异质适配层改善钨/铜第一壁部件服役性能及机理研究

Tungsten (W) is the promising plasma facing material in fusion devices.But the interface stresses between the tungsten coating and the copper (Cu) substrate due to the mismatch of W/Cu thermal expansion coefficients degrade the high heat flux performance and reduce the lifetime of W/Cu plasma facing component (PFC). The project will research the effects of the heterogeneous compliant layers, such as Ti (titanium), NiCrAl (nickel-chromium-aluminum), W/Cu, on the heat flux performances of the interface of W/Cu PFC and the behaviors of W/Cu mock-up exposed to the plasma in the full superconducting tokamak - EAST device. Firstly, the optimum compliant layer architectures of W/Cu PFC are designed using ANSYS code. Then, 2mm W-coatings with the heterogeneous compliant layers are sprayed by means of vacuum plasma spraying technology.Finally, the high heat load tests of W/Cu PFC with the heterogeneous compliant layer are carried out by the electron beam facility and the EAST device.The heat flux performances of W coatings with the heterogeneous compliant layers will be evaluated by their heat transfer capability in time, the thermal fatigue lifetime, the heat load limit, the thermal stability, the micro-structure evolution with the increase of the load power density. Failure behaviors and mechanism of W/Cu PFC will be studied by means of the steady state and transient heat load tests. The effects of the heterogeneous compliant layers on the heat load behavior of W/Cu interface will be discussed, which include the bonding strength of W/Cu mock-up according to the ASTM C-633-79 standard by the tensile tests, the distributions of thermal Mises stress by X-ray diffraction analysis, the thermal conductivity of the W/Cu mock-up by means of laser flash method at room termperature, and so on. In addition, the improvement mechanism of the heterogeneous compliant layers in the high heat flux performances and the physical properties of interface between W/Cu PFC will be analyzed. The project can accelerate the development of the fuison project in China.

钨被认为是最有应用前景的核聚变实验装置面对等离子体材料，然而与铜热沉集成及服役过程中界面处会产生较大的热应力，从而影响了钨/铜材料高热负荷服役性能，降低其使用寿命。本项目拟开展异质适配层对等离子体喷涂钨涂层/铜基体界面行为改善，及异质适配层钨/铜样品高热负荷服役性能研究。通过ANSYS优化设计最佳的适配层结构，利用真空等离子体喷涂设备在铜基体上制备具有异质（Ti、NiCrAl、W/Cu等）适配层的2mm钨涂层面对等离子体材料，通过"等离子体辐射模拟热负荷平台"和"聚变实验装置EAST"评价异质适配层钨/铜模块在准稳态等离子体辐照下的实时传热能力、热疲劳寿命、热负荷承受极限及热稳定性等性能，分析其界面失效行为及失效机理，阐明异质适配层材料对钨/铜第一壁部件界面改善机理及服役性能增强机理，优化并发展钨/铜第一壁部件的适配层连接技术，促进我国核聚变工程和等离子体物理实验的发展。

核聚变实验装置托卡马克在运行过程中会不断有热负荷能量流以及粒子流沉积到内壁（面对等离子体材料）上，面对等离子体材料的性能优劣成为关系到核聚变装置能否正常运行的关键问题之一。高Z材料钨由于具有较高的熔点、较低的溅射率、较高的热导率等优点而被认为是最有前景的面对等离子体材料。同时，等离子体喷涂成膜技术成熟、成本较低、可以实现复杂形状样品大面积喷涂、且具有损坏位置定点修复的优点而被选作该项目涂层的制备方法。该项目对钨涂层制备参数及涂层界面结构进行了系统优化设计，分析了涂层复合材料热负荷性能以及损伤演变行为。Ti、NiCrAl、W/Cu适配层引入均能有效降低界面热应力，其中W/Cu缓解效果最佳，0.1-0.2mm、20-35Vol.%W是比较优化的适配层结构，最大热应力降低幅度高达25%。喷涂功率对涂层性能影响较大，Ar/H2比值大小也会影响钨粒子飞行速度和粒子熔化状态，进而影响涂层性能。在功率大于40 kW、Ar/H2=35/15 时钨粒子熔化状态较好，涂层表面粗糙度较小，涂层气孔率较小，传热性能较好。在稳态热负荷条件下，涂层晶体再结晶并长大、层间微裂纹出现、裂纹扩展和气孔出现、最后材料分层，而表面熔化、蒸发以及溅射直至材料失效则是瞬态热负荷下涂层损伤演变行为。原尺寸钨瓦倒角结构以及涂层梯度设计有效缓解了侧面热应力，有效提高了钨瓦热负荷性能。