【作者】 宋贤良；

【导师】 温其标； 陈玲；

【作者基本信息】 华南理工大学 ， 食品科学， 2003， 博士

【摘要】 原位凝固成型技术是高性能陶瓷研究的热点之一。本文是以Al₂O₃陶瓷作为研究对象，利用淀粉及改性淀粉受热吸水膨胀及糊化后形成高分子凝胶化网络，以实现高性能陶瓷原位凝固成型。通过研究淀粉或改性淀粉用量、分散剂用量、固相体积分数和球磨时间等工艺参数对陶瓷浆料的流变学性质和成型坯体结构和性能的影响规律，并通过正交实验得到淀粉原位凝固胶态成型技术的最佳工艺条件。进一步考察了不同品种的淀粉和改性淀粉对Al₂O₃陶瓷原位凝固成型时浆料流变性质和成型坯体性能的影响，并在此基础上对淀粉-Al₂O₃陶瓷浆料凝固成型机理进行初步探讨。 通过对淀粉及改性淀粉凝胶化性质的研究表明：淀粉品种及改性方式不同，则糊化温度、糊粘度、糊的热稳定性以及形成凝胶的能力等凝胶化性质具有很大差异。淀粉糊粘度还受浓度、温度、pH值和分散剂等因素的影响。淀粉及改性淀粉凝胶化性质的研究是将其成功地应用于高性能陶瓷原位凝固成型的基础和前提，也是深入探讨淀粉及改性淀粉对成型后坯体性能影响规律的基本依据，其中淀粉糊化温度是决定Al₂O₃陶瓷浆料凝固成型温度的关键。 陶瓷浆料分散性和稳定性的研究，获得了由不同粒度的α-Al₂O₃粉体制备高分散、高稳定、高固相含量的陶瓷浆料所需的最适条件。研究表明：平均粒径分别为2.47μm、0.63μm和0.15μm的Al₂O₃粉体得到稳定浆料的最适pH值范围分别是8.5～9.5、8.0～9.0、10.0～12.0；分散剂最佳用量分别是0.03～0.05％、0.2％和0.5％。 陶瓷浆料流变学性质的研究是实现各种复杂形状陶瓷部件的成功注模，获得高性能陶瓷产品的有力保障。Al₂O₃浆料的粘度随醋酸酯淀粉用量和固相体积分数的增加而增加，而分散剂用量和球磨时间的变化对浆料表观粘度的影响规律如下：当分散剂用量为0.05％，球磨时间为12h时，可获得低粘的浆料，大于或小于该条件，Al₂O₃浆料的表观粘度都呈上升趋势。淀粉及改性淀粉对Al₂O₃浆料的流变性质也有显著影响，一般支叉结构多的淀粉比支叉结构少的淀粉影响大；改性淀粉对浆料粘度的影响要比原淀粉的大。特别是氧化淀粉和磷酸酯淀粉添加到Al₂O₃浆料后使其粘度增加，流变性能恶化。但球磨一段时间后，浆料的流变性能又得到明显改善。淀粉—Al₂O₃陶瓷浆料一般为塑性流体，具有剪切稀化的流变行为。 醋酸酯淀粉用量、分散剂用量、固相体积分数和球磨时间等工艺参数的对成型后坯体性能的影响研究表明：增加醋酸酯淀粉用量，干燥后素坯的线收缩率和相对密度下降，而干坯强度呈近线性增加：醋酸酯淀粉用量较低时，成型的坯体致密，断口细腻、平整，气孔较小。随固相体积分数的增加，素坯的线收缩率和干坯强度更多还原

【Abstract】 The in-situ consolidation forming technology is one of the hotspots of the research on high performance ceramics. To achieve in-situ consolidation forming of Al₂O₃ ceramics, the gelling network formed by swelling and gelatinization of starches or modified starches in heat uptake was used in this paper. The optimal technological parameters were achieved after the investigation on the effects of technological parameters, such as starches or modified starches content, dispersant content, solid volume loading, time of ball milling, etc. on the rheological behavior of ceramics slurry, the structure and character of formed green body, and by orthogonal experiments. The consolidation forming mechanism of alumina slurry containing starch was further studied based on the investigation of the effects of different kinds of starches or modified starches on the rheological behavior of alumina slurry and capability of formed bodies.The gelatination properties of starches or modified starches, including gelatinized temperature, viscosity and thermal stability of paste, and the ability of gel formation, etc. are greatly influenced by species of starch and modified methods. Some factors, such as concentration, temperature, pH value and dispersant, obviously affect the viscosity of starches or modified starches paste. The research of gelling properties provides a foundation that aim to the application of starch or modified starch in the in-situ consolidation forming of high performance ceramics, and will also probe further into the effect of starches and modified starches on the capability of formed bodies. Thereinto, gelatinized temperature of starch is the key factor which decides the consolidation formed temperature of alumina slurries.By researching on the dispersibility and stability of ceramics slurry, the optimal condition for the preparation of ceramics slurry with high dispersion, high stabilization and high solid volume loading by using alumina powder with different average particle size, is obtained. The result shows that the optimal pH ranges are 8.5⁹.5, 8.0⁹.0 and 10.0¹2.0 for average particle size of 2.47μm, 0.63μm and 0.15μm respectively. And the corresponding optimal dosages of dispersant are 0.03⁰.05%, 0.2% and 0.5% respectively.The research on rheological behavior of ceramic slurries is the base of successively casting for different shape ceramics parts and obtaining high performance ceramic products. The apparent viscosity of alumina slurries increases with the increment of acetate starch content and solid volume loading. The更多还原