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Preparation of very hard and tough ceramics using a reactive resistance-heated hot-pressing accompanied by solid-state displacement reaction

Research Project

Project/Area Number 16560625
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field Material processing/treatments
Research InstitutionAkita University

Principal Investigator

TAIMATSU Hitoshi  Akita University, Faculty of Resource Science and Engineering, Professor, 工学資源学部, 教授 (60125721)

Project Period (FY) 2004 – 2005
Project Status Completed (Fiscal Year 2005)
Budget Amount *help
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2005: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2004: ¥3,100,000 (Direct Cost: ¥3,100,000)
Keywordstungsten carbide / tungsten boride / vanadium carbide / pressure sintering / mechanical properties
Research Abstract

Dense W-B-C ceramics were prepared by a reactive resistance-heated hot-pressing of B_4C-W-WC powders which induced the solid-state reaction B_4C + 5W + 80WC→4WB+81WC to find the most suitable range of sintering temperature. Dense ceramics were obtained above 1650 ℃ Sintered bodies obtained at 1650 ℃. had fine WC grains and hence high hardness. Above 1700 ℃, grain-coarsening of WC occurred and hardness greatly decreased. Since the narrow range of sintering temperature make it more difficult to control their quality. Therefore, it is necessary to widen the sintering temperature range by adding a grain-growth inhibitor. Thus, the effect of VC, which are widely know as the most effective grain-growth inhibitor for WC in WC-Co, was examined on mechanical properties. Fully dense ceramics were obtained above 1750 ℃ for a powder containing VC-doped WC. Dense ceramics obtained at 1800 ℃ had almost the same grain size of WC as the starting powder, showing a good grain-growth inhibitor. Below 1700 ℃, WB, W_2B and W_2C were formed as reaction products, and, above 1750 ℃, WB was not produced. VC did not dissolve in WC grains, and precipitated at WC/WC grain boundaries and around WB and W_2B grains. The bulk density increased with sintering temperature and approached 15.5 g cm^<-3> above 1750 ℃. Young's modulus increased gradually with sintering temperature and became constant above 1750 ℃. Its maximum value was 689 GPa. Poissons' ratio was constant in the sintering temperature range. Vicker's hardness was above 25 GPa in the sintering temperature range because the grain growth of WC was effectively impeded. The fracture toughness had a maximum value of 5.3 MPa m^<1/2>, being a little lower than that without VC.

Report

(3 results)
  • 2005 Annual Research Report   Final Research Report Summary
  • 2004 Annual Research Report
  • Research Products

    (3 results)

All 2004

All Journal Article (3 results)

  • [Journal Article] Mechanical Properties of WC-WB-W_2B Composites Prepared by Reaction Sintering of B_4C-W-WC Powders2004

    • Author(s)
      Shigeaki Sugiyama
    • Journal Title

      Materials Science Forum Vol.449-452

      Pages: 309-312

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2005 Final Research Report Summary 2004 Annual Research Report
  • [Journal Article] Preparation of W-C-B composites by Reactive Resistance-Heated Hot Pressing2004

    • Author(s)
      S.Sugiyama
    • Journal Title

      Journal of the European Ceramic Society Vol.24, No.5

      Pages: 871-876

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2005 Final Research Report Summary 2004 Annual Research Report
  • [Journal Article] Preparation of W-C-B composites by Reactive Resistance -Heated Hot Pressing2004

    • Author(s)
      S.Sugiyama
    • Journal Title

      Journal of the European Ceramic Society Vol.24, No.5

      Pages: 871-876

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2005 Final Research Report Summary

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Published: 2004-04-01   Modified: 2016-04-21  

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