Experimental investigation and characterization of an efficient nanopowder-based flame retardant coating for atmospheric-metallic substrates

• TiO2 nanopowder in APP/PER/MEL flame retardant coating for steel structure
• Eggshell micropowder (40 μm) in traditional APP/PER/MEL flame retardant coating
• Experimental evaluation and characterization of different intumescent coatings
• Usability of nano-based coating in exterior application
• Minimum equilibrium temperature of steel in the proposed formulation

Intumescent flame retardant coatings are fire protection and space saving materials widely used in steel construction. The objective of this work is to study the effect of different flame retardant formulations on the performance of steel in case of fire. Seven kinds of samples were synthesized as intumescent fire resistive coatings. Titanium dioxide nanopowder (nano-TiO2) in different amounts (1%–20% by weight) and chicken eggshell micropowder (ESP) were used as modifiers to improve the fire protection of intumescent fire resistive coating. The influences of these synergistic effects on the properties of the coatings were investigated in detail using themogravimetric analysis (TGA), differential scanning calorimeter (DSC), X-ray diffraction (XRD), X-ray fluorescence spectrometry (XRF), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and Bunsen burner test. The results generally showed that the performance of intumescent coating is improved as the weight fraction of nanopowders is increased. The TGA results proved that the addition of nano-TiO2 and ESP could increase the residue weight of the coatings and enhance the anti-oxidation of the char layers at high temperature. The XRD and XRF results indicated that anti-oxidation of the coating was improved by adding nano-TiO2 and ESP. The SEM images revealed that the addition of ESP and nano-TiO2 could improve the surface structure of the carbonaceous layer and the best result is achieved with the combination of both synergistic agents.

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