Vol.3 No.4 2011

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Research paper : New material development by the integration of cast technology and powder metallurgy technology (K. Kobayashi et al.)−295−Synthesiology - English edition Vol.3 No.4 (2011) on top of the hard particles and binder phase, as shown in Fig. 6. When the boundary of the WC-FeAl and the DLC film was observed microscopically, a thin layer was observed in the boundary. When this layer was analyzed carefully, it was found that an aluminum oxide film was formed, and this was thought to increase the oxidation resistance at high temperature. This thin layer formed at approximately room temperature and was found to improve adherence to the DLC film. When the DLC film is formed on the surface of WC-FeAl hard material, it is expected to increase the mold release characteristics of the formed material. In fact, the WC-FeAl die whose the surface was coated with DLC reduced the force that was necessary for blanking of Mg foil and Cu foil.In the WC-FeAl hard material fabricated by the developed process, the crystal growth of the WC particle, which was known to be a problem in the conventional cemented carbide, was hardly observed during sintering. In addition, there was no formation of a composite carbide phase such as the W3Fe3C that is known to be a brittle phase. In the early stage of the development, we did consider these results closely as these were considered to be the result of low-temperature sintering. However, some researchers are beginning to investigate the effect of Al from an academic aspect, and it is necessary to examine further the interaction between the carbides and the FeAl intermetallic compounds. As we devoted most of our efforts towards practical use, there is a lack of academic considerations, and we intend to investigate this further through joint researches with universities.By using a hard material FeAl as the binder phase, it was possible to reduce the amount of tungsten carbide whilst attaining the same hardness, and it is thought that the use of the WC-FeAl hard material will result in tungsten-saving technology. However, there is only a little reduction effect of the tungsten by this method. A hard particle other than tungsten carbide must be composited to further reduce tungsten usage. Considering the recent rise in tungsten prices, immediate measures are highly valuable. Therefore, by using the fabrication process of WC-FeAl, we investigated the compositing of titanium hard particles and FeAl. We attempted the development of a hard material in which titanium boride particles with high heat conductivity were bound with Fe-Al intermetallic compound[12][13]. The obtained TiB2-20 mass% (Fe-Al) sintered compact had more than 95 % of the theoretical density. While its hardness changed according to the Fe:Al ratio, it was over 1500 Hv. Since the sintering property of the TiB2 particle was good when the Fe content of the binder phase was high, the Fe-Al intermetallic compound with high Fe content was used. In addition, the TiC-30 mass% TiB2-30 mass% (Fe-Al) hard material, in which the titanium carbide and titanium boride particles were used as hard particles and Fe-Al intermetallic compound was used for the binder phase, showed heat conductivity of 30 W/mK, and had intermediate value between the conventional cemented carbide and cermet (TiC-Ni alloy). As various additional uses are found for cemented carbide in which the WC is bound by the FeAl intermetallic compound, we anticipate that new uses will be found for the TiB2-(Fe-Al) or TiC-TiB2-(Fe-Al) hard materials. In fact, the TiB2-(Fe-Al) hard material is lighter than cemented carbide, and new applications to wear-proof parts can be considered by further evaluating the abrasion resistance. 6 SummaryHerein, we describe details concerning the development of a WC-FeAl hard material with excellent resistance in AIST, and explain the R&D from the basic research to Type 2 Basic Research undertaken in our research group. Figure 7 shows the schematic diagram of the course of the development. It can be seen that the current WC-FeAl was created as a result of the fusion of various elemental technologies over Fig. 7 Development process of WC-FeAl hard materialPracticalapplicationresearchValleyof deathType 2Basic ResearchBasicresearchMoldCutting toolOthersDLC coatingCharacteristicimprovementPulsed currentsinteringWC-FeAlCastingPowdermetallurgyDevelopment ofcemented carbideSemi-solid forming ofmagnesium alloyLevitation melting andcasting of intermetalliccompounds1980s1990s2000s2010sObservation ofmicrostructureFeAl basedhard materialNew hard particles

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