OXIDE CERAMICS CHARACTERIZED BY ELEVATED STRENGTH.

摘要

The present invention relates to the high-temperature dense mullite-corundum-ZrO2 oxide ceramic materials obtained at elevated (above 600oC). Due to their high melting/decomposition temperature (at about 1550oC) they are long-time exploitable at temperatures equal or above 1000oC maintaining shape stability and characteristic parameters of properties. Dominant are strength ratio (pressure and flexural strength, elastic modulus) as well as chemical and thermal resistance. High parameter of hardness and wear resistance broadens their application at room temperature. Described ceramics could be obtained from mixed composition powder with 50-450 nanometer particle size dispersion. Powders consist of (in weight %): (gamma)A2O3 - 56,47 to 63,05; amorphous SiO2 - 22,25 to 27,10; ZrO2(monoclinic) - 3,60 to 3,45; Y2O3 - 3,39 to 3,60; illite-clay - 0,5 to 8,57 and La2O3 - 4,60 to 0,40. The offered mixture of raw materials guarantees formation of dense ceramics at temperature range from 1200 to 1400 centigrade, using spark plasma sintering method in 3-6 Pa vacuum and temperature raising rate 100 centigrade per minute up to maximum temperature. The ceramics obtained in such way (sintering at 1200 centigrade) possesses pressure strength 270 to 372 MPa as well as long-term temperatures resistance up to 1200 centigrade. The hardness of obtained ceramics is between 9 and 10 in accordance with Mohs’ hardness scale (it is approaching to hardness of diamond).