ALUMINA PORCELAIN WITH IMPROVED THERMAL PROPERTIES AND PROCEDURE OF ITS MANUFACTURE

The subject of the invention is alumina porcelain and a procedure of its manufacture. Alumina porcelain according to the invention belongs to the group of alkali alumosilicate porcelains with low thermal dilatation coefficient and contains from 58 to 62 wt.% aluminium oxide, from 0.1 to 0.3 wt.% sodium oxide, from 1.5 to 2.5 wt.% potassium oxide and from 1.0 to 1.4 wt.% lithium oxide. The iron oxide content in the material is less than 0.5 wt.%. After sintering in the temperature range from 1290 to 1330 degrees Celsius, ceramic material is thermally treated at a temperature between 900 and 1050 degrees Celsius in the period of 10 to 240 minutes. Ceramic material with the said composition and sintered and thermally treated according to the procedure described shows a thermal dilatation coefficient from 4.6 to 5.2 x 10 exp6/K within the temperature range from 20 to 600 degrees Celsius, a flexural strength higher than 160 MPa and contains minerals such as corundum, mullite and lithium alumosilicate. Predmet izuma je glinični porcelan in postopek njegove izdelave Glinični porcelan po izumu spadav skupino alkalijskih alumosilikatnih porcelanov z nizkim toplotnim razteznostnim koeficientom in vsebuje od do ut aluminijevega oksida od do ut natrijevega oksida od dout kalijevega oksida ter do ut litijevega oksida Vsebnost železovega oksida v materialu je nižja kot ut Po sintranju v temperaturnem območju od do stopinj celzija se keramični material toplotno obdela na temperaturi od do stopinj celzija v času trajanja od do minut Keramični material z navedeno sestavo ter sintran in termično obdelan po opisanem postopku ima toplotni razteznostni koeficient do x exp K v temperaturnem območju od do stopinj celzija upogibno trdnost višjo kot MPa ter vsebuje minerale korund mulitin litijev alumosilikat