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.)−297−Synthesiology - English edition Vol.3 No.4 (2011) Discussions with Reviewers1 Market scale of cemented carbides and effect of cobalt free productComment (Norimitsu Murayama, Advanced Manufacturing Research Institute, AIST)To have the readers from different fields appreciate the economic significance of cemented carbide and the effect of achieving cobalt free hard material as the background of your research, I think you should numerically present the market scale of cemented carbide, share of Japan, and economic effect of achieving cobalt free.Answer (Keizo Kobayashi)According to the statistics of the Japan Cemented Carbide Tool Manufacturers Association, the domestic production of cemented carbide in FY 2007 grew to over 350 billion yen. Kimihiro OzakiObtained doctorate (Engineering) at the Department of Production Process Engineering, Graduate School of Engineering, Osaka University in March 1994. Joined the Nagoya National Industrial Research Institute, Agency of Industrial Science and Technology in 1994. Engaged in the development of magnesium amorphous alloys by mechanical alloying and pulsed current sintering, and in clarifying the basic mechanism of pulsed current sintering. In this disclosure, expanded the research into use as molds and developed the current sintering technology.Akihiro MatsumotoDoctorate (Engineering) obtained at the Department of Metallurgy and Department of Iron and Steelmaking, Graduate School of Engineering, Nagoya University in March 1992. Joined the Nagoya National Industrial Research Institute, Agency of Industrial Science and Technology in April 1992. Engaged in the development of high melting point structural intermetallic compounds, the synthesis of titanium amorphous and quasi-crystal alloys and energy use, and the development of environmentally-friendly cemented carbides. Leader of Structural Control Research Group, Material Research Institute for Sustainable Development in 2007. In this disclosure, expanded the results into use as cutting tools, and developed the DLC coating technology based on microscopic structure observation.Hiroyuki NakayamaDoctorate (Engineering) obtained at the Department of Functional Materials Engineering, Graduate School of Engineering, Toyohashi University of Technology in March 2004, followed by post-doctoral positions at the University of Washington and the Nagoya Institute of Technology. Joined AIST in April 2008. In this disclosure, developed the compositing and mixing technologies of various hard particles and Fe-Al intermetallic compounds to expand the research to tungsten-saving technology.Although it decreased after the Lehman Shock, a market scale of over 200 billion yen is maintained, and has since increased. In the international share of cemented carbide, Japan’s Mitsubishi Material Corporation and Sumitomo Electric Industries, Ltd. follow Sandvik AB, Kennametal Inc., and Iscar Ltd. However, we were unable to obtain accurate figures for the share of the Japanese companies. For the effect of cobalt free, along with the cost reduction of the raw material (in raw material price, compared as reagents, the iron and aluminum powders are less than 1/4 of cobalt powder), certain aspects, such as the environmental concerns (carcinogenic issues) and the application to new high-temperature uses, are difficult to express numerically. As you indicated, we added and modified the text to include the figures where we could. The forging mold that we are developing from Type 2 Basic Research to application research has a market potential of about 15 billion yen (source from the Materials Process Technology Center).2 Originality of the researchComment (Norimitsu Murayama)The number one originality of this research is to use Fe and Al instead of Co as the binder phase of cemented carbide. Al is used as the binder phase in the liquid state during sintering, and FeAl is synthesized to work around the disadvantages of Fe and Al. I think the paper will mature by explaining this point in chapters 2 or 3. The second originality is that you found that if both Fe and Al are in liquid form, Al evaporates rapidly and the synthesis does not go well, but when only Al become liquid, it functions as the binding agent and the synthesis of FeAl will progress. This is an example where the result did not go as in the scenario designed by thought experiment, but a way opened by patiently conducting experiments.I think you can communicate the dynamism of the material research to the readers if you divide “3 Research scenario to realize the goal” into the scenario design by thought experiment and the changes in scenario after the actual experiments.Answer (Keizo Kobayashi)As you have understood, the greatest characteristic of this research was the use of Fe and Al instead of Co. Al is melted during sintering, and the target intermetallic compound is synthesized by subsequent heating. I added this point to chapter 2. In addition, I think by what process the WC-FeAl alloy is fabricated is very important in this research. While we were developing the material by following the concepts of the conventional cemented carbide, we were unable to synthesize stable materials, even though we could clarify the properties of the materials. Afterwards, we did some alternative thinking, and various secondary effects were found by reviewing the process. As a result, we were able to advance the research greatly. I added the points that you indicated and modified the “3 Research scenario to realize the goal”. However, since I was unable to discern the extent to which the thought experiment would cover, I intentionally did not use the word “thought experiment”.3 Time needed for material developmentComment (Norimitsu Murayama)Material development takes a long time. This is one characteristic of material development. Why don’t you add a time axis to the development of WC-FeAl hard material in Fig. 7, and add some explanation in the text?Answer (Keizo Kobayashi)As you indicated, I think the addition of the time axis will be effective in enabling readers understand the progress of the material. However, in practice, the technological developments progressed side by side, and I feel it is difficult to present an exact time axis. Though very rough, I added a time axis in units of

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