The Effect of Nano MgCr2O4 Functionalized By Silanol Group to Improve Physical and Mechanical Properties of Direct Bonded Mag- Chrome Refractories

In this research in order to disperse nano additives through the matrix of mag- chrome refractories, a novel approach by using the silanol surface group was reported. In this regard, the modified of nano MgCr2O4 particles have been done by functionalizing of MgCr2O4 by 3-(thriethoxsilyl)propyl amine (APTES) silanol group. Then 1% MgCr2O4 nano additives (with and without surface group) were added to mag- chrome matrix and pressed under a uniaxial press at 120 MPa pressure and then fired at 1600 ℃. XRD and TEM analysis were used to evaluate the synthesis of nano particles. FTIR and XRD analysis were carried out to investigate the presence of surface group of nano particles. Phase analysis and microstructure investigation have been done by XRD and SEM analysis.  The physical and mechanical properties, were determined according to the respective DIN standards. Also XRD and FTIR analysis confirmed the presence of functionalized groups on the surface of nano particles. DLS analysis of functionalize and not functionalized nanoparticles shows the the decrease of particle size in presence of silanol groups,  the UV analysis confirmed better dispersion of nano particles due to higher adsorption of functionalized nano particles.  XRD results of mag-chrome samples showed increasing of secondary spinel in presence of functionalized nano additives which could related to better dispersion of nano additives which caused to promote nucleation of spinel phases and result in solid state sintering and could effect on the physical and mechanical properties.