锆合金表面Cr涂层的循环热冲击行为

Cyclic Thermal Shock Behavior of Cr Coating on Zirconium Alloy

为了研究锆合金表面Cr涂层的循环热冲击行为,使用自研的热冲击设备模拟循环热冲击环境,针对多弧离子镀技术制备的Cr涂层进行不同循环次数的热冲击试验。通过X射线衍射仪(XRD)和显微硬度计分别分析热冲击前后的物相变化和硬度变化,采用扫描电镜(SEM)和能谱仪(EDS)探究Cr涂层的表面破坏行为。循环热冲击过程中,Cr涂层生成的氧化层有“自愈”效果,可以有效阻挡O进入锆合金基体,同时诱发Cr-Zr中间层的非均匀扩散。大量Cr元素的内部扩散会促使α-Zr(O)的生成。热冲击生成的裂纹大量分布于外部氧化层、非均匀扩散的中间层以及α-Zr(O)层。经过N=24次循环热冲击后,残余的Cr涂层仍然可以有效保护锆合金基体,避免Zr与大量O反应。通过将锆合金表面Cr涂层的循环热冲击行为分为三个阶段,进一步揭示了循环热冲击作用下锆合金Cr涂层的组织结构和抗热冲击性能的演变规律。

In order to study the cyclic thermal shock behavior of the Cr coating on the surface of zirconium alloy,the self-developed thermal shock equipment is used to simulate the cyclic thermal shock environment,and the thermal shock test of the Cr coating prepared by the multi-arc ion plating technology is carried out with different cycles.The phase change and hardness change before and after thermal shock are analyzed by X-ray diffractometer(XRD)and microhardness tester,and the surface damage behavior of Cr coating is explored by scanning electron microscope(SEM)and energy spectrometer(EDS).During the cyclic thermal shock process,the oxide layer generated by the Cr coating has a“self-healing”effect,which can effectively block O from entering the zirconium alloy matrix and induce non-uniform diffusion of the Cr-Zr intermediate layer.The internal diffusion of a large amount of Cr element will promote the generation ofα-Zr(O).A large number of cracks generated by thermal shock are distributed in the outer oxide layer,the non-uniformly diffused intermediate layer and theα-Zr(O)layer.After N=24 cycles of thermal shock,the residual Cr coating can still effectively protect the zirconium alloy matrix and prevent Zr from reacting with a large amount of O.By dividing the cyclic thermal shock behavior of the Cr coating on the surface of the zirconium alloy into three stages,this paper further reveals the evolution of the microstructure and thermal shock resistance of the Cr coating on the zirconium alloy under the action of the cyclic thermal shock.