Ionic liquid microseeded WC/RF ablative composite for heat shielding

Abstract

The in situ incorporation of tungsten(IV) carbide (WC), with a particle size of 2 μm, in three dimensional thermosetting resorcinol formaldehyde (RF) resin was carried out in order to fabricate a resol type WC/RF heat shielding ablative material and, separately, the infusion of the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate was also done to study its effect on thermal insulation properties. The analysis of ablation characteristics was done by studying the degradation of the linear dimensions and mass of the thermoset sample through performing an economical yet effective oxyacetylene flame test. The linear ablation rate (LAR) and mass ablation rate (MAR) were calculated after exposing the material to an oxyacetylene flame generating a temperature of 2700 °C for 60 s and were found to be reduced by 69.5% and 40.86% respectively, with ablation rates as low as 0.0159 mm s⁻¹ and 0.0499 g s⁻¹ for RF/WC samples. While in the case of the ionic liquid infused samples, the reduction in the LAR was only 64.5% but an exceptional decrease in the MAR of 56.19% was observed with corresponding values of 0.0185 mm s⁻¹ and 0.0370 g s⁻¹. FESEM, XRD and FTIR analyses were also carried out in order to understand the particle/matrix interactions. The results confirm that impregnation with tungsten(IV) carbide and the microseeding of an ionic liquid enhance the ablative and thermal insulation properties of the RF resin and therefore it is suitable to use instead of conventional phenolic resins for hyper thermal applications.