Effect of sintering atmosphere on microstructures and properties of synthesized microporous MgO refractory raw material

Abstract

Effects of sintering atmosphere on the microstructure and strength of magnesite were investigated using magnesite powder as raw material through X‐ray diffraction, scanning electron microscopy, mercury porosimetry measurement, and so on. The results showed that the sintering atmosphere strongly affected the sintering behavior of magnesite. The specimens sintered in the reducing atmosphere had more and finer micro‐sized pores inside the MgO particles compared with that in the oxidizing atmosphere at the same sintering temperature. Besides, MgO refractory raw material containing porous MgO microparticles with core–shell structure was obtained through the carbothermal reduction of MgO microparticles and subsequent oxidation of Mg vapor at the surface of MgO particles at 1500°C in the reducing atmosphere. At the reducing atmosphere and 1500°C, the microporous MgO refractory raw material with the core–shell structure of external dense and internal porous had an apparent porosity of 22.1% and a compressive strength of 51.6 MPa.

Microstructure and properties of microporous MgO–Al2O3 refractory aggregates from Mg(OH)2 and Al(OH)3

“…Compared with these methods, the in-situ decomposition synthesis method is suitable for the large-scale manufacture of microporous MgO-Al 2 O 3 refractory aggregates with a simple process and environment-friendly. [33][34][35][36][37] For example, microporous spinel aggregates were prepared with magnesite and Al(OH) 3 , which gained a bulk density of 1.40-1.48 g/cm 3 , an apparent porosity of 58.2%-60.4% and a median pore size of 6.8-10.0 μm. 38 However, due to the impurity of raw material magnesite, a small amount of liquid phase promoted the merging and growth of nanopores in the magnesite pseudomorph particles.…”