Inconel617合金表面电子束熔覆NbMoCr显微组织和耐腐蚀性的探讨

为了提高Inconel617合金(简称617合金)材料的表面性能,利用电子束熔覆技术在617合金表面制备了NbMoCr熔覆层. 对它的显微组织、硬度和耐腐蚀性能进行了研究,并与617合金进行了对比. 结果表明,NbMoCr熔覆层的组织更均匀,晶粒更细小,气孔等缺陷更少,且生成了微量M₂₃C₆,Cr₇C₃,Cr₄Si₄Al₁₃,CoCx等硬质相,提高了熔覆层的表面硬度及耐腐蚀性. 经检测,熔覆层硬度相比617合金硬度高出86 HV10. 电化学腐蚀测试表明,在1 mol/L H₂SO₄溶液中,617合金自腐蚀电流密度是NbMoCr熔覆层的5.16倍;在3.5 %的NaCl溶液中,617合金自腐蚀电流密度是NbMoCr熔覆层的4.6倍;在1 mol/L NaOH 溶液中,617合金自腐蚀电流密度是NbMoCr熔覆层的3.12倍.     

Corrosion behavior in boiling dilute HCI solution of different ceramic coatings fabricated by plasma spraying

An Al₂O₃ ceramic coating (A), a 13 wt.% TiO₂-Al₂O₃ (13TA) composite ceramic coating, and a Ni-Al-13wt.%TiO₂-Al₂O₃ (NA-13TA) gradient composite ceramic coating were prepared on Q235 steel by plasma spraying. The corrosion behavior of samples sprayed with these coatings in a boiling 5% HCl solution was investigated. It was shown that an A ceramic coating and a 13TA composite ceramic coating were destroyed after immersion for 17 and 23 h, respectively. The NA-13TA gradient composite ceramic coating was still sound after 14 days of immersion. The corrosion resistance of samples with the NA-13TA gradient composite ceramic coating was sharply improved due to the decreased amount of connected pores in the coating. The corrosion of the sample sprayed with the gradient ceramic coating included the partial corrosion of the surface ceramic coating and the interlayer coatings. The corrosion weight loss depended on the degree of open porosity.     

The effects of crosshead speed and temperature on the stress corrosion cracking of Cu-30% Zn alloy in ammoniacal solution

Stress corrosion cracking (s.c.c. of Cu-30% Zn alloy in Mattsson's solution (0.05 mol/l CuSO₄ + 0.5 mol/l (NH₄)₂SO₄, pH 7.2) was investigated as a function of temperature (298 K–323 K) and crosshead speed (10^?5 mm/min to 1 mm/min). Crack propagation behaviour in a crosshead speed of 10^?4 mm/min at 298 K was also studied. All tests were carried out using a slow strain rate technique. Cracks occurred intergranularly under all experimental conditions used. At high crosshead speeds (5 × 10^?3 mm/min to 1 mm/min) the susceptibility to s.c.c. increased with increasing temperature. At slow crosshead speeds, however, an inverse effect of temperature on the susceptibility was revealed. Constant crack velocities were obtained in both specimens with or without surface coating, and the velocity in the coated specimen was lower than that in the uncoated specimen by one order of magnitude. Scanning electron microscopic examination revealed that ahead of intergranular cracks small corrosion pits were formed along grain boundaries.Based on the above experimental results, the mechanism of intergranular s.c.c. of Cu-30%Zn alloy was discussed by considering the growth rate of microcrack formed along grain boundary and the corrosion rate (or repassivation rate) of the microcrack.     

Effect of plasma-sprayed alumina on the strength,elastic modulus,and damping of Ti-25Al-10Nb-3V-1Mo intermetallic

