scholarly journals Practical and Economical Effects of the Use of Screen Meshes for Steel Nitriding Processes with Glow Plasma

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3808
Author(s):  
Jerzy Pisarek ◽  
Tadeusz Frączek ◽  
Tomasz Popławski ◽  
Michał Szota
Keyword(s):  
Electric Fields ◽  
Diffusion Processes ◽  
Plasma Nitriding ◽  
Nitrided Layer ◽  
Hydrogen Atmosphere ◽  
Austenitic Steels ◽  
Diffusion Layers ◽  
Processed Material ◽  
Glow Plasma ◽  
Screen System

The dynamically developing energy sector forces technologists to create new materials that meet the increasingly higher mechanical, chemical, and electrical requirements. The paper relates to the method of reducing the energy consumption of the plasma nitriding process of austenitic steels. The method proposed by the authors involves the modification of nitriding technology in glow plasma. It consists of introducing perforated screens between the anode and nitrided surface made of a material with a composition similar to the processed material and the use of an HF power supply with controlled mean current generating negative voltage peaks of about 1000 V. Nitriding is carried out in a nitrogen-hydrogen atmosphere. The processed material has a negative potential in relation to the surrounding plasma and strongly negative in relation to the vacuum chamber jacket. The actual treatment is preceded by ionic cleaning of the surface of the detail and heating it to the temperature that activates the diffusion processes. The authors analyse the dynamic distribution of electric fields generated at the surface of the nitrided material with different configurations of the cathode-sample-screen system, trying to find the correlation of treatment parameters with the parameters of the nitrided layer. A significant influence of the screening meshes on the depth of the obtained diffusion layers containing nitrogen was found. The oscilloscopic measurements of the plasma in the boundary layer allowed for the observation of voltage peaks, probably leading to an increase in the peak kinetic energy of nitrogen ions and their easier penetration into the material. The work is of a cognitive nature and is probably one of the first to look for relationships between the dynamic electrical parameters of plasma and the efficiency of nitriding.

scholarly journals Nitriding of steels of various structural classes manufactured by laser additive technologies

2020 ◽  
Vol 63 (1) ◽  
pp. 63-70
Author(s):  
E. V. Tsvetkova ◽  
K. O. Bazaleeva ◽  
I. S. Chekin ◽  
O. G. Klimova-Korsmik ◽  
A. S. Zhidkov
Keyword(s):  
Heat Treatment ◽  
Austenitic Steel ◽  
Powder Material ◽  
Plasma Nitriding ◽  
Nitrided Layer ◽  
Austenitic Steels ◽  
Bainitic Steel ◽  
Laser Remelting ◽  
Diffusion Layers ◽  
Structural Classes

The authors have conducted a comparative analysis of diffusion layers of steels of various structural classes manufactured by complex technology including laser remelting of powder material and plasma nitriding. Parameters of diffusion layers of bainitic steel (Fe – 0.09 % C – 1 % Cr – 2 % Ni – 1 % Mo – 1 % Cu) and martensitic steel (Fe – 0.25 % C – 13 % Cr – 2 % Ni) manufactured by direct laser deposition (DLD) and austenitic steel (Fe – 0.03 % C – 17 % Cr – – 14 % Ni – 3 % Mo) manufactured by selective laser melting (SLM) were investigated. During plasma nitriding at 540 °C for 24 h of martensitic and austenitic steels, diffusion layer of 140 – 160 μm was formed, additionally maximum microhardness of surface layer was 800 HV0.1 and 1050 HV0.1 and it is almost constant on thickness of 100 μm. Diffusing layer of bainitic steel is 900 μm and its microhardness monotonously decreases from the surface. Reinforcing phases of nitrided layer were determined by X-ray analysis: γ′ (Fe4N) is fixed in the bainitic steel, γ′ and CrN are fixed in martensitic and austenitic steels. Moreover on the surface of austenitic steel solid nitrided layer is formed. The influence of heat treatment after laser remelting of powder material was also studied. It was determined, that despite decreasing of crystal structure defects after heat treatment, the thickness of nitrided layer changes slightly. Also the authors have investigated the influence of porosity of austenitic steel on the thickness of nitrided layer. It was shown, that porosity of 0.5 – 2.0 % doesn’t result in changing of diffusion layer’s thickness.

