Die for Hot Pressing of Ferrites
Original Publication Date: 1984-Mar-01
Included in the Prior Art Database: 2005-Feb-02
The silicon carbide (SiC) die 5 and punch 6, 7 arrangement is shown in the figure as used to hot-press MnZn ferrite. The hot-pressing of ferrites in a SiC die requires a protective barrier between the ferrite and the SiC to prevent a reaction therebetween which occurs at temperatures greater than 1100ŒC. This is done using a fused oxide grain barrier layer, such as Al2O3 or ZrO2 . However, the thermal expansion of the fused grain must be close to that of the ferrite, or cracking of the ferrite will take place on cooling. Fused Al2O3 grain, which is readily available, is most closely matched to the expansion of the particular ferrite being produced. There is a 0.100" clearance between the I.D.