碳氮比对Ti(C,N)粉末抗氧化性的影响

本文对不同碳氮比Ti(C,N)固溶体粉末分别进行了等温氧化和非等温氧化,通过TG-DSC热分析、氧化动力学分析和物相分析,研究了碳氮原子比对Ti(C,N)粉末氧化行为的影响。Ti(C,N)粉末在O2气流中从室温加热至1 000~1 200℃的非等温氧化,以及在650℃的静置空气中的等温氧化。结果表明,Ti(C,N)粉末在非等温氧化过程中,氧化过程可分为2个阶段或3个阶段,第1氧化阶段氧化脱氮占主导地位,第2氧化阶段氧化脱碳占主导地位,Ti(C0.5,N0.5)粉末表现出最优的抗氧化性能。在650℃的等温氧化中,Ti(C,N)粉末氧化遵循随机形核动力学模型,Ti(C0.7,N0.3)具有最小的一阶速率常数,表现出最优的抗氧化性能。初始氧化固体产物为锐钛矿结构TiO2,随氧化时间延长,逐渐向金红石结构TiO2转变。     

Ti—Al—N薄膜的性能及应用

利用多弧离子沉积技术在W18Cr4V高速钢表面沉积（Ti,Al）薄膜,实验结果表明（Ti,Al）N薄膜的硬度和抗氧化性能明显优于TiN薄膜,（Ti,Al）N膜层刀具的寿命大大高于TiN膜层刀具。     

钛合金高温玻璃—陶瓷保护涂料的研究

开发出一种用于高温钛合金热加工条件下的防氧化玻璃－陶瓷保护涂料，该涂料是以硼铝硅酸盐玻璃为主体，加入有机粘结剂，用水做溶剂，配制而成的水悬浮液。讨论和研究了由该涂料在高温条件下形成涂层，以及涂层对钛合金保护作用的机理和涂料配方的设计原则。通过能谱（EDS）和恒温增重的分析，比较了有涂层保护和无涂层保护钛合金片表面氧含量的差异，表明了所制备的玻璃－陶瓷涂料在高温下对钛合金有很好的保护作用。     

颗粒补强Al2O3／SiC／（W,Ti）C复相陶瓷刀具材料的氧化行为与强度特性

研究了颗粒补强Al2O3/SiC/(W,Ti)C复相陶瓷刀具材料的纤为及其对材料抗弯强度的影响,结果表明：该材料在空气中静态氧化时的氧化增重符合抛物线规律,随弥散相SiC和（W,Ti)C的增加,其氧化活化能有不同程度的降低,由于SiC的添加,使得氧化膜在高温下能以粘性流动的方式缓解残余应力,降低氧化速度,从而使得材料的抗氧化性能有所提高,此外,适当的氧化处理可使Al2O3/SiC/(W,Ti)C陶瓷刀具材料的抗弯强度得到提高。     

钛铝基合金渗硅层结构及抗高温氧化性能初探

研究了钛铝基合金固体渗硅后的渗层结构、抗高温循环氧化性能。结果表明：钛铝基合金固体渗硅后表层形成主要由Ti5Si3、Al3O3和Al3Ti、TiSi2、Si构成的复合渗层，该复合渗硅层有效阻止了高温氧化过程的进行，显著提高了钛铝基合金的抗高温循环氧化能力。     

High-Temperature Oxidation Behavior of Laser-Surface-Alloyed Ti with Si and Si + Al

This study concerns an attempt to enhance the resistance to high-temperature isothermal and cyclic oxidation of Ti in dry air by laser-surface alloying (LSA) with Si and Si+Al. LSA was carried out by codeposition of alloy powders during lasing under the predetermined, optimum-processing routine that ensured formation of a compact, well-adherent, crack-free and homogeneous alloyed zone. The results of oxidation kinetics in the temperature range 950–1150 K for 1–400 hr indicate that surface alloying with Si imparts excellent oxidation resistance up to 1050 K. However, at a higher temperature of 1150 K, surface alloying with 3Si+Al yields a better resistance to oxidation. A detailed characterization of the microstructure and distribution of the phases within the scale and alloyed zone following oxidation studies has been undertaken to suggest the possible mechanism for enhanced oxidation resistance of Ti imparted by laser-surface alloying.     