Nitriding of yttria-stabilized zirconia in atmospheric pressure microwave plasma

2009 ◽  
Vol 24 (6) ◽  
pp. 2021-2028 ◽  
Author(s):  
R. Milani ◽  
R.P. Cardoso ◽  
T. Belmonte ◽  
C.A. Figueroa ◽  
C.A. Perottoni ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Atmospheric Pressure ◽  
Microwave Plasma ◽  
Plasma Nitriding ◽  
Nitrided Layer ◽  
Zirconium Nitride ◽  
Stabilized Zirconia ◽  
Partially Stabilized Zirconia ◽  
X Ray ◽  
Yttria Partially Stabilized Zirconia

High temperature plasma nitriding of yttria-partially-stabilized zirconia in atmospheric pressure microwave plasma was investigated. The morphological, mechanical, and physicochemical characteristics of the resulting nitrided layer were characterized by different methods, such as optical and scanning electron microscopy, microindentation, x-ray diffraction, narrow resonant nuclear reaction profiling, secondary neutral mass spectrometry, and x-ray photoelectron spectroscopy, aiming at investigating the applicability of this highly efficient process for nitriding of ceramics. The structure of the plasma nitrided layer was found to be complex, composed of tetragonal and cubic zirconia, as well as zirconium nitride and oxynitride. The growth rate of the nitrided layer, 4 µm/min, is much higher than that obtained by any other previous nitriding process, whereas a typical 50% increase in Vickers hardness over that of yttria-partially-stabilized zirconia was observed.

scholarly journals A Novel Decarburizing-Nitriding Treatment of Carburized/through-Hardened Bearing Steel towards Enhanced Nitriding Kinetics and Microstructure Refinement

Coatings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 112
Author(s):  
Fuyao Yan ◽  
Jiawei Yao ◽  
Baofeng Chen ◽  
Ying Yang ◽  
Yueming Xu ◽  
...  
Keyword(s):  
Surface Engineering ◽  
Plasma Nitriding ◽  
Nitrided Layer ◽  
Metallographic Analysis ◽  
Material Surface ◽  
Low Carbon ◽  
High Carbon ◽  
Softening Effect ◽  
Microstructure Refinement ◽  
Bearing Steels

Decarburization is generally avoided as it is reckoned to be a process detrimental to material surface properties. Based on the idea of duplex surface engineering, i.e., nitriding the case-hardened or through-hardened bearing steels for enhanced surface performance, this work deliberately applied decarburization prior to plasma nitriding to cancel the softening effect of decarburizing with nitriding and at the same time to significantly promote the nitriding kinetics. To manifest the applicability of this innovative duplex process, low-carbon M50NiL and high-carbon M50 bearing steels were adopted in this work. The influence of decarburization on microstructures and growth kinetics of the nitrided layer over the decarburized layer is investigated. The metallographic analysis of the nitrided layer thickness indicates that high carbon content can hinder the growth of the nitrided layer, but if a short decarburization is applied prior to nitriding, the thickness of the nitrided layer can be significantly promoted. The analysis of nitriding kinetics shows that decarburization reduces the activation energy for nitrogen diffusion and enhances nitrogen diffusivity. Moreover, the effect of decarburization in air can promote surface microstructure refinement via spinodal decomposition during plasma nitriding.

scholarly journals Combined Use of Surface Texturing, Plasma Nitriding and DLC Coating on Tool Steel

Coatings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 201
Author(s):  
Elisangela Aparecida dos Santos de Almeida ◽  
Julio Cesar Giubilei Milan ◽  
César Edil da Costa ◽  
Cristiano Binder ◽  
José Daniel Biasoli de Mello ◽  
...  
Keyword(s):  
Surface Topography ◽  
Tool Steel ◽  
Photoelectron Spectroscopy ◽  
Plasma Nitriding ◽  
Nitrided Layer ◽  
Multilayer Coating ◽  
Surface Texturing ◽  
X Ray ◽  
Dlc Coating ◽  
Hard Chrome

In cold rolling, a textured roll can be used to imprint a desired surface topography onto the sheet during rolling. This work proposes the use of diamond-like carbon (DLC) coatings to protect the surface topography of the rolls in replacement of the carcinogenic hard chrome. For that, hydrogenated amorphous carbon (a-C:H) was deposited on plasma nitrided tool steel, both for ground and textured specimens. Changes in surface topography due to DLC coating were assessed using a confocal microscope. Coating adhesion was evaluated using the method VDI 3198. The specimens were characterized using X-ray diffraction (XRD), microhardness test and scanning electron microscopy (SEM). The coating was characterized using Raman spectroscopy (RS) and X-ray photoelectron spectroscopy (XPS). The results showed a soft multilayer coating consisting of a plasma nitrided layer for load support, a Si-rich interlayer to improve adhesion and an a-C:H top layer. DLC deposition reduced the roughness of the textured specimens. The coating resulted in relatively stable friction and good durability, with small damage and negligible wear even under dry sliding.

