微波能、有机粘合剂对蜂窝陶瓷快速稳定干燥的影响

本文介绍了蜂窝陶瓷体在干燥过程中,有机粘合剂在微波场的作用下,产生凝固、收缩,并且在蜂窝陶瓷体内形成网络结构,使蜂窝陶瓷体内部存在的应力和缺陷得到分散和固定,从而达到稳定干燥的目的;蜂窝陶瓷体自身吸收微波能产生热量,其热量流动方向与水份迁移的方向一致,为快速稳定干燥提供了重要条件;以及在负载量、材料性质一定的情况下,蜂窝陶瓷体的壁厚是影响其干燥速度的重要因素,而与蜂窝陶瓷体的形状、尺寸没有很大关系。     

新型蜂窝陶瓷的研制

开发适用于高效换热器用的蓄热体——对新型蜂窝陶瓷的结构、原料选用、成形方法以及干燥烧结进行了系统研究，使蜂窝陶瓷的抗热震性等性能大大提高，确定了一套合理的生产蜂窝陶瓷的工艺制度，并且使其能够满足生产实际需要。     

微波干燥在陶瓷行业的应用

对微波干燥的原理、特点及相关设备组成进行了简单介绍,着重评述了微波干燥技术在建筑陶瓷、日用陶瓷、卫生陶瓷、蜂窝陶瓷及结构功能陶瓷粉体中的应用研究,并展望了微波干燥技术在陶瓷行业的应用前景。     

微波辅助干燥技术的应用进展

微波辅助干燥是一种比微波干燥更有优势、应用前景更广阔的干燥技术,它结合了微波干燥和传统干燥技术的诸多优点。主要阐述了微波辅助干燥的原理、特点以及在国内外的研究和应用现状,同时对该技术在陶瓷坯体干燥过程中的应用进行了分析。     

微波干燥技术及其在陶瓷坯体干燥中的应用研究

阐述了微波干燥的基本原理、理论及其特点，同时分析了微波应用于陶瓷坯体干燥的几个技术问题；也对其在国内外陶瓷材料干燥中的应用进行了研究分析。     

微波辅助干燥技术的应用进展

微波辅助干燥是一种比微波干燥更有优势、应用前景更广的干燥技术，它结合了微波干燥和传统干燥技术的优点。本文主要阐述了微波辅助干燥的原理、特点以及在国内外的研究和应用现状。同时对该技术在陶瓷坯体干燥中的应用进行了分析。     

陶瓷工业干燥技术和设备

本文分析了陶瓷干燥过程的基本原理、干燥的种类、各瓷种所用干燥器分类以及微波干燥技术的先进性。     

陶瓷坯体干燥的新方法—微波干燥

本文对比分析了微波干燥法和传统干燥方法的干燥特性,介绍了陶瓷坯体在微波干燥室内的干燥过程与优化的微波干燥工艺参数。     

微波干燥技术在陶瓷行业中的应用

本文结合陶瓷坯体的组成及形状要求,分析了利用微波干燥技术干燥陶瓷坯体的原理和特点,并阐述了微波干燥设备的选择及干燥过程中应注意的事项。     

微波干燥过程中功率密度对多孔陶瓷干燥品质的影响及应用研究

本文主要针对具有三维网络结构的多孔陶瓷在制备过程中挂浆后,采用微波干燥工艺,通过控制微波功率密度,对比分析了不同微波功率密度干燥后产品含水率及对产品性能的影响.结果表明,微波功率密度越高,产品最终含水率越低,但是产品的性能降低,当功率密度超过26W/g时,产品干燥后显微镜下可见明显裂纹,当功率密度低于26W/g时,产品...     

R&D OPPORTUNITES IN DRYING OF ADVANCED ELECTRO-CERAMICS

ABSTRACT

This article presents an inaoduction to the various drying processes operational in the ceramic processing industry, with special emphasis on electro ceramics. An attempt is made to arouse the interest of drying specialists in fields other than ceramics to participate in a concentrated group effort to solve a number of existing problems related to ceramics drying. The importance of materials education is highlighted by referring to a few examples depicting the effect of the drying process on the final product quality. It is argued that with more research, conventional processes like spray drying, rotary drum drying, etc. can be improved or replaced with alternative processes like freeze drying, microwave drying, infrared drying and vibrated fluidized bed drying.     

陶瓷坯体不同干燥方式的对比研究

分别采用普通热风、远红外和微波干燥方式对陶瓷坯体的干燥过程进行实验研究,研究不同干燥方法对干燥速度、坯体内外温差的影响。结果表明,热空气干燥主要靠水分浓度差实现,内外温差较大;远红外线干燥的坯体内外温度均匀,恒速阶段的干燥速度是热风干燥恒速阶段速度的1.2倍;微波干燥主要靠温度差实现水分扩散,最大干燥速度可达4.26%/min(干基),约为热风干燥速度的12倍。将含水量为22wt%的陶瓷坯体干燥至恒重,普通电热干燥的运行成本最高,约为远红外干燥的1.5倍和微波干燥的4.2倍。分析了远红外干燥和微波干燥在陶瓷工业应用的可行性,指出了需要解决的技术难题。     

微波加热在毛条烘干中的应用研究

介绍了应用微波加热烘干毛条的基本原理,研究了微波干燥设备的烘干效率、节能效果及烘干效果,结果表明,微波加热可以应用于纺织印染行业,为微波加热在纺织印染行业的推广应用提供了研究基础。通过生产应用,在计算微波加热毛条烘干工艺参数时,微波烘干机的干燥效率可取1.1kg/kW﹒h,微波干燥后,毛条含水率均匀,颜色前后色差无变化,纤维的强度和手感得到改善,微波干燥节能效果,比射频烘干节能约20%。     