Ti65合金磷酸盐涂层抗高温氧化性能研究

目的通过表面涂层提高高温钛合金Ti65的抗高温氧化性能。方法采用喷涂法在Ti65合金基体上制备以磷酸铝为粘结剂、Al和Al/SiC为填料的两种磷酸盐抗高温氧化复合涂层。研究Ti65合金和涂层样品在650℃准等温、静态空气条件下的氧化动力学行为。用XRD和SEM/EDS分别对涂层样品氧化前后的物相组成、组织形貌和微区成分进行表征分析;用电子探针(EPMA)分析涂层样品的元素分布情况。结果650℃抗高温氧化实验结果表明,磷酸盐涂层样品的准等温氧化动力学曲线均符合抛物线规律,两种涂层样品的抛物线氧化速率常数kp分别为3.922×10^-2、1.768×10^-2 mg/(cm^2·h^1/2)和2.48×10^-2、3.385×10^-4 mg/(cm^2·h^1/2),均小于Ti65合金,氧化增重显著降低。以Al/SiC为填料的磷酸铝涂层的抗氧化性能最好,氧化1000 h,质量增加0.20 mg/cm^2,约为Ti65基体氧化增重(1.13 mg/cm^2)的1/6。微观分析结果表明,两种磷酸盐涂层样品在650℃准等温氧化后,涂层与基体形成扩散层,生成TiAl3金属间化合物,涂层表面均保持完好,没有裂纹和孔隙,有效阻止了氧元素向Ti65基体的扩散,保护基体不受氧化。结论磷酸盐涂层能有效阻止650℃温度下氧向Ti65合金基体的扩散,具有优异的抗高温氧化性能。     

热氧化处理对钛合金表面耐磨性能影响的研究

为研究热氧化工艺对钛合金表面耐磨性的影响,提高钛合金的表面硬度和耐磨性能,采用热氧化处理技术在钛合金表面生成热氧化陶瓷层,借助电子探针、X衍射仪对热氧化层进行了成分和结构分析.采用MRH-3型高速滑块磨损试验机,在润滑务件下对经热氧化处理和未处理的Ti6Al4V合金耐磨性进行滑动一滚动试验.结果表明:热氧化后的Ti6Al4V合金的磨损量明显减少,该热氧化处理方法能显著增强Ti6Al4V合金的耐磨性.根据试验结果和系统分析,讨论了热氧化处理后材料的摩擦磨损机制.     

The influence of Y,Zr or Ti additions on the high temperature oxidation resistance of Fe-Ni-Cr-Al alloys of variable purity

The influence on oxidation behaviour of both minor elements, such as Si and Mn, and of deliberate small additions of Y, Zr or Ti, has been studied in an austenitic Fe-Ni-Cr-Al alloy. During oxidation, this material develops an inner layer of alumina and an outer layer of Cr₂O₃ and spinels. Y enhances oxidation resistance by promoting alumina formation, decreasing the weight gain under isothermal conditions and improving oxide adherence during temperature cycling. Zr, when added alone, has little effect but produces an additional amelioration in spalling resistance when combined with Y. To a minor extent, Si also appears to have a favourable effect, whereas Ti and Mn, which concentrate in the outer oxide layer, tend to accentuate spinel formation and enhance spalling under cyclic conditions. The stress level measured by deflection during isothermal oxidation is in general agreement with the behaviour under temperature cycling conditions. It is attempted to explain some of these observations on the basis of diffusion mechanisms within the oxide.     

Oxidation of Mechanically Alloyed Al-rich Al–Ti Powders

The oxidation behavior of Al-rich, metastable mechanically alloyed powders in the Al–Ti binary system has been examined in the context of their potential application in high-energy-density materials. Scanning calorimetry and thermogravimetric analysis in an oxygen atmosphere up to 1500°C have been performed on powders, synthesized with compositions ranging from Al_0.95Ti_0.05 to Al_0.75Ti_0.25. Oxidation proceeds in three distinguishable steps, similar to the oxidation steps observed for pure aluminum. The steps become less pronounced with increasing Ti concentration. For both the first and second oxidation steps, the apparent activation energies are close to 400 kJ/mol. Partially oxidized material was recovered from intermediate temperatures for quantitative phase analysis by X-ray diffraction, Al₂O₃ and TiO₂ are the main oxidation products. Similarly to pure aluminum, metastable γ-alumina is present at temperatures below ∼ 1000°C, suggesting that the stepwise oxidation is related to phase transitions of the alumina in the oxide scale. At temperatures above 1300°C, oxidation follows melt formation in the binary Al–Ti system, as the aluminum component oxidizes selectively, leaving a titanium-rich metallic residue. No correlation was observed between the oxidation and melting of aluminum.     

