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

  • enhanced Chromizing kinetics of tool steel by means of surface mechanical attrition treatment
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2010
    Co-Authors: Z B Wang
    Abstract:

    Abstract A nanostructured surface layer of about 20 μm in thickness was fabricated on a hot-working tool steel (AISI H13) plate by means of surface mechanical attrition treatment (SMAT). Chromizing behaviors of the SMAT sample were investigated in comparison with its coarse-grained counterpart. Relative to the coarse-grained form, the Cr-diffusion depth was obviously enhanced by SMAT at various Chromizing temperatures, with a maximum increment at 600 °C. A duplex Chromizing treatment at 600 °C followed by at a higher temperature led to the formation of a much thicker chromized surface layer (up to 30 μm in thickness) on the SMAT sample. This might be attributed to the formation of a large amount of nano-sized chromium compounds in the surface layer at 600 °C, which retarded growth of nano-sized ferrite grains and improved the Cr diffusion at higher temperatures. Gradient distributions of Cr concentration, microstructure and hardness were formed in the chromized surface layer in the SMAT steel after the duplex Chromizing treatment, leading to an obvious enhancement in the wear resistance.

  • wear and corrosion properties of a low carbon steel processed by means of smat followed by lower temperature Chromizing treatment
    Surface & Coatings Technology, 2006
    Co-Authors: Z B Wang
    Abstract:

    A duplex lower temperature Chromizing treatment at 600 degrees C for 120 min followed by 860 degrees C for 90 min was performed on a low carbon steel plate with a nanostructured surface layer, induced by surface mechanical attrition treatment (SMAT) [Z.B. Wang, J. Lu, K. Lu, Acta Mater. 53 (2005) 2081]. Microhardness, wear and corrosion resistances of the chromized SMAT sample were measured, in comparison with those of the chromized coarse-grained counterpart and the as-annealed coarse-grained sample. Experimental results showed that these properties were improved markedly. The much enhanced properties of the chromized SMAT sample relative to the chromized coarse-grained counterpart might originate from its superior microstructures, i.e., a much thicker chromized surface layer with smaller grains and more homogenous phase-distribution, due to the employed processes of the SMAT and the duplex lower temperature Chromizing treatment. (c) 2006 Elsevier B.V. All rights reserved.

  • Wear and corrosion properties of a low carbon steel processed by means of SMAT followed by lower temperature Chromizing treatment
    Elsevier, 2006
    Co-Authors: Z B Wang, Lu J, Lu K
    Abstract:

    A duplex lower temperature Chromizing treatment at 600 °C for 120 min followed by 860 °C for 90 min was performed on a low carbon steel plate with a nanostructured surface layer, induced by surface mechanical attrition treatment (SMAT) [Z.B. Wang, J. Lu, K. Lu, Acta Mater. 53 (2005) 2081]. Microhardness, wear and corrosion resistances of the chromized SMAT sample were measured, in comparison with those of the chromized coarse-grained counterpart and the as-annealed coarse-grained sample. Experimental results showed that these properties were improved markedly. The much enhanced properties of the chromized SMAT sample relative to the chromized coarse-grained counterpart might originate from its superior microstructures, i.e., a much thicker chromized surface layer with smaller grains and more homogenous phase-distribution, due to the employed processes of the SMAT and the duplex lower temperature Chromizing treatment.Department of Mechanical Engineerin

  • Chromizing behaviors of a low carbon steel processed by means of surface mechanical attrition treatment
    Acta Materialia, 2005
    Co-Authors: Z B Wang, Jian Lu, K Lu
    Abstract:

    A nanostructured surface layer of about 20 mu m thick was produced in a low carbon steel plate by means of the surface mechanical attrition treatment (SMAT). Chromizing behaviors of the SMAT sample were investigated by using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Experimental results showed that a much thicker Cr-diffusion layer was obtained in the SMAT sample than in the coarse-grained one after the same Chromizing treatment, especially at low temperatures. In the SMAT sample, the formation temperature of chromium compounds was found to be much lower and the amount of chromium carbides was higher than those in the coarse-grained counterpart. The enhanced Chromizing kinetics originates from numerous grain boundaries with a high excess stored energy in the nanostructured surface layer due to severe plastic deformation during the SMAT. (c) 2005 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

E Kasprzycka - One of the best experts on this subject based on the ideXlab platform.

