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Liang Wang - One of the best experts on this subject based on the ideXlab platform.

  • influence of temperature and duration on the nitriding behavior of 40cr low alloy steel in mixture of nh3 and n2
    Surface & Coatings Technology, 2019
    Co-Authors: Hongyu Shen, Liang Wang
    Abstract:

    Abstract 40Cr low alloy steel samples was Nitrided by plasma nitriding with hollow cathode discharge assistance in a gas mixture of N2 and NH3 with different ratios at temperatures ranging from 520 °C to 560 °C for processing time from 2 to 6 h. The influences of processing temperature and time on the thickness and phase composition of Nitrided Layer were researched. Nitrided Layers were evaluated using scanning electron microscope (SEM), X-ray diffraction and microhardness tester. The thickness of white Layer increased with the processing temperature and time increasing. For samples Nitrided at 540 for 4 h, the white Layer is 5.6 μm in ammonia and 10.2 μm in mixture gas respectively. The maximum thickness of white Layer about 15 μm thick is obtained after Nitrided at 560 °C for 6 h in this study. The phases of Nitrided Layer are mainly composed of e-Fe2-3N with a small amount of Fe4N. Such Nitrided Layer was beneficial to reducing the friction coefficient. The corrosion resistance of the Nitrided sample was improved with the increasing thickness of the white Layer.

  • Characteristics of the Nitrided Layer formed on AISI 304 austenitic stainless steel by high temperature nitriding assisted hollow cathode discharge
    Materials & Design, 2014
    Co-Authors: Shangzhou Zhang, Yongyong He, Lei Zhang, Liang Wang
    Abstract:

    Abstract A series of experiments have been conducted on AISI 304 stainless steel using a hollow cathode discharge assisted plasma nitriding apparatus. Specimens were Nitrided at high temperatures (520–560 °C) in order to produce nitrogen expanded austenite phase within a short time. The Nitrided specimen was characterized by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, potentiodynamic polarization and microhardness tester. The corrosion properties of Nitrided samples were evaluated using anodic polarization tests in 3.5% NaCl solution. The Nitrided Layer was shown to consist of nitrogen expanded austenite and possibly a small amount of CrN precipitates and iron nitrides. The results indicated that rapid nitriding assisted hollow cathode discharge not only increased the surface hardness but also improved the corrosion resistance of the untreated substrate.

  • surface properties of Nitrided Layer on aisi 316l austenitic stainless steel produced by high temperature plasma nitriding in short time
    Applied Surface Science, 2014
    Co-Authors: Yang Li, Zhuo Wang, Liang Wang
    Abstract:

    Abstract It has generally been believed that the formation of the S phase or expanded austenite γN with enough thickness depends on the temperature (lower than 480 °C) and duration of the process. In this work, we attempt to produce nitrogen expanded austenite Layer at high temperature in short time. Nitriding of AISI 316L austenitic stainless steel was carried out at high temperatures (>520 °C) for times ranging from 5 to 120 min. The microstructures, chemical composition, the thickness and the morphology of the Nitrided Layer, as well as its surface hardness, were investigated using X-ray diffraction, X-ray photoelectron spectroscopy, optical microscopy, scanning electron microscopy, and microhardness tester. The corrosion properties of the untreated and Nitrided samples were evaluated using anodic polarization tests in 3.5% NaCl solution. The results confirmed that Nitrided Layer was shown to consist of γN and a small amount of free-CrN and iron nitrides. High temperature plasma nitriding not only increased the surface hardness but also improved the corrosion resistance of the austenitic stainless steel, and it can critically reduce processing time compared with low temperature nitriding.

  • plasma nitriding of aisi 304 austenitic stainless steel with pre shot peening
    Surface & Coatings Technology, 2010
    Co-Authors: Yi Zuo Wang, Lie Shen, Liang Wang, Chunhua Wang
    Abstract:

    AISI 304 austenitic stainless steel was plasma Nitrided at the temperature ranging from 410 to 520 °C with pre-shot peening. The structural phases, micro-hardness and electrochemical behavior of the Nitrided Layer were investigated by optical microscopy, X-ray diffraction, micro-hardness testing and anodic polarization testing. The effects of shot peening on the nitride formation, nitride Layer growth and corrosion properties were discussed. The results showed that shot peening enhanced the nitrogen diffusion rate and led to a twice thicker Nitrided Layer than the un-shot peening samples under the same plasma nitriding conditions (410 °C, 4 h). The Nitrided Layer was composed of single nitrogen expanded austenite (S-phase) when nitriding below 480 °C, which had combined improvement in hardness and corrosion resistance.

