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  • MDPI AG  (6)
  • Zhang, Hongmei  (6)
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  • MDPI AG  (6)
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  • 1
    Online Resource
    Online Resource
    Effect of Particle Size on Microstructure and Element Diffusion at the Interface of Tungsten Carbide/High Strength Steel Composites
    MDPI AG ; 2019
    In:  Materials Vol. 12, No. 24 ( 2019-12-11), p. 4164-
    Details
    In: Materials, MDPI AG, Vol. 12, No. 24 ( 2019-12-11), p. 4164-
    Abstract: The microstructure and micro-hardness of tungsten carbide/high strength steel (WC/HSS) composites with different particle sizes were analyzed by optical microscopy (OM), scanning electron microscopy (SEM), ultra-high temperature laser confocal microscopy (UTLCM) and micro-hardness testing. The composites were prepared by cold pressing and vacuum sintering. The results show that WC density tends to increase as the average grain size of WC decreases and the micro-hardness of WC increases with the decrease of WC particle size. The micro-hardness of WC near the bonding interface is higher than that in other regions. When the particle size of WC powder particles is 200 nm, a transition layer with a certain width is formed at the interface between WC and HSS, and the combination between the two materials is metallurgical. The iron element in the HSS matrix diffuses into the WC structure in contact with it, resulting in a fusion layer of a certain width, and the composite interface is relatively well bonded. When the average particle size of WC powder is 200 nm, W, Fe and Co elements significantly diffuse in the transition zone at the interface. With the increase of WC particle size, the trend of element diffusion decreases.
    Type of Medium: Online Resource
    ISSN: 1996-1944
    URL: Article
    DOI: 10.3390/ma12244164
    Language: English
    Publisher: MDPI AG
    Publication Date: 2019
    detail.hit.zdb_id: 2487261-1
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    Online Resource
  • 2
    Online Resource
    Online Resource
    The Effect of Immersion Corrosion Time on Electrochemical Corrosion Behavior and the Corrosion Mechanism of EH47 Ship Steel in Seawater
    MDPI AG ; 2021
    In:  Metals Vol. 11, No. 8 ( 2021-08-20), p. 1317-
    Details
    In: Metals, MDPI AG, Vol. 11, No. 8 ( 2021-08-20), p. 1317-
    Abstract: In this paper, electrochemical corrosion tests and full immersion corrosion experiments were conducted in seawater at room temperature to investigate the electrochemical corrosion behavior and the corrosion mechanism of high-strength EH47. The polarization curve, EIS (electrochemical impedance spectroscopy), SEM (scanning electron microscope), and EDS analyses were employed to analyze the results of the electrochemical corrosion process. The electrochemical corrosion experiments showed that the open circuit potential of EH47 decreases and then increases with an increase in total immersion time, with the minimum value obtained at 28 days. With an increase in immersion time, the corrosion current density (Icorr) of EH47 steel first decreases and then increases, with the minimum at about 28 days. This 28-day sample also showed the maximum capacitance arc radius, the maximum impedance and the minimum corrosion rate. In the seawater immersion test in the laboratory, the corrosion mechanism of EH47 steel in the initial stage of corrosion is mainly pitting corrosion, accompanied by a small amount of crevice corrosion with increased corrosion time. The corrosion products of EH47 steel after immersion in seawater for 30 days are mainly composed of FeOOH, Fe3O4 and Fe2O3.
    Type of Medium: Online Resource
    ISSN: 2075-4701
    URL: Article
    DOI: 10.3390/met11081317
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
    detail.hit.zdb_id: 2662252-X
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  • 3
    Online Resource
    Online Resource
    Effect of Different Rotational Speeds on Graphene-Wrapped SiC Core-Shell Nanoparticles in Wet Milling Medium
    MDPI AG ; 2021
    In:  Materials Vol. 14, No. 4 ( 2021-02-17), p. 944-
    Details
    In: Materials, MDPI AG, Vol. 14, No. 4 ( 2021-02-17), p. 944-
    Abstract: The effects of the wet milling rotating speed on the number of graphene layers and graphene quality, and the conversion efficiency of graphite exfoliate to graphene, were investigated by scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The results show that the number of few-layer graphene nanometer sheets (GNSs) (≤10 layers) gradually increases with the increase of rotational speed in the range of 160–240 rpm. The proportion of GNSs with 0–10 layers reaches more than 80% as the rotational speed is increased to 280 rpm. GNS defect types in the composite materials are marginal defects with minimal influence and almost no oxidation. In the range of 160–280 rpm, the intensity of graphite peak decreases and the conversion efficiency of graphene increases with the increase of rotational speed. This is the same as the experimental result obtained by HRTEM.
