Advanced Ceramic Processing and Future Development Trends
Design of Mono-disperse Ceramic Powders
Many of the current limitations to the performance of ceramics in high–technology areas are a direct consequence of non-optimum physico-chemical properties of the powders used in their fabrication. The average particle size, particle size distribution, degree of agglomeration, and dispersion characteristics of the precursor powders combine to limit the macroscopic homogeneity of the ceramics in the green and final sintered states. The microstructural homogeneity of the ceramics can be optimized by processing powders with tightly controlled characteristics. Mono-disperse metal oxide powders derived from sol–gel processes are prime examples of these materials. Such powders offer many processing advantages over conventional ceramic powders, since their spherical shape and narrow particle size distribution allow for a tight control over the packing density of the powder particles in the green ceramic. Since there are very few agglomerates, the particles pack very uniformly, with residual pore sizes in the green ceramic often being on the order of just two particle diameters – that is, less than 1 ?m.
Nano-sized Ceramic Powders
Today, the research into, and manufacture and applications of, nano-sized ceramics powders are emerging as one of the fastest growing segments of the ceramics industry. Nanoparticles are defined as particles having at least one dimension less than 100 nm, whereby in the case of platelet (nano-platelets) or rod - like (nanowires) morphologies one dimension may be as small as 1 nm, corresponding to roughly four or five bonded atoms.
المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .
الرجوع الى لوحة التحكم
|