微波干燥卫生陶瓷的研究与设备开发

本文利用微波干燥法进行卫生陶瓷坯体干燥试验,探究微波可以实现对卫生陶瓷快速干燥的原因。在此基础上,对围绕着微波设备大型化、连续化中面临的关键技术及微波干燥电耗相对较高等技术进行攻关,开发了卫生陶瓷微波干燥辊道窑,并在实际工厂使用。结果表明:微波干燥过程实现了沿坯体纵向与沿坯体局部区域横向的均匀干燥及微波干燥能显著提高干燥的内扩散速率,最终实现对卫生陶瓷的快速干燥;采用微波、热风耦合加热技术能显著降低微波干燥电耗;开发的卫生陶瓷微波干燥辊道窑,可极大缩短干燥周期,降低场地占地面积,提高干燥合格率。     

A heuristic approach to the automated analysis of drying curves

In the context of ceramics production, the purpose of drying is to remove water from a ceramic body after forming. Drying should be performed at an appropriate rate, at an acceptable cost, and in such a way as not to damage the ceramic body. Although the determination of the best drying conditions is critical to ceramics production, the experimental determination of drying parameters, particularly of the critical moisture content, use to be very subjective. In this work, we propose an empirical mathematical expression, based on the generalized logistic model, which is capable of describing the complete drying curve. The critical moisture is thus unambiguously obtained as the intersection point of two straight lines derived from the mathematical modeling of the full drying curve. The heuristic proposed in this work may find particular application in automated procedures, data acquisition, and analysis of drying curves of ceramic masses.     

CONDUCTIVE DRIlNG CHARACTERISTICS OF GELATINIZED RICE STARCH

ABSTRACT

The drying mechanism of shaped ceramics is reviewed and some methods for eliminating defects produced by drying are discussed in this report. The types of defects depend upon the shaping method, shape, properties of the raw materials, drying process and other items. Most defects of dried ceramics are produced during the initial or middle drying stage when large shrinkage of the ceramic body occurs. These defects may be successfully eliminated by heating the body from the inside. Self-deformation caused by weight is also a serious defect. The near net shaping of fine ceramics to reduce machining requires uniform body shrinkage and hence, highly controlled drying. Examples of electric current drying, dielectric drying, and dewaxing are also shown in this report.     

Colloidal processing: enabling complex shaped ceramics with unique multiscale structures

Colloidal processing of fine ceramic powders enables the production of complex shaped ceramics with unique micro and macro structures which are not possible to produce via conventional dry processing routes. Because of this enhanced structural control and shaping capabilities, colloidal processing has been exploited to produce ceramic components with ever increasing complexity and functionalities. In this review, we revisit some of the research efforts on this topic to highlight its relevance and growing importance for the advanced manufacturing of functional ceramics. Selected examples of colloidal systems with increasing level of complexity are discussed to showcase the wide range of structures that can be generated through wet processing approaches. The historical development and background knowledge pertaining to colloids and surface interactions is first briefly reviewed. The major colloidal shape forming and additive manufacturing processes that utilize colloidal pastes and inks are then reviewed, highlighting the control of suspension rheology needed in these techniques. Next, methodologies that combine suspended particles with a pore‐forming phase are discussed as a means to produce porous ceramic materials. Further control over the interactions between anisotropic particles and their alignment in suspensions can be gained via externally applied fields (such as magnetic) to produce texturally aligned green bodies. This leads to bioinspired ceramics that can programmably morph into complex shaped objects upon sintering. Hierarchical porous structures with high mechanical efficiency are also shown as an example of the multiscale designs that can be generated through advanced colloidal processing. As drying of ceramic bodies is an inevitable consequence of wet colloidal processing, the current understanding of this critical processing step is reviewed. Finally, the gaps in knowledge in these fields are discussed to provide our perspective on where the field may support advances in ceramics in the future.     

R&D OPPORTUNITES IN DRYING OF ADVANCED ELECTRO-CERAMICS

This article presents an inaoduction to the various drying processes operational in the ceramic processing industry, with special emphasis on electro ceramics. An attempt is made to arouse the interest of drying specialists in fields other than ceramics to participate in a concentrated group effort to solve a number of existing problems related to ceramics drying. The importance of materials education is highlighted by referring to a few examples depicting the effect of the drying process on the final product quality. It is argued that with more research, conventional processes like spray drying, rotary drum drying, etc. can be improved or replaced with alternative processes like freeze drying, microwave drying, infrared drying and vibrated fluidized bed drying.     

Microwave Freeze Drying of Apple Slices Based on the Dielectric Properties

Freeze drying (FD) yields the best quality of dried apple slices but requires a long drying time and is not cost-effective. To mitigate these problems, a microwave freeze drying (MFD) technique was developed to dry apple slices. The relationship between corona discharge and microwave power at various pressures and initial moisture content conditions was studied to avoid the possibility of corona discharge during MFD. It was found that with change of moisture content and temperature of samples during MFD, the dielectric property also changed, which resulted in dynamic microwave dissipation. Based on the dielectric property of samples, a changed microwave loading scheme can lead to perfect product quality and greatly reduce the drying time; thus, MFD can be used to replace the traditional FD technique.