Controlling hydrolysis and dispersion of AlN powders in aqueous media
Controlling hydrolysis and dispersion of AlN powders in aqueous media
复制标题
DOI：
10.1016/s0021-9797(03)00065-1
复制
发表时间：
2003-05-15
影响因子：
9.9
通讯作者：
Ferreira, JMF
中科院分区：
文献类型：
--
作者：
Oliveira, M;Olhero, S;Ferreira, JMF
在不同表面活性剂（即 H3PO4 和阴离子表面活性剂）存在下制备了氮化铝 (AIN) 粉末的水悬浮液，以避免 AIN 粉末水解并增强分散性。水解过程的最具决定性的参数（DeltapH 和接触时间）和 AIN 颗粒在水中的稳定性（表面结晶度、表面化学改性和表面离子电荷）被认为强烈依赖于酸剂。 H3PO4 处理可有效防止 AIN 的水解，因为在颗粒表面形成磷酸盐保护层，尽管它使悬浮液的 pH 值保持在 4 以下，但并不能保证良好的分散。阴离子表面活性剂在AlN颗粒表面的单独吸附并没有完全抑制水解，但确实提高了分散程度。两种表面活性剂的适当组合能够制备相对低粘度和高AlN浓度的AlN水悬浮液，这可以成为水基胶体成型技术或冷冻造粒或喷雾干燥以获得适合干压技术的颗粒粉末特性的良好起点。提出了表面活性剂在颗粒表面上的吸附机制，并得到 NMR 和 FT-IR 分析的支持。 (C) 2003 年爱思唯尔科学（美国）。版权所有。
Aqueous suspensions of aluminum nitride (AIN) powders have been prepared in the presence of different surface-active agents, namely, H3PO4 and an anionic surfactant, to avoid the hydrolysis of AIN powders and to enhance dispersion. The most determinant parameters to the hydrolysis process (DeltapH and time of contact) and the stabilization of AIN particles in water (surface crystallinity, surface chemical modification, and surface ionic charge) were seen to be strongly dependent on the acidic agent. The H3PO4 treatment was effective against hydrolysis of AIN due to the formation of a phosphate-based protection layer on the particles' surface, and, although it keeps the pH of the suspension below 4. it does not guarantee a good dispersion. The individual adsorption of the anionic surfactant at the surface of AIN particles did not completely suppress the hydrolysis but it did enhance the degree of dispersion. A proper combination of the two types of surface-active agents enabled the preparation of AIN aqueous suspensions of relatively low viscosity and high AIN concentration, which can be a good starting point for aqueous-based colloidal shaping techniques or for freeze granulation or spray drying to obtain suitable granulate powder characteristics for dry-pressing technologies. An adsorption mechanism of the surface-active agents onto the particles' surface is proposed and supported by NMR and FT-IR analyses. (C) 2003 Elsevier Science (USA). All rights reserved.