    Type of Medium: Online Resource
    ISSN: 1996-1944
    URL: Article
    DOI: 10.3390/ma14040944
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
    detail.hit.zdb_id: 2487261-1
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  • 4
    Online Resource
    Online Resource
    Factors Affecting the Mechanical Performance of High Manganese Austenitic Steel
    MDPI AG ; 2022
    In:  Metals Vol. 12, No. 9 ( 2022-08-25), p. 1405-
    Details
    In: Metals, MDPI AG, Vol. 12, No. 9 ( 2022-08-25), p. 1405-
    Abstract: High manganese austenitic steel has attracted increasing attention for its application in liquefied natural gas storage tank materials due to its excellent ductility and low cost. This paper presents an overview of the research progress of high manganese austenitic steel in recent years. As a structural material used at a low temperature environment, high manganese steel should not only have certain strength, but also good toughness to prevent brittle fracture at a low temperature. In this work, factors affecting mechanical properties of high manganese steel are discussed, possible reasons for the deterioration of low-temperature properties are analyzed, and the strengthening and toughening mechanisms of materials are elaborated, which may be beneficial to improve properties of high manganese austenitic steel.
    Type of Medium: Online Resource
    ISSN: 2075-4701
    URL: Article
    DOI: 10.3390/met12091405
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
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  • 5
    Online Resource
    Online Resource
    Effect of Ni on the Microstructure and Diffusion Behavior at the Interface of WC/High-Speed Steel Composites
    MDPI AG ; 2021
    In:  Metals Vol. 11, No. 2 ( 2021-02-18), p. 341-
    Details
    In: Metals, MDPI AG, Vol. 11, No. 2 ( 2021-02-18), p. 341-
    Abstract: In this study, WC-Ni/high-speed steel composite materials for application as micro-drills were prepared by cold pressing and high-temperature vacuum sintering using a self-designed mold in the laboratory. The effect of Ni on the microstructure and diffusion behavior at the interface of the WC/high-speed steel composite was investigated. The results show that the addition of Ni promoted the diffusion of elements, and reduced defects such as micropores and microcracks at the WC/high-speed steel composite interface. It also improved the bonding strength of the WC/high-speed steel composite interface, and significantly decreased the WC hardness.
    Type of Medium: Online Resource
    ISSN: 2075-4701
    URL: Article
    DOI: 10.3390/met11020341
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
    detail.hit.zdb_id: 2662252-X
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  • 6
    Online Resource
    Online Resource
    Corrosion Behavior of Copper Bearing Steels and the Derived In-Situ Coating
    MDPI AG ; 2021
    In:  Metals Vol. 11, No. 9 ( 2021-09-15), p. 1462-
    Details
    In: Metals, MDPI AG, Vol. 11, No. 9 ( 2021-09-15), p. 1462-
    Abstract: Using a period immersion wet/dry cyclic corrosion test, in-situ copper-coated steels prepared by corroding copper-bearing steels were investigated in this study. The steel with a higher copper content ( 〉 3%) has a higher initial corrosion rate due to its obvious two-phase microstructure. The corrosion rates of all copper bearing steels tend to be stable after a certain time of corrosion. A copper-rich layer is formed between the matrix and the rust layer, which is due to the diffusion of copper from the rust layer to the metal surface. The copper’s stability under this corrosion condition led to the formation of a thin copper-rich film, which was uncovered after removing the rust by choosing appropriate descaling reagents. The copper coating was generated from the matrix itself during the corrosion process at 25 °C, which provided a new approach for producing in-situ composite materials without any bonding defect. It is found that the corrosion rate, corrosion time, and copper content in steel all affect the formation of copper-rich layer. In addition to the noble copper surface, the electrochemical corrosion test results show that the corrosion resistance of copper-coated steel has been significantly improved.
    Type of Medium: Online Resource
    ISSN: 2075-4701
    URL: Article
    DOI: 10.3390/met11091462
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
    detail.hit.zdb_id: 2662252-X
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