大风沙地区铝合金接触网零部件表面处理的优选

目的提高铝合金接触网零部件表面耐磨损性能,以增加其在大风沙地区的使用寿命。方法对接触网零件切割进行试样制备。在硅酸盐体系电解液中,采用20 k W直流脉冲微弧氧化设备对试样表面进行微弧氧化处理,电解液为硅酸盐,氧化时间为30 min。同时制备阳极氧化处理的平行试样。通过硬度测试、摩擦磨损试验以及扫描电子显微镜(SEM)测试,分别评价两种表面处理方式的表面硬度、耐磨性能,利用中性盐雾试验来评价其耐腐蚀性能,并通过扫描电子显微镜来观察两种膜层的差异。结果通过对铝合金接触网进行阳极氧化和微弧氧化处理能明显提高表面耐磨性。阳极氧化膜层硬度为350.3HV,微弧氧化膜层硬度约为阳极氧化膜硬度的4倍,达到1510.8HV。经过HT-600高温摩擦磨损试验机30 min的磨损试验,铝合金基体质量损失2 mg,阳极氧化膜质量损失0.8 mg,而微弧氧化膜的质量损失只有0.15 mg左右,且微弧氧化膜层表现出了更好的耐腐蚀性能。结论微弧氧化膜层能表现出更加优异的耐磨及耐腐蚀性能,因此微弧氧化更适合大风沙地区铝合金零件的表面处理。     

7475铝合金阳极氧化膜摩擦与磨损性能（英文）

采用阳极氧化法在7475铝合金表面制备一层氧化膜,在摩擦磨损试验机上考察不同载荷情况下氧化膜摩擦磨损性能。利用XPS、扫描电镜、硬度计和X射线应力仪对膜层原子结合能谱、阳极氧化前后表面磨损形貌、表面硬度变化和表面残余应力变化进行了分析。结果表明,阳极氧化后表面较致密,氧化膜是以Al_2O_3形式存在,其界面为扩散型结合形式;阳极氧化后平均摩擦系数减小,摩擦性能得到提高;原始状态试样的磨损机理为粘着磨损,并伴随着磨粒磨损,而阳极氧化后试样的磨损机理为磨粒磨损;表面的高硬度是提高耐磨性能的主要因素。     

7075铝合金基体粗糙度对微弧氧化陶瓷膜层表面质量的影响

铝合金微弧氧化陶瓷膜层的应用主要取决于膜层表面质量,而影响表面质量的因素有很多。在恒压下采用固定的氧化工艺对不同表面粗糙度的7075铝合金进行微弧氧化处理,并通过粗糙度仪、测厚仪、划痕仪、高温摩擦磨损试验机、X射线衍射仪(XRD)和扫描电镜(SEM)研究了基体粗糙度对膜层表面质量的影响及形成机理。结果表明:在固定的微弧氧化工艺参数下,随着基体粗糙度的降低,膜层表面粗糙度和厚度及其分布随之下降,且下降趋势逐渐变缓并趋于稳定,而膜层结合力随之增强,但对耐磨性的影响不大。此外,对于基体粗糙度大的铝合金,微弧氧化处理能有效降低其膜层表面粗糙度,而对于基体粗糙度小的铝合金,微弧氧化处理反而增加了膜层表面粗糙度。     

铝合金表面润滑耐蚀复合镀层的制备及性能分析

针对铝合金表面易磨损、易腐蚀的问题,开展铝合金阳极氧化和磁控溅射二硫化钼复合镀技术研究,制备润滑耐蚀复合镀层。通过表面形貌分析、摩擦磨损试验、电化学测试和磨痕分析,分别评价复合镀层的湿热存储前后的润滑性能、耐蚀性能和润滑机理。结果表明,当氧化膜厚度为15μm,溅射二硫化钼膜为2μm时,复合膜在载荷分别为1、5、10和20 N的往复运动模式下,湿热存储2 160 h前后的摩擦因数均小于0.1,摩擦寿命大于20 000次;采用EDS对磨痕的形貌和成分分析,表明复合膜层表面与9Cr18对偶件对磨时形成了转移膜,磨损机制为粘着磨损;采用动电位极化曲线分析,表明复合膜层主要通过提高铝合金表面的腐蚀电位来提高铝合金表面的耐蚀性。研究证明制备的复合镀层有效地提高了铝合金表面的润滑耐蚀性能,在航空航天领域有较好的应用前景。     

