Systemic analysis of MgO hydration effects on alumina–magnesia refractory castables

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

“…8e). Although this behavior has been described in the literature under comparable conditions [16,25,27,36,40,45], to the best of our knowledge, this is the first time such a fragmentation has been documented in situ by SEM.…”

“…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.…”

Mg(OH)2 Nucleation and Growth Parameters Applicable for the Development of MgO‐Based Refractory Castables

“…Therefore, a balance between the amount of formed magnesium hydroxide and the available room for expansion fitting must be considered during the design of engineered MgO-containing compositions. 5,6 Considering this, instead of inhibiting the MgO hydration, one may also consider the possibility of speeding up its formation when the consolidated structure still has some flexibility to accommodate the brucite crystal growth. [5][6][7][8][9][10][11] This can take place, for instance, before the castables' hardening.…”

“…The likelihood of developing binder-free Al 2 O 3 -MgO refractory castables, by mastering the magnesia hydration process, has already been suggested by some authors. 5,6 However, a better understanding is needed of the mechanisms involved and the available mathematical models that can be used to predict and describe this reaction rate under different conditions. The following sections highlight some of the main aspects presented in the scientific literature concerning the MgO hydration.…”

“…Consequently, at this moment, the precipitation of magnesium hydroxide takes place [Eq. (5)]. 12,13 MgðOHÞ þ :OH À ðsurfaceÞ !…”