Green ceramic compacts

FIGURE 23.9 Schematic illustrating the drain-casting process, (a) Fill the mold with slip the mold extracts liquid, forming a compact along the mold walls (b) after excess slip is drained and after partially dryed, green ceramic is removed. 

Ceramic characterization 30-32 range from a process as simple as determining the bulk density of a green powder compact from its mass and dimensions, to a process as complicated as identifying the composition and structure of a submicron size crystal in a dense ceramic matrix using analytical electron microscopy (AEM). Some of the important characteristics evaluated during ceramic consolidation are outlined in Figure 5.2. 

The mercury porosimetry results presented in Figure 5.6 illustrate the influence of particle size and size distribution on the size and size distribution of the porosity in green ceramic filled glass (CFG) composites consisting of 65 vol % of 0.4—1.5-)lm median particle size alumina and 35% borosilicate glass. The porosimetry results reveal that a relatively broad size distribution of pores exist within the green powder compacts and that pore size distribution and mean pore radius decreases with the substitution of fine alumina for the coarse in the CFG composites. The mean equivalent cylindrical pore radius, r, and surface-volume mean equivalent spherical particle radius, of a powder compact consisting of >l- J,m particles are proportional to one another and related by the fractional porosity, e, of the powder compact by... 

As in a green ceramic body, important chemical characteristics of a powder compact during and after sintering include bulk chemical composition, chemical homogeneity, and the compositions and concentrations of impurities or undesired phases. Composition can be characterized by ICP, XRD, and XRF. ... 

CLA 70] CLAUSSEN N. and JAHN J., Green strength of metal and ceramic compacts as determined by the indirect tensile test . Powder Metall. Inter., vol. 2, no. 3, p. 87-91, 1970. 

The welded Rh stack was welded to a cover plate and inserted into a ceramic holder, made of a special shrinkage-free material that can be machined as green compact [3]. The ceramic holder prevents heat losses from the metallic stack. 

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