報告書番号

W02012

タイトル（和文）

移行形アークプラズマを用いた高純度窒化アルミニウム超微粒子の生成特性

タイトル（英文）

Synthesis characteristics of ultra fine particles of aluminum nitride by transferred type arc plasma

概要 （図表や脚注は「報告書全文」に掲載しております）

電力機器のコンパクト化に伴い，電気絶縁材料に放熱性が要求されている。この絶縁材料を開発するためには，高熱伝導セラミックスの窒化アルミニウム（AlN）粉をエポキシ樹脂に高充填する必要がある。ミクロンオーダーの粒子に100nm以下の超微粒子を添加することによりその実現が期待できるが，AlN超微粒子を低コストで大量に合成できる技術が不可欠である。本報告では，超微粒子の大量合成が期待できる移行形アークプラズマを用いて，原材料Al粉からのAlN生成特性，AlN純度が高い超微粒子を得る条件を検討した。化学平衡計算および生成実験を行った結果，トーチガスをN2とし，反応･急冷ガスとしてNH3を1800～2000℃の温度領域に吹き込むことによりAlN純度が高い超微粒子が得られ，さらにこの粒子をエタノールに通過させることにより市販破砕粉のAlN純度と同等レベルの99%wt.以上にできることを明らかにした。

概要 （英文）

Downsizing of electrical equipments has meant that such equipments have required high thermal conductivity. In order to develop solid insulating materials with high thermal conductivity, it is necessary to add large quantities of ceramic powder with high thermal conductivity to organic insulating materials. Mixing small powder with large powder is considered a good way to achieve a high ceramic powder content. Aluminum nitride (AlN) is a ceramic with high thermal conductivity. Commercially available AlN powder is sized at a few microns, therefore AlN ultra fine particle (UFP) is required. However the low production capacity of UFP makes it extremely expensive. Transferred type arc plasma has the advantage of making it easy to upgrade plasma power, and therefore has the potential to reduce production costs. This report describes the synthesis of AlN UFP from aluminum (Al) powder using transferred type arc plasma. Calculations of chemical equilibrium composition and experiments of synthesis of AlN UFP were carried out. Main results are as follows. In order to increase AlN content in synthesized particles, nitrogen had better be used as a plasma gas and ammonia was recommended to be used as a reacting/quenching gas and to be flowed into a zone with high temperature between 1800 and 2000 degrees. AlN content in particles increased more than 99%wt (commercial level) when the synthesized UFP passed through ethanol, because ethanol reacts with Al and not with AlN.

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