热浸镀铝钢材的抗高温氧化性能

将经热浸镀铝处理后的A3钢,在相同条件下与1Cr18Ni9Ti奥氏体不锈钢进行了高温抗氧化性能对比试验,结果表明.A3钢经热浸镀铝后,其抗高温氧化性能可与1Cr18Ni9Ti不锈钢相比     

Effect of Ti on aluminide coating for DZ40M alloy

The effect of Ti on the aluminide coating has been investigated for a new Co‐base superalloy DZ40M. The results showed that the addition of Ti into aluminiser could reduce the permeation of Al into the substrate, and quicken the oxidation and degradation of the coating.     

In-Service Oxidation and Microstructural Evolution of a Nickel Superalloy in a Formula 1 Car Exhaust

The oxidation response and microstructural evolution of an Inconel 625 alloy exhaust manifold exposed to an automobile racing environment has been examined using a range of advanced electron microscopy-based techniques, atom probe tomography and high-sensitivity laser ablation mass spectrometry. The dynamic, corrosive gas conditions result in accelerated oxidation, with the inner exhaust surface also heavily contaminated by multiple species including Zn, P, K and Na. Nb carbides and Ti nitrides identified in stock control samples evolve into mixed (Ti, Nb)N species during exposure, decorated by smaller Mo, Si-rich precipitates. The exposed alloy component therefore reveals unique surface and subsurface features following in-service use.     

Surface protection of titanium and titanium–aluminum alloys against environmental degradation at elevated temperatures

Experiments have been undertaken to explore the possibility of creating an oxygen barrier coating, which is effective in preventing oxidation and oxygen embrittlement of Ti and several low-Al content Ti-base alloys during exposure to oxidizing environments at elevated temperatures. The fabrication process has involved three steps, namely co-deposition of Ti and Al by magnetron sputtering onto a substrate material to be protected, followed by vacuum annealing and plasma immersion ion implantation of fluorine. The first two steps produce an overlay of γ-TiAl while the last step provides the necessary conditions for bringing about the halogen effect upon subsequent high-temperature oxidation. Analysis techniques such as cross-sectional transmission electron microscopy (XTEM) in conjunction with electron energy loss spectroscopy (EELS), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and elastic recoil detection (ERD) have been used to study the microstructure, phase formation and depth distribution of the elements in the coating material. Following oxidation in air at 600 °C for 100 h, specimens have been prepared for metallographic analysis, and their cross sections have been characterized by scanning electron microscopy (SEM) in combination with EDX, and electron probe microanalysis (EPMA). The results obtained show that during oxidation exposure the coating is capable of forming a protective alumina-containing scale which serves as an oxygen barrier, thereby preventing oxygen embrittlement. In addition, since the only constituents of the coating are Ti and Al, it exhibits excellent chemical substrate compatibility.     

Ti_3Al氧化行为的电子理论研究

根据固体与分子经验电子理论分析计算了氧作用下Ti3Al合金各相的价电子结构.结果表明,Ti3Al固溶氧使其键结构呈更严重的各向异性,导致Ti3Al脆性加剧;在氧含量较高时,氧化物TiO2的形成将导致更加恶劣的脆性,而形成最强键nA较大、热稳定性较高的Al2O3将会有好的抗氧化性.进而也提出了一些提高Ti3Al抗氧化性的合金化途径.     

Early high-temperature oxidation behavior of Ti(C,N)-based cermets with multi-component AlCoCrFeNi high-entropy alloy binder

The early high-temperature oxidation behavior of Ti(C,N)-based cermets with equiatomic AlCoCrFeNi high-entropy alloy binder has been studied, as well as the cermet with Ni/Co binder as a reference. Experiments were performed at the temperature range of 800–1100 °C in static laboratory air. The micro-structural evolution of the multi-layered oxide scales on the cermets was investigated and the effect of binder phase constituent on the oxidation characteristics of Ti(C,N)-based cermets was evaluated. The results demonstrated that the cermet with AlCoCrFeNi multi-element alloy binder possesses superior oxidation resistance, which is greatly better than that of the cermet with Ni/Co metallic binder under the same condition. We suggest that the formation of a continuous and dense external oxide scale can effectively impede the outward diffusion of volatile tungsten oxides and inward oxygen transport, leading to a remarkable improvement of oxidation resistance. In addition, the enhanced oxidation resistance was related to the high Cr and Al concentration in AlCoCrFeNi binder phase that urges the formation of oxide layers with more efficient passivation effect against oxidation.     

