Boosting the efficiency of water-based intumescent coatings with fumed silica nanoparticles: A synergistic approach

This research looked into how well the water-based intumescent coating (WBIC) with fumed silica nanoparticles (FSNs) worked to keep steel parts safe from cellulose fire. The adhesion strength of the coatings was evaluated using the pull-off test according to ASTM D4541. Flame retardant performance was studied by a lab-scale simulated big panel test at 950 °C for 1 hour. Thermogravimetric analysis (TGA) and the UL94 test were used to study the thermal stability and burning characteristics of the WBIC. An FESEM, an X-ray diffraction (XRD), and a Fourier transform infrared spectroscopy (FTIR) analysis were used to fully characterize the residual chars of the optimized formulation and the control coating. Adhesion strength test results showed that adding 0.2 wt% of FSNs increased paint adhesion strength from 0 to 2 MPa and changed the failure mode from adhesive to cohesive. It was found that at the optimal FSNs content (0.2 wt% SiO 2 ), the lowest steel backside temperature of 181℃ after 1 hour of fire testing was obtained. Adding fumed silica from 0.1 to 0.3 wt% has resulted in a reduction of the char layer's intumescent factor by 5.3–42.1 %. The SEM images indicated that fumed silica enhanced the formation of dense, crack-free char layers with small pore sizes. Thermogravimetric analysis revealed that intumescent coatings' thermal stability and residual weight increased with the addition of 0.2 wt% fumed silica. Additionally, the coating contained 0.2 wt% SiO 2 passed the V0 rating in the UL94 vertical burning test. The XRD and FTIR tests also revealed that the leftover chars had rutile titanium oxide, aluminum metaphosphate, and titanium pyrophosphate in them. At high temperatures, these ceramic compounds exhibit thermal insulation performance, preventing heat and oxygen penetration into the char layer.