  • thermal stability of nitrogen expanded austenite formed by plasma nitriding on aisi304 austenitic stainless steels
    Key Engineering Materials, 2008
    Co-Authors: Liang Wang, Yi Zuo Wang
    Abstract:

    The effect of thermal annealing temperature on the microstructure and phase composition of Nitrided Layer formed on AISI 304 stainless steel by plasma nitriding were investigated. The phase composition and structure of the Nitrided have been analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD analysis of Nitrided samples at 420oC showed the presence of γN phase in the Nitrided Layer. The temperature at which the nitrogen expanded austenite started to decompose was about 450oC. Above this critical temperature the γN phase transformed into a mixture of CrN and α-phase. The surface hardness of Nitrided Layer also slightly changed with annealing temperature.

J Tacikowski - One of the best experts on this subject based on the ideXlab platform.

  • Heat treatment of Nitrided Layer formed on X37CrMoV5-1 hot working tool steel
    IOP Conference Series: Materials Science and Engineering, 2017
    Co-Authors: A. Ciski, Piotr Wach, J Tacikowski, T. Babul, P. Suchmann
    Abstract:

    The paper presents the technology consisting of combination of the nitriding process with subsequent austenitizing at temperature above eutectoid temperature of the Fe-C system and further rapid cooling. Such treatment will cause formation of the martensite in the area of the primarily Nitrided Layer and the additional precipitation hardening by tempering of heat treated steel. The article shows that the heat treatment process of Nitrided Layer formed on X37CrMoV5-1 steel leads to strengthening of surface Layer, the substrate and the core of Nitrided part. Heat treatment of Nitrided steel with the tempering in inert (nitrogen) or active (ammonia) atmosphere can increase the thickness of the Layer formed by short-term nitriding process. After the nitriding process of X37CrMoV5-1 steel the Nitrided Layer had a thickness of about 160 μm, while a subsurface Layer of iron nitrides had a thickness of 7 μm. After subsequent quenching and tempering processes, the Nitrided Layer undergoes additional diffusion and its thickness is increased to about 220 μm (inert atmosphere) or 280 μm (active atmosphere). If the tempering process is carried out in an inert atmosphere, the primarily formed Layer of iron nitrides disappears. Tempering in an active atmosphere leads to forming of white Layer with a thickness of 7 μm. Basic properties of Nitrided Layers formed in such way, like the hardness and the wear resistance, are presented.

  • influence of the structure of the composite Nitrided Layer pvd coating on the durability of tools for hot working
    Surface & Coatings Technology, 2000
    Co-Authors: Jerzy Smolik, Ja Walkowicz, J Tacikowski
    Abstract:

    Abstract The paper presents research results of the influence of the ‘Nitrided Layer/PVD coating’ composite on the durability of tools for hot plastic working. Four structures of the composite differing in the PVD coating material were investigated. They were: TiN, CrN, (Ti,Cr)N and Ti(C,N). The composites investigated were created by means of the surface ‘duplex’ treatment method in a two stage separable cycle (the nitriding process and the PVD coating deposition were carried out with different devices). The nitriding process was executed with the use of the regulated gas nitriding method, whereas the PVD coating was executed by means of the arc-vacuum method. The tools tested were forge dies made of ISO steel 35CrMoV5 (0.4%C, 0.4%Mn, 1.0%Si, 5.0%Cr, 1.3%Mo, 0.3%V) designed for the plastic working of automotive half-shafts. The paper presents the results of maintenance investigations, executed under manufacturing conditions, obtained for tools used for hot forging which were covered with different composites. The investigations proved that the best durability was achieved for tools covered with the composite ‘Nitrided Layer/CrN coating’, for which the increase in durability was almost 90%. The smallest durability was noted for tools covered with the composite ‘Nitrided Layer/TiN coating’. The results obtained proved that a proper choice of the composite ‘Nitrided Layer/PVD coating’ structure may increase the durability of tools considerably for hot plastic working.

  • optimization of Nitrided case structure in composite Layers created by duplex treatment on the basis of pvd coating adhesion measurement
    Surface & Coatings Technology, 1999
    Co-Authors: Ja Walkowicz, Jerzy Smolik, J Tacikowski
    Abstract:

