钛合金的高温固态渗氧-扩散固溶复合处理

为了提高钛合金的表面耐磨性能，发展了一种表面无氧化膜的高温固态渗氧．扩散固溶复合处理方法（OP-DS）。利用TGA，SEM，XRD，XPS及显微硬度计对OP-DS处理后的钛合金进行了研究。结果表明：OP-DS方法能显著提高合金表面层的硬度，硬化层深度随预渗氧时间的延长而增加；预渗氧处理时间对扩散固溶效果有很大的影响，适当的预渗氧时间可在表面形成无膜强化固溶层。从热力学及动力学角度对渗氧．扩散固溶机理进行了探讨。     

钛合金氧碳共渗层性能

将经磨平、抛光、超声波乙醇清洗、吹干的Ti6Al4V合金样品放入专用设备中进行氧碳共渗。分别采用X射线衍射仪（XRD）、扫描电子显微镜（SEM）、能谱仪（EDS）、HV硬度仪、万能材料试验机对渗层的物相、显微组织形貌、成分、硬度、摩擦磨损、力学性能进行分析。XRD结果表明,渗层中出现TiC和TiO_x相。氧碳共渗改变了原Ti6Al4V合金的组织,渗层的显微组织明显区别于Ti6Al4V的渗碳、渗氧以及在CO₂气氛下处理的组织。EDS结果表明,C、O元素含量呈现梯度变化。相比基体硬度,渗层表面硬度提高了3.8倍,渗层硬度呈梯度变化。氧碳共渗改变了原始样的粘着磨损和摩擦状态,渗层样表面只有轻微的摩擦痕迹、无磨损。氧碳共渗后磨损量是原始样的3.5%,摩擦系数约为原始样的30%。渗层样在拉断过程中,外表面有一定的剥落,表面布满裂纹,样品的强度略有下降,断面延伸率和断面收缩率与原始样相当。Ti6Al4V合金经过氧碳共渗后,提高了表面硬度,降低了磨损率和摩擦系数,基本保持了基体的力学性能。     

近β钛合金表面包覆渗氧强化

利用一种钛合金表面防护涂料对近β钛合金Ti-1023进行表面包覆后,在不同温度和气氛环境下进行高温渗氧强化处理。对渗氧处理后的合金表层显微组织和硬度梯度进行表征。结果表明,涂层包覆可以有效减缓Ti-1023合金的高温氧化行为,抑制表面疏松的脆性氧化物的形成,提高合金表面硬度。在空气气氛下,经850 ℃×24 h渗氧处理后Ti-1023合金表层显微硬度由321 HV0.2提高到544 HV0.2,硬化深度达500 μm以上。在T_β以下750 ℃氧气气氛中渗氧48 h后,合金表层显微硬度可达459 HV0.2,并且合金基体组织基本不受影响。     

喷砂预处理与离子氮碳氧硫复合工艺

按照不同共渗工艺参数,分别对38CrMoAl钢试样进行喷砂预处理离子氮碳氧硫共渗复合处理和离子氮碳氧硫共渗处理.结果表明,喷砂预处理离子氮碳氧硫共渗复合工艺有利于缩短共渗时间和降低共渗温度;在相同的共渗介质与共渗参数下,喷砂预处理离子氮碳氧硫共渗复合处理的表面硬度可达913 HV0.2,渗层厚度大约为0.33 mm,比离子氮碳氧硫共渗分别增加了35％和43％;经喷砂预处理离子氮碳氧硫共渗复合处理后耐腐蚀性增加.     

热氧化处理钛表面渗氧层的组织与性能研究

商业用纯钛在空气炉中700℃～900℃,1h～4h进行热氧化处理,得到由氧化层和渗氧层构成的表面结构.通过金相观察、显微硬度测试、X射线衍射(XRD)及扫描电镜(SEM)分析,研究了渗氧层的结构和性能.结果表明,经一定温度及时间处理,试样渗氧层被一条连续的界线分为内渗氧层和外渗氧层,在光学显微镜下观察,内外两层渗氧层形貌无差别,但在扫描电镜下观察可发现在较高温度形成的外渗氧层较疏松,内渗氧层则仍致密.随着热处理温度的升高、时间的延长,渗氧层厚度和含氧量增加,晶格常数c伸长,表面硬度显著增大.     

