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为了研究颗粒冲刷条件下硅橡胶绝热材料的烧蚀规律和特性,采用一种颗粒冲刷状态可调的实验发动机,以添加有短切碳纤维和高硅氧玻璃纤维的硅橡胶为研究对象,开展了颗粒聚集浓度范围为34.5~75.3kg/m3,冲刷速度为9.4~35.9m/s,角度为19.3°~55.5°条件下的13次热试车实验,获得了颗粒冲刷状态参数和炭化烧蚀率之间的宏观影响规律,通过对试验后试件的宏观形貌和微观结构特征进行分析,初步探讨了硅橡胶绝热材料的烧蚀机理。研究结果表明:(1)和EPDM绝热材料的烧蚀规律和特性不同,实验条件下硅橡胶炭化层更厚且致密,硅橡胶材料的最大烧蚀率随颗粒聚集浓度变化较为敏感,当超过50kg/m3临界浓度值时,烧蚀率随浓度的增加而急剧增大。最大烧蚀率随颗粒冲刷速度增加而增大,并呈现出先急剧增加后缓慢增加的趋势;(2)在颗粒冲刷速度较低条件下,硅橡胶材料烧蚀率要高于EPDM的,在颗粒冲刷速度较高条件下,硅橡胶耐冲刷性能要略优于EPDM的;(3)硅橡胶的热分解温度区间约为623~989K,在烧蚀过程中,高硅氧纤维和硅橡胶分解产生的Si O2会渗透到炭化层骨架中,进一步和C反应形成Si C,从而使炭化层致密化,具备耐冲刷特性;(4)通过分析烧蚀形貌和微观特征,初步提出了三层一面(基体层,热解层,炭化层,冲刷面)的烧蚀物理模型。
In order to study the ablation rules and characteristics of silicone rubber thermal insulation materials under the condition of particle scouring, an experimental engine with adjustable particle scrubbing condition was adopted. Silicone rubber with chopped carbon fibers and high silica glass fibers was used as the research object The particle agglomeration concentration was in the range of 34.5-75.3 kg / m3, the erosion rate was 9.4-35.9 m / s and the angle was 19.3 ° -55.5 ° for 13 cycles of heat test. The parameters of particle erosion and carbonization ablation were obtained Macroscopically influential laws between the two samples. The macroscopic morphology and microstructure characteristics of the samples after the test were analyzed, and the ablation mechanism of the silicone rubber thermal insulation material was preliminarily discussed. The results show that: (1) The ablation rules and characteristics of EPDM insulation are different. Under the experimental conditions, the carbonized layer of silicone rubber is thicker and denser. The maximum ablation rate of silicone rubber material is more sensitive to the change of particle aggregation concentration. / m3 critical concentration value, the ablation rate increases sharply with increasing concentration. The maximum ablation rate increases with the increase of particle scrubbing velocity and shows a trend of increasing firstly and then slowly increasing. (2) The ablation rate of silicone rubber material is higher than that of EPDM at lower particle scouring velocity, (3) The thermal decomposition temperature range of silicone rubber is about 623 ~ 989K, during the ablation process, high silicon fiber and silicone rubber decomposition generated Si O2 penetrates into the skeleton of the carbonized layer and further reacts with C to form Si C, thereby making the carbonized layer densified and has the characteristics of erosion resistance. (4) By analyzing the ablation morphology and microscopic features, Substrate layer, pyrolysis layer, carbonized layer, erosion surface) of the physical model of ablation.