Cr18Ni30Mo2Al3Nb合金的高温抗氧化性能

采用称重法测得Cr18Ni30Mo2Al3Nb合金在不同温度下的高温氧化动力学曲线。结果表明,该合金的氧化曲线遵循抛物线氧化规律,具有优良的抗氧化性能。利用扫描电镜、X射线衍射的方法对氧化膜表面形貌及结构进行研究,该合金在3个温度下氧化膜完整致密,700℃氧化膜主要由Fe和Cr的混合氧化物(Fe0.6Cr0.4)2O3和少量Al的氧化物组成;800℃氧化膜主要是Al和Cr的混合氧化物(Al0.9Cr0.1)2O3和少量Al2O3及少量Fe的氧化物;900℃氧化膜主要是(Al0.9Cr0.1)2O3和Al的氧化物,还含有少量Fe(Cr,Al)2O4和MnFe2O4。     

含铝奥氏体耐热钢的高温氧化性能

以Fe-18Cr-30Ni为基础,添加不同含量的Al设计了4组新型奥氏体耐热钢。利用氧化质量增加法研究了4组新型奥氏体耐热钢在700、800和900 ℃下空气中的氧化行为,绘制了氧化动力学质量增加曲线,并利用XRD、SEM和EDS对氧化膜的表面形貌及结构进行了表征。结果表明,1～3号钢在900 ℃时均形成了较为致密的Al2O3内层氧化膜,合金表面生成的复合氧化膜由内到外依次为 Al2O3、(Al0.9Cr0.1)2O3、尖晶石氧化物Fe(Cr, Al)2O4;1号钢氧化过程中还形成了富（Cr, Fe）的混合氧化物,降低了Al2O3氧化膜的连续性;4号钢900 ℃并没有形成致密的Al2O3内层氧化膜,生成的复合氧化膜由内到外依次为 (Al0.9Cr0.1)2O3、尖晶石氧化物Fe(Cr, Al)2O4。     

Fe-30Mn-9Al奥氏体钢高温循环氧化特征

研究了Fe-30Mn-9Al奥氏体钢在700℃、800℃和950℃空气中循环氧化160 h表面形成的氧化膜形貌、成分和组织结构.Fe-30Mn-9Al奥氏体钢在700℃和800℃氧化时,初期增重较快,随着循环次数增加,氧化增重减小,氧化160 h分别增重1.00和4.08 mg/cm2.氧化层主要由Mn2O3,Al2O3和(Mn,Fe)2O3等相组成.在950 ℃,钢的氧化增重显著上升,160 h增重43.50 mg/cm2,表面形成了Fe2O3、MnO2以及MnAl2O4、Al2Fe2O6等复合氧化物.800℃下循环氧化后形成了多层氧化物膜 ,外层以Mn2O3型氧化物为主,内层以Al2O3为主;钢基体表面为 富Fe、贫Mn的铁素体层.      

新型Cr18Ni31Al合金的高温抗氧化性能

利用氧化增量法测得新型Cr18Ni31Al合金的不同温度下的高温氧化动力学曲线,使用X射线衍射仪(XRD)、扫描电镜(SEM)和能谱仪(EDS)对合金表面高温氧化膜的形貌及组成进行了分析和检测。结果表明,新型Cr18Ni31Al合金的高温氧化动力学曲线为Δm=atn。700℃和800℃氧化后,氧化膜均由Fe2O3和NiCr2O4组成;900℃氧化后,氧化膜表面有尖晶石结构的Fe(Cr,Al)2O4氧化物生成。     

铝硅复合对Fe32Mn7Cr3Al2Si钢氧化改性层耐蚀性的影响

利用XRD、EPMA、阳极极化和电化学阻抗技术研究了铝硅复合合金化对Fe32Mn7Cr3Al2Si钢高温氧化诱发转变层的组织、成分及电化学腐蚀性能影响.在700和800℃空气中对Fe32Mn7Cr3Al2Si奥氏体钢进行循环氧化表面改性,形成的氧化层由内层Al2O3、中间层Mn2SiO4,外层Mn2O3组成.经800℃...     