  • properties of crc ni w duplex layers produced in vacuum Chromizing process combined with galvanic treatment
    Materials Performance and Characterization, 2016
    Co-Authors: E Kasprzycka, B. Bogdański
    Abstract:

    Diffusion Chromizing was applied to increase the durability of tools, which operate under wear conditions. Vacuum Chromizing, as opposed to other known methods, i.e., powder pack, gas, and molten salt baths, is ecological on account of non-toxic substrates, as well as absence of harmful wastes. Vacuum Chromizing of tool steel results in hard and wear resistant chromium carbide coatings. However, the obtained carbide layers exhibited rather poor corrosion resistance in chloride media. To improve their corrosion resistance, Ni-W alloy was deposited electrolytically on the steel surface before the Chromizing process. This resulted in the formation of CrC+(Ni-W) type duplex layers with modified characteristics. The objective of this paper was to determine the structure of these duplex layers on tool steel surface, their tribological properties and corrosion resistance in chloride solutions. Investigations of layers’ thickness, their morphology, phase composition, hardness, and depth profiles of elements in the layer diffusion zone have been carried out. The chemical composition and distribution of the phases formed in the surface region of the samples were examined by a SEM microscope, equipped with a BSE detector and an EDS spectrometer. Wear resistance tests were carried out by the three-cylinder-cone method. Electrochemical corrosion measurements of obtained layers were performed in a 0.5 M NaCl solution. The tests proved that the wear resistance of duplex layers of the CrC+(Ni-W) type, produced by vacuum Chromizing of electrolytically coated steel, is as good as that of carbide layers of the CrC type, produced on bare steel surface, but their corrosion resistance is higher.

  • of Chromized Layers Produced on Low-Carbon Iron Alloys by Means of CVD
    2015
    Co-Authors: E Kasprzycka
    Abstract:

    Abstract. Chemical vapour deposition of chromium on the surface of low-carbon iron alloys has been investigated uslng a novel CVD method tha t combines t h e low cost of pack metal l isat~on w ~ t h the advantages of vacuum technique. Chrom~zlng processes have been c a r r ~ e d o u t In a hot-wall vacuurn oven with a mass spectrometer t o determine the chernical composition of residual gases The processes have been performed in chromium chlorides atmosphere a t a low pressure range from I to 800 hPa. the t r ea tment t empera tu re 800 to 950°CC. The effect of t h e vacuum level during the process and the process parameters such a s t ime and t empera tu re on the growth k ~ n e t ~ c s of diffusron layers has been determined. Studies of layer thickness, i t s morphology, i ts phase composi t~on. Cr and Fe depth profiles in t h e diflusion zone of chrornized layers have been conducted. The invest lgat~ons have proved lha l l h e chromizjng process under low pressure, with s t a t i c vacuum instead of d y n a m ~ c vacuum conditions during the holding is t h e most eflective a s far a s the growth kinetics of diffusiorl layers IS concerned. li has been shown tha t t h e kinetics of the process is conlrolled by the dif ius~on of chromium In t h e steel. Diffusion Chromizing is one of many types of thermochemical treatment enlploved todav fo

  • diffusion layers produced on carbon steel surface by means of vacuum Chromizing process
    Journal of Materials Engineering and Performance, 2003
    Co-Authors: E Kasprzycka, Jan Senatorski, Aleksander Nakonieczny, Tomasz Babul
    Abstract:

    This work investigated diffusion layers produced on carbon (C) steel surfaces in the vacuum Chromizing process. Studies of layer, thickness, morphology, and chromium (Cr), C, and iron (Fe) concentration depth profiles in the diffusion zone of chromized layers were carried out. The effect of process parameters such as time and temperature on the kinetics of layer growth on steel surface was investigated. The tribocorrosion resistance of chromized layers was determined.

  • Parameters of Vacuum Process as the Factors Changing the Growth Kinetics of Chromized Layers Produced on Low-Carbon Iron Alloys by Means of CVD
    Journal de Physique IV Proceedings, 1995
    Co-Authors: E Kasprzycka
    Abstract:

    Chemical vapour deposition of chromium on the surface of low-carbon iron alloys has been investigated using a novel CVD method that combines the low cost of pack metallisation with the advantages of vacuum technique. Chromizing processes have been carried out in a hot-wall vacuum oven with a mass spectrometer to determine the chemical composition of residual gases. The processes have been performed in chromium chlorides atmosphere at a low pressure range from 1 to 800 hPa, the treatment temperature 800 to 950°C. The effect of the vacuum level during the process and the process parameters such as time and temperature on the growth kinetics of diffusion layers has been determined. Studies of layer thickness, its morphology, its phase composition. Cr and Fe depth profiles in the diffusion zone of chromized layers have been conducted. The investigations have proved that the Chromizing process under low pressure, with static vacuum instead of dynamic vacuum conditions during the holding is the most effective as far as the growth kinetics of diffusion layers is concerned. It has been shown that the kinetics of the process is controlled by the diffusion of chromium in the steel.

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

  • cavitation erosion behaviors of surface Chromizing layer on 316l stainless steel
    Ultrasonics Sonochemistry, 2019
    Co-Authors: Zhihao Dong, Tong Zhou, Jie Liu, Xinwen Zhang, Bin Shen, Lei Liu
    Abstract:

    To enhance the cavitation erosion resistance of industrial components, two types of Cr-rich diffusion layers were fabricated on 316L stainless steel through pack Chromizing process. The Chromizing layer before post heat treatments exhibited poor cavitation erosion performances, which could be ascribed to its high brittleness and the galvanic corrosion. The Chromizing layer after post heat treatments showed the excellent cavitation erosion resistance with a 3.97 times lower erosion mass loss compared with that of 316L stainless steel. The corrosion resistance was significantly improved with a 12.5-time lower free corrosion current density than 316L stainless steel, and the surface mechanical properties of Chromizing layer also exhibited great combination of hardness and toughness. Therefore, the higher cavitation resistance was attributed to the better corrosion and mechanical performances originating from the more homogeneous microstructure after post heat treatments.

