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Direct Measurement of Ceramic Particle Size in Slurries and Green Ceramic Sheets

IP.com Disclosure Number: IPCOM000041570D
Original Publication Date: 1984-Feb-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Herron, LW: AUTHOR [+2]

Abstract

The analysis of ceramic particle size can be readily determined using the Coulter Counter principle, where the particles are analyzed while suspended in an electrolyte (e.g., aqueous NaCl). The size of the particles are determined by a change in electrical potential as the particle passes through an orifice of known size. Since the potential is applied on both sides of the orifice, a voltage pulse occurs as the particle passes through this opening which is equivalent to the reduction in cross-sectional area of that opening. This technique is quite effective in measuring virgin particulate; however, when ceramic materials are dispersed in organic based slurries, difficulties are encountered. The organic binders must be removed by thermal degradation at temperatures in excess of 500ŒC.

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Direct Measurement of Ceramic Particle Size in Slurries and Green Ceramic Sheets

The analysis of ceramic particle size can be readily determined using the Coulter Counter principle, where the particles are analyzed while suspended in an electrolyte (e.g., aqueous NaCl). The size of the particles are determined by a change in electrical potential as the particle passes through an orifice of known size. Since the potential is applied on both sides of the orifice, a voltage pulse occurs as the particle passes through this opening which is equivalent to the reduction in cross-sectional area of that opening. This technique is quite effective in measuring virgin particulate; however, when ceramic materials are dispersed in organic based slurries, difficulties are encountered. The organic binders must be removed by thermal degradation at temperatures in excess of 500OEC. Above these temperatures certain materials, such as low melting temperature glasses, can fuse or sinter into larger particles or agglomerates, contributing to significant particle size error. When ceramic slurries and cast ceramic green sheets use polyvinylbutyral binders, these same problems are encountered. At the binder-ignition temperatures the glasses form hard agglomerates. This situation was solved using a special electrotype that dissolves the binder and permits complete dispersion of the particles while also having the proper conductance for particle size measurement using the Coulter principle...