Manufacturing Process And Properties Of Quartz Fiber Reinforced Phenolic Resin Composites By RTM Process

According to the requirement of resin transfer molding (RTM) process for fabricating the ablation resistant cephalic cone structure, properties of phenolic resins were investigated in this paper first. Then process parameters, thermal and mechanical properties of quartz fiber reinforced barium-phenolic resin composites by RTM process were further studied.Curing reaction behaviors of barium-phenolic, ammonia-phenolic, benzoxazine and cyanate ester of novolac were studied by differential scanning calorimetry(DSC) technique and gelatin experiment. Mechanical properties, thermal properties and micro-morphologies of the resins casting were investigated. Rheological behavior of the resins for RTM process was studied through dynamic viscosity experiments and isothermal viscosity experiments. Based on the experimental data, a chemorheology model was developed and the model can be used to predict the processing window of RTM. Results show that the barium-phenolic and benzoxazine are of wide range of low viscosity and long time for keeping low viscosity, therefore, they are suitable for the matrix of ablation resistant composites fabricated by RTM process.Flat samples of the quartz/barium-phenolic and the quartz/benzoxazine composites were fabricated by RTM process. Effects of injection pressure, fibre volume fraction, thickness of the samples on porosities, mechanical properties and ablative properties of the composites were investigated. Results show that injection pressures influence mechanical properties of the composites significantly, better sequence of applying injection pressure is low pressure at early stage of the injection process and high pressure at later stage. Porosities of composites decrease with the increase of fibre volume fraction, whereas the mechanical properties increased. No effects of thickness of the samples on the porosities and ablative properties of the composites can be observed. Properties of the quartz/benzoxazine composites are very good, and tensile, flexural, compressive, shear and impact strengths of the composites are 600MPa, 691MPa, 480MPa, 64MPa and 497kJ·m^-2 respectively, while the rate of mass losing by ablation is 0.0527g·s^-1 when fibre volume fraction is 50%.A cephalic cone structure of the quartz/barium-phenolic composites was fabricated by RTM process. In order to solve difficulties of fabricating fibre preform of the complex structure, a braiding technique was developed. Results show that fabricated structure exhibits higher dimension accuracy, much better apparent quality and uniformity, thermal and mechanical porosities of the structure reach that of the flat composites.