Ageing effect in nanocrystalline TiCx/C studied by EPR

TiC/C nanocrystalline material: titanium carbide TiC dispersed in a carbon matrix has been prepared by a nonhydrolytic sol–gel process. Temperature dependence of the electron paramagnetic resonance (EPR) spectra of this material has been studied in the 3.5–120 K range. Two very different EPR lines have been recorded in fresh sample at temperatures below 120 K arising from the Ti(III) complex (broad and asymmetric line) and conduction electrons (very narrow line). In the same aged sample (1 year old) the magnetic anisotropy of Ti(III) line has increased while a narrow line attributed to conduction electrons has vanished. The existence of the paramagnetic centers connected with trivalent titanium ions could the result of disordering processes. The increase of anisotropy in Ti(III) line could be connected with the oxidation processes. The temperature dependence of the integrated intensity of the broad line revealed the presence of titanium antiferromagnetic dimers. The disappearance of a narrow EPR line suggests that the oxidation process (ageing effect) could influence also the electrical properties of titanium carbide.     

纯钛TIG焊接接头的高温氧化行为

对纯钛氩弧焊焊接接头在550 ℃下氧化不同时间（2,4,6,8 h）以及在不同温度（650,750,850,950 ℃）下氧化4 h的氧化动力学、氧化形态和氧化产物进行了研究。结果表明,在550 ℃下,氧化时间对焊接接头氧化行为的影响有限,而氧化温度对纯钛焊接接头的氧化行为有显著影响,且温度越高,氧化越严重。在低温下,纯钛焊接接头的氧化动力学接近准线性定律,随着温度升高,氧化速率呈指数增长。此外,焊接接头表面产生的氧化产物是具有锐钛矿和金红石结构的TiO₂,温度对TiO₂的类型没有明显影响。纯钛焊接接头的氧化过程可描述为：氧气在表面被吸收;氧化物优先在缺陷区形核;氧化物横向生长、增厚。在较高温度下,氧化膜中出现裂纹或空隙,成为O原子传输通道,导致O和Ti原子的高扩散速率和氧化速率。     

合金元素对Ni基高温合金1223K氧化行为的影响

研究了不同Cr、Ti、Ta含量定向凝固Ni基高温合金的1223 K恒温氧化行为。结果表明：Cr、Ti、Ta对合金的抗氧化性能在氧化的不同阶段作用各异。在氧化初期,由于Ti元素与O的亲和力很强,Ti含量高的No.3合金在氧化曲线上增重较为明显,而随着氧化的进行,Cr含量高的No.1合金增重较大,这是由于Cr的选择性氧化所致。在1223 K,No.1合金中Ti和Ta含量较低无法形成有效弥散分布于Cr2O3之中,难以形成连续的保护性氧化膜,从而不能有效地阻碍Cr3＋向合金内部持续扩散。而No.2和No.3合金中Ti和Ta含量适中,形成连续膜可延缓Cr3＋的持续向外扩散,对改善合金的抗氧化能力有积极作用。     

Effect of Cr, Nb, Mn, V, W and Si on high temperature oxidation of TiAl alloys

Alloys of Ti−(47,51)Al, Ti47Al−4Cr, Ti48Al−2Cr2Nb, Ti47Al−1Mn, Ti39.4Al−10V, Ti48.4Al−1.9W, and Ti43Al−2W0.1Si were oxidized at temperatures between 800 and 1000 °C in air to determine the effect of each alloying element on oxidation behavior. Among the alloys tested, the Ti48.4Al-1.9W alloy displayed the best oxidation resistance, due to the beneficial effects of W, whereas the Ti39.4Al-10V alloy displayed the worst oxidation resistance, due to the formation of volatile V-oxides. Cr was harmful while Nb was beneficial. The oxidation rate of each alloy was not strictly proportional to temperature, because each alloying element had different temperature sensitivity with respect to oxidation rate.