Machining Channels on Mesoscale Ceramic Components

Abstract

Compaction of ceramic powder, partial sintering, machining, sintering of the ceramic compact, and finally joining are used to form functional channels on mesoscale ceramic components. This paper reports on a new simple machining technique that has been developed to introduce channels. Because no binder phase is used and the partially sintered powder is readily machinable, this technique is easier and more cost effective than green and white machining. However, the applicability of this technique is limited to samples with small length-to-diameter ratio because a uniform density in the ceramic compact must be attained to eliminate the warpage caused by the density gradient. A small bench-top CNC mill is used to fabricate complex surface channels on flat surfaces of partially sintered alumina and zirconia compacts. Machining parameters such as feed rate and revolution per minute (rpm) and ceramic processing parameters such as the pre-sintering temperature have been varied to determine the ideal conditions under which partially sintered ceramics can be readily machinable without any damage (chipping). The machined specimens are then sintered to produce dense ceramic specimens, which are then joined to form complex channels.