原子结合能测量法研究稀土氧化物对α—Al2O3膜氧化动力学的…

在１１００℃恒温氧化条件下，研究了稀土氧化物ＣｅＯ２，Ｇｄ２Ｏ３对ＮｉＡｌ基上形成的α－Ａｌ２Ｏ３膜的生长速率及其粘附性等氧化动力学参数的影响，并在此基础上采用ＳＩＭＳ测量二次离子流强度与阻止电压曲线方法，研究了Ａｌ２Ｏ３膜内及Ａｌ２Ｏ３／ＮｉＡｌ基界面处Ａｌ、Ｎｉ原子间结合能的变化规律。实验结果表明，稀土氧化物存在于氧化膜的晶界等处，具有促进氧化膜的晶粒间“微烧结”作用面提高了原子间的结合能。同     

3种锆合金的高温氧化行为

对Zr-A和Zr-B锆合金在700-1200℃的O_2中进行了等温氧化实验,观察了合金的氧化动力学行为和基体微观结构演变,并与低Sn的Zr-4合金作了对比.结果表明,700—1200℃氧化时,3种锆合金的动力学曲线基本服从抛物线规律,Zr-B合金在700℃氧化1200 s后速率出现转折;800℃时Zr-A和Zr-B合金的氧化速率出现转折;1000℃时3种合金动力学曲线由抛物线变为近似直线;1100℃以上氧化时,动力学曲线呈抛物线规律,未出现转折.在1100℃以上氧化时,合金成分对3种合金的高温氧化性能影响甚微.依据氧化增重数据得到了3种合金在700—1200℃氧化反应的抛物线速率常数K_p的表达式.     

原子结合能测量法研究稀土氧化物对α－A1_2O_3膜氧化动力学的影响

在１１００℃恒温氧化条件下，研究了稀土氧化物ＣｅＯ２，Ｇｄ２Ｏ３对ＮｉＡｌ基上形成的α－Ａｌ２Ｏ３膜的生长速率及其粘附性等氧化动力学参数的影响，并在此基础上采用ＳＩＭＳ测量二次离子流强度与阻止电压曲线方法，研究了Ａｌ２Ｏ３膜内及Ａｌ２Ｏ３／ＮｉＡｌ基界面处Ａｌ、Ｎｉ原子间结合能的变化规律。实验结果表明，稀土氧化物存在于氧化膜的晶界等处，具有促进氧化膜的晶粒间“微烧结”作用而提高了原子间的结合能。同时，还从稀土氧化物的化学性质出发，研究了稀土氧化物种类对氧化动力学产生不同影响的作用机制。     

Zr-Nb-Cu合金高温水蒸气氧化动力学研究

研究了Zr-Nb-Cu合金微观组织及其在700~1000℃范围等温水蒸气氧化动力学,并分析了氧化膜宏观形貌与微观组织演变规律。结果表明,Zr-Nb-Cu合金水蒸气氧化增重曲线在700~900℃范围内服从抛物线规律,在1000℃时曲线偏离抛物线规律;根据氧化增重曲线,计算了合金水蒸气氧化激活能Q、抛物线速率常数K p和氧化增重W的表达式。氧化膜组织分析结果显示,氧化温度越高,氧化膜开裂和鼓起也越明显。     

三相Cu—Ni—30Cr合金高温氧化行为研究

研究了Cr含量相对较高的Cu—Ni—30Cr合金在700℃-800℃，0．1MPa纯氧气中的氧化行为。结果表明：合金氧化动力学较复杂，其瞬时抛物线速率常数随时间而降低，氧化动力学曲线通常不是由单一的抛物线或直线组成而是由几段组成。Cu—Ni—Cr为三相合金，3相的存在增加了合金表面形成Cr2O3氧化膜所需临界浓度，但30at％Cr足以使合金表面形成连续的Cr2O3外氧化膜。氧化膜内层是合金和氧化物相共存的混合区，被氧化的岛状物是由Cr2O3和Cu，Ni组成。这种混合内氧化机制与经典内氧化明显不同。     

Ti811合金的高温氧化行为

利用扫描电子显微镜(SEM)和光学显微镜,研究了Ti811合金在700～900℃的静止空气中的氧化行为,分析氧化时间、温度等因素对合金氧化动力学行为的影响.结果表明,合金的氧化动力学曲线主要为抛物线类型;低温短时氧化时,铝的热力学优势占主导,高温长时氧化时,钛的氧化动力学优势占主导;氧化皮与被氧化金属之间、氧化皮不同层次及复杂混合型氧化皮中不同相之间,由于结构上存在差异,将在界面上产生结构内应力,使氧化皮发生开裂或剥落.     