W6Mo5Cr4V2钢和H13钢的氧氮共渗组织与工艺

用滴尿素溶液的方法对W6Mo5Cr4V2钢进行氧氮共渗处理和在氨气与水蒸气环境中对H13钢进行氧氮共渗处理。利用SEM、XRD、显微硬度计和数码相机等研究氧氮共渗层的微观组织、结构及表面形貌。结果表明:两种氧氮共渗工艺均可在两种钢表面形成光滑、稳定、无裂纹的渗层。H13钢氧氮共渗工艺能得到共渗组织为Fe3O4和Fe3N的化合物层,且渗层厚,硬度梯度平缓,渗氮效果好。     

38CrMoAl钢循环等离子氮碳氧硫共渗工艺的研究

对38CrMoA l钢进行了常规等离子渗氮、循环等离子渗氮以及循环等离子氮碳氧硫共渗处理,研究这几种工艺对表面硬度、渗层组织、硬度梯度的影响。结果表明：循环等离子氮碳氧硫共渗有利于形成共渗元素进一步扩散的通道,加速共渗元素的渗入;综合表面硬度和渗层厚度,循环等离子氮碳氧硫共渗工艺明显优于常规等离子渗氮和循环等离子渗氮。     

交流电场对工业纯钛TA2粉末法渗氧的影响

在650℃进行工业纯钛TA2的粉末法渗氧,通过渗罐内一组平行电极,对渗剂和TA2试样施加交流电场,进行交流电场增强粉末法渗氧。研究发现,以尿素作为供氧剂的粉末法渗氧生成的渗层表层主要由TiO₂组成,还有少量Ti₂N和固溶氧的α-Ti;交流电场能够大幅度提高纯钛的渗氧效率,随电场电流增加,渗层厚度、硬度增加,沿层深硬度分布改善;在电场电流为2 A和渗剂含2%尿素时,6 h渗扩所得渗层厚度约46μm,渗层峰值硬度约1150 HV0.01。交流电场的物理作用能够强化渗氧剂中的反应,从而增加氧原子及含氧活性基团的产率和活性;交流电场通过提高试样内部的空位浓度,为氧原子的扩散提供更多通道;这两个因素加快氧向试样内部扩散。这种新技术可以在较低温度对钛进行高效渗氧处理,减少工件畸变。     

45钢的离子氮碳共渗-离子渗氧复合处理

研究了45钢离子氮碳共渗-离子渗氧复合处理工艺。试验表明，45钢经离子氮碳共渗-离子渗氧复合处理后，表层可获得化合物和氧化物的复合层，该复合处理可以明显提高45钢的耐磨性。     

前置渗氧对TC4钛合金低温等离子复合渗层微观结构和耐磨损性能的影响

针对钛合金硬度低、耐磨性差的缺点,提出了一种由渗氧和氧氮共渗两个过程组成的低温等离子复合渗工艺,并着重研究了前置渗氧对钛合金表面微观结构、物相组成及耐磨性能的影响。利用SEM、TEM、XRD等手段对复合渗层的微观结构和相组成进行了分析,结果表明,等离子复合渗处理的钛合金样品渗层主要由化合物层和扩散层组成,物相为金红石型TiO₂和氮化物TiN_0.26。采用显微硬度计、纳米压痕仪和往复式摩擦试验机对渗层的显微硬度和摩擦磨损性能进行了表征,结果表明,与传统等离子渗氮相比,等离子复合渗处理可增加渗层的厚度,显著提高钛合金的硬度和弹性模量,大幅改善钛合金的耐磨损性能。     

The analysis of Armos fibers reinforced poly(phthalazinone ether sulfone ketone) composite surfaces after oxygen plasma treatment

The effects of oxygen plasma treatment on both the fiber surface and interfacial adhesion of Armos fiber reinforced PPESK composites were investigated in this paper. X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) were used to analyze fiber surface chemical composition and surface roughness, respectively. The results indicated that oxygen plasma treatment had introduced a large amount of reactive functional groups onto the fiber surface and the fiber surface roughness was increased largely. The interlaminar shear strength (ILSS) of the untreated and oxygen plasma-treated composites was measured to evaluate the interfacial adhesion. The values of ILSS were enhanced dramatically; the water molecule diffusion into composite along interface was prevented effectively. The composite fracture mode was observed by scanning electron microscopy (SEM), which showed that the primary failure mode varied from interface failure to matrix failure after oxygen plasma treatment. Results indicated that oxygen plasma treatment was an effective method to improve the interfacial adhesion properties of Armos fiber reinforced PPESK composites by both chemical bonding and physical effects.     

Zur Kinetik der Sauerstoffreduktion bei der Korrosion von Nickel in sauerstoffhaltiger Schwefelsäure

Kinetics of oxygen reduction during the corrosion of nickel in oxygen containing sulfuric acid The rate of oxygen reduction was determined for the corrosion of nickel in sulphuric acid containing oxygen. The rate depends upon the oxygen concentration and the acidity of the electrolyte. For a second order reaction with a preceding diffusion of oxygen and protons the values of the rate constant and the thickness of the diffusion layer were calculated. It could be shown that in In sulphuric acid the reduction rate is control led by the oxygen diffusion while in the weaker acids the rate controlling step is a proton transfer to the oxygen, adsorbed at the metal surface. Measurements of the dependance of the corrosion in In sulphuric and hydrochloride acid confirm these results.     