热轧退火态430不锈钢的高温抗氧化性能

研究了热轧退火态的430铁素体不锈钢在700~900℃的高温氧化行为,测量了其恒温氧化增重曲线,利用扫描电镜(SEM)和能谱仪(EDS)观察分析了氧化表面形貌和组成,使用X射线衍射仪(XRD)鉴定了氧化物的种类。结果表明:在700℃生成的Cr2O3氧化膜不足以覆盖基体,材料氧化缓慢;800℃时氧化速率相对较大,生成的氧化物主要为Cr Mn1.5O4和Fe2O3;900℃时氧化十分迅速,材料表面有大量Fe2O3突起;退火温度对材料高温氧化性能影响不大。     

真空荧光显示屏阵列材料氧化过程的研究

研究了真空荧光显示屏阵列材料FeNi42Cr6合金在高温湿氢气氛中的氧化行为。其氧化过程为：首先形成Cr2O3，然后(Fe,Mn)Cr2O4氧化物形核、生长，形成完整氧化膜，成熟氧化膜由颗粒状刚玉型氧化物Cr2O3和块状尖晶石型(Fe,Mn)Cr2O4氧化物组成。实验同时表明，阵列板电阻率随氧化膜厚度增加而增大，电阻率过高会导致与之焊接的Ni丝熔断，氧化膜厚度应控制在1μm～2μm。借助扫描电镜、X射线衍射研究了氧化时间、氢气流量、氢气露点等工艺参数对阵列板氧化增重、氧化膜相结构及、氧化膜表面形貌的影响。得出氧化温度为950℃，时间40min～60min，氢气露点(dp)35℃，流量8L／mm为最佳阵列材料氧化工艺。     

二元双相Cu-50Cr合金在700─900℃空气中的氧化

Cu－50Cr合金在700—900℃空气中的氧化结果表明,合金的氧化动力学在700和800℃遵循抛物线速度规律,在900℃其瞬时抛物线速率常数随时间而降低．合金氧化外层膜是CuO和Cu2O,内层膜由氧化铜和尖晶石型氧化物为基并嵌有Cr颗粒组成,Cr表面有Cr2O3和Cu2Cr2O4膜。900℃的氧化膜与基体金属界面上可观察到连续的Cr2O3层.合金未形成Cr的选择性外氧化．     

含铝奥氏体耐热钢的高温抗氧化性能

以Fe-18Cr-30Ni为基础,添加不同含量的Al设计了4组新型奥氏体耐热钢。利用氧化质量增加法研究了4组新型奥氏体耐热钢在700、800和900℃下空气中的氧化行为,绘制了氧化动力学质量增加曲线,并利用XRD、SEM和EDS对氧化膜的表面形貌及结构进行了表征。结果表明,1~3号钢在900℃时均形成了较为致密的Al2O3内层氧化膜,合金表面生成的复合氧化膜由内到外依次为Al_2O_3、(Al_(0.9)Cr_(0.1))_2O_3、尖晶石氧化物Fe(Cr,Al)_2O_4;1号钢氧化过程中还形成了富(Cr,Fe)的混合氧化物,降低了Al_2O_3氧化膜的连续性;4号钢900℃并没有形成致密的Al_2O_3内层氧化膜,生成的复合氧化膜由内到外依次为(Al_(0.9)Cr_(0.1))_2O_3、尖晶石氧化物Fe(Cr,Al)_2O_4。     

新型含铝奥氏体耐热钢高温氧化行为

对新型含铝奥氏体耐热钢分别在700、800和900℃下进行了循环氧化试验,并采用增重法研究了高温氧化动力学曲线,结合扫描电镜(SEM)、能谱分析(EDS)、X射线衍射(XRD)和X射线光电子能谱仪(XPS)系统地表征氧化膜层的元素、结构和形态。结果表明:该新型耐热合金氧化动力学曲线遵循抛物线规律; 700℃氧化膜主要由C_r2O_3和Fe_2O_3的混合氧化物与少量Al_2O_3构成;800和900℃氧化膜由内层的Al_2O_3和亚表层的(Cr,Al)_2O_3与表层的尖晶石结构的Fe(Al,Cr)_2O_4构成。     

Oxidation characteristics of Ti-25Al-10Nb-3V-1Mo

Static oxidation kinetics of Ti-25Al-10Nb-3V-1Mo (atomic percent) were investigated in air over the temperature range of 650–1000°C using thermogravimetric analysis. The oxidation kinetics were complex at all exposure temperatures and displayed up to two distinct stages of parabolic oxidation. Breakaway oxidation occurred after long exposure times at high temperatures. Oxidation products were determined using x-ray diffraction techniques, electron microprobe analysis, and energy dispersive x-ray analysis. Oxide scale morphology was examined using scanning electron microscopy of the surfaces and cross-sections of oxidation specimens. The oxides during the parabolic stages were compact and multilayered, consisting primarily of TiO₂ doped with Nb, a top layer of Al₂O₃ and a thin bottom layer of TiN. The transition between the first and second parabolic stage is linked to the formation of a TiAl layer at the oxide-metal interface. Porosity also formed in the TiO₂ layer during the second stage, causing degradation of the oxide and breakaway oxidation.     

