Decomposition mechanism of boron phenolic resin composites under temperature gradient

ABSTRACT As the classic second-generation high silica/boron phenolic ablation resistant composite, it has been widely used in rockets and aerospace fields and has shown excellent performance. This paper studies its thermal protection and ablation resistance. Boron phenolic resin/high silica fibre composite containing wollastonite is well fabricated by compression moulding. Fourier transform infrared spectrometer reveals that due to the cleavage and oxidation of methylene groups, the phenolic system collapse. Aromatics are converted into amorphous carbon through a polycyclic reaction. The results of scanning electron microscopy and X-ray diffraction analysis demonstrate that inorganic fibres melted at high temperature and formed a new dense matrix with residual carbon and wollastonite filler. The main composition of the new phase is still silica, and the mechanical properties have been improved by 12%. The well-bonded matrix provides the ablative material better heat resistance at high temperature.