Effect of Mesophase Pitch Incorporation on the Ablation Behavior and Mechanism of Phenolic Composites

Abstract

Phenolic resin plays a critical role in ablative thermal protection materials. However, its ablation and insulation properties need to be further improved to meet the growing requirements of the entire aerospace industry. In this work, composites are altered with various loadings of mesophase pitch (MP) to make mesophase pitch-modified boron-phenolic resin (BPR) composites (MPBPR). The compressive strengths of carbonized MPBPR composites are significantly improved (optimally by 2.7 times) via this modification, indicating the improved mechanical performance of MPBPR composites under high temperatures. Results reveal that the obtained MPBPR composites show better ablation resistance and thermal insulation performance under oxyacetylene flame. The linear ablation rates (4 MW/m2, lasting for 30 s) of the composites with 10 and 20 wt % MP are reduced by 41.5 and 55.4% compared to that of neat BPR. Meantime, MPBPR composites exhibit lower back-face temperature during the ablation process. Furthermore, results also show that the introduction of MP can effectively avoid the growth of large transversal microcracks, increase the proportion of micropores in the ablated char layer, and simultaneously improve the graphitization of resultant char. Both the microporous and graphitic structures of the residual char contribute to the improved ablation and insulation properties of MPBPR composites. The abovementioned results indicate that these MP-modified boron-phenolic resins are promising materials for application in a thermal protection system.

Enhancing ablation and oxidation resistance of phenolic resin with modified pickling asbestos

“…The static ablation test was performed in a Muffle furnace at 1000°C with a heating rate of 5°C/min and dwelling for 10 min in an air atmosphere. The compressive strength of the samples (ϕ30 × 10 mm) after static ablation was determined using an electron universal testing machine (Model 5576, Instron, USA) 2 . Scanning electron microscopy (SEM; JSM‐5900, JEOL, Tokyo, Japan) was used to study the surface and cross‐section microstructures of MPABPR composites before and after the ablation test.…”

“…The compressive strength of the samples (ϕ30 Â 10 mm) after static ablation was determined using an electron universal testing machine (Model 5576, Instron, USA). 2 Scanning electron microscopy (SEM; JSM-5900, JEOL, Tokyo, Japan) was used to study the surface and cross-section microstructures of MPABPR composites before and after the ablation test. In addition, the elemental composition of the composite surface after ablation was analyzed by the EDS spectrum.…”

“…Boron phenolic resin (BPR) is an ideal ablative polymer composite matrix for thermal protection systems in aerospace and military due to its stable carbon layer and high carbon content. [1][2][3] Currently, compounding with inorganic fillers is an effective strategy to improve the ablation resistance properties of BPR-based polymer composites. [4][5][6][7][8] The ceramic fillers can form dense ceramic phases at high temperatures and protect the internal material from the erosion of heat flow.…”

Improving the Ablation Properties of Liquid Silicone Rubber Composites by Incorporating Hexaphenoxycyclotriphosphonitrile

“…The in-line back-face temperature of ablative samples was recorded using a K-type thermocouple thermometer. Raman spectroscopy was employed to study the quality of the char layer [ 30 ]. The Thermogravimetric-Fourier Transform Infrared Spectra-Gas Chromatography-Mass Spectroscopy (TG-FTIR-GCMS) tests were performed according to the literature [ 31 ].…”

Enhanced ablation resistance of carbon/phenolic composites based on mesophase pitch reinforced particles

“…8 However, the char layer formed by the carbonization of PR consists of difficultto-graphitize carbon, 9 and the amorphous char layer with a low degree of graphitization is susceptible to serious mechanical exfoliation and thermal oxidation reactions 10 due to the scouring effect of gas flow. And defects such as cracks and pores are produced during the ablation process, resulting in severe recession of the ablative surface, 11 problems such as char layer exfoliation may occur during flight.…”