Special Issue "Cermets and Hardmetals"

A special issue of Metals (ISSN 2075-4701).

Deadline for manuscript submissions: 28 February 2018

Special Issue Editor

Guest Editor
Prof. Dr. Kevin Plucknett

Department of MDepartment of Mechanical Engineering, Dalhousie University, Halifax, NS B3H 4R2, Canada
Website | E-Mail
Interests: coatings; powder metallurgy; tribology; advanced structural and functional ceramics; composites (including fibre-reinforced); inorganic foams and porous materials; materials processing; mechanical behavior; electron microscopy; oxidation and corrosion; biopolymers

Special Issue Information

Dear Colleagues,

Ceramic–metal composites, or cermets, are widely used in demanding wear and corrosion applications, as both bulk materials and coatings. Common implementation areas include tooling for grinding, cutting and machining, mechanical seals, friction surfaces, aerospace coatings, etc. The most ubiquitous example of cermets are based on WC-Co, which are typically referred to as ‘hardmetals’, and have been actively developed for many decades. More recently, lightweight systems based on alternate carbides, borides and nitrides have come to prominence. The mechanical, wear and corrosion properties of these composite systems are highly dependent on their composition and microstructure, and there is an increasing drive towards nano-structured cermets, particularly for their improved wear response. In many scenarios, tribo-corrosion environments are also encountered, such that the physical and chemical demands on the materials are extreme. Consequently, there is a continuing research demand for new cermet and hardmetal systems. The primary aim of this Special Issue is, therefore, to provide a platform for researchers to overview the current state-of-the-art in the development, characterization and applications of high performance ceramic-metal composites. 

Prof. Dr. Kevin Plucknett
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Metals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Processing studies (including emerging technologies such as spark plasma sintering and additive manufacturing)
  • Raw materials evaluation and replacement (resource scarcity, alternative constituents)
  • Cermet and hardmetal coating development (including cladding technologies)
  • Functionally graded structures and hierarchical materials
  • Microstructural characterization of advanced cermets and hardmetals
  • Mechanical behavior (including ductile phase toughening)
  • Wear, corrosion and tribo-corrosion of cermets and hardmetals
  • Modelling of physical behavior
  • Commercial applications (current and emerging)

Published Papers (3 papers)

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Research

Open AccessArticle Surface Characterization and Corrosion Resistance of 36Cr-Ni-Mo4 Steel Coated by WC-Co Cermet Electrode Using Micro-Electro Welding
Metals 2017, 7(8), 308; doi:10.3390/met7080308
Received: 5 July 2017 / Revised: 24 July 2017 / Accepted: 25 July 2017 / Published: 12 August 2017
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Abstract
In this paper the influence of spark energy on corrosion resistance, hardness, surface roughness and morphology of WC-Co coated 36Cr-Ni-Mo4 steel by Micro-Electro Welding (MEW) was investigated. Frequencies of 5, 8 and 11 kHz, currents of 15, 25 and 35 A and duty
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In this paper the influence of spark energy on corrosion resistance, hardness, surface roughness and morphology of WC-Co coated 36Cr-Ni-Mo4 steel by Micro-Electro Welding (MEW) was investigated. Frequencies of 5, 8 and 11 kHz, currents of 15, 25 and 35 A and duty cycles of 10, 30 and 50 % were applied for coating of the samples using a WC-Co cermet electrode. The results indicate that increasing the current, Duty cycle and frequency of the process increases spark energy. As spark energy increases, efficiency of coating increases to 80% and then decreases. X-ray diffraction (XRD) analysis was used to identify the phases. The results indicated that other than the peaks obtained for the metallic Iron with BCC (Body Centered Cubic) structure, Tungsten Carbide, Cr7C3 and Titanium Carbide phases were also seen on the surface. Vickers micro hardness method was used for hardness measurement of the samples. Surface hardness increases to 817.33 HV0.05 with spark energy increasing up to 1.03 mJ, and then reducing. Optical Microscopy (OM) and scanning electron microscopy (SEM) to study Microstructural and atomic force microscopy (AFM) to study the topography, morphology and roughness were used. Polarization technique in 3.5 wt % NaCl solution was used to evaluate the corrosion properties. The results of the energy dispersive X-ray spectroscopy (EDS) analysis indicate that with increasing spark energy, the amount of Tungsten in surface increases to 41.95 wt % and then decreases. As spark energy increases up to 2.17 mJ, thickness of coating increases to 8.31 μm and then decreases. As spark energy increases, surface roughness is also increased. Corrosion test results indicated that the lowest corrosion rate (2.6 × 10−8 mpy) is related to the sample with the highest level of efficiency. Full article
(This article belongs to the Special Issue Cermets and Hardmetals)
Figures

