Hardmetal

A special issue of Crystals (ISSN 2073-4352). This special issue belongs to the section "Inorganic Crystalline Materials".

Deadline for manuscript submissions: closed (15 December 2020) | Viewed by 9614

Special Issue Editors


E-Mail Website
Guest Editor
KTH Royal Institute of Technology, Department of Materials Science, Stockholm, Sweden
Interests: novel synthesis; magnetic materials; bulk metal glass; high entropy alloys; superconductors

E-Mail Website
Co-Guest Editor
KTH Royal Institute of Technology, Stockholm, Sweden
Interests: computational materials design; integrated computational materials engineering; cemented carbides; alternative binders; microstructures; properties

E-Mail
Co-Guest Editor
Materials Science and Engineering, KTH Royal Institute of Technology, Stockholm, Sweden
Interests: Phase transformations in metallic alloys and hardmetals

Special Issue Information

Dear Colleagues,

‘Hardmetal’ has a very particular meaning – it is not about a hard metal in general - it means a composite of (typically) tungsten-carbide grains in a cobalt matrix, the so called ‘binder’ (CoWC). It is used as inserts in all sorts of tools in a wide variety of applications for metal cutting and rock drilling and wherever high wear resistance is needed. ‘Hardmetal’ as such represents a huge market of 10s of thousands of tons pa at present.

Historically it has been around for ca 100ys, and it is industrially prepared by a sintering process. Powders/grains of the hard constituent is mixed with the binder, compressed and sintered at about 1500C. Obviously this concept has experienced substantial development over the years. E.g. the grain size has decreased from several micrometers at the beginning to being in the nanometer range at present. However, these improvements are still rather incremental, and today’s product is not dramatically different from the earlier. Moreover, the cobalt content is now considered becoming increasingly problematic. Cobalt is relatively expensive and has recently become suspect of being carcinogenic. Also, the mining of cobalt in areas like Congo, has made it a ‘conflict mineral’. Thus, there is a definite strive to replace Co with ‘friendlier’ alternatives.

Therefore, we invite researchers in the field of metallurgy as well as from novel preparation techniques like additive manufacturing to contribute to the effort of replacing cobalt and possibly also replace WC with alternatives. Efforts in this direction have shown that even a ‘simple’ FeNi alloy might be a replacement candidate to the binder.

In hindsight it appears that this very combination of the extremely hard WC phase with the particular binder – cobalt – is quite fortuitous. Not only gives cobalt the right amount of plasticity to accommodate slight deformation, but it has also given the composite a very convenient way for quality control by magnetic measurements well suitable for production. Saturation magnetization is directly related to the Co content, and the coercivity is a well understood function of grain size.

Despite this, we are confident that a serious effort, both theoretical and experimental, will eventually lead to a better Hardmetal.

Dr. Ström Valter
Dr. Joakim Odqvist
Dr. David Linder
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 submissions that pass pre-check are 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. Crystals 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 2100 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

  • High Entropy Alloys
  • Characterization of the grain-binder interface
  • Thermodynamic modeling
  • Preparation from a uniform precursor
  • Wear – models and assessment
  • Increased temperature of operation
  • Additive Manufacturing
  • Spark Plasma Synthesis

Benefits of Publishing in a Special Issue

  • Ease of navigation: Grouping papers by topic helps scholars navigate broad scope journals more efficiently.
  • Greater discoverability: Special Issues support the reach and impact of scientific research. Articles in Special Issues are more discoverable and cited more frequently.
  • Expansion of research network: Special Issues facilitate connections among authors, fostering scientific collaborations.
  • External promotion: Articles in Special Issues are often promoted through the journal's social media, increasing their visibility.
  • e-Book format: Special Issues with more than 10 articles can be published as dedicated e-books, ensuring wide and rapid dissemination.

Further information on MDPI's Special Issue polices can be found here.

Published Papers (2 papers)

Order results
Result details
Select all
Export citation of selected articles as:

Research

10 pages, 3141 KiB  
Article
Hardness, Young’s Modulus and Elastic Recovery in Magnetron Sputtered Amorphous AlMgB14 Films
by Alexander M. Grishin
Crystals 2020, 10(9), 823; https://doi.org/10.3390/cryst10090823 - 16 Sep 2020
Cited by 12 | Viewed by 5393
Abstract
We report optical and mechanical properties of hard aluminum magnesium boride films magnetron sputtered from a stoichiometric AlMgB14 ceramic target onto Corning® 1737 Glass and Si (100) wafers. High target sputtering rf-power and sufficiently short target-to-substrate distance appeared to be critical [...] Read more.
We report optical and mechanical properties of hard aluminum magnesium boride films magnetron sputtered from a stoichiometric AlMgB14 ceramic target onto Corning® 1737 Glass and Si (100) wafers. High target sputtering rf-power and sufficiently short target-to-substrate distance appeared to be critical processing conditions. Amorphous AlMgB14 films demonstrate very strong indentation size effect (ISE): exceptionally high nanohardness H = 88 GPa and elastic Young’s modulus E* = 517 GPa at 26 nm of the diamond probe penetration depth and almost constant values, respectively, of about 35 GPa and 275 GPa starting at depths of about 2–3% of films’ thickness. For comparative analysis of elastic strain to failure index  H/E*, resistance to plastic deformation ratio H3/E*2 and elastic recovery ratio We were obtained in nanoindentation tests performed in a wide range of loading forces from 0.5 to 40 mN. High authentic numerical values of H = 50 GPa and E* = 340 GPa correlate with as low as only 10% of total energy dissipating through the plastic deformations. Full article
(This article belongs to the Special Issue Hardmetal)
Show Figures

Graphical abstract

10 pages, 4187 KiB  
Article
Microstructure and Properties of Ultrafine Cemented Carbides Prepared by Microwave Sintering of Nanocomposites
by Yanju Qian and Zhiwei Zhao
Crystals 2020, 10(6), 507; https://doi.org/10.3390/cryst10060507 - 13 Jun 2020
Cited by 6 | Viewed by 3198
Abstract
Ultrafine cemented carbides were prepared by microwave sintering, using WC-V8C7-Cr3C2-Co nanocomposites as a raw material. The effects of sintering temperature and holding time on the microstructure and mechanical properties of cemented carbides were studied. The [...] Read more.
Ultrafine cemented carbides were prepared by microwave sintering, using WC-V8C7-Cr3C2-Co nanocomposites as a raw material. The effects of sintering temperature and holding time on the microstructure and mechanical properties of cemented carbides were studied. The results show that the ultrafine cemented carbides prepared at 1300 °C for 60 min have good mechanical properties and a good microstructure. The relative density, Vickers hardness, and fracture toughness of the specimen reach the maximum values of 99.79%, 1842 kg/mm2 and 12.6 MPa·m1/2, respectively. Tungsten carbide (WC) grains are fine and uniformly distributed, with an average grain size of 300–500 nm. The combination of nanocomposites, secondary pressing, and microwave sintering can significantly reduce the sintering temperature and inhibit the growth of WC grains, thus producing superfine cemented carbides with good microstructure and mechanical properties. Full article
(This article belongs to the Special Issue Hardmetal)
Show Figures

Figure 1

Back to TopTop