Phosphate chemical binder as an anti-hydration additive for Al2O33MgO refractory castables

Reasons for crack propagation and strength loss in refractory castables based on changes in their chemical compositions and micromorphologies with heating: special focus on the large blocks

“…It should be noted in connection with mechanical strength that, as reported by some authors [34][35][36][37], castables containing finer magnesia (<45 μm) present better performance for all evaluated temperatures, than those containing coarser magnesia (<100 μm). Many refractory producers consider it as a major challenge to add fine magnesia particles to castables due to the major drawbacks related to the hydration of this component.…”

“…particle size, specific surface area, purity, CaO/SiO 2 ratio, production route, magnesite calcination temperature, etc. ); (2) the pH and temperature of the liquid medium; and (3) the interaction of magnesia with other castables' raw materials (such as silica fume, CAC, or HA) as well as the use of various other additives [3,36].…”

“…Among the best-described MAHT, microsilica (silica fume) is an especially good choice because it prevents cracking or strength loss by magnesia-containing castables after curing or drying. Additionally, this additive is the most popular due to its low cost and binder content control characteristics [3,36].…”

A systemic investigation on the hydroxylation behavior of caustic magnesia and magnesia sinter

“…Alternatively, to prevent hydroxylation, several studies have proposed antihydroxylation (or anti-hydration) additives particularly useful to refractory castables. In general, they reduce the dissolution rate or inhibit further Mg(OH) 2 precipitation by forming an insoluble coating on the surface of the MgO particles [14,15,31,35,36,38,44].…”

“…Depending on the application aimed at, MgO hydroxylation can be either valuable or undesired and, in both cases, the knowledge of how this process occurs can be highly useful. The hydroxylation process must be efficient for the production of fertilizers [1,18], animal and human nutrition [1,27], watertreatment input [1,28], medicaments [1,27,28], fast-hardening Sorel and MgO-based cements [1,[29][30][31] and anti-flame agents for polymer composites [32][33][34] and generates particles of controllable size distribution, specific surface area and shape at competitive costs. On the other hand, it must be avoided or at least minimized in applications to refractory [10,13,14,16,[35][36][37][38][39][40] and abrasive [1] materials and optic and electronic devices.…”