Ube Industries, Inc.

Michio Honda

Takeshi Yamao

Shinsuke Jida

Masataka Fujinaga

Koji Shibata

Takayuki Fujii

Takuji Ohmaru

A silicon nitride powder having a specific surface area of 4.0 to 9.0 m/g, a &#x3b2; phase proportion of less than 40 mass %, and an oxygen content of 0.20 to 0.95 mass %, wherein a frequency distribution curve obtained by measuring a volume-based particle size distribution by a laser diffraction scattering method has two peaks, peak tops of the peaks are present respectively at 0.4 to 0.7 &#x3bc;m and 1.5 to 3.0 &#x3bc;m, a ratio of frequencies of the peak tops ((frequency of the peak top in a particle diameter range of 0.4 to 0.7 &#x3bc;m)/(frequency of the peak top in a particle diameter range of 1.5 to 3.0 &#x3bc;m)) is 0.5 to 1.5, and a ratio D50/D(&#x3bc;m/&#x3bc;m) of a median diameter D50 (&#x3bc;m) determined by the measurement of particle size distribution to a specific surface area-equivalent diameter D(&#x3bc;m) calculated from the specific surface area is 3.5 or more.

Silicon nitride powder, silicon nitride sintered body and circuit substrate, and production method for said silicon nitride powder

A method of producing a silicon nitride powder includes heating an amorphous Si&#x2014;N(&#x2014;H)-based compound in which assuming that the specific surface area is RS (m/g) and the oxygen content ratio is RO (mass %), RS/RO is 500 or more, at a temperature rising rate of 12 to 100&#xb0; C./min in a temperature range from 1,000 to 1,400&#xb0; C. while flowing the compound by a continuous firing furnace.

Silicon nitride powder production method, silicon nitride powder, silicon nitride sintered body and circuit substrate using same

A polycrystalline silicon ingot casting mold, and method for producing same. Mold release material being obtained by blending a silicon nitride powder (A) having an average particle diameter along the short axis of 0.6 to 13 &#x3bc;m with a silicon nitride powder (B) having an average particle diameter along the short axis of 0.1 to 0.3 &#x3bc;m at a weight ratio of 5:5 to 9:1; coating the mold surface with the slurry; and a heating the mold at 800 to 1200&#xb0; C. in an atmosphere containing oxygen.

Polycrystalline silicon ingot casting mold and method for producing same, and silicon nitride powder for mold release material for polycrystalline silicon ingot casting mold and slurry containing same

Mold for casting a polycrystalline silicon ingot, and a silicon nitride powder for a mold release material thereof, a slurry containing a silicon nitride power for a mold release layer thereof, and a mold release material for casting thereof. The present invention relates to a silicon nitride powder for a mold release material of a mold for casting a polycrystalline silicon ingot characterized in that the percentage of primary particles of granular crystals monodispersed in powders is not less than 95% in terms of the area ratio calculated by analysis of an SEM image.

Mold for casting polycrystalline silicon ingot, and silicon nitride powder for mold release material thereof, slurry containing silicon nitride powder for mold release layer thereof and mold release material for casting thereof

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Ube, Japan

Michio Honda