钛表面不同厚度氧化钛纳米管层的摩擦磨损行为*

为了改善钛的摩擦学性能,采用阳极氧化法在钛表面制备了纳米管径约100nm,厚度分别为500nm、1 000nm和1 500nm的TiO2纳米管层,并在450℃保温3h进行热处理。对试样的表面形貌、显微硬度和粗糙度进行测试。利用摩擦磨损试验考察了热处理前后不同试样在大气环境下的摩擦磨损行为。结果表明:干摩擦下,纳米管层的存在降低了钛与GCr15轴承钢球之间的摩擦系数;随TiO2纳米管层厚度的增加,试样的摩擦因数逐渐降低,磨损逐渐下降;热处理使纳米管由无定型氧化钛转变为锐钛矿晶型,进一步降低了摩擦因数,增加了钛的耐磨性能;纳米管层的磨损机制为磨粒磨损,接触疲劳磨损和粘着磨损。     

铝合金表面微弧氧化陶瓷层摩擦学性能的研究

利用微弧氧化技术在以硅酸钠为主要溶质，配以辅助添加剂Na2W04、KOH、Na2EDTA的电解液中，在LY12铝合金表面原位生长陶瓷层。用WTM-IE型球-盘磨损实验机对试样的摩擦学性能进行了研究。并用SEM、XRD分析了微弧氧化陶瓷层的表面形貌和相结构。结果表明：铝合金在电流密度10A／din2，电解液温度40～60℃，处理时间10～60min条件下，可以原位形成均匀致密的表面陶瓷改性层。微弧氧化处理后的试样在干摩擦小滑动距离下表现出良好的耐磨性能。     

表面氧化处理对铝合金A356性能的影响

为了提高A356铝合金的力学性能以及耐蚀性能,对其分别进行了化学氧化、阳极氧化以及微弧氧化三种不同的表面处理。通过SEM技术,磨损实验以及耐腐蚀试验,对经过三种表面处理后铝合金的表面形貌、氧化层厚度、耐磨性及耐蚀性等进行了详细的分析比较。结果表明,经过不同表面处理铝合金表面能形成不同厚度的氧化膜,表面硬度及耐磨性明显提高,合金耐蚀性也得到不同程度的改善。总体性能上,微弧氧化优于阳极氧化,阳极氧化又优于化学氧化。     

铝合金表面微弧氧化陶瓷层摩擦学性能的研究

利用微弧氧化技术在以硅酸钠为主要溶质,配以辅助添加剂Na2WO4、KOH、Na2EDTA的电解液中,在LY12铝合金表面原位生长陶瓷层。用WTM-1E型球-盘磨损实验机对试样的摩擦学性能进行了研究,并用SEM、XRD分析了微弧氧化陶瓷层的表面形貌和相结构。结果表明:铝合金在电流密度10 A/dm2,电解液温度40～60℃,处理时间10～60 min条件下,可以原位形成均匀致密的表面陶瓷改性层。微弧氧化处理后的试样在干摩擦小滑动距离下表现出良好的耐磨性能。     

温度对铝阳极氧化的影响

为了提高铝合金零件的防腐蚀能力,增加零件耐磨性,铝及铝合金制品通常需要进行阳极氧化处理或硬质阳极氧化处理。铝的阳极氧化是以铝或铝合金作阳极,以铅板、不锈钢板作阴极,在硫酸、草酸、铬酸等水溶液中电解,使其表面生成氧化膜层。其中,硫酸阳极处理应用最为广泛。铝和铝合金硫酸阳极氧化膜层有较强的吸附能力,易进行封孔或着色处理,以提高其抗蚀性和美观性。阳极氧化膜层厚一般5—25um,铝合金硫酸阳极氧化工艺操作简单,电解液稳定,成本也不高,是成熟的工艺方法。     

