摘要
目的提高高超声速飞行器用铌合金构件的高温抗氧化性能,拓展其在复杂服役环境中的应用范围。方法采用微弧氧化粒子(HfC+HfO_(2))沉积烧结技术,在渗硅铌合金表面制备HfC-HfO_(2)改性硅化物基复合涂层。通过1200℃下的静态空气氧化试验,研究复合涂层的高温氧化行为。采用扫描电子显微镜、X射线衍射仪和高分辨透射电镜研究复合涂层的组织结构、相成分,以及复合涂层在不同氧化时间下的微观结构演变规律。结果渗硅铌合金表面HfC-HfO_(2)粒子沉积层的厚度约为45μm。复合涂层在整个等温氧化过程中表现出最佳的抗氧化性,其质量增益仅为6.41 mg/cm^(2),抛物线速率常数为0.367 mg^(2)/(cm^(4)·h),而单一NbSi_(2)涂层则呈加速氧化的趋势,其质量增益达到13.6 mg/cm^(2)。结论将HfC作为耗氧相引入复合涂层,最终在高温下形成了HfSiO_(4)骨架结构,从而提高了氧化皮的稳定性,且富Hf氧化物锚定了SiO_(2)氧化皮,形成了致密的氧扩散阻挡层,显著减缓了铌氧化物的生长和裂纹的萌生,这是复合涂层具有优异高温抗氧化性能的主要原因。
Niobium alloy is one of the most promising candidate materials as the critical components of hypersonic vehicles due to its excellent high-temperature performance.However,poor high-temperature oxidation resistance is the major problem that needs to be solved for industrial applications at present because of the catastrophic oxidation of niobium alloy at high temperatures.Silicide coating is considered an effective method to broaden the engineering application of niobium alloys due to the formed dense oxygen shielding layer at high temperatures.However,the thermal growth stress will continue to accumulate when the silicide coating is exposed to air at high temperatures,greatly restricting the long-term service.It is proven that a novel coating with altered chemical compositions and functionalities can be prepared by the micro arc oxidation technique with the functional particle incorporated into the electrolyte.The work aims to propose a micro arc oxidation particle deposition sintering technology by introducing HfC-HfO_(2)nanoparticles,forming a multilayer ceramic protective coating on the siliconized niobium alloy.Nb521 alloy sheet with a nominal composition of Nb-5W-2Mo-1Zr was cut into 10 mm×10 mm×1 mm by wire cutting and polished with SiC sandpaper.Then,the NbSi2 bottom layer was obtained by HAPC treatment on Nb521 alloys.The polished samples were buried in a mixture powder of Si,NaF,and Al2O3,with a weighted ratio of 16∶5∶9.HAPC treatment was in a vacuum atmosphere furnace with the argon shield,heated from room temperature to 1300℃at a heating rate of 5℃/min,and held for 8 h.HfC-HfO_(2)outer layer was deposited on the NbSi2 layer by micro arc oxidation particle deposition sintering technology,which was carried out on a double electrodes system with the AC power facility.The NbSi2 coated sample acted as the anode,while the cathode was the stainless steel sheet.The used electrolyte consisted of Na2SiO3(15 g/L),(NaPO3)6(6 g/L),NaOH(1.2 g/L),HfC particles(20 g/L)and HfO_(2)particles(10 g/L)with a size of 500 nm,completely dispersing in the distilled water.The electrical parameters were set to a frequency of 600 Hz,a duty cycle of 10%,a voltage of 600 V,and an optimized applied time of 11 min.All the samples were subject to isothermal oxidation tests by a muffle furnace(KSL-1700X)at 1200℃in air to evaluate the high-temperature oxidation resistance.A scanning electron microscope(SEM,Helios Nanolab600i,FEI,U.S.A.)equipped with an energy dispersive spectrometer(EDS),and a transmission electron microscope(TEM,Talos F200x,FEI,U.S.A.)were used to characterize the microstructures of the coatings.An X-ray diffractometer(XRD,Empyrean,PANalytical,Netherlands)was used to analyze the phase composition.The thickness of the HfC-HfO_(2)particle deposition layer on the siliconized niobium alloy surface was approximately 45μm.The composite coating demonstrated optimal oxidation resistance throughout the isothermal oxidation process,with a mass gain of only 6.41 mg/cm^(2)and a parabolic rate constant of 0.367 mg^(2)/(cm^(4)·h).In contrast,a single NbSi_(2)coating exhibited accelerated oxidation,with a mass gain of 13.6 mg/cm^(2).The incorporation of HfC as an oxygen-consuming phase in the composite coating ultimately formed the HfSiO4 skeletal structure at high temperatures,enhancing the stability of the oxide scale.Additionally,Hf-rich oxides anchored the SiO_(2)oxide scale,forming a dense oxygen diffusion barrier layer,which significantly suppressed the growth of niobium oxides and crack initiation.
作者
叶志云
郭锦恒
吾可来·德艾吾勒特
姜雨桐
周锦博
陈远哲
王小龙
王树棋
王亚明
YE Zhiyun;GUO Jinheng;WUKELAI Deaiwulete;JIANG Yutong;ZHOU Jinbo;CHEN Yuanzhe;WANG Xiaolong;WANG Shuqi;WANG Yaming(State Key Laboratory of Precision Welding&Joining of Materials and Structures,Harbin Institute of Technology,Harbin 150001,China;Institute for Advanced Ceramics,Harbin Institute of Technology,Harbin 150001,China;Key Laboratory of Advanced Structure-Function Integrated Materials and Green Manufacturing Technology,Harbin Institute of Technology,Harbin 150001,China)
出处
《表面技术》
北大核心
2025年第15期24-32,共9页
Surface Technology
基金
国家自然科学基金(523B2010,U21B2053)。
关键词
渗硅铌合金
微弧氧化
复合涂层
高温抗氧化
siliconized niobium alloy
micro arc oxidation
composite coating
high-temperature oxidation resistance
作者简介
通信作者:王亚明。