scholarly journals Influence of hydrogen content in working gas on diffusion processes at ion nitriding of martensitic and austenitic steels

2017 ◽  
Vol 872 ◽  
pp. 012017 ◽  
Author(s):  
U G Khusainov ◽  
K N Ramazanov ◽  
R D Agzamov ◽  
E L Vardanyan ◽  
R S Esipov
Keyword(s):  
Hydrogen Content ◽  
Diffusion Processes ◽  
Austenitic Steels ◽  
Ion Nitriding

scholarly journals Acceleration of Plasma Nitriding at 550 °C with Rare Earth on the Surface of 38CrMoAl Steel

Coatings ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1122
Author(s):  
Dongjing Liu ◽  
Yuan You ◽  
Mufu Yan ◽  
Hongtao Chen ◽  
Rui Li ◽  
...  
Keyword(s):  
Rare Earth ◽  
Electron Microscope ◽  
Weight Gain ◽  
Plasma Nitriding ◽  
Nitrided Layer ◽  
Surface Hardness ◽  
Optical Microscope ◽  
Steel Microstructure ◽  
Transmission Electron ◽  
Modified Layer

In order to explore the effect of the addition of rare earth (RE) to a steel microstructure and the consequent performance of a nitrided layer, plasma nitriding was carried out on 38CrMoAl steel in an atmosphere of NH3 at 550 °C for 4, 8, and 12 h. The modified layers were characterized using an optical microscope (OM), a microhardness tester, X-ray diffraction (XRD), a scanning electron microscope (SEM), a transmission electron microscope (TEM), and an electrochemical workstation. After 12 h of nitriding without RE, the modified layer thickness was 355.90 μm, the weight gain was 3.75 mg/cm2, and the surface hardness was 882.5 HV0.05. After 12 h of RE nitriding, the thickness of the modified layer was 390.8 μm, the weight gain was 3.87 mg/cm2, and the surface hardness was 1027 HV0.05. Compared with nitriding without RE, the ε-Fe2-3N diffraction peak was enhanced in the RE nitriding layer. After 12 h of RE nitriding, La, LaFeO3, and a trace amount of Fe2O3 appeared. The corrosion rate of the modified layer was at its lowest (15.089 × 10−2 mm/a), as was the current density (1.282 × 10−5 A/cm2); therefore, the corrosion resistance improved.

Novel Electrodeposited Ni-Based Nanocomposite Precursors for Nitriding and Low Temperature Chromizing

2006 ◽  
Vol 522-523 ◽  
pp. 331-338
Author(s):  
X. Peng ◽  
J. Zhao ◽  
Hong Yan Zhang ◽  
Fu Hui Wang
Keyword(s):  
Low Temperature ◽  
Oxidation Resistance ◽  
Plasma Nitriding ◽  
Nitrided Layer ◽  
Pack Cementation ◽  
Coarse Grained ◽  
Crn Coating ◽  
Cr Content ◽  
Oxidation Resistant

Two types of Ni-base nanocomposites were prepared by co-deposition of Ni with nano-sized particles of Cr or CeO2, respectively. Both Ni-Cr and Ni-CeO2 nanocomposites were mainly composed of nanocrystalline Ni matrix, in which certain content of nanoparticles of Cr or CeO2 randomly dispersed. The Ni-Cr nanocomposite was used as a precursor for preparing a novel hard Ni/CrN coating by plasma nitriding at 560oC. The Ni-CeO2 nanocomposite was used as a precursor to develop a novel oxidation-resistant chromia-forming coating by low temperature chromizing using a conventional pack-cementation method. The microhardness of the nitrided layer on the Ni-Cr nanocomposite and the oxidation resistance of the chromizing coating on the Ni-CeO2 nanocomposite were both greatly increased, in comparison to the corresponding counterparts, which were obtained by plasma nitriding on a conventional coarse-grained Ni-Cr alloy with similar Cr content and by chromizing on a coarse-grained Ni metal, respectively. The relationships among the microstructures of the nanocomposite precursors and the nitrided/or chromized coatings, and their properties were investigated and discussed.