添加剂对铝合金微弧氧化陶瓷膜耐磨性的影响

研究了铝合金在硅酸盐和磷酸盐复合溶液体系中微弧氧化膜的耐磨性，采用XRD和SEM分析了铝合金微弧氧化膜的物相和表面形貌，采用UMT-Ⅱ型微观摩擦磨损试验机测试了膜层的摩擦磨损性能。研究结果表明，添加剂Na2WO4和M2提高了微弧氧化陶瓷涂层的耐磨性，稳定剂胺盐使微弧氧化膜更致密、更光滑，从而减小了氧化膜的前期磨损失重。     

Effects of aluminum on the oxidation of 25Cr-35Ni cast steels

The oxidation kinetics and morphological development during reaction of two cast austenitic steels at 1000°C in pure dry oxygen at 20 kPa are reported. Both steels contained approximately 25 wt.% Cr and 35 wt.% Ni and, in addition, one steel contained 3.3 wt. %. Both steels oxidized to form external scales consisting mainly of Cr₂O₃ with a thin outer layer of manganese rich spinel. Scale growth kinetics were parabolic, and somewhat faster rates were observed for the aluminum bearing steel. In both steels, deep internal oxidation occurred at the site of primary (interdendritic) carbides. The kinetics of this process were parabolic, and rate control was attributed to oxygen diffusion along the interface between internal oxide and matrix metal. In the aluminum-free steel, interdendritic carbides were converted to chromium rich oxide, but when aluminum was present, a sheath of aluminum rich oxide formed around the carbides. In this latter case, the rate of interdendritic penetration was somewhat slower. The aluminum bearing steel also formed large numbers of rod-shaped Al₂O₃ precipitates within the austenitic dendrites. Deepening of the Al₂O₃ precipitate zone also proceeded according to parabolic kinetics at a rate consistent with rate control by diffusion of oxygen along the oxide-alloy interfaces.     

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.     

等离子喷涂NiCrCoAlY涂层氧化控制研究

利用等离子喷涂技术制备了NiCrCoAlY粒子和涂层,研究了等离子喷涂过程中NiCrCoAlY粒子的氧化行为以及屏蔽气体对NiCrCoAlY涂层抗高温氧化性能的影响。结果表明,粒子在飞行过程中存在对流氧化和扩散氧化两种氧化机制,对NiCrCoAlY粒子来说,在距喷嘴55 mm以内的射流中心处以对流氧化为主,在距离喷嘴55 mm以外将以扩散氧化为主;除飞行中的氧化外,粒子在喷涂过程中还发生形成涂层后的氧化,NiCrCoAlY粒子以飞行中的氧化为主;添加屏蔽气体能减少喷涂过程中涂层的氧化,提高涂层的抗高温氧化性能     

The Effect of Crystallographic Orientation on the Oxidation Behavior of a Single-Crystal Nickel-Base Superalloy

The oxidation kinetics of DD100 nickel-base single-crystal alloy, with (221) and (100) surface orientations were tested in this study by thermogravimetry. A pronounced anisotropy in both the cyclic and isothermal oxidation resistance of DD100 alloy was observed. The (221) crystallographic surface of DD100 had a slower oxidation rate than the (100) surface when isothermally exposed to stationary air at 950°C, whereas the opposite results were obtained at 1050°C. When cyclically oxidized at 1100°C, the weight loss of samples with (221) surfaces was significantly greater than that of (100) surfaces, so that the cyclic-oxidation anisotropy was more remarkable at 1100°C than at 950°C. The different spatial alignment of the / interface is thought to be responsible for the anisotropic oxidation behavior of the nickel-base single crystal alloy.     

