Development of technology for the viscosity measurement of Fe-S alloy melt using the new material anvil under high-pressure

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We have developed the techniques for manufacturing the SiC/diamond-composite anvils, which have higher hardness and compressive strength than those of the conventional WC anvils. We evaluated the high-pressure and high-temperature generation of the SiC/diamond-composite anvils using a multi-anvil high pressure apparatus(SPEED-Mk.II) combined with the synchrotron radiation at the Spring-8. Based on the techniques, we also attempted the viscosity experiment of Fe-S alloy melt using the falling sphere method.1. Evaluation of the SiC/diamond-composite anvils We optimized the manufacture method of the SiC/diamond-composite cube by changing a hot isostatic pressing(HIP) synthesis conditions between diamond powders and molten Si, including the grain size, temperature, pressure, vacuum and so on. Fabricated cubes with 14 mm edge length were used as the second-stage anvils in the SPEED-Mk.II, and they showed higher-pressure and higher-temperature generations, 38 Gpa at room temperature and 17 G … More pa at 1600℃, than those by the WC cubes. Moreover, we successfully synthesized the large size SiC/diamond-composite cubes with 26 mm edge length, which were recovered without any damages after the compression test to 20 Gpa.2. Development of the viscosity experiment of Fe-S alloy melt The SiC/diamond-composite anvils show good X-ray transparency(>30%) enough for X-ray diffraction or radio-graphic studies. We attempted the viscosity experiments of Fe90S10 melt using the SPEED-Mk.II whose second stage anvils were composed of four SiC/diamond-composite and four WC cubes. Development of high-pressure cell for the falling sphere method enabled to generate 15 GPa and 1600℃, and we observed good radiographic image of Fe90S10 melt from CCD camera by penetrated X-ray through the SiC/diamond-composite anvils. However, because of the chemical reaction between the melt and the falling metal spheres(Re, Ta, Au), viscosity experiments were unsuccessful at the P-T conditions. Further technical improvements are needed to overcome this experimental difficulty. Less