粉末烧结Cu-Al合金内氧化动力学的研究

研究了粉末烧结Cu-0.75%(wt)Al合金在高纯氮气体介质中的内氧化动力学。结果表明:内氧化动力学曲线,前期服从抛物线规律,后期服从直线规律。测出氧在Cu基体中的扩散系数和内氧化过程激活能,进而得到不同阶段反应界面迁移的速度方程。     

Fe-Y合金在800℃空气中的氧化行为

研究了Fe-5Y和Fe-10Y合金在800℃空气中的氧化行为。结果表明：二元Fe-Y合金氧化动力学曲线不规则,此温度下Fe-10Y合金的氧化速率高于Fe-5Y合金的氧化速率。Fe-5Y合金及Fe-10Y合金形成了相似的氧化膜结构,且它们都发生了内氧化现象。同时合金未形成单一的Y₂O₃层,这归结于Y在Fe中非常低的溶解度及合金中两相共存而阻碍了Y通过合金向外扩散。     

引线框架用Cu-0．35Al-Ce合金薄板内氧化动力学研究

对Cu-0.35Al-Ce合金薄板在短时间内的内氧化工艺参数及其动力学进行了实验研究.结果表明:Cu-0.35Al-Ce合金薄板在短时间内进行内氧化,其内氧化动力学曲线近似为一条直线;在同一内氧化时间下,950℃比900℃内氧化所得内氧化层明显要厚;微量稀土元素Ce的加入促进了Cu-0.35Al合金薄板的内氧化:本实验条件下,经950℃×2.5 h内氧化处理后,Cu-Al合金薄板试样内氧化层深可达429μm.     

AgSnO_2电接触材料内氧化热力学与恒温氧化行为（英文）

研究了Ag-Sn合金内氧化热力学与恒温氧化行为。热力学计算结果表明,Ag-Sn合金内氧化在热力学上是可行的,并绘制了合金氧化热力学区位图。经氧化实验获得Ag-Sn合金恒温氧化行为曲线。Ag-Sn合金快速氧化的温度区间为550℃至800℃。随内氧化温度的升高,合金的氧化更为彻底并逐步趋于平稳。实验所得AgSnO2材料中,SnO2颗粒弥散分布于Ag基体中。在内氧化过程中,氧的扩散使合金内部发生氧化,并生成呈网状排布的氧化物。     

钇对M38'合金1000℃氧化性能的影响

本文研究了添加0.1%和0.5Wt%钇对 M38′合金氧化行为和机构的影响。试样在大气中1000℃氧化100hr。实验结果表明,加入0.1%钇的合金,其氧化速率比不加钇合金有明显的降低;将合金中钇含量增加到0.5%,其氧化速率略有增加。三种合金的氧化动力学基本遵从抛物线规律。当氧化70hr 后,不加钇合金的氧化速率向较快方向变化。金相观察到不加钇合金形成一个内氧化带,而含钇乙合金基体内不再产生内氧化。     

Cyclic oxidation of β-NiAl with various reactive element dopants at 1200 °C

Cyclic oxidation of β-NiAl alloys doped with different reactive elements (REs) each of which had an optimized concentration was investigated. All of REs effectively suppressed growth of voids beneath oxide scales formed on the alloys. The La-doped alloy suffered from severe internal oxidation. The Hf or Zr-doped alloys exhibited lower oxidation rate, while the Dy-doped alloy showed less scale rumpling. The effect mechanisms associated with solid solubility and ion size of RE dopants on cyclic oxidation were discussed. Co-doping of REs, such as Dy and Hf or Zr, could be anticipated to provide better cyclic oxidation performance.     

含Sc镁镍储氢合金的电化学性能

采用机械合金化方法制备Mg1-xScxNi(x=0,0.01)系列储氢合金.XRD结构分析表明,该系列合金为非晶态合金.XPS分析结果表明,加入微量Sc可以有效地抑制合金表面的氧化程度和提高合金表面Ni与Mg的原子个数比.电化学测试结果表明,微量Sc改善了合金电极的电化学性能,Mg0.99Sc0.01Ni合金电极的放电容量、容量保持率S10、高倍率放电能力HRD200、交换电流密度I0和极限电流密度,IL分别较MgNi合金电极提高10.5%、14.7%、30.4%、202.7%和77.8%.     

添加铟对Ag-CuO电触头材料的影响

用合金内氧化法制备了Ag-CuO-In2O3电触头材料样品,采用金相显微镜、扫描电镜及电光分析天平研究了In对Ag-Cu合金内氧化组织和性能的影响。结果表明,添加In可以促进Ag-Cu合金的内氧化,细化晶粒,提高合金的抗电弧侵蚀性能。     

显微组织对Cu—Cr—Ni合金高温氧化行为的影响

研究了两种单／双相Cu-Cr-Ni合金的高温氧化行为。结果表明,合金氧化动力学偏离抛物线规律,其瞬时抛物线速率常数随时间延长而降低。两种合金表面氧化膜的结构差别较大,单相合金表面形成－连续的Cr2O3层,双相合金表面氧化膜外层是一边疆的CuO层,Ni和Cr的氧化发生在合金内部,这种合金与氧化物共存的混合内氧化与经典的内氧化明显不同,氧化层最里面形成了一连续的CrO3膜,抑制了合金的进一步氧化。     

