TC4钛合金表面Cr_2AlC涂层的制备及高温氧化行为

Preparation of Cr_2AlC Coatings on TC4 Titanium Alloy and Its High-temperature Oxidation Behaviour

目的为提高钛合金在高温条件下的服役性能,探索Cr_2AlC MAX相涂层对TC4钛合金高温氧化行为的影响。方法采用低温反应直流磁控溅射技术再经后续退火处理的方法,在TC4钛合金基体表面制备高纯度的Cr_2AlC MAX相涂层。利用X射线衍射仪、拉曼光谱仪、扫描电子显微镜和能谱仪,分析了Cr_2AlC涂层试样和TC4钛合金经750℃静态空气恒温氧化前后的相结构、组织形貌和组分,并采用分析天平测定了TC4钛合金和Cr_2AlC涂层试样在750℃静态空气中氧化后的氧化动力学曲线。结果经750℃空气中氧化10 h后,TC4钛合金表面形成厚度达13μm的疏松团絮状TiO_2和Al_2O_3混合物氧化膜。而Cr_2AlC涂层表面能够形成以α-(Al,Cr)2O3为主的致密氧化膜,可有效阻止氧元素向内扩散。Cr_2AlC涂层试样在750℃空气中氧化90 h后的氧化增重仅为无涂层TC4钛合金在750℃空气中氧化10 h后的6.6%。结论 Cr_2AlC涂层具有优异的抗高温氧化性能,能够明显提高TC4钛合金的使用温度,使其氧化增重速率大幅降低。

The work aims to improve the service performance of the titanium alloy at high temperature and explore the influence of Cr2AlC MAX coating on the high-temperature oxidation behavior of TC4 titanium alloy. Highly purified Cr2AlC MAX coating was successfully prepared on TC4 titanium alloy by low temperature reaction DC magnetron sputtering combined with follow-up annealing treatment. The phase composition, morphology and ingredients of Cr2AlC coating specimen and TC4 titanium alloy before and after isothermal oxidation in air at 750 were investigated by XRD, SEM, EDS and raman spectro℃ scopy. The analytical balance was employed to measure oxidation kinetic curve of oxidized TC4 titanium alloy and Cr2AlC coating specimen in static air at 750 ℃. The results showed that nearly 13 μm thick flocculent Al2O3 and Ti O2 mixture oxide filmwas formed on the surface of TC4 titanium alloy after isothermal oxidation at 750 in air for 10 h. However, a compact ℃oxide film main consisting of α-（Al,Cr）2O3 was formed on the surface of Cr2AlC coating, it could prevent inward diffusion of oxygen element effectively. The oxidation weight gain of Cr2AlC coating specimen after isothermal oxidation at 750 in air ℃for 90 h was only 6.6% of that of the uncoated TC4 titanium alloy after isothermal oxidation at 750 in air for 10 h. Cr℃2Al C coating is provided with excellent high temperature oxidation resistance and can improve the operating temperature of TC4 titanium alloy significantly to reduce its rate of oxidation weight gain greatly.