An examination of the mechanisms involved in the oxidation of the aligned eutectic alloy Ni3Al-Ni3Nb

The aligned eutectic alloy Ni₃Al -Ni₃Nb at 1155°C exhibits an initial very rapid rate of oxidation which rate eventually decreases to a very significantly lower level. This decrease in the rate of oxidation has been shown to be associated with the formation of an aluminum oxide layer. The work reported here was conducted to determine both how such a layer forms in oxidation at 1155°C as a function of time and which elements are the active diffusing species in the oxidation process.     

High-temperature oxidation of Ti3Al−Nb alloys

Titanium aluminide (Ti₃Al–Nb) has potential for high-temperature applications because of its low density and high-temperature strength. This research is aimed at improving the high-temperature oxidation resistance of a Ti₃Al–Nb alloy by modification of its composition. The oxidation rates of Ti₃Al–Nb alloys were measured from 600 to 900°C in air. The oxide layer was examined by X-ray diffraction, scanning electron microscopy, and electron probe microanalysis. The experimental results reveal that alloys with added Nb tend to form denser oxide layers and that oxidation rate can be reduced by increasing Nb content (up to 11 at.% in this study), which is in good agreement with other investigators. The only exception is a Ti₆₅Al₂₅Nb₁₀ alloy, which shows better oxidation resistance than the commercial Ti₆₅Al₂₄Nb₁₁ alloy. The oxidation resistance of Ti₆₅Al₂₅Nb₁₀ alloy can also be improved slightly by the addition of small amounts of Si or Cr. An increase in the oxidation resistance of Ti₆₅Al₂₅Nb₁₀ alloy containing Y was observed at 900°C but not at 800°C or below. The parabolic oxidation rate equation is adequate to describe the high-temperature oxidation reaction of the Ti₃Al–Nb alloys in the atmosphere.     

INTERNAL OXIDATION OF Fe_3Al DURING HIGH TEMPERATURE OXIDATION

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Influence of Superficial Y2O3 Coatings on High-Tempera- ture Oxidation of Ni

在Ni基体上制备了Y2O3涂层, 并对其如何影响Ni在900 ℃的氧化性能进行了研究。作为对比,采用相同的工艺在Ni基体上制备了CeO2涂层。900 ℃下恒温氧化表明： Y2O3或CeO2对Ni的氧化机理没有影响;但与CeO2相比,Y2O3在降低Ni的氧化速度上有更强的作用。此外Y2O3和CeO2涂层的厚度也对Ni的氧化影响不明显。对Y2O3或CeO2如何影响Ni的氧化性能进行了分析     

Ti3Al基合金在700～850℃空气中的循环氧化行为

研究了2种成分相近的Ti3Al基合金(Ti-24Al-14Nb-3V-0.5Mo-0.3Si(摩尔分数)及Ti-24Al-14Nb-3V-0.5Mo-0.6Si在700～850℃空气中的循环氧化行为;重点考察了合金的循环氧化动力学行为;结合SEM/EDX及EPMA分析了循环氧化后样品的表面、断面微观形貌及断面成膜元素面分布.结果表明:2种合金在各氧化温度下表面生成了Al2O3和TiO2混合氧化物,Al2O3主要分布在最外层;在700℃下2种合金具有较好的抗循环氧化性能,而在800℃及以上的温度条件下,表面氧化膜易于开裂和剥落;合金在较高温度下表面氧化膜失效方式为膜层中微裂纹的复合及由于这一过程的反复进行而导致的氧化膜间物理分层开裂.     

Oxidation Resistance of Ti5Si3 and Ti5Si3Zx at 1000°C (Z = C,N, or O)

The oxidation behavior of Ti₅Si_3+y (y=0 or 0.2) and Ti₅Si₃Z_x (Z=C, N or O, x=0.25 or 0.5) was studied at 1000°C in air or argon–oxygen mixtures for up to 500 h. Ti₅Si₃ has poor oxidation resistance in air because of the formation of an oxide scale rich in rutile and subscale formation of TiN, TiSi, TiSi₂ and Si. In contrast, Ti₅Si_3.2 has excellent oxidation resistance because of the formation of a silica scale. Samples with interstitial oxygen or nitrogen show only slight improvements in the early stages of oxidation, compared to Ti₅Si₃, which is in stark contrast to previous research. However, samples with interstitial carbon displayed excellent oxidation resistance at 1000°C, consistent with previous research.     

CORRELATION BETWEEN OXIDATION BEHAVIOUR AND BORON CONTENT IN Ni_3Al3

The effect of boron content(0 to 2.22 at.-% )on isothermal oxidation behaviour of Ni_3Al at750 to 1150℃ for 3 to 100 h has been studied.The results show that the isothermal oxidationkinetics of Ni_3Al with various B contents at different temperatures obeys the parabolic law.The compounds with 0.52 to 1.37 at.-%B show the best oxidation resistance.The morphologyand microstructure of the scales have also been investigated.