Open AccessArticle Vickers Indentation Fracture Toughness of Near-Nano and Nanostructured WC-Co Cemented Carbides
Metals 2017, 7(4), 143; doi:10.3390/met7040143
Received: 13 January 2017 / Revised: 1 April 2017 / Accepted: 12 April 2017 / Published: 19 April 2017
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Abstract
In this paper, the fracture toughness KIc of near-nano and nanostructured WC-Co cemented carbides by Vickers indentation fracture toughness (VIF) was investigated. The aim was to research the type of cracking occurring in near-nano and nano-grained WC-Co cemented carbides with respect to
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In this paper, the fracture toughness KIc of near-nano and nanostructured WC-Co cemented carbides by Vickers indentation fracture toughness (VIF) was investigated. The aim was to research the type of cracking occurring in near-nano and nano-grained WC-Co cemented carbides with respect to the Co content and, consequently, to evaluate the appropriateness of different models for the fracture toughness calculation. The mixtures with different binder content—4, 6, and 9 wt. % Co—were consolidated by sintering in a hydrogen atmosphere. Vickers indentation using a test force of 294 N was used for the determination of fracture toughness. The type of crack that occurred as a consequence of the applied load on the corners of the Vickers indentations was analysed with optical microscopy before and after repolishing the samples. Different crack models, Palmqvist and radial-median, were applied for the calculation of KIc. Instrumented indentation testing was used to determine the modulus of elasticity of the consolidated samples. From the research it was found that near-nano and nanostructured cemented carbides with 9 and 6 wt. % Co do not exhibit median cracking and the indenter cracks remain radial in nature, while near-nano and nanostructured cemented carbides with 4 wt. % Co exhibit both radial and median cracking. Accordingly, it was concluded that the critical amount of the binder phase in near-nano and nanostructured WC-Co at which the crack changes its geometry from Palmqvist to radial-median is around 4 wt. % Co. Comparing different models it was found that KIc values are not consistent and differ for each method used. Models from Exner crack resistance for the Palmqvist crack showed good agreement. Radial-median crack models showed significant KIc deviations for the same testing conditions for all samples. Full article
(This article belongs to the Special Issue Cermets and Hardmetals)
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Figure 1

Open AccessArticle Electrochemical Corrosion Behavior of Near-Nano and Nanostructured WC-Co Cemented Carbides
Metals 2017, 7(3), 69; doi:10.3390/met7030069
Received: 1 December 2016 / Revised: 29 January 2017 / Accepted: 17 February 2017 / Published: 23 February 2017
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Abstract
In this paper, the electrochemical corrosion resistance of near-nano and nanostructured WC-Co cemented carbides was investigated. WC powders with an average grain size dBET in the range from 95 nm to 150 nm and with an addition of vanadium carbide (VC) and
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In this paper, the electrochemical corrosion resistance of near-nano and nanostructured WC-Co cemented carbides was investigated. WC powders with an average grain size dBET in the range from 95 nm to 150 nm and with an addition of vanadium carbide (VC) and chromium carbide Cr3C2 as grain growth inhibitors were used as starting powders. The mixtures with 6 wt. % and 9 wt. % Co were consolidated by two different processes; sintering in hydrogen atmosphere and the sinter-HIP process. WC-Co samples were researched by direct current and alternating current techniques in the solution of 3.5% NaCl at room temperature. Corrosion parameters such as corrosion potential (Ecorr), corrosion current density (jcorr) and polarization resistance (Rp) were determined by electrochemical techniques. From the conducted research, it was found that the consolidation processes and microstructural characteristics—grain growth inhibitors, grain size of the starting WC powders and η-phase—influenced the electrochemical corrosion resistance. η-phase enhanced the formation of a passive layer on the samples’ surfaces, thereby reducing the tendency of the sample dissolution and increasing the stability of oxides forming therewith a passive layer on the sample surface. Full article
(This article belongs to the Special Issue Cermets and Hardmetals)
Figures

Figure 1

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