    Abstract The paper concerns the process of the composite: ‘Nitrided Layer-PAPVD coating’ creation on substrates made of hot working steel. The composite properties are determined by the appropriate selection of coating parameters and Nitrided case structure. The results of research concerning the influence of a method of substrate nitriding and the created Nitrided case structure on the adhesion and plastic properties of the PAPVD coatings are presented in the paper. Substrates made of hot working steel EN X35CrMoV5 (0.4% C, 0.4% Mn, 1.0% Si, 5.0% Cr, 1.3% Mo, 0.3% V) underwent different processes of thermo-chemical and finishing surface treatment in order to obtain a Nitrided Layer of a different structure: Fe α (N), Fe α (N)+‘white Layer’-E,γ′. Research was carried out for Nitrided Layers created in a controlled gas nitriding process. Four different coatings of nitrides, TiN, Ti(C,N), CrN, (Ti,Cr)N, were deposited on substrates with Nitrided Layers using the arc-vacuum method and the MZ-383 equipment manufactured by Metaplas Ionon. For composite Nitrided Layer/PAPVD coating’ prepared in this way, the authors carried out a metallographic analysis, using the optical microscope Neophot32, and measurements of surface roughness of the deposited nitrides. The X-ray phase analysis carried out on the Philips PW1830 diffractometer enabled the phase composition of Nitrided Layers and the phase composition and the lattice parameter of the deposited PAPVD coatings to be determined. Then, the authors carried out measurements of the coating adhesion for all investigated composites using the scratch-test method by means of Revetest-CSEM. The authors demonstrated the significant influence of the presence of titanium ions (Ti + ), in the vacuum arc deposition process, on the properties of the composite Nitrided Layer/PVD coating. The presence of titanium ions in the technological process deteriorates adhesion of the PVD coating to the Nitrided substrate, when the Nitrided Layer includes the compound zone. This effect was not observed for a CrN coating deposited without the participation of titanium ions.

J Duszczyk - One of the best experts on this subject based on the ideXlab platform.

  • the influence of the depth of a plasma Nitrided Layer in tool steel substrate on the scratch resistant properties of pacvd tibn coating
    Surface & Coatings Technology, 2007
    Co-Authors: I Apachitei, Jian Zhou, T Walstock, J Duszczyk
    Abstract:

    Abstract A hot-work tool steel was plasma Nitrided (PN) to create a diffusion Layer beneath the surface. Plasma-assisted chemical vapour deposition (PACVD) was then applied deposit a superhard nano-columnar TiBN coating to the Nitrided substrate. The depth of the Nitrided diffusion Layer was varied to determine its influence on the cohesion and adhesion properties of the coating. Radio frequency glow discharge optical emission spectroscopy (rf-GDOES) revealed multiLayers of TiBN and TiN compounds with compositional gradients across the TiBN coating Layer. Microhardness measurements (HV 0.025 ) across the PN diffusion Layer in combination with optical microstructure observation showed that an increase in the depth of the Nitrided diffusion Layer led to an increase in the maximum hardness at the interface between the TiBN coating and the substrate. The maximum hardness correlated linearly with the scratch-resistant properties determined from scratch tests in the progress mode, notably the critical loads corresponding to the first microcracking related to cohesive failure ( L C1 ), spallation related to adhesive failure ( L C2 ) and worn out ( L C4 ). In addition, the scratching coefficients of the TiBN coating on a thicker PN diffusion Layer, determined in a scratch test along a scratch track, were all lower than those on a thinner diffusion Layer in the substrate. An excessive depth of the Nitrided diffusion Layer however caused transverse cracking in the substrate. A Nitrided Layer with an optimum depth can thus improve the adhesion of the PACVD TiBN coating to the tool-steel substrate and the scratch resistance of the coating.

Jiajun Liu - One of the best experts on this subject based on the ideXlab platform.

  • a comparative study on the tribological behaviors of Nitrided and sulfur Nitrided 35crmo steel lubricated in pao base oil with modtc additive
    Tribology International, 2011
    Co-Authors: Wen Yue, Chengbiao Wang, Yuandong Liu, Xuejie Sun, Jiajun Liu
    Abstract:

    A Nitrided Layer on 35CrMo steel was prepared by the ion nitriding process, and then a sulfur-Nitrided Layer was obtained by low temperature ion sulfuration. The results showed that both the Nitrided and sulfur-Nitrided surfaces improved the wear resistance efficiently under PAO lubrication, and exhibited the best wear resistance and friction-reducing property under PAO with 0.75% MoDTC lubrication. Compared with the plain and Nitrided surfaces, the sulfur-Nitrided surface exhibited the best synergistic effect with MoDTC displaying the lowest friction coefficient and wear volume. The mechanism of the best effect was due to MoS2 and FeS formed on the sulfur-Nitrided surface.

