芳氧基聚磷腈与成瓷填料的协同成炭行为研究

Co-carbonation behavior between polyaryloxyphosphazene and porcelain filler

通过机械共混法,在芳氧基聚磷腈中分别添加针状硅灰石、云母、碳化硼、氮化硼成瓷填料,制备了耐烧蚀复合材料。材料经管式炉高温炭化后对炭层的三点弯曲强度进行测试,并采用氧乙炔火焰烧蚀方法对材料耐烧蚀性能进行表征,通过扫描电子显微镜和热重分析仪对材料烧蚀后的形貌以及热失重行为进行分析和研究。研究表明硅灰石、云母的加入使高温下芳氧基聚磷腈表面形成坚硬、致密、连续的陶瓷状壳层,这种连续陶瓷状壳层可明显降低其下层复合材料的热分解速率,在氧乙炔火焰冲刷过程中能够使复合材料保持完整的炭层形貌以及低线烧蚀率。硅灰石、云母的加入提高了复合材料的阻燃性能,硅灰石添加量为30%(质量分数)时,复合材料高温炭化后三点弯曲强度最高,达到21.3MPa,最低线烧蚀率为0.093mm/s;云母添加量为30%质量分数)时,复合材料阻燃效果最好,氧指数为42。

The ablation-resistant composite materials were prepared by mechanical blending with four ceramic fillers,namely aciculate wollastonite,mica,boron carbide and boron nitride.The three-point bending strength of the carbon layers was characterized after the high-temperature carbonization of the tubular furnace,and the ablative performance of the material was characterized by the method of oxyacetylene flame ablation.SEM was used to analyze the morphology of the material after ablation.The thermal weight loss behavior of the material was studied to understand the thermal decomposition in the process of heating.Studies shown that two kinds of fillers,silicate wollastonite and mica,can lead to hard,dense and continuous ceramic shells under thermal treating process,and the continuous ceramic shells can obviously reduce thermal decomposition rate of underneath virgin materials.These polyaryloxyphosphazene composites owned intact appearances of carbon layers and presented low linear ablation rate after oxyacetylene flame test.Among porcelain fillers,wollastonite and mica showed better effects of improving flame retardancy of the materials.Effects of dosage of wollastonite and mica on the carbonization behavior of aroxylpolyphosphazene composites were investigated as well.And results showed that when the dosage of wollastonite was 30 wt%,the strength and linear ablation rate of carbonized charred layer of polyphosphazene composites reached 21.3 MPa and 0.093 mm/s respectively.Its oxygen index(LOI)was 42 when the mica content was 30 wt%.