Evaluation of combustion characteristics for wood specimens coated with metal oxides of different oxidation states in the secondary stage of combustion (II)

Metal oxides were applied to cypress wood typically used as an interior building material. Combustion characteristics were evaluated focusing on the oxidation state of metal ions and char characteristics of the second stage of combustion. The burning properties of the materials were measured using a cone calorimeter (ISO 5660-1). The external heat flux was fixed at 50 kW/m(2). FeO, Fe2O3, SnO and SnO2 were used as the metal oxides, and sodium silicate was mixed with increasing the flame-retardant effect. SnO2SS was 1.05 times lower than the 164.76 kW/m(2) of the uncoated specimen. The other specimens increased 1.03-1.09 times. The peak smoke production rate of the wood specimens coated with flame retardant was 1.2-1.6 times lower than the uncoated specimens. SnO2SS had the lowest value and showed a synergetic effect with SS. The CO/CO2 ratio of the test specimens coated with the silicate compound was 1.6-2.3 times lower than that of the uncoated specimen. In SnO2SS, HRR2nd_peak and SPR2nd_peak decreased because the generated heat was dispersed by convection because of pores in the char. This formed a relatively hard and heat-stable char structure.

Automated summary

This study investigated the combustion characteristics of cypress wood coated with metal oxides as an interior building material. The results showed that the coated specimens exhibited improved burning properties, with SnO2SS coating showing the best effect.