Synthesis and characterization of dense MgO–TiO2 nanocomposites obtained by two novel processing routes

Abstract

The aim of the present manuscript is to obtain dense MgO refractories by means of two novel different routes: TiO2 nanoparticles in brucite (Mg(OH)2, R1) and TiO2 nanoparticles in caustic magnesia (MgO, R2). Therefore, contents of TiO2 nanoparticles were added at 1, 3, and 5 wt % to brucite and caustic magnesia while the reference sample consisted in 100 wt % MgO (R0), which was obtained from calcined brucite. The nanoparticles were mixed with the brucite in the first route (R1), and the mixtures were first calcined at 960 °C and then cold uniaxially pressed at 150 MPa and subsequently sintered at 1600 °C for 4 h. Also, TiO2 nanoparticles were mixed with the caustic magnesia in the second route (R2), and the mixtures were then cold uniaxially pressed and sintered at 1600 °C. Different techniques were considered to characterize the composites: Thermal Analysis, XRD, SEM, bulk density and porosity, and cold crushing strength (CCS). Results suggest that the route 1 produces MgO–TiO2 composites with greater densification rate (density is at least a 3.29% greater) and better mechanical properties (CCS is at least a 20% better) than the route 2. Therefore, starting from brucite (Mg(OH)2) to obtain MgO–TiO2 composites is a better alternative to produce a material with greater densification and better mechanical properties.