Plasma nitriding of low alloy steels at floating and cathodic potentials

is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. The aim of the study is to apply a plasma nitriding process to the 90CrMoV8 steel commonly employed in wood machining, and to determine its efficiency to improve both mechanical and electrochemical properties of the surface. Treatments were performed at a constant N 2 :H 2 gas mixture and by varying the temperature and process duration. The structural and morphological properties of nitrided layers were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) coupled with EDS microanalyses. Surface hardening and hardness profiles were evaluated by micro hardness measurements. To simulate the wood machining conditions, electrochemical tests were carried out with an oak wood electrolyte with the purpose of understanding the effects of the nitriding treatment on the corrosion resistance of the tool in operation. X-ray diffraction analyses revealed the presence of both γ′ (Fe 4 N) and ε (Fe 2-3 N) nitrides with a predominance of the ε phase. Moreover, α-Fe (110), γ′ and ε diffraction peaks were shifted to lower angles suggesting the development of compressive stresses in the post nitrided steel. As a result, it was shown that nitriding allowed a significant hardening of steel with hardness values higher than 1200 HV. The diffusion layers were always composed of an outer compound layer and a hardened bulk layer which thickness was half of the total diffusion layer one. No white layer was observed. Similarly, no traces of chromium nitrides were detected. The temperature seemed to be a parameter more influent than the process duration on the morphological properties of the nitrided layer, while it had no real influence on their crystallinity. Finally, the optimal nitriding conditions to obtain a thick and hard diffusion layer are 500°C for 10 h. On the other hand, to verify the effect of these parameters on the corrosion resistance, potentiodynamic polarization tests were carried out in an original "wood juice" electrolyte. After corrosion, surface was then observed at the SEM scale. Electrochemical study indicated that the untreated steel behaved as a passive material. Although the very noble character of steel was somewhat mitigated and the corrosion propensity increased for nitrided steels, the passive-like nature of the modified surface was preserved. For the same optimized parameters as those deduced from the mechanical characterization (500°C, 10 h), surface presented, in addition to a huge surface hardening, a high corrosion resistance.

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“…Characteristics of this reactor are described in previous studies [4,7]. The initial pressure was 0.5 Pa and the working pressure was 500 Pa.…”

Section: Nitriding Processmentioning

confidence: 99%

“…Different processes, based on diffusion of liquid [2] or gaseous states [3], have already proved their effectiveness. Physical vapor deposition can also be used for improving surface properties [4][5][6], but their application was often limited owing to poor adhesion of the coating [7].…”

Section: Introductionmentioning

confidence: 99%

Plasma nitriding of 90CrMoV8 tool steel for the enhancement of hardness and corrosion resistance

Nouveau

Steyer

Rao

et al. 2011

Surface and Coatings Technology

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“…This technique differs from other processes because it can produce films with high uniformity and permits reasonable control of roughness and crystallinity [2]. Several authors made a certain modification in this system to attain the best performance, such as using an outer cathodic cage without holes (for better samples heating) [59], using a titanium-containing plate at high cathodic potential [60], and using multilayer titanium cathodic cages [61], as depicted in Figs. 2, 3, and 4.…”

Section: Cathodic Cage Plasma Depositionmentioning

confidence: 99%

Synthesis of TiN and TiO2 thin films by cathodic cage plasma deposition: a brief review

Abreu

Naeem

Borges

et al. 2020

J Braz. Soc. Mech. Sci. Eng.

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The cathodic cage plasma deposition (CCPD) is an advanced technique recently developed from an active screen plasma nitriding system, which has been used for thin film deposition such as titanium nitride and titanium dioxide (TiO 2). These coatings can improve the physical, mechanical, and optical properties of numerous materials, and such coatings can be developed by several techniques. Unfortunately, the conventional deposition techniques exhibit certain drawbacks, including high cost, the complexity of the operation, very low pressure, and high processing temperature; as a result, CCPD is an advantageous technique. In this review, brief information on the deposition of titanium nitride and oxide coatings on steel alloys, titanium, glass, and silicon substrates, and the effect of control parameters on deposition efficiency is provided. The effectiveness of this system for the synthesis of thin films on various substrates, including insulators and conductors, is also summarized. The recent developments and applications of CCPD for titanium-based coatings are described in detail.

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“…This technique as an effective and simple method was widely used to improve the surface hardness [7,[13][14]. During the plasma nitriding, nitrogen diffused into the surface of the material where it connected to the substrate, with iron and alloying elements [15].…”

Section: Introductionmentioning

confidence: 99%

The influence of laser re-melting on microstructure and hardness of gas-nitrided steel

Panfil

Wach

Kulka

et al. 2016

Archives of Mechanical Technology and Materials

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In this paper, modification of nitrided layer by laser re-melting was presented. The nitriding process has many advantageous properties. Controlled gas nitriding was carried out on 42CrMo4 steel. As a consequence of this process, ε+γ’ compound zone and diffusion zone were produced at the surface. Next, the nitrided layer was laser remelted using TRUMPF TLF 2600 Turbo CO2 laser. Laser tracks were arranged as single tracks with the use of various laser beam powers (P), ranging from 0.39 to 1.04 kW. The effects of laser beam power on the microstructure, dimensions of laser tracks and hardness profiles were analyzed. Laser treatment caused the decomposition of continuous compound zone at the surface and an increase in hardness of previously nitrided layer because of the appearance of martensite in re-melted and heat-affected zones

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Plasma nitriding of low alloy steels at floating and cathodic potentials

Cited by 36 publications

References 16 publications

Plasma nitriding of 90CrMoV8 tool steel for the enhancement of hardness and corrosion resistance

Plasma nitriding of 90CrMoV8 tool steel for the enhancement of hardness and corrosion resistance

Synthesis of TiN and TiO2 thin films by cathodic cage plasma deposition: a brief review

The influence of laser re-melting on microstructure and hardness of gas-nitrided steel

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