The invention relates to a method for preparing high-strength and high-
porosity ceramic by preparing an active
alumina precursor from inorganic aluminum salt, adding
ceramic fibers and
ceramic powder into the active
alumina precursor, and carrying out filtering, washing, molding and
sintering. Concretely, the method comprises the following steps of adding a dispersant and short ceramic fibers into an inorganic aluminum
salt solution, carrying out uniform dispersion, adding the dispersion liquid into a precipitating agent solution to obtain precipitates, adding ceramic
powder into the precipitates, carrying out filtering and washing to obtain the precursor, mixing the precursor and a binder to obtain a uniform mixture, carrying out molding and
drying to obtain a high-strength green blank, carrying out
machining such as turning according to demand, and carrying out two-step
sintering in
atmosphere, wherein in the two-step
sintering, the first sintering process comprises that
activated aluminum oxide in the ceramic blank is transformed into alpha-
alumina in reduction
atmosphere or
inert gas
atmosphere and simultaneously, the
organic matter is transformed into carbon, and the second sintering process comprises that the carbon is oxidized and volatilized in oxidation atmosphere so that the porous ceramic is obtained. Compared with the foamed ceramic which is prepared by the prior art and has a similar cost, the foamed ceramic prepared by the method has high ceramic strength and high
porosity.