Thermal shock damage behavior of CVD ZnS by oxygen propane flame：A numerical and experimental study

Chemical vapor deposition zinc sulfide （CVD ZnS） is widely used as an infrared window material to transmit infrared signals, keep the aerodynamic shape and protect its imaging system, which often suffers high temperature and complicated thermal stresses. The purpose of this paper is to investigate the thermal shock damage of CVD ZnS through a finite element method and oxygen propane flame experiments. The finite element model is developed to simulate the temperature and thermal stress fields by an oxygen propane flame. Then, the thermal shock experiments are performed to investigate the thermal shock damage behavior. The results show that the temperature rising rate of the shock surface is fast during the initial heating stage resulting in high thermal stress. After the thermal shock experiment, the scanning electron microscope （SEM） photographs shows that the shock surface of the specimen becomes rough and the microcracks occur in the thermal shock zone. Good agreements are achieved between the numerical solutions and the experimental results.     

M55J碳纤维/氰酸酯复合材料X、Y方向低温热导率的测试研究

碳纤维/氰酸酯复合材料是目前广泛在航天器应用的新型材料.该材料在X、Y方向的低温热导率是设计、使用的重要参考依据.目前一些测量方法不能表征材料传热特性,本文提出采用传统的一维稳态热流法.以M55J碳纤维/氰酸酯复合材料为例,对X、Y方向的低温热导率进行了测试、分析.在试验分析的基础上,采用单层板热导率测量数据,用分析模型计算了M55J碳纤维/氰酸酯复合材料的低温热导率并与测量数据进行了比对,两者最大偏差在18%之内,说明与从计算单层板的热导率开始的方法相比较,采用这种计算方法较简单准确.文章分析表明,碳纤维/氰酸酯复合材料的低温热导率可以通过铺层设计改变,以减少材料设计的盲目性,满足航天器的特殊需求.     

PVC 阻燃酚醛纤维的制备及其性能

以聚氯乙烯(PVC)改性酚醛树脂为原料,采用熔融纺丝法制备出PVC阻燃酚醛纤维.通过SEM、DMA、TG、Fr-IR等分析手段,对PVC阻燃酚醛纤维的结构和性能进行了研究.与纯酚醛纤维相比,PVC阻燃纤维的韧性和阻燃性提高,但其热稳定性和残碳率稍有降低.当PVC含量为0.5wt％时,其拉伸强度从123 MPa提高至150 MPa,极限氧指数从32.1％提高至38.5％,在空气气氛下600℃的残碳率从87.4％降至70.9％,在氮气气氛下1 000℃的残碳率从62.8％降至59.7％.     

加热温度对TC4钛合金的空冷组织及热疲劳抗力的影响

对经不同温度加热随后空冷的ＴＣ４钛合金在－１９６～３５０℃范围内进行了外约束型热疲劳试验。结果表明：经单相区加热的合金，其热疲劳裂纹易于沿原β相晶界处萌生，以穿晶的方式扩展，对热疲劳裂纹萌生抗力较低。而经９５０℃加热的合金，其热疲劳裂纹易于沿初生α相与基体（条形的α＋β相）的界面处萌生，裂纹易于切过条形的α＋β相扩展，其热疲劳裂纹萌生抗力最高。经９００℃加热的合金，其热疲劳裂纹易于沿初生α相与基体的界面处萌生并沿其扩展，合金的热疲劳裂纹萌生抗力也较低     

四酚基乙烷环氧树脂的固化性能

研究了甲基四氢邻苯二甲酸酐(Me THPA)和4,4-二氨基二苯基砜(DDS)两种固化剂对1,1,2,2,-四(对羟基苯基)乙烷四缩水甘油醚环氧树脂(TGE)固化反应及固化性能的影响。通过DSC研究了树脂的固化行为,结果表明Me THPA体系与DDS体系的固化反应活化能分别为65.8和68.4 k J/mol;同时通过DMA、TGA以及万能材料试验机等方法对树脂的热力学和力学性能等进行研究。Me THPA体系的Tg为188℃,初始热分解温度为219.9℃,拉伸强度为33 MPa,弯曲强度为48 MPa。而DDS体系的Tg为203℃,初始分解温度为292.3℃,拉伸与弯曲强度分别为61和93 MPa。     

Thermal protection mechanism of heat pipe in leading edge under hypersonic conditions

Sharp local structure, like the leading edge of hypersonic aircraft, confronts a severe aerodynamic heating environment at a Mach number greater than 5. To eliminate the danger of a material failure, a semi-active thermal protection system is proposed by integrating a metallic heat pipe into the structure of the leading edge. An analytical heat-balance model is established from traditional aerodynamic theories, and then thermal and mechanical characteristics of the structure are studied at Mach number 6–8 for three refractory alloys, Inconel 625, C-103, and T-111. The feasibility of this simple analytical method as an initial design tool for hypersonic aircraft is assessed through numerical simulations using a finite element method. The results indicate that both the isothermal and the maximum temperatures fall but the von Mises stress increases with a longer design length of the leading edge. These two temperatures and the stress rise remarkably at a higher Mach number. Under all investigated hypersonic conditions, with a 3 mm leading edge radius and a0.15 m design length, the maximum stress exceeds the yield strength of Inconel 625 at Mach numbers greater than 6, which means a material failure. Moreover, both C-103 and T-111 meet all requirements at Mach number 6–8.     

飞机环控系统管道气流温度的测量

根据实际使用中出现的问题，对各种实用的管道气流温度传感器的误差进行了计算，对电阻式和热电偶式温度传感器的误差原因作了定量分析。由于带密封罩的温度传感器在实际使用中存在着明显的缺点，建议今后使用热电偶测量飞机环控系统管道气流温度，并提出了一种实用热电偶温度传感器的结构形式，同时也介绍了如何减小由于热传导和热辐射引起的误差。     

Numerical simulation on antenna temperature field of complex structure satellite in solar simulator

A thermal network model is developed for studying the temperature variation of complicated structure satellite surfaces. The solar incident areas, the infrared and solar radiation transfer coefficients among surfaces are numerically simulated by means of Monte Carlo ray tracing (MCRT) method in model. The non-uniformity and the instability of solar radiation, which plays the important roles in simulating outer-space heat flux designation parameters by solar simulator, are studied for analysis variation of antenna temperature fields in detail. Results showed non-uniformity irradiation effects are greater than those of instability for this kind of geometry sheltering structure.     

烧蚀材料的热分解动力学研究

用热重分析技术研究了３种烧蚀材料的热失重信息，分别用直接法和差减微分法确定了其分解动力学参数，并以ＣａＣＯ３火已动力学参数的标准物对这２种方法作了标定。     

在轨温度环境对J-47C 胶黏剂粘接性能的影响

为考察在轨温度环境对J-47C结构胶黏剂粘接性能的影响,利用动态热机械分析和热重分析方法,对其Tg、热分解温度进行了测试,掌握了胶黏剂的耐热指标。通过不同温度下力学性能测试,温度冲击及真空热循环试验研究了卫星特殊的温度环境对胶黏剂性能的影响。结果表明,J-47C胶黏剂在高温以及真空热循环和温度冲击后其仍具有较高的力学强度保持率,满足卫星的温度环境对胶黏剂性能的需求。