Microstructure,thermophysical property and ablation behavior of high thermal conductivity carbon/carbon composites after heat-treatment

Uni-directional carbon/carbon composites with high thermal conductivity are suitable to supply continuous thermal protection for future reentry vehicles since they could reduce surface temperature and ablation rates simultaneously in harsh environments. In this work, the high thermal conductivity carbon/carbon composites were prepared by chemical vapor infiltration. After heat-treatment, both their open porosity and internal friction increase due to the fiber/matrix thermal expansion mismatch; while their thermal conductive performance become better due to more complete carbon structure. With raising heat-treatment temperature from 1800 °C to 2450 °C, the mass and linear ablation rates of C/C composites with fibers vertical to the oxyacetylene torch for 60 s decrease from 0.66 mg/s and 2.95 μm/s to 0.51 mg/s and 2.05 μm/s respectively. The improved ablation resistance is resulted from the increased thermal conductivity from 282 to 508 W/(m·K) and more carbon fibers exposed to the flame during ablation, which have better oxidation resistance than those of carbon matrix. While such ablation rates become larger for composites with fibers parallel to the flame, from 1.02 mg/s and 3.73 μm/s to 1.28 mg/s and 5.01 μm/s respectively since the ablation occurred more easily through gaps at the fiber/matrix interfaces, which become larger and are always exposed to the flame for this case.     

倾斜轨道卫星活动天线热控特点分析

对某低轨倾斜圆轨道卫星的外热流环境进行了分析。用蒙特卡罗法计算了卫星六个表面的外热流。研究了该轨道条件下舱外活动天线热控特点,提出了该类卫星活动天线的热控设计原则和初步方案。     

Thermal drill sampling system onboard high-velocity impactors for exploring the subsurface of Europa

The planned Europa Jupiter System Mission (EJSM) will provide a unique opportunity to place scientific instruments onto the surface of Jupiter’s moon Europa in the late 2020s. After the Galileo mission, this will be a long awaited chance to have a close glimpse into some of the mysteries of this moon. Care must be taken in the choice of in-situ science that will be undertaken on the surface.     

固体材料热物性参数智能测试系统设计与研制

为实现厚度较薄固体板状材料热物性的准确测试。基于平行热线法基本原理,将温度测点由原来与热线平行布置,改为试样厚度方向布置,并考虑热穿透效应的影响,利用数值解法结合计算机编程直接测算材料热导率及热扩散率。研制了热物性智能测试系统,对硼硅玻璃、石棉、硅藻土耐火砖等进行热物性测试实验,结果表明与国家标准测试方法测试值和文献值较为吻合。考虑热穿透效应的影响,通过适当的数据处理手段,不用通过熔融加厚也可实现薄固体板状材料热物性的准确测试,有效拓展了热线法应用范围。     

某涡喷发动机涡轮导向器的热应力分析

应用有限元方法建立了某涡轮喷气发动机涡轮导向器有限元计算模型,根据实测的温度边界条件计算了涡轮导向器温度分布,在此基础上对涡轮导向器进行了热应力分析。其结果为涡轮导向器叶片设计改进提供了依据。     

3,3′-二硝基-4,4′-氧化偶氮呋咱(DNOAF)的热分解特性

采用热重实验(TG)、差示扫描量热实验(DSC)和气体(固体)原位反应池/快速扫描傅里叶变换红外光谱(RSFTIR)联用技术,研究了3,3′-二硝基-4,4′-氧化偶氮呋咱(DNOAF)的热分解特性。结果表明:DNOAF的热分解特性对压强敏感,随着压强的升高,DNOAF的热分解放热峰温呈降低趋势。其热分解气体中具有红外活性的有CO2,N2O,NO,NO2,CO和DNOAF蒸汽;凝聚相热分解产物主要为碳,其中还含有少量的氰酸酯基-O-C≡N。在实验基础上提出了DNOAF的热分解历程,DNOAF的热分解首先发生在呋咱环间的C-N键,然后是呋咱环的开环分解。     

过渡金属/稀土金属氧化物纳米粒子催化AP热分解研究

1引言纳米材料由于特殊的表面特性而作为催化剂被广泛地研究。按一定的比例将不同的催化剂进行掺杂混合,有可能获得优于单一催化剂的催化性能。如Cu-Zn纳米催化剂就可替代昂贵的铂或钯催化剂实现对某些有机化合物氢化反应的催化[1]。随着纳米技术的发展,纳米过渡金属氧化物[2](     

电子封装用SiCp/ZL101复合材料热膨胀性能研究

采用无压渗透法制备了SiCp／ZL101复合材料，测定了SiCF／ZL101复合材料在25℃-400℃区间的线膨胀系数值，运用理论模型对复合材料的线膨胀系数进行了计算，分析了热膨胀性能的影响因素。结果表明，复合材料的线膨胀系数比基体合金显著降低，Turner模型对SiCp／ZL101复合材料线膨胀系数的计算值与实验值相接近，复合材料热应力引起线膨胀性能的变化随温度的不同而不同。     

双基推进剂热分解反应动力学参数的计算

本文根据在CDR-1型热分析仪上测得的一条非等温DSC曲线,确定了双基推进剂热分解反应的最可几机理函数,提出了计算三个动力学参数(E,A和n)的数值方法.该法用线性最小二乘法、迭代法以及二分法与最小二乘法相结合的方法,以积分方程、微分方程和放热速率方程拟合实验数据.在逻辑选择建立了微分形式或积分形式的机理函数的最可几一般表达式后,用放热速率方程计算相应的动力学参数E,A和n的值.     

低太阳吸收率加成型有机硅热控涂层的研制

为了制备低αs/εh值热控涂层，必须选择合适的粘料。系统研究了组成对加成型热控涂层性能的影响，探讨了颜料与粘粒配比、含氢硅油种类、乙烯基硅橡胶种类、Si－H与CH＝CH配比、涂布方式等对热控涂层太阳吸收率（αs）、红外辐射率（εh）及αs/εh影响规律。