A method of studying the dielectric properties of periclase

Abstract

A comparison of the density of sintered alumina specimens processed in the ball mill and planetary mill shows that the difference in the density is especially marked at low temperatures of firing, and is reduced with a rise in the firing temperature. An increase in the density of the blanks made from GLMK alumina as a result of planetary milling means an increase in the density of the specimens, after sintering at 1650~ from 98 to 9970.The density of the blanks made of calcined alumina pressed at 200 MPa is only 49.570; after processing in a planetary mill (specific surface 3.3 m2/g) it is increased to 57.570, which proves to be adequate for densilying the specimens made from this alumina to 99.570 after they have been sintered at 1650~The results obtained indicate that this form of alumina is much more active than GLMK, since even at the low density levels for the blanks it is sintered to a higher density.Thus, the use of finely dispersed alumina obtained by the calcination of finely dispersed aluminum hydroxide with additions of NH4C1 , H3BO3, and MgO, in, combination with processing in a planetary mill, enables us to obtain corundum ceramics with a density of 99.5~0 at a firing temperature of 1650~ At present the standard corundum ceramics produced industrially (density 99.570) from VK 100-1 material are usually fired at 1750~ [2]; therefore, the use of the technology examined above will permit us to extend the service of high-temperature furnaces and reduce the energy capacity of this process.