摘要
将PEG(聚乙二醇)溶液干燥法应用于BaTiO3半导瓷注凝成型坯体的干燥,由于PEG溶液可以和坯体的所有表面接触,因此可提供更均匀的干燥介质,从而减小在干燥过程中产生的应力.研究表明,注凝成型坯体在PEG溶液中干燥2～3h即可在无变形、无开裂等安全情况下失去(质量分数为)20%～30%的水分,完成大部分收缩,接着在室温空气中或加温干燥,不会引起坯体变形开裂,与传统的空气干燥法相比,大大提高了干燥效率.坯体干燥时间与固相体积分数、试样的厚薄、试样尺寸的纵横比等密切相关,若固相体积分数越低,试样越薄,则干燥速度越快;若减小圆柱体试样的纵横比,则水分扩散方式由径向往纵向转变.
Gel casting is useful method for forming articles of ceramic. Conventional drying generally comprises exposing a gel cast article to air under particular conditions of temperature and humidity. The drying time is long, moreover, non-uniform and differential drying in various regions due to the solvent gradient, induces structural and residual stresses, which cause defects and make the articles useless. Drying of gel cast parts of BaTiO_3-based semiconduting ceramics via the liquid desiccant method was studied. The results showed that the liquid desiccant provides a more uniform drying medium in comparison with conventional air by contacting with all of the surfaces of the article to be dried, deducing the tresses developed during drying. The parts lose safely about 20?%～30?% of interior water in very short time i.e. 2～3?h and most of the shrinkage associated with drying occurs. After the critical stage of drying process, the gel cast parts could continue drying in air at the room conditions or in an oven. Compared with conventional drying method, the liquid desiccant method can speed up the time required to dry an article to the point where shrinkage generally stops. The effects of factors such as loading level of ceramic powders, effective thickness and geometry of pats on the drying rate were studied. The lower solid content in the gel, and lower effective thickness of parts, increase the drying rate. When the aspect ratio in cylindrical parts decreased, the diffusion mechanism changed from radial to longitudinal direction.
出处
《华中科技大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2005年第7期50-53,共4页
Journal of Huazhong University of Science and Technology(Natural Science Edition)
基金
国家高技术研究发展计划资助项目(2001AA320504).
