DEVELOPMENT STUDY ON TURBINE DISK MADE OF C/C COMPOSITE SUBJECTED TO HIGH TEMPERATURE ENVIRONMENT

对三维纤维增强碳/碳复合材料(3D-C/Cs)在ATREX(膨胀机循环空气涡轮冲压发动机)涡轮盘上应用的可行性进行了研究。利用3D-C/C圆盘进行了室温下的自旋爆炸试验，并对其断裂行为进行了表征。3D-C/C盘在516m/S(r=150 mm)的圆周速度下完全断裂，这对于ATREX应用是足够的。然而，椎间盘周边的纤维束过早地遭受了微小规模的破坏，纤维束单元的碎片在完全骨折发生之前就飞了出来。为了防止飞出行为，盘只在其外围附近浸渍了硅。虽然这种处理提高了飞出行为的启动速度，但这种改进被认为不足以用于ATREX应用。其次，进行了简化分析，以表征飞出行为。在此基础上，讨论了以下三种措施：(1)减小纤维束厚度(即利用细小的纤维织构)，(2)增加纤维束界面的韧性，(3)最小化纤维束在圆周方向上的波动度局部曲率。第三种对策被认为是最有效的，并验证了最小化局部曲率的圆盘满足ATREX要求。此外，还进行了试验以确认3D-C/Cs的耐久性。这类研究包括高温行为、蠕变、疲劳和缺口不敏感。研究发现，3D-C/Cs具有足够的耐久性，可用于ATREX应用。

A feasibility study of three-dimensionally fiber-reinforced carbon-carbon composites (3D-C/Cs) for application to a turbine disk of ATREX (Air-turbo-ramjet engine with expander cycle) was carried out. Spin burst tests at room temperature were conducted using 3D-C/C disks, and the fracture behaviors were characterized. A 3D-C/C disk was totally fractured at a peripheral speed of 516 m/s (r = 150 mm), which is sufficient for the ATREX application. However fiber-bundles at the disk periphery prematurely suffered micro-scale damage, and fragments of the fiber bundle unit flew out before total fracture occurred. In order to prevent the fly-out behavior, the disk was impregnated with Si only near its periphery. Although This treatment increased the initiation speed of the fly-out behavior, this improvement was considered insufficient for purposes of the ATREX application. Next, a simplified analysis was conducted to characterize the fly-out behavior. Based on this analysis, the following three measures were discussed: (1)decreasing bundle thickness, (i.e.,using fine fiber texture),(2)increasing toughness of the fiber bundle interface, and (3)minimizing local curvature in waviness of the fiber bundles in the circumferential direction. The third countermeasure was found to be most effective and disks minimizing local curvature were verified to satisfy ATREX requirement.In addition to above study, experiments to confirm durability of 3D-C/Cs were carried out. This category of study included, high temperature behavior, creep, fatigue, and notch insensitivity. The 3D-C/Cs were found to possess sufficient above durability for the ATREX application.