The effect of a plasma-sprayed Al₂O₃ coating on the bend strength, elastic modulus, and damping of Ti-25Al-10Nb-3V-1Mo intermetallic substrate was measured. Two coating thicknesses of 0.1 and 1.0 mm were used in the study. The average strength and Weibull coefficients of the intermetallic samples coated with the 0.1 mm Al₂O₃ coating were very similar to those of the uncoated intermetallic samples. On the other hand, the average strength of the samples coated with 1.0 mm Al₂O₃ was significantly lower than the strength of the uncoated intermetallic substrate. The lower strength of the 1.0 mm coated samples was attributed to the higher volume fraction of the Al₂O₃ coating (which has a lower strength than the Ti-25Al-10Nb-3V-1Mo substrate) and higher porosity in the 1.0 mm coating. The Young’s modulus and damping values of the 0.1 mm Al₂O₃-coated intermetallics did not vary significantly from those of the uncoated substrate. However, the damping values of the 1.0 mm Al₂O₃-coated intermetallics were significantly larger than those of the uncoated substrate. The higher damping values measured for the 1.0 mm Al₂O₃-coated samples were attributed to the higher porosity in the thicker coating and to defects in the coating as a result of the spraying process.     

Investigation on the Phase Diagram of LiCl-KCl-NdCl<Subscript>3</Subscript> Pseudo-Ternary System

The ternary phase diagram of LiCl-KCl-NdCl₃ system has been investigated by differential thermal analysis (DTA), followed by characterization of the coexisting phases in the solid state by x-ray diffraction, in order to understand the interactions in the NdCl₃-LiCl-KCl ternary system. The results of these experiments showed that LiCl and K₂NdCl₅ form a non binary join section. This divides the LiCl-KCl-NdCl₃ system into two quasi-ternary sections, namely (1) LiCl-KCl-K₂NdCl₅ and (2) LiCl-K₂NdCl₅-NdCl₃ systems. Both are simple eutectic ternary phase diagrams. The ternary eutectic temperatures and eutectic compositions are determined to be 316?±?3 °C and 53.9 mol.% LiCl-38.7 mol.% KCl-7.4 mol.% K₂NdCl₅ in the LiCl-KCl-K₂NdCl₅ quasi-ternary section, while the other eutectic temperature and composition are determined to be 376?±?9 °C and 46.2 mol.% LiCl-32.5 mol.% K₂NdCl₅-21.3 mol.% NdCl₃ in the LiCl-K₂NdCl₅-NdCl₃ quasi-ternary section. A quasi-ternary peritectic reaction is observed at 37.7 mol.% LiCl-36.2 mol.% KCl-26.1 mol.% K₂NdCl₅ at 445?±?1°C. The primary and secondary crystallization temperatures for the samples are deduced from the heating runs of DTA traces, and the phases responsible for the various thermal events are ascertained. Isothermal sections at chosen temperatures and polythermal liquidus projection with isothermal contours are drawn over the ternary phase field.     

Effect of solidification process parameters on dry sliding wear behavior of AlNiBi alloy

As-cast samples of the Al–3wt.%Ni–1wt.%Bi alloy resulting from the horizontal directional solidification process were subjected to the micro-abrasive wear test. The effects of the solidification thermal and microstructural parameters, such as the growth and cooling rates and the cellular and primary dendritic spacings (V_L and T_R; λ₁ and λ_c; respectively), were evaluated in the wear resistance of the investigated alloy. The tribological parameters analyzed were the wear volume and rate (V_w and R_w). The solidification experiments and the wear tests were carried out by means of a water-cooled horizontal directional solidification device and a rotary-fixed ball wear machine, respectively. The results show lower V_w and R_w values correspond to finer microstructures and the V_w dependence on λ₁ is characterized by an experimental mathematical equation. A better distribution of Bi soft droplets and Al₃Ni hard intermetallic particles is observed within the finer interdendritic region and, in consequence, the better wear resistance is achieved in as-cast samples with dendritic morphology rather than cellular morphology. A transition of wear mechanism from adhesive to abrasive is observed.     

Comparison of Single-Phase and Two-Phase Composite Thermal Barrier Coatings with Equal Total Rare-Earth Content

