Authors:
Prof. Amirabbas Nourbakhsh | Arvin Dirgodaz Vijeh Co/Azad University | Islamic Republic of Iran
Dr. Najmeh Lotfian | Arvin Dirgodaz Vijeh Co | Islamic Republic of Iran
Dr. Mozhdeh Malekpour | Azad University | Islamic Republic of Iran
Mahsa Masoud | Azad University | Islamic Republic of Iran
Elham Rahimi | Mehr godaz Refractories Co | Islamic Republic of Iran
Amir Hossein Nourbakhsh | Arvin Dirgodaz Vijeh Co | Islamic Republic of Iran
Prof. Farhad Golestani-fard | Iran university of Science and Technology | Islamic Republic of Iran
This work addresses a novel approach to improve the dispersion of nano MgCr2O4 and MWCNT-alumina nanocomposite additives by functionalizing the nano particles by silanol groups in the Mag-chrome and Alumina-C refractories respectively. In this way, surface of nano additives have been modified with 3-Aminopropyl triethoxysilane (APTES). Then, 1% wt of nano additives (with and without functionalizing by silanol group) were added to matrix and pressed under 150MPa uniaxial press. Mag-chrome and Alumina-C refractories were fired at temperature between 1400 and 1600 ℃, and 1450℃ under reduced atmosphere, respectively. The presence of the silanol groups on the nano additives was approved by XRD, FTIR, zeta potential measurements, UV-visible spectroscopy, Dynamic Light Scattering, and TEM. The physical and mechanical properties, such as permanent linear changes, bulk density, apparent porosity, cold crushing strength, and hot modulus of rupture were determined according to DIN standards. Results indicated that the surface modification and well distributed nano additives through the matrix of refractories not only promoted the secondary spinel phase formation in Mag-Chrome refractories, but also increased SiC formation in Alumina-C refractories. The mentioned phase formation caused the increase in CCS (from 67.4 MPa to 81.5 MPa) and HMOR (from 5.4 MPa to 6 MPa) of Mag-chrome samples due to higher secondary spinel formation; also, it reduced 200℃ of sintering temperature. The spinel formation would increase the CCS (from 137 MPa to 156 MPa), and HMOR (from 6 to 7.5 MPa ) of alumina-C refractories due to promotion of higher SiC whiskers formation through the matrix.