The invention provides
alumina ceramics and a manufacturing method of the
alumina ceramics. The main materials of the
alumina ceramics are as follows: alumina micro mist or a superfine alumina micro mist which is formed by Gamma alumina and an Alpha alumina with an particle
diameter of between zero point one to three point five micron and a purity of ninety-nine point nine percent or more than ninety-nine point nine percent according to certain proportion. One or a mixture of a small quantity of magnesia, yttria, lanthana, thulia and
yttria stabilized zirconia is added into the micro mist as sinter accessory ingredient and is subject to
dry pressing, grouting and isostatic cool pressing after being even mixed evenly, thus ceram green pressing is obtained. Only a little organic addition agent is needed to be added. After
drying, the green pressing body does not need to be roasted and can be directly introduced to an ordinary high temperature si-mo rod resistance furnace or a
continuous type si-mo rod electrothermal
tunnel kiln to be sintered for one to three hours at a temperature below one thousand six hundred and seventy Celsius
system. Therefore, the alumina ceramics can be obtained with high tightness,
mechanical property and good
dielectric property and with a nonconventional structure and a placode the size of which is zero point two to two hundred
millimeter and a purity of ninety nine to ninety-nine point nine percent.