Temperature and common-ion effect on magnesium oxide (MgO) hydration


Autoria(s): AMARAL, L. F.; OLIVEIRA, I. R.; SALOMAO, R.; FROLLINI, E.; PANDOLFELLI, V. C.
Contribuinte(s)

UNIVERSIDADE DE SÃO PAULO

Data(s)

20/10/2012

20/10/2012

2010

Resumo

MgO based refractory castables draw wide technological interest because they have the versatility and installation advantages of monolithic refractories with intrinsic MgO properties, such as high refractoriness and resistance to basic slag corrosion. Nevertheless, MgO easily reacts with water to produce Mg(OH)(2), which is followed by a large volumetric expansion, limiting its application in refractory castables. In order to develop solutions to minimize this effect, a better understanding of the main variables involved in this reaction is required. In this work, the influence of temperature, as well as the impact of the chemical equilibrium shifting (known as the common-ion effect), on MgO hydration was evaluated. Ionic conductivity measurements at different temperatures showed that the MgO hydration reaction is accelerated with increasing temperature. Additionally, different compounds were added to evaluate their influence on the reaction rate. Among them, CaCl(2) delayed the reaction, whereas KOH showed an opposite behavior. MgCl(2) and MgSO(4) presented similar results and two other distinct effects, reaction delay and acceleration, which depended on their concentration in the suspensions. The results were evaluated by considering the kinetics and the thermodynamics of the reaction, and the mechanical damages in the samples that was caused by the hydration reaction. (C) 2009 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

FAPESP

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

CAPES

Identificador

CERAMICS INTERNATIONAL, v.36, n.3, p.1047-1054, 2010

0272-8842

http://producao.usp.br/handle/BDPI/31680

10.1016/j.ceramint.2009.12.009

http://dx.doi.org/10.1016/j.ceramint.2009.12.009

Idioma(s)

eng

Publicador

ELSEVIER SCI LTD

Relação

Ceramics International

Direitos

restrictedAccess

Copyright ELSEVIER SCI LTD

Palavras-Chave #Suspensions #Chemical properties #MgO #Refractories #DISSOLUTION #KINETICS #VAPOR #Materials Science, Ceramics
Tipo

article

original article

publishedVersion