Oxidation of nickel base alloys strengthened by different hardening effects

Abstract

Three nickel base alloys strengthened by different hardening effects were investigated by thermogravimetry in air under isothermal conditions. The alloys investigated were γ′-Ni₃ (Al, Ti)-hardening alloy 80A (75Ni, 21Cr, 2·5Al, 1·7Ti, DIN No. 2·4952),solid solution hardened alloy C22 (59Ni, 21Cr, 13Mo, 3·5 Fe, 2·8W, DIN No. 2·4602) and a new high nitrogen containing and nitride hardening alloy N (61Ni, 27Cr, 10W, 1·4Ti, 0.2N). Tests were conducted in air between 900 and 1100° C for 48 h. Parabolic oxidationrates were determined and the formation of the oxide layer was investigated by optical microscopy and SEM. Oxidation data showed that the hardening mechanism has almost no influence on the oxidation kinetics. All of the alloys investigated formed chromia layers. After initial transient stateoxidation, the kinetics followed a parabolic law. Alloy 80A had the highest oxidation rate of the investigated alloys, which is attributed first to its lower chromium content and second to the formation of chromium carbides. At grain boundaries, internal oxidation, mainly of aluminium andtitanium, took place. The Al and Ti contents of alloy 80A were too low for the formation of a protective inner oxide layer of one of the two elements to take place. Alloy C22 showed the best resistance to oxidation since its chromium content of 21% is close to that for the minimum in the kineticsof oxide formation that has been found for binary Ni–Cr alloys. Additionally, there were no chromium rich precipitates to shift this chromium content to values that would result in higher oxidation rates. The nitride-containing alloy N contained a higher chromium content of 26%, whichled to a higher oxidation rate than that for alloy C22. A certain amount of inner oxidation took place, especially at coarse Cr₂N precipitates. Conclusions are presented about the optimised chemical composition of chromia laye-forming nickel base alloys for minimised oxidationrate.     

Ce对Fe-Cr合金高温氧化行为的影响

Fe-15Cr 和 Fe-30Cr 合金在1000至1200℃空气中氧化时,表面富铁氧化伤的发展导致保护性Cr_2O_3层衰退,氧化速率增大。添加 Ce 可延迟衰退过程的发生,从而大幅度减低氧化速率。随氧化温度和合金成份变化,Cr_2O_3层衰退的开始时间和发展特征随之改变,Ce 对氧化行为的影响因而呈现出规律性的变化。研究发现,合金中 Cr 的内氧化使 Cr_2O_3层形成小舌包卷合金并使其氧化成富铁氧化物。这是Cr_2O_3层衰退的原因之一。含 Ce 合金中 Ce 的优先内氧化则降低自氧化层进入合金的氧浓度,抑制Cr 的内氧化。氧浓度降低还能促进 Si 的内氧化物在氧化层/合金界面集聚。     

Cyclic Oxidation of Heat Resisting Steels

Standard cast, heat resisting steels containing 25–29 w/o (weight percent) chromium and 30–36 w/o nickel together with cast alloys containing 45 or 60 w/o nickel plus low levels of aluminium were subjected to cyclic oxidation in air at 1000 and 1150°C. The standard materials suffered rapid weight loss which was somewhat mitigated by the presence of cerium. The 45 w/o nickel alloys were much more resistant and the 60 w/o nickel alloys showed superior resistance to cyclic oxidation. This improvement was due to alumina formation at or near the alloy surface. In the absence of aluminium, alloys underwent subsurface chromium carbide oxidation at a rate independent of alloy chromium content. This effect is shown to be a consequence of rapid oxygen diffusion along internal phase boundaries.     

Fast Internal Oxidation of Ni–Zr–Y Alloys at Low Oxygen Pressure

Oxidation tests of Ni alloys with additions of Zr and Y were carried out at 1000° C under low oxygen partial pressure. Oxidation kinetics as well as particle morphologies and structures were investigated by scanning-electron microscopy, energy-dispersive X-ray analysis and X-ray diffraction. Internal oxidation was observed under all circumstances. The kinetics of the internal oxidation was determined. A binary Ni–Zr alloy shows in situ internal oxidation according to theory. Yttrium was found to have a strong influence on the oxidation kinetics. Even minor Y contents considerably accelerate internal oxidation. Fast internal oxidation of ternary Ni–Zr–Y alloys can not be explained by standard internal oxidation theory.     

The oxidation of nickel—tungsten alloys

The oxidation behaviour of NiW alloys and NiWCr alloys containing up to 40 wt%W has been studied in the temperature range 900–1200°C. The parabolic rate constant for oxidation increases with increasing tungsten content in the alloy. Addition of 10 or 15%Cr causes a significant reduction in the oxidation rate.In the Ni—7·5W alloy, spherical internal oxide particle of WO₃ are formed within the alloy, whereas as the tungsten content is increased the tendency to internal oxidation diminishes but the alloy/scale interface develops a highly irregular morphology. The roughened alloy/scale interface is less marked at the higher oxidation temperatures, and also when chromium is present in the alloy. The morphology of the interface is probably related to the relatively low interdiffusion coefficient in NiW alloys.