  • performance of surface Chromizing layer on 316l stainless steel for proton exchange membrane fuel cell bipolar plates
    International Journal of Hydrogen Energy, 2019
    Co-Authors: Zhihao Dong, Tong Zhou, Jie Liu, Xinwen Zhang, Bin Shen, Lei Liu
    Abstract:

    Abstract Stainless steels as proton exchange membrane fuel cell bipolar plates have received extensive attention in recent years. The pack Chromizing layer was fabricated on 316L stainless steel to improve the corrosion resistance and electrical conductivity. The corrosion properties were investigated in 0.5 M H2SO4 + 2 ppm HF solution at 70 °C purged with hydrogen gas and air. Higher electrochemical impedance and more stable passive film were obtained by Chromizing the 316L stainless steel. Potentiodynamic polarization results showed the corrosion current densities were reduced to 0.264  μA cm−2 and 0.222  μA cm−2 in two simulated operating environments. In addition, the interfacial contact resistance was decreased to 1.4 mΩ⋅cm2 under the compaction force of 140 N⋅cm−2 and maintained at low values after potentiostatic polarization for 4 h. The excellent corrosion and conductive performances could be attributed to the chromium carbides and high alloying element content in Chromizing layer.

  • effects of pack Chromizing on the microstructure and anticorrosion properties of 316l stainless steel
    Surface & Coatings Technology, 2019
    Co-Authors: Zhihao Dong, Tong Zhou, Jie Liu, Xinwen Zhang, Bin Shen, Lei Liu
    Abstract:

    Abstract To extend the applications of 316L stainless steel in corrosive environments and correlate the corrosion resistance with composition and microstructure, homogeneous Cr-rich layer with the thickness of 75 μm was fabricated on 316L stainless steel by pack Chromizing and post heat treatment. The Chromizing layer was mainly composed of Fe Cr solid solution. Post heat treatment eliminated the precipitates and Cr-depletion in the Chromizing layer. The corrosion behaviors were studied by electrochemical measurements and corrosion morphology observation. The pitting corrosion in Cl− containing solutions was avoided after Chromizing treatment, which was ascribed to the reduced sensitivity of Cr-rich surface to Cl− ions. The higher Cr concentration in the modified layer also improved the long-term stability of corrosion resistance. After immersion in NaCl solution for 24 days, the charge transfer resistance of Chromizing sample was higher than that of 316L by a factor of 8.19. In addition, the free corrosion potential shifted to the positive direction after post heat treatment, and the corrosion current density was also reduced to 0.066 μA/cm2. The further improvement on anticorrosion performance was attributed to the homogeneous microstructure.

Tomasz Babul - One of the best experts on this subject based on the ideXlab platform.

  • diffusion layers produced on carbon steel surface by means of vacuum Chromizing process
    Journal of Materials Engineering and Performance, 2003
    Co-Authors: E Kasprzycka, Jan Senatorski, Aleksander Nakonieczny, Tomasz Babul
    Abstract:

    This work investigated diffusion layers produced on carbon (C) steel surfaces in the vacuum Chromizing process. Studies of layer, thickness, morphology, and chromium (Cr), C, and iron (Fe) concentration depth profiles in the diffusion zone of chromized layers were carried out. The effect of process parameters such as time and temperature on the kinetics of layer growth on steel surface was investigated. The tribocorrosion resistance of chromized layers was determined.

Ganfeng Zou - One of the best experts on this subject based on the ideXlab platform.

  • A Novel Duplex Low-temperature Chromizing Process at 500oC
    Journal of Materials Science & Technology, 2009
    Co-Authors: Huiliang Cao, Jiangwen Liu, Chengping Luo, Ganfeng Zou
    Abstract:

    a duplex Chromizing process which consists of a precursor plasma nitriding, and afollowed salt bath thermoreactive deposition and diffusion (TRD) Chromizing process. CrN layer with a thindiffusion layer underneath was formed. The duplex Chromizing process was studied by optical microscopy(OM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction(XRD), and transmission electron microscopy (TEM). It was found that the Chromizing speed at 500

  • formation of a nanostructured crn layer on nitrided tool steel by low temperature Chromizing
    Scripta Materialia, 2008
    Co-Authors: Huiliang Cao, Jiangwen Liu, Chengping Luo, Ganfeng Zou
    Abstract:

    A duplex Chromizing process involving the salt bath Chromizing of a plasma-nitrided tool steel was carried out at 773 K for 3–24 h. A single-phase CrN layer with a grain size ranging from 20 to 50 nm and an underlying layer consisting of α-Fe and nanosized CrN grains with a grain size ranging from 40 to 80 nm were formed by a 24 h Chromizing at 773 K. The duplex Chromizing mechanism was discussed.