Flame retardancy and thermal degradation behavior of red gum wood treated with hydrate magnesium chloride

Flame retardancy and thermal degradation of wood treated with magnesium chloride (MgCl2·6H2O) were investigated. Results showed that MgCl2·6H2O decreased flame intensity and heat release rate, and reduced smoke concentration and gas yield. From ambient temperature to 250 °C, MgCl2·6H2O reduced wood combustibility by gas dilution mechanism. The chemical started to decompose at 350 °C and produced MgOHCl, in which -Cl and -Mg free radicals were generated and intervened the chain reactions of wood combustion. Hydrogen chloride gas generated promoted wood charring. MgCl2·6H2O gradually converted to MgOHCl and MgO compounds at higher temperatures, and MgO suppressed wood combustion by the wall effect mechanism.