Functionalisation of titanium alloy surface through oxygen gas jet-assisted gliding arc discharge plasma

A modified surface layer was fabricated on Ti–6Al–4V samples by gliding arc discharge plasma assisted with an oxygen jet gas under atmospheric conditions. The oxidation reaction on the sample surface was promoted by active species with strong oxidising performance, such as oxygen and hydroxyl radicals. An amorphous titanium oxide layer was detected on the generated surface. The oxygen diffusion layer penetrated the substrate to an approximate depth of 500 nm. The generated surface exhibited higher biological cell adhesiveness and a lower elution amount of metal ions than the untreated sample surface.     

超细Ni,Co—石墨层间化合物的制备及其电极催化性能

采用二步法先合成钾的石墨层间化合物,然后再通过它合成Ｃｏ,Ｎｉ系石墨层间化合物。化学分析、Ｘ射线衍射、Ｘ射线光电子能谱及透射电镜的分析结果表明,这些化合物中金属主要以正２价形态存在,化合物的粒度为纳米级。用微电极测试了它们在ＫＯＨ溶液中对氧还原的催化活性,发现Ｃ４８Ｃｏ及Ｃ４８Ｎｉ为好,尤以Ｃ４８Ｃｏ为优;加入Ｃ４８Ｃｏ的气体扩散电极的电流密度,比未加的高６８倍。用旋转圆盘电极研究了对氧的还原过程,发现该过程同时受扩散与化学反应两种作用的混合控制,反应电子数为２。     

晶界氧吸附对SrTiO3基压敏陶瓷的作用

研究了SrTiO3基压敏陶瓷热处理过程中氧的作用。发现SrTiO3基压敏陶瓷的压敏电压U10mA与试样的厚度无关，且随着热处理温度的升高而增大。进一步的试验表明SrTiO3基压敏陶瓷的压敏特性主要受试样表面高阻层的控制。X射线光电子能谱（XPS）的Mn2p和O1s谱图表明，表面高阻层是氧在热处理过程中通过晶界的扩散和化学吸附产生的。因此，氧在晶界处的化学吸附是SrTiO3基陶瓷压敏特性产生的根源。     

The Effect of Surface Finish on the Scaling Behavior of Stainless Steel in Steam and Supercritical Water

The effect of surface finish on the scaling behavior of Super 304H was investigated in steam and supercritical water (SCW). The oxide scales were analyzed using scanning electron microscope with an energy dispersive X-ray detector, X-ray diffraction, and Raman spectroscopy. The results showed that surface deformation improved the oxidation resistance by promoting the preferable formation of chromia and improving the scale adhesion. In SCW, the absence of hematite may be ascribed to the low oxygen partial pressure; while the whisker growth on the sandblasted sample may have resulted from the low oxygen partial pressure and the increased chromium diffusion flux.     

热处理对Pt纳米线电催化性能的影响

采用阳极氧化铝(AAO)模板法电化学沉积制备了Pt纳米线催化剂,并进行了热处理。通过X射线衍射(XRD)、扫描电子显微镜(SEM)和电化学测试对热处理前后Pt纳米线催化剂的晶体结构、形貌和电催化性能进行了表征,并与商业碳载铂(Pt/C)做对比。SEM照片表明制备了表面粗糙的Pt纳米线。循环伏安法(CV)和计时电流曲线表明,Pt纳米线较Pt/C催化活性高,退火后Pt纳米线更利于甲醇氧化,且稳定性更好。旋转圆盘电极(RDE)测试研究发现,未经热处理的Pt纳米线催化剂氧还原反应(ORR)极化曲线的半波电势相对Pt/C有正移,有更大的极限扩散电流,利于氧还原反应的发生。     

Oxidation of double-glow plasma chromising coating on TC4 titanium alloys

Double-glow plasma surface chromising was performed on TC4 (Ti–6Al–4V) alloys, and the isothermal oxidation behaviour of TC4 was investigated at 650, 750, and 850 °C. The surface treatment caused the formation of a Ti–Cr mutual diffusion layer beneath the alloy surface. The chromising coating consisted of Cr, Cr_1.97Ti_1.07, and CrTi₄. During oxidation, Cr, Ti, and Al diffused outward to form multi-layer oxide films, which prevented the diffusion of oxygen.     

A theoretical evaluation of the influence of mechanical variables on the concentration of oxygen in a corrosion fatigue crack

The oxygen concentration in a corrosion fatigue crack has been evaluated theoretically assuming that oxygen was consumed by cathodic reduction on the walls of the crack and mass transport occurred by diffusion and advection (forced convection) with the latter resulting from the sinusoidal variation of the displacement of the crack walls. Using parameters relevant to a compact tension specimen the time-dependent distribution of the oxygen concentration in the crack was calculated as a function of ΔK (the range of the stress intensity factor), R-value (minimum load/maximum load), frequency, crack length and electrode potential (within the constraint of no significant potential drop in the crack). The influence of advection was to enhance significantly the mass transport of oxygen in the crack compared to “diffusion-only” even at low frequencies and low values of ΔK. Regions in the crack were identified in which advection dominance or diffusion dominance of the mass transport of oxygen occurred.