摘要
目的 改善海洋环境下钛合金的耐腐蚀性能。方法 通过多弧离子镀技术在钛合金表面沉积CrN单层及CrN/Cr多层涂层。分析热腐蚀前后样品的表面形貌、截面形貌及腐蚀前后物相组成,探究NaCl诱导下钛合金及表面涂层的高温腐蚀损伤行为。结果 钛合金样品增重曲线呈先增加后降低(表面腐蚀层严重剥落所致)的趋势,腐蚀优先发生在β相及α/β相界处。相比之下,涂层样品的腐蚀增重较低。CrN/Cr涂层腐蚀期间出现剥落现象,且涂层表面形成了厚度为2~3μm的氧化层。经分析发现,表面氧化层的形成与涂层内部Cr元素向上扩散有关,并非完全是涂层表面的直接氧化。结论 涂层的应用改善了钛合金的力学性能和耐腐蚀性能。CrN/Cr涂层剥落与Cr元素在高温腐蚀环境下的热稳定性和化学稳定性较差有关。Cr元素的表面扩散现象破坏了涂层内部结构的完整性,成为加速涂层失效的重要原因之一。
Corrosion damage of titanium alloy in marine environments has been widely concerned.The application of protective coatings is the key to enhance its comprehensive properties.To improve the hot corrosion resistance of titanium alloy in marine environments,in this study,the Multi-arc Ion Plating technique is used to deposit CrN single layers and CrN/Cr multilayer coatings on the surface of titanium alloy.The hot corrosion damage behavior of titanium alloy and its surface coating induced by NaCl is investigated by the surface and cross-sectional morphology and phase composition of samples are analyzed before and after hot corrosion at 500℃for 60 h.The results show that the corrosion weight gain of titanium alloy is obvious,and the maximum weight gain is about 3.5 mg/cm^(2) after corrosion for 30 h.The weight gain curve shows a trend of first increasing and then decreasing(caused by severe spallation of the corrosion layer on the surface,and the weight gain is less than the amount of spalling).Moreover,it is found that theαandβphases have different corrosion sensitivities,and the corrosion preferentially occurs at theβphase and theα/βinterface.Compared with titanium alloy,the coating has a lower weight gain,and the corrosion resistance of the CrN coating is better.The corrosion of CrN coating mainly occurs in the large droplet inside the coating and the surrounding defects,forming corrosion holes,which further confirms the adverse effect of large droplets on the overall coating properties.It is worth noting that different from most nitride/metal multilayer coatings,the introduction of Cr layers reduces the corrosion resistance of the coating.After hot corrosion,the CrN/Cr coating appears interlayer corrosion cracking,and an oxide layer of about 2~3μm is formed on the surface.The analysis reveals that the surface oxide layer is related to the upward diffusion of Cr elements in the coating rather than by direct oxidation of the coating surface entirely.Surface diffusion of Cr elements in this high temperature corrosive environment leads to the depletion of Cr layer elements inside the coating and the formation of holes,which destroys the internal structural integrity of the coating.As the corrosion process progresses,the corrosion inhomogeneity within the coating becomes more serious.Due to the difference in molar volume and thermal expansion coefficient between the corrosion product and the coating itself,internal stress is induced,which becomes one of the main reasons for the accelerated coating failure.Therefore,it can be concluded that the peeling of the CrN/Cr coating is related to the poor thermal and chemical stability of the Cr element in a high-temperature corrosive environment.Besides,the application of the coating improves the hardness and load bearing capacity of titanium alloy.Compared with the CrN coating,the mechanical properties of the CrN/Cr multilayer coating are better,and the improvement of its performance is related to the obstruction of the dislocation movement by the multilayer structure.So,the mechanical properties and corrosion resistance of the coating should be considered comprehensively during service in the marine environment.
作者
栗荣枝
邓尕平
程从前
蒲吉斌
曹铁山
赵杰
LI Rongzhi;DENG Gaping;CHENG Congqian;PU Jibin;CAO Tieshan;ZHAO Jie(School of Materials Science and Engineering,Dalian University of Technology,Liaoning Dalian 116024,China;Ningbo Institute of Materials Technology and Engineering,Chinese Academy of Sciences,Zhejiang Ningbo 315201,China)
出处
《表面技术》
北大核心
2025年第14期26-36,共11页
Surface Technology
基金
国家自然科学基金(52325503,U21A200955)
浙江省‘尖兵’‘领雁’研发攻关计划(2022C01017)。