Structural Investigations of Iron-Based Sintered Alloys after Plasma Nitriding

2011 ◽  
Vol 674 ◽  
pp. 121-128
Author(s):  
Joanna Karwan-Baczewska ◽  
Tomasz Dymkowski ◽  
Jerzy Robert Sobiecki ◽  
Jan T. Bonarski
Keyword(s):  
Surface Properties ◽  
Plasma Nitriding ◽  
Hydrogen Atmosphere ◽  
Phase Identification ◽  
Structural Investigations ◽  
Gas Nitriding ◽  
Microstructure Morphology ◽  
Iron Based ◽  
Structural Parts ◽  
Sintered Alloys

Various nitriding methods are applicable, viz.: gas nitriding, nitriding in powders and plasma nitriding which is one the latest nitriding technologies applicable for parts made of constructional and tool steels. A large of motor car products made from iron-based alloying powders has been subjected to plasma nitriding process in order to enhance their surface properties like: hardness and abrasive wear. One of the main problems of chemical heat treatment alloys produced by powder metallurgy technology is their porosity degree. In the experiments Fe-Ni-Cu-Mo and Fe-Mo sintered structural parts modified by boron were made. Boron activates the sintering process which results in their considerable consolidation in the sintering at 1473 K for 60 minutes in the atmosphere of hydrogen. The experiments are related to the production of sintered structural elements based on iron powder - NC 100.24 as well as Astaloy Mo (Fe-Mo) and Distaloy SA (Fe-Ni-Cu-Mo) modified by 0.2 wt%, 0.4 wt% and 0.6 wt% B. Sintered parts were obtained by mixing powders said above, followed by compacting at 600 MPa pressure and sintered at 1473 K during 60 minutes time in hydrogen atmosphere. Selected sintered parts were plasma nitrided at 883 K during 4 hours time. After plasma nitriding microstructure morphology using light microscopy and phase identification by Xray diffraction technique have been made. The influence of structure and phase composition on the surface properties of examined sintered parts modified by boron, after plasma nitriding have been analyzed.

scholarly journals Evaluation of stress-strain behavior of surface treated steels by X-ray diffraction

2012 ◽  
Vol 2 (1) ◽  
Author(s):  
Luis Coelho ◽  
A. Batista ◽  
J. Nobre ◽  
M. Marques
Keyword(s):  
Yield Strength ◽  
Plasma Nitriding ◽  
Nitrided Layer ◽  
Experimental Methodology ◽  
X Ray Diffraction ◽  
Stress Strain ◽  
X Ray ◽  
Strain Behavior ◽  
Four Point Bending ◽  
Nitride Layers

AbstractX-ray diffraction assisted four-point bending method (XRDABM) enables to analyze the evolution of surface stress with the strain during bending of specimens. This experimental methodology was used to characterize the stress-strain behavior of two plasma nitriding steels, DIN 40 Cr Mn Mo 7 and DIN 32 Cr Mo V 13, with gradients of mechanical properties across the surface layers, allowing the characterization of the in-depth evolution of the local yield strength in the nitrided layer. The results show a significantly increase of the yield strength of the nitride layers and a good agreement between the in-depth evolution of the yield strength and the XRD peak breadth for the two nitrided steels.

ELECTRO-OPTICAL PHENOMENA DUE TO INFLUENCE OF LIGHT BEAMS ON MATERIAL PARAMETERS OF LIQUID CRYSTALS

1999 ◽  
Vol 08 (03) ◽  
pp. 389-401 ◽  
Author(s):  
NELSON V. TABIRYAN ◽  
CESARE UMETON
Keyword(s):  
Liquid Crystals ◽  
Electric Fields ◽  
Diffusion Processes ◽  
Material Parameters ◽  
Ac Electric Fields ◽  
Absorption Of Light ◽  
Optical Phenomena ◽  
Light Beams

Modulation of material parameters of liquid crystals (LC) due to absorption of light beams allows to control the reorientation of the LC under the influence of ac electric fields. Particularly, it makes possible recording of photorefractive-like orientation gratings. Such gratings are phase shifted with respect to the pattern of interfering light beams. The material and external parameters determine the magnitude of the shift. These photorefractive-like phase shifted gratings are stationary, and no diffusion processes are involved in their build-up.

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