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Research paper : New material development by the integration of cast technology and powder metallurgy technology (K. Kobayashi et al.)−294−Synthesiology - English edition Vol.3 No.4 (2011) cooled, and could be envisioned for use as mold material for high temperature.Moreover, the WC-FeAl hard material showed machining precision at processing speeds equivalent to the conventional cemented carbide in the grinding process using abrasive stone. A prototype of the complexly shaped blade of a ball end mill was fabricated. This blade tip was able to perform equally to conventional cemented carbide, as shown in Fig. 5. However, in this ball end mill, the new material was used only at the tip that was joined to the high-speed steel rod by brazing. This was because a long sintered compact cannot currently be fabricated with the newly developed process, this being a subject for future study.The result of this Type 2 Basic Research greatly reduced the timescale to the adoption for practical use. Several companies expressed desire to actually use this material. All of these companies wished to manufacture the material on their own. They wanted to introduce the new process technology, and then investigate the practical uses and business applications by combining the new technology with their own technology. Therefore, we set the cutting tools and molds as the outlet, and performed the examination to practical use through the research involving the material manufacturers and the machining companies.5 DiscussionsThe developed WC-FeAl hard material is a new composite material using FeAl intermetallic compound as the binder phase, and has the potential to resolve the problems associated with conventional WC-Co cemented carbide. For example, Co, which is the binder phase of the conventional cemented carbide, has a Vickers’ hardness of 130 Hv, and is softer than tungsten carbide. Therefore, when the surface of the cemented carbide is polished, some unevenness occurs between the binder phase and hard particles. On the other hand, the FeAl intermetallic compound has a Vickers’ hardness of 320 Hv, and the unevenness caused by the hardness difference between the binder phase and hard particles should be reduced. To examine this, the WC-FeAl hard material in which the volume ratio of the binder phase had been adjusted, and the conventional WC-Co cemented carbide were both polished with diamond abrasives, and the surfaces were coated with diamond-like carbon (DLC) by sputtering. Although there were some differences due to the observed area in the coarseness of the polished sample surfaces, values were Ra = 4.3 nm for the WC-FeAl, and Ra = 5.3 nm for the WC-Co; the polished surface was smoother in WC-FeAl because the binder phase was hard. When the adherences of the DLC film formed on each hard substrate were measured by a scratch test, the WC-FeAl required approximately 25 % higher load for separation. It was confirmed that in the boundary between the DLC film and the cemented carbide substrate, the even DLC film adhered Fig. 6 Microstructure observation of the interface portion of DLC film and the WC-based hard material(a) Interface of DLC and WC-FeAl. (b) Interface of DLC and WC-Co.Aluminum oxide is formed at EDX2 area of (a).Fig. 5 Prototype ball end mill made using WC-FeAlFig. 4 Photograph of WC-based hard materials quenched in water from 900 ºC in the airWC-Co (conventional material) is cracked, but the WC-FeAl is not cracked.10 mmWC-CoWC-FeAlBall end millCutting edge:WC-FeAI(b)(a)30 nm

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