Fire Safety Science Digital Archive

The formation of an effective fire retardant coating which contains three layers as well as results of the thermophysical investigation of this coating and the foamcoke (carbon foam) formed from it are discussed. The three layer coating contains a) glass reinforced plastics or organoplastics modified by the phosphorus vanadium containing fire retardant system, b) the layer of these plastics partly pyrolyzed and also c) the epoxy resin layer with a crosslinking agent which contains carbonization agent, carbonization catalyst and gasificator. The following facts of the investigation are established: 1. The thermal conductivity of the first layer (the glass- and organoplastics layer which has been modified by the phosphorus-vanadium containing fire retardant system) increases 2-3 times slower than the heat capacity when the temperature increases. The consequence of this process is the decreasing of temperature conductivity. 2. The temperature conductivity of the second layer formed after six heat shocks decreases to a greater extent compared to the temperature conductivity of the first layer, bat a packed density and heat capacity increase. 3. The third layer (or an outer layer relative to the heat source) is transformed to the foamcoke or carbon foam under the action of a flame source. Pores of the carbon foam are occupied by ammonia and water vapours, and the inner surface of pores contains carbon substances and polyphosphates with polyammonium phosphates. The temperature conductivity of this layer is small, and its adhesion to the pyrolyzed layer (the second layer) is the greatest because chemical bonds between layers are formed. 4. The three layer fire resistant coating when heated by the heat flow with a power more than 30 kW/m² gets intumescent and can be stable to heat flows during the fire for an hour and longer without a stratification. The degree of intumescence of the outer (third) layer is determined by the composition of this layer, and also by the composition and defectness of the second layer.