Ceramics-Silikáty 31, (3) 219 - 226 (1987)

Periklasospinelové žiaruvzdorné stavivá zhotovené zo slinutej magnézie a spinelu propraveného slinovaním výtvorkouv zo zmesi MgO a Al₂O₃ sa vyznačujú odolnosťou proti náhlym zmenám teplôt pri obsahu MgAl₂O₄ 10 až 30 %. Mikrotrhliny a ich zárodky utvorené počas výpalu výliskov ako dôsledok rozdielnych fyzikálnych vlastností obidvoch komponentov znižují modul pužnosti a sú zdrojom relaxácie termických napätí. S obsahom spinelu klesá tepelná vodivosť pri nízkych teplotách a klesá teplotná rozťažnosť. Prídavok do 5 % chrómovej rudy zvyšuje výrazne vysokoteplotné pevnosti a eliminuje mikromedzery.

Periclase-spinel refractory bricks made from sintered magnesia and co-clinker, prepared by sintering of compacts from MgO and Al₂O₃ in proportion near to the composition of MgAl₂O₄ are the actual material for lining of sintering and transition zones of the furnaces used in the cement works. Microcracks or their germs formed during the firing of compacts as the result of different properties of both components reduce the modulus of elasticity and they are the source of thermal stress relaxation and the cause of thermal shock resistance especially at the content 10 - 30 % of MgAl₂O₄. Temperatures of the start of rapid relaxation of introduced stresses and unstoppable decrease of the modulus of elasticity are identical or closely resembling. 5 % addition of chrome ore in the form of matrix to the shaping mixtures causes the significant increase of high-temperature strenghts, of their ratio to the modulus of elasticity, decrease of creep, increase of volume stability at temperatures to 1750 °C owing to an interaction of spinels with different structural arrangment.