Rare-earth zirconates have been the focus of advanced thermal barrier coating research for nearly two decades; however, their lack of toughness prevents a wide-scale adoption due to lack of erosion and thermal cyclic durability. There are generally two methods of improving toughness: intrinsic modification of the coating chemistry and extrinsic modification of the coating structure. This study compares the efficacy of these two methods for a similar overall rare-earth content via the air plasma spray process. The extrinsically toughened coatings were comprised of a two-phase composite containing 30 wt.% Gd₂Zr₂O₇ (GZO) combined with 70 wt.% of a tougher t′ low-k material (ZrO₂-2Y₂O₃-1Gd₂O₃-1Yb₂O₃; mol.%), while a single-phase fluorite with the overall rare-earth content equivalent to the two-phase composite (13 mol.% rare-earth) was utilized to explore intrinsically toughened concept. The coatings were then characterized via x-ray diffraction, energy-dispersive spectroscopy, and scanning electron microscopy, and their performance was evaluated via erosion, thermal conductivity, thermal annealing (500 h), and thermal cycling. It was shown that the extrinsic method provided an improved erosion and thermal conductivity response over the single phase, but at the expense of high-temperature stability and cyclic life.     

纳米级和微米级稀土氧化物掺杂W-La2O3-Y2O3-ZrO2 阴极尖端的组织和性能

使用粉末冶金法将纳米级(70–80 nm)和微米级(500–600 nm)稀土氧化物(La₂O₃,Y₂O₃)与钨粉混合,随后通过冷等静压、中频感应烧结、旋锻、拉拔等一系列工艺制备了W-1.5La₂O₃-0.1Y₂O₃-0.1ZrO₂(质量分数,%)材料。对含有纳米和微米尺寸稀土氧化物的阴极样品使用相同的焊接电流,分别进行了0.5、1、2 h的氩弧焊。结果表明,具有纳米级稀土氧化物的样品在焊接过程中表现出更高的工作稳定性,烧损同比降低了近85.4%。此外,随着工作时间的延长,阴极尖端不同区域的稀土氧化物聚集度显著增加。结合COMSOL Multiphysics温度模拟发现,第二相的扩散活化能降低了近34%。这是因为更为细小的第二相有效地控制了钨基体组织的演变,保留了大量晶界作为通道,促进了活性物质在电子发射过程中的扩散。     

Electrodeposition of tin, copper and tin-copper alloys from a methanesulfonic acid electrolyte containing a perfluorinated cationic surfactant

Tin, copper and tin-copper alloys were electrodeposited from a methanesulfonic acid electrolyte containing a perfluorinated cationic surfactant at 296 K. The electrolyte composition was 0.02 to 0.05 mol dm^− 3 SnSO₄, 0.02 to 0.2 mol dm^− 3 CuSO₄, 12.5 to 15% vol MSA (1.9 to 2.3 mol dm^− 3 CH₃SO₃H, pH < 1), 0.01 mol dm^− 3 hydroquinone and 0.008 to 0.012% vol perfluorinated cationic surfactant. Electrodeposition was studied at a rotating disc electrode (RDE), a rotating cylinder electrode (RCE) and a rotating cylinder Hull (RCH) cell. Cyclic voltammetry and linear sweep voltammetry were used to investigate the current-potential relationships at static and rotating disc electrodes. Tin-copper alloys were deposited over a wide range of operating conditions to produce surface finishes from dark-grey (3 to 9 wt.% Cu), light-brown (50 to 60 wt.% Cu) and golden-yellow (70 to 80 wt.% Cu). The influences of copper(II) and surfactant concentration, applied current and surfactant adsorption were investigated; while the surface microstructure and composition of the deposits were studied.     

玻璃包覆FeSiBNbCu非晶丝的微波吸收性能(英文)

制备以石蜡为基体并具有玻璃包覆Fe73.5Si13.5B9Nb3Cu1非晶丝不同填充比的同轴介电样品,在相对较高的微波吸收频段(2~18 GHz)下研究短丝填充比(质量分数3%~9%)和样品厚度(1~7 mm)对同轴介电样品的微波吸收性能的影响规律。采用X射线衍射谱(XRD)、差示扫描量热分析(DSC)、扫描电子显微分析(SEM)和矢量网格分析仪(SNA)表征材料的微结构并评价其吸波性能。结果表明,不同填充比的同轴介电样品的复磁导率和复介电常数存在重要的频率范围(6~18 GHz)。模拟结果显示,具有3 mm厚度和7%填充比的样品具有较好的微波吸收性能,其反射率在14 GHz时达到峰值-34 dB。这对于开发具有更宽微波吸收范围应用的微丝介电材料是十分有益的。     

Mechanically Assisted Solid-State Mixing and