  • Tribological properties of sulfurized-Nitrided Layer prepared by a two-step method
    Vacuum, 2011
    Co-Authors: Wen Yue, Chengbiao Wang, Xiaocheng Gao, Yuandong Liu, Xuejie Sun, Jiajun Liu
    Abstract:

    Abstract The tribological properties of Nitrided Layer and sulfurized-Nitrided Layer of AISI 4135 steel were investigated under oil lubrication, and the Layers were prepared by the ion nitriding treatment and a two-step method as the ion nitriding plus sulfurizing duplex treatment, respectively. A ball-on-disc friction and wear tester was adopted to evaluate the tribological performance. Scanning electron microscope (SEM), scanning Auger microprobe (SAM) and X-ray photoelectron spectroscope (XPS) were used to identify the morphologies and chemical compositions of the treated Layer and the worn surface. It was presented that the sulfurized-Nitrided sample with a thin FeS Layer possessed much better tribological behaviors than the Nitrided sample, including load carrying capacity, wear resistance, friction reduction and duration time. The mechanism was supposed that the decomposed activated S atoms of FeS Layer promoted a new FeS chemical reaction film formation, which induced to the thin FeS Layer playing as a solid lubricant for a longer time.

Dezhuang Yang - One of the best experts on this subject based on the ideXlab platform.

  • a study of friction and wear behavior of Nitrided Layer on 2cr13 steel in vacuum
    Tribology Letters, 2010
    Co-Authors: Jianqun Yang, Yong Liu, Dezhuang Yang
    Abstract:

    Tribological characteristics and wear mechanisms of gas-Nitrided Layer on a 2Cr13 steel in vacuum were investigated using a pin-on-disk type tribometer under self-mating dry sliding conditions with various normal loads and sliding velocities. The wear mechanisms involved were investigated by microscopic observations of the worn surfaces, the wear debris, and the corresponding cross sections. Experimental results show that for both sliding velocities of 0.2 and 1.6 m s−1, friction forces are relatively stable in the case of lower loads (≤50 N), whereas become unstable and show high fluctuations under higher loads (>50 N). Wear mechanisms of the Nitrided Layer in vacuum are different for the lower and the higher sliding velocities. In the former case, mild abrasive wear dominates. In the latter case, a transition takes place from mild adhesive wear to severe adhesive or even delamination wear, with increasing normal load from 10 to 90 N.

  • grease lubricated tribological behaviour of Nitrided Layer on 2cr13 steel in vacuum
    Applied Surface Science, 2010
    Co-Authors: Jianqun Yang, Zhuyu Ye, Dezhuang Yang, Shiyu He, Xinlei Li
    Abstract:

    Tribological behaviour of the Nitrided Layer sliding against self-mating under dry sliding and grease-lubricated conditions in vacuum was investigated on a pin-on-disk type tribometer, with the interaction among the Nitrided Layer and grease being focused on. The morphologies of the worn surfaces were observed by scanning electron microscopy (SEM). The chemical states of typical elements on the worn surfaces of the Nitrided disks and pins were examined by means of X-ray photoelectron spectroscopy (XPS). The chemical compositions of grease samples taken from worn surfaces on the Nitrided disks were analysed by Fourier transform infrared spectroscopy (FTIR). Experimental results show that under grease-lubricated conditions, the Nitrided Layer exhibits lower average friction coefficient and higher wear resistance than those for the dry sliding. In the former case, the wear of Nitrided Layer shows a transition from the mild adhesive to the severe adhesive wear and even to the delamination wear, with increasing normal load from 10 to 90 N. In the latter case, a transition takes place from the mild abrasive wear to the micro-fatigue type one with increasing the normal load. Tribochemical reactions occur between the Nitrided Layer and perfluoropolyalkyl ether (PFPE) grease during the lubricated sliding of the Nitrided disks against self-mating in vacuum.

  • Microstructure and tribological characteristics of Nitrided Layer on 2Cr13 steel in air and vacuum
    Surface and Coatings Technology, 2009
    Co-Authors: Jianqun Yang, Yong Liu, Dezhuang Yang
    Abstract:

    Abstract A 2Cr13 steel was gas Nitrided in pure NH3 gas atmosphere at 793 K for 20 h. The microstructure, composition and microhardness of the Nitrided samples were examined. The tribological behaviour of the Nitrided 2Cr13 steel in air and vacuum was investigated in order to analyse effects of the nitriding on wear resistance of the 2Cr13 steel. The results show that the Nitrided Layer consists of a compound Layer and diffusion zone. The nitriding increases both the surface hardness and wear resistance of 2Cr13 steel in air and vacuum, and the anti-wear characteristic of the Nitrided 2Cr13 steel in vacuum is much higher than that in air. The Nitrided Layer exhibits a mild wear in air, and avoids the severe wear that happens on the unNitrided steel. While the adhesion dominates the wear process in vacuum. The material transfer between the wear couples helps to improve the tribological characteristics of the Nitrided Layer in vacuum.