||Applying an intumescent fire-retardant coating to a substrate is an effective and passive method for fire protection. To better understand the coating performance, two different laboratory-scale tests were established in this study to investigate the effects of convective and radiative fluxes on the coating. In addition, the corresponding numerical models were also developed to obtain the thermal flow fields, which are difficult to measure, in the tests. Experiments combined with numerical models can further understand the coating performance in actual fire conditions. |
Two different heat sources (radiation and convection) were individually applied to a 100 mm x 100 mm substrate covered by intumescent coating. The radiative and conductive heat fluxes were respectively provided by a hot plate and a burner for 30 and 20 minutes. The thermal response of coating were recorded by using a camera. In addition, the temperatures of the coating and the substrate, and the heat flux at the back side of substrate were also measured. Therefore, the coating response for different types of heat source can be observed and analyzed from the measurements. Very different coating performances were found between the radiative heat source and convective heat source. Because it is difficult to measure the gas flow fields from the experiments, the corresponding three-dimensional models were used to analyze the gas flow fields and the thermal effects on the coating surface. It is found that, in the test of radiative heat flux, the convective heat loss on the coating surface is about 4% and can be ignored. Moreover, in the test of convective heat flux, the burner cannot provide a uniform convective heat flux, therefore, the model results can help understand the distribution of convective heat flux applied on the coating surface. Therefore, the numerical models take an important role on analyzing the defects in bench-scale tests in this study.
Using bench-scale tests, the coating performance can be easily obtained and analyzed, so the implement of coating on a protected sample can be better determined before a large-scale test, which can help reduce the costs of time and money. In addition, the bench-scale tests can give a better understanding of coating in the heating process, so they can be used to examine the performance of new coating formula.