中国古代制釉核心原料釉灰制备工艺的科学原理及釉用机理

Lime-ash is a special and the key material in ancient Chinese glaze, especially to the one which was produced in Jingdezhen has the most representativeness and influence. And even had the saying of "no ash, no glaze" in ancient China. Not only did lime-ash achieve the pomp of porcelain making in Jingdezhen Song, Yuan, Ming and Qing Dynasty, but also it has a complex, rigorous and a touch of “mysterious” preparation process. Therefore, the preparation process, technical principle and glaze mechanism research of the lime-ash has been being an important subject in the processing of exploring the “recipe” in Chinese ancient porcelain production by the Chinese and foreign researchers. The study will be take Jingdezhen lime-ash as the main research object, and systematically reveal and demonstrate the scientific significance and inner mechanism on the thrice simmer burned of lime-ash, the urinary retting and elutriation technique firstly by combining the experimental techniques with scientific analysis. At the same time, comparison researches on the performance parameters among the firewood ashes from different areas in ancient China will be taken in this study to search the reasons for selecting the wolf grass during Jingdezhen lime-ash preparation for a long time. In order to reveal the mechanism and scientific value in the glaze lime-ash, enrich and perfect our country basic glaze in theory, and then provide scientific materials for proven the earliest use time of lime-ash, the contrast analysis between introducing lime-ash and directly adding limestone and various firewood ashes into the glaze will be carried out by detecting the glaze composition, structure and color and other physicochemical property by the use of modern science and technology methods.

釉灰是我国古代独特的传统釉用核心原料，其中以景德镇生产的釉灰最具代表性和影响力，正所谓“无灰不成釉”。它不仅成就了景德镇宋元明清的制瓷盛况，而且拥有复杂、严谨且带有一丝“神秘”色彩的制备工艺。因此，其制备过程、工艺原理、釉用机理长期以来一直是中外研究者探究我国古代制瓷“秘诀”的一个重要课题。研究将以景德镇釉灰为主要研究对象，采用工艺实验和科学分析相结合的方法，首次科学、系统地揭示和论证釉灰三次煨烧，及尿沤、淘洗的科学意义和内在机理。同时，对比我国古代不同地区常用柴草灰的性能参数，研究探明景德镇釉灰制备长期以来独选狼萁草的原因。对比分析釉灰与直接添加石灰石和各类柴草灰入釉所产生效果的差异性，并采用现代科技方法检测分析釉的组成、结构和呈色等理化性能，以期揭示釉灰在釉中的作用机理和科学价值，丰富和完善我国瓷釉基础理论，进而为探明釉灰的最早使用时间提供科学素材。

本课题以景德镇传统釉灰制备工艺为研究对象，在调查研究和工艺实验的基础之上，借助能量色散X荧光光谱分析、差热热重分析、X射线衍射分析、高温显微镜、色差计、数字粘度计、扫描电子显微镜等现代测试分析技术，对比分析不同制备工艺所得灰料的组成和釉用性能差异，初步揭示了景德镇传统釉灰制备工艺的原料选择、加工方法的科学原理。. 课题从化学组成、烧失实验和差热热重分析等角度，综合对比分析了狼萁草和稻草、竹子、芦苇、松木、木杮炼灰，及黝黑色石灰石与普通的灰色石灰石之间的差异，研究发现，狼萁草灰相对于其它五种柴草灰，具有高铁高锰的特征，有助于釉色呈现“白里泛青”、“颜如玉”的质感；熔融区间大，性状稳定；TG-DTA图谱显示狼萁草灰在368.7°C和397.1°C有两个放热峰，燃烧分解释放的热量大，能均匀持久地释放CO2；黝黑色石灰石出灰率高，组成更纯，更适合烧炼釉灰。. 对釉灰煨烧和尿沤等工艺环节所制备的样品进行测试、工艺模拟实验和分析讨论，结果表明：（1）煨烧和尿沤的主要作用：使熟石灰碳酸盐化，增加CaCO3含量，并向釉灰中引入K2O、P2O5、MnO、Fe2O3等物质；有利于釉灰粉料颗粒的细化和提纯，增强粉料的化学组成稳定性，改善粉体配釉性能；煨烧次数和尿沤时间与釉浆性能、釉面效果、胎釉结合性成正比，减少釉面缺陷；减小釉灰颗粒，增大了灰釉熔融区间，使釉更易烧成。（2）煨烧的科学机理：狼萁草低温分解放出大量的热和CO2，CO2与Ca(OH)2反应生成CaCO3，CaCO3易悬浮，增加釉浆的悬浮性。（3）尿沤的科学机理：尿液陈腐，有机质分解催生大量微生物，微生物新陈代谢产生的有机酸和CO2与Ca(OH)2发生化学反应生成CaCO3，尿液中的尿素和无机酸也参与到Ca(OH)2的碳酸盐化反应中，减少施釉造成的破损和釉面干燥开裂现象。