in two different types of reactors, (i) a cylindrical industrial scale active screen plasma nitriding (ASPN) reactor and (ii) a laboratory scale plasma nitriding monitoring reactor (PLANIMOR) with a linear electrode configuration. Applying infrared laser absorption spectroscopy (IRLAS) the evolution of the molecular concentrations of four stable molecules, CH4, HCN, NH3, and C2H2 has been monitored. The degree of dissociation of the carbon containing precursor, CH4, varied between 80 and 95%. The concentrations of the molecular reaction products have been found in a range of 10 11 to 10 16 molecules cm −3 . By analyzing the development of the molecular concentrations at changes of the screen plasma power, the gas mixture and the admixture of CH4, a similar behavior of the monitored species depending on the varied parameters has been found in both reactors with NH3 and HCN as the main products of plasma conversion. The fragmentation efficiency of methane has been determined, decreasing from 2.4 to 0.8×10 15 molecules J −1 with the increasing power of the screen plasmas in both reactors. With the help of optical emission spectroscopy (OES) the rotational temperature of the N + 2 ions in the plasma could be determined, being in a range of 650. . . 920 K where the rotational temperature of the screen plasma in the ASPN reactor is approximately 100 K higher than that in PLANIMOR. Also with power the ionic component of nitrogen molecules, i.e. the intensity of the N + 2 -(0-0) band of the first negative system, which has been used as the reference parameter for comparing both reactors, increases strongly in relation to the intensity of the neutral component, represented by the N2-(0-0) band of the second positive system. In addition, steel samples have been treated in both the ASPN reactor and PLANIMOR leading to comparable nitriding results.

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Investigation of nitrogen mass transfer within an industrial plasma nitriding system I: The role of surface deposits

Cited by 75 publications

References 11 publications

Effect of Surface Deposits on Nitriding Layer Formation of Active Screen Plasma Nitriding

Effect of Surface Deposits on Nitriding Layer Formation of Active Screen Plasma Nitriding

A Study on Formation and Growth Mechanism of Nitride Layers During Plasma Nitriding Process of Plastic Injection Mold Steel

Spectroscopic Investigations of Plasma Nitriding and Nitrocarburizing Processes Using an Active Screen: A Comparative Plasma Chemical Study of Two Reactor Types

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