【作者】 缪大梅；

【导师】 周竹发；

【作者基本信息】 苏州大学 ， 材料学， 2006， 硕士

【摘要】 随着现代科学技术的发展和高性能结构陶瓷材料在各行业的广泛应用,对陶瓷材料的可靠性及可控制性提出了更高的要求,这对现有陶瓷成型工艺提出了挑战。本文在综述现有成型方法的基础上,比较其在工艺上对材料性能的影响,选择一种新型的成型工艺-凝胶注模成型作为本课题研究的对象,其原理为在高固相含量的陶瓷浆料中加入可聚合有机单体及交联剂,在引发剂和催化剂的作用下,引发单体聚合使陶瓷浆料原位成型。运用该原理,本文制备出高固相体积含量的氧化铝坯体。制得坯体强度高,收缩变形小,组织结构均匀,具有良好的可加工性。本课题主要研究了如何制得高固相体积含量的流动性能良好的浆料,讨论了固相含量、分散剂、pH及球磨时间等对浆料流动性能的影响,研究得出浆料中固相含量为55Vol%时,以聚丙烯酸胺为分散剂,在pH=9时,可获得100mPa·s的低粘度浓悬浮液。本文还进行了浆料固化、干燥及脱胶工艺的研究。从聚合反应角度探讨了凝胶固化原理为单体自由基聚合,分析了单体、引发剂、催化剂等因素对聚合反应速率及聚合物分子量的影响,并用红外光谱对聚合物结构进行了表征。实验结果表明:反应受引发剂和催化剂的影响显著,浆料中引发剂(浓度为10wt%)体积含量为0.4%～0.6%、催化剂体积含量为0.04%～0.5%时,开始凝胶化时间可控制在5～30分钟,保证了浆料在浇注前有一定流动性而不会很快固化。本文还分析了坯体干燥和脱胶过程中,水分和有机物的失去过程,通过控制加热温度和时间,缩短了工艺周期;通过加入聚丙稀酰胺抑制表面氧阻聚,克服了坯体表面易起皮的问题。本研究使用SEM等技术对坯体的显微结构进行了表征,测定了坯体的收缩变形、抗弯强度及硬度,并分析了影响其性能的因素和机理。实验结果和显微结构分析表明:高固相含量浆料可浇注各种复杂器件,所得坯体强度高(25MPa)、组织结构均匀,更多还原

【Abstract】 The forming process of gel-casting of alumina was provided, wherein, slurry of ceramic powder in good dispersion was casted in a mould with the organic system,which could be caused the polymerization and made the slurry in-situ formation. This process can promise the uniformity of the powder dispersion and improve the reliability of ceramic materials,which also gave the green body in high strength and little shrinkage for machining process. Further, the process is optimized by decreasing the amount of organic substances so that a large amount of time was saving for giving away the organics.For the requirement of in-situ forming and machining process, the solid content of slurry more than 50 %( by volume) is needed. Otherwise, the critical point is to obtain thick suspension in good fluidity. The effect of solid content,dispersant,pH and the ball milling time to the fluidity were discussed in the present thesis. The study showed that alumina slurry of 55%( by volume) in solid content with viscosity 100mPa.s was obtained by adding the dispersant of ammonium poly-acrylate with pH9, which gave the green body with good performance by casting, for example, the three point bending strength was more than 20MPa and the linear shrinkage was less than 2%. By scanning on the broken surface,the SEM picture showed that the inner of the green body was well dispersed without co-aggregation. The effects of catalyst, initiator and temperature on the gelation time were also discussed in the present study. The experiment showed after adding catalyst with 0.04%～0.5%(by volume) and initiator 0.4%～0.6%( by volume), there was 5～30 min remained for slurry casting without gelation. The study also included the process of dryness and degumming, discussing how to reduce time and remove shortage.The present study also included the effect of variable solid content on the performance of the green body and the structure, it showed that high solid content (>50Vol %) was prior to control the microstructure of the green body and less shrinkage which has well uniformity and high consistency for application. Machining test showed adding lubricant更多还原