油系鈦酸鋇漿體之分散行為研究

鈦酸鋇是最早被發現的電子陶瓷材料之一，鈦酸鋇晶體構造簡單，容易和其他氧化物形成固溶體進而改善電性，並應為具有介電、壓電、光學、強電等特性，因此在電子工業上廣泛的利用。近年來由於電子元件不斷朝微型、薄型、高穩定的方向發展，然而好的強度或電性的陶瓷元件，漿料分散情形的好壞對於最後形成的元件性質有很大的影響。應用於陶瓷粉末的分散劑多為高分子型介面活性劑。此種分散劑解離後會吸附在陶瓷顆粒的表面，因彼此帶有相同電荷，而產生斥力達到分散。另外由於吸附在顆粒表面的高分子的支鏈，也會產生空間位阻﹙steric hindrance﹚避免顆粒互相聚集。所以高分子分散劑結構的官能基種類以及其支鏈為影響分散效果的重要因素。本研究主要是添加不同種類的高分子分散劑探討分散劑對鈦酸鋇漿體的分散情形，評估在有機溶劑系統下的分散效果。分散效果的評估包含︰粒徑分布量測、漿體流變行為、沉降實驗、高分子對顆粒表面的吸附量以及微結構觀察。結果顯示分散劑D2可以有效的分散鈦酸鋇漿體，使顆粒粒徑變小、降低漿體黏度值以及提高漿體穩定性。D2在漿體分散的效果與D1相當或更佳，原因為D2與D1兩者在結構上的差異造成不同的分散行為以及對於溶劑的媒合效應，使得D2在本研究的溶劑系統下有較佳的分散效果。

關鍵字

分散劑；鈦酸鋇；膠體溶液；有機溶劑

並列摘要

Ceramic materials based on perovskite-like oxides are intense of interests because of their applications in electronic devices. Due to its high dielectric constant, barium titanate（BaTiO3） is one of the most studied compounds of this family and widely used material in making electronic devices such as multilayer capacitor, communication filters, and piezoelectric sensors. The current trend is towards miniaturization in the fabrication of electronic devices and higher dielectric permittivity. To prepare green sheets with high packing density and uniform microstructure, well dispersed slurry is essential. Many studies focusing on the dispersion and stabilization of microsized BaTiO3 suspension, and various polymers as dispersant were tested. In general, BaTiO3 suspension can be stabilized by electrostatic, steric and electrosteric mechanisms. For electrostatic stabilization, powders need to have a sufficient zata potential to provide strong repulsion between two particles in suspension. For steric hindrance, polymer adsorption with reasonable coverage and adsorption layer thickness is necessary to promote stability. Electrosteric stabilization requires the presence of adsorbed polymer and significant electrical double-layer repulsion. The main purpose of this investigation is to characterize in detail the dispersion of BaTiO3 powder in organic suspension with different type and dosage of polymer dispersants. The dispersing effectiveness on organic BaTiO3 slurry were examined and discussed from particle size distribution, rheological measurement, sedimentation volume, polymer adsorption and SEM observation. Base on the results, D2 shows good dispersion ability because it can reduce the particle size and slurry viscosity, make the slurry more stable. Compare with D1, D2 is more effective in preparing stabilized suspension. This is related to the chemical nature and adsorption behavior between D1 and D2. Consequently, D2 shows better dispersion behavior in the organic BaTiO3 slurry.

並列關鍵字

dispersant ； barium titanate ； suspensions ； organic media

參考文獻

[1] T. Chartier, E. Jorge, P. Boch “Dispersion Properties of BaTiO3 Tape-castingSlurries,” J. Eur. Ceram. Soc., 11 (1993) 387

[3] K.R. MIKESKA ” Non-Aqueous Dispersion Properties of Pure Barium Titanate for Tape Casting,” Colloids and Surfaces, 29 (1988) 305

[4] G. D. Parfitt, ”Dispersion of Powders in Liquids,”3rd. ed. Applied Science Publishers, Inc., New Jersey, 1981

[5] H. Rumpf, Chem.-Ing.Tech.,30（1958）144（in Germany）

[6] R. G. Horn, “Surface Forces and Their Action in Ceramic Materials” J. Am. Ceram. Soc.,73（1990）1117

國際替代計量

油系鈦酸鋇漿體之分散行為研究

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