ПОЛОЖИТЕЛЬНОЕ ВЛИЯНИЕ НАНОДОБАВОК НА ТЕРМОМЕХАНИЧЕСКИЕ СВОЙСТВА ОГНЕУПОРОВ Al2O3 – C И MgO – C

Abstract

Carbon bonded alumina and magnesia refractories with approximately 30 mass % and 10 mass % residual carbon after coking, respectively, are widely used in various sectors of steel production. Compositions with less residual carbon after coking based on nanoscaled magnesium aluminate spinel (MgAl 2 O 4 ), alumina ( α -Al 2 O 3 ) and carbon nanotubes (CNTs) either as single additives or combinations of them have been investigated according to their physical, machanical and thermo-mechanical properties. Regarding the Al 2 O 3 – C system, a combination of nanoscaled powders of carbon nanotubes and alumina nanosheets lead to superior thermal shock performance with approximately 30 % less residual carbon in comparison to commercial available functional components, after coking at the low temperature of 1000 °C. Moreover, this composition was functionalised due to the reaction between alumina nanosheets and CNTs, forming the Al 3 CON new phase and thus, off ering a chemical interconnecting phase for both carbon and alumina fi ller. The new refractory composite structure presented excellent thermo-mechanical properties in spite the lower carbon content, while the Al 3 CON phase was identifi ed with the aid of electron backscatter diff raction (EBSD) analyses on fracture surfaces of the coked samples. As for the MgO – C system, the best thermo-mechanical performance could be attained with the additions of nanoscaled magnesium aluminate spinel or alumina nanosheets, thus with the use of spinel containing or spinel forming nanoscaled additives. These two MgO – C compositions coked at 1000 °C were able to approach the thermo-mechanical performance of the reference composition, which had with 10 mass % the double amount of graphite. Ill. 15. Ref. 46. Tab. 6.