Effects of Mass Ratio of Phenolic Fiber to Quartz Fiber on the Ablative Properties of Hybrid Fabric Reinforced Composites

Phenolic-quartz hybrid fabric reinforced phenolic resin composites were fabricated by compression molding and the mass ratios of phenolic fiber to quartz fiber were 1:3, 1:1 and 3:1, respectively. The ablative properties of the composite specimens were quantitatively evaluated by oxyacetylene flame test and exhaust plume ablative test with a small liquid motor (EPSLM). The effects of mass ratio of phenolic fiber to quartz fiber on the ablative properties of the composites were investigated. In the oxyacetylene flame test, the mass loss rate of the composite specimens, which can be predicted by the mixture rule, increased with rising content of phenolic fiber. However, the mixture rule was not applicable to predict the mass loss of the composite specimen in EPSLM. The mass loss of the hybrid composite specimens decreased with increasing content of phenolic fiber. As suggested by the patterns and microstructures of the char after ablation, it is useful to stabilize the char by adding phenolic fiber, and the resistance of the hybrid composite specimens to heat-flow erosion was evidently augmented when the mass ratio of phenolic fiber to quartz fiber was higher than 1:1.