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。     

High temperature oxidation of metals under time-dependent gas pressure

A theoretical study on the high-temperature oxidation of thick oxide films grown under a time-dependent gas partial pressure is reported. The diffusion across the film is assumed to be the rate-limiting step of the overall reaction, and Wagner's hypotheses were used as the starting point for our reasoning. A general formulation for the oxidation under no time constant gas pressure, in terms of a time-dependent answer function is given. The effect of an external electric field on the reaction rate is also reported when a constant current density,J, is applied to the oxide scale. If the oxide is a good electronic conductor atJ=0 andt , we found that the reaction rate assumes formally the well-known Wagner's expression of the rate constant but with a gas partial pressure at oxide/gas interface which is a time function. If the oxide is a good ionic or electronic conductor, the effect due to an external electric field,J 0, on the reaction rate is the same as predicted by the Wagner's theory.     

V/Nb对Ti-45Al-9(V, Nb, Y)合金抗氧化性能的影响

βγ-TiAl合金具有良好的高温变形能力,为TiAl合金的发展开辟了新的途径。成功制备了不同x=V/Nb(x=1,1.5,2,3.5)的βγ-TiAlTi-45Al-9(V,Nb,Y)合金,研究了上述合金在800℃静止空气中的氧化行为。结果表明:当x=1时,Ti-45Al-9(V,Nb,Y)合金中形成条带状、连续致密的Al2O3氧化层,显著提高了合金的抗氧化能力。随着x=V/Nb的增加,Al2O3氧化层厚度变薄,合金的抗氧化能力下降。     

Preferential oxidation of carbon during the initial stage of oxidation of an Fe-0.8%C alloy at 400°C

The preferential oxidation of carbon in an Fe-0.8%C alloy during the first 60 min of oxidation in air at 400°C was studied by a thermogravimetric method and by measuring the quantity of evolved carbon oxides. The morphology of the external oxide surface depended on the type of exposed phase—a rosettelike oxide grows over ferrite, whereas the oxide surface over cementite is relatively smooth. A possible mechanism for the preferential oxidation of carbon and its subsequent cessation is proposed.Formerly of Institute of Materials Engineering, Academy of Mining and Metallurgy, Cracow, Poland.     

铸造镍基合金K444在900℃空气中的长期氧化行为

用热重法研究镍基高温合金K444在900℃下氧化1000 h的动力学。结果表明,K444合金氧化动力学遵从抛物线规律,以x射线衍射、扫描电镜和能谱分析及电子探针成分分析测定氧化膜的组成,结果表明氧化膜由多层组成,外层为TiO₂,内层以Cr₂O₃为主还包括内氧化层和贫Υ′层。观察到沿晶界偏聚的碳化物氧化,提出了氧化饥制。     

Oxidation resistance of eight heat-resistant alloys at 870°, 980°, 1095°, and 1150°C

Oxidation testing of heat-resistant alloys is described. The testing procedure utilized weight-gain measurements using one specimen, which was withdrawn and weighed at intervals of 1 week, for 10–18 weeks. The specimen was placed in a porcelain cup during exposure and covered upon cooling to retain spalled oxide. Weight gain was used to determine the kinetics of oxidation and was extrapolated to 3000 hr. The specimen was withdrawn at the end of the exposure, weighed, cathodically descaled, and reweighed. The ratio of oxygen ions to metal ions was determined for each alloy and test temperature. This ratio approaches the stoichemetric ratio for Fe₃O₄ or Cr₂O₃. The ratio for each test is used to convert weight gain to weight loss. The amount of adherent oxide was determined as well as the total amount of oxide, leading to an expression for oxide adherency. The oxidation resistance of Fe-Cr-Ni alloys increased with increasing Cr and Ni, with Cr being the most critical element. Additions of Si, Al, or Ce were shown to extend the usefulness of Fe-Cr-Ni alloys.