奈米級晶粒α-Al_2O_3的生坯製作

Preparation of Nano-grained α-Al_2O_3 Compacts

黃雯巧(W.C. Huang) ； 黃姵文(P.W. Huang) ； 向性一(H.I. Hsiang) ； 黃啓原(C.Y. Huang) ； 顏富士(F.S. Yen)

《鑛冶：中國鑛冶工程學會會刊》 65卷4期 (2021/12) Pp. 76-81

https://doi.org/10.30069/MM.202112_65(4).06

摘要

本文說明利用氧化鋁（Al_2O_3）的θ-至α-相變過程會自然出現的熱力學穩定晶徑80 ∼ 100 nm，可製作組成晶粒小於100 nm的α-Al_2O_3生坯。除基於降低生產成本，為拓展氧化鋁的工業應用，取得奈米級晶粒α-Al_2O_3生坯以製作微米級晶粒之氧化鋁陶瓷，乃是陶瓷界多年來未解的心願。唯因市場迄無細於100 nm的α-Al_2O_3原料粉末，而使生產此等產品必須採用熱壓（Hot pressing）或熱均壓（Hot isostatic pressing）等高成本技術製作，限制氧化鋁拓展應用領域。本文模擬核殼技術製作θ-Al_2O_3（核）外包聚乙二醇（Polyethylene glycol, PEG）（殼）（或θ-Al_2O_3@PEG）之混合粉末，以壓力成型先製得含PEG的θ-Al_2O_3坯，由PEG將θ-Al_2O_3粒體均勻分離隔開。再透過熱處理，藉θ-Al_2O_3粒體可同步相轉換，生成的α-Al_2O_3同時達到100 nm穩定晶徑的過程，製得由小於100 nm晶徑α-Al_2O_3組成的生坯。生坯密度可達60%理論密度（T.D.）。

關鍵字

氧化鋁 ； 核殼技術 ； PEG ； 陶瓷生坯

並列摘要

The preparation of nano-grained α-Al_2O_3 green compacts composed of ＜ 100-nm α-Al_2O_3 based on the presence of thermodynamic stable size of α-Al_2O_3 80~100 nm during θ- to α- Al_2O_3 phase transformation was described. It has been an important issue to develop the finer-grained α-Al_2O_3 compacts for reducing production cost as well as providing better function performance after sintering the fabricated α-Al_2O_3. Unfortunately, because of no α-Al_2O_3 powders with particle size less than 100 nm in diameter can be purchased at the moment, α-Al_2O_3 ceramics of submicron- grain- sized has long been fabricated using expensive HP or HIP techniques that restricts its application scopes. The modified θ-Al_2O_3@PEG powder was fabricated by mixing θ-Al_2O_3 powders with PEG. The core-shell powder was then converted into cylindrical samples by uniaxial pressing, by which a homogeneously distribution of PEG in the θ-Al_2O_3 compact was made. The θ-Al_2O_3 particles were apart individually in this case. The PEG-θ-Al_2O_3 compacts were then thermal treated, removing PEG and converting into α-Al_2O_3 compacts. Based on the presence of 80~100 nm crystallite size phenomena occurs during the θ- to α-Al_2O_3 phase transformation, the PEG-free θ-Al_2O_3 compacts were converted into α-Al_2O_3 compacts via appropriate thermal treatments. These α-Al_2O_3 compacts were composed of α-Al_2O_3 crystallites of diameter 50-100 nm, with phase purity of ＞85% α-Al_2O_3. And the relative density can be ＞60% of the theoretical value.

並列關鍵字

Alumina ； Core-shell technology ； Phase transformation ； Green compact

參考文獻

Taimei Chemical Co., Ltd http://www.taimei-chem.co.jp

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