China's Refractories

Abstract: Gaseous phases of carbon-containing and metastable oxides will be resulted from the carbonization of phenolic resin binders and the reduced reactions between C and oxides at high temperatures in carbon-containing refractories. With the in-situ catalysis technique, these gaseous phases can be transformed to one- or two-dimensional bonding phases by deposition, which is favorable for the improvement on strength and toughness of carbon-containing refractories, especially low carbon refractories. The research results reveal that: (1) the amorphous carbon resulted from phenolic resin can be transformed to carbon nanotubes, thus, the oxidation peak temperature is raised from 506 to 664.6 ℃; (2) one-dimensional whiskers of MgO or MgAl2O4 can be in-situ formed in MgO-C refractories, and their CMOR, CCS, rupture displacement and residual CCS (two water quenching cycles, 1 100 ℃) are increased by 66%, 47%, 13% and 26%, respectively; (3) two-dimensional array structure of flake β-SiAlON can be in-situ formed in Al2O3-C refractories, which improves the material strength by 60% and decreases the residual strength after thermal shock by only 4.5 MPa. It is believed that the in-situ formation of one- or two-dimensional bonding phases at high temperatures can improve the comprehensive thermal physical properties of carbon-containing refractories, and will be the developing trend of the strengthening and toughening of low carbon-containing refractories.

Key words: carbon-containing refractories, bonding phase, one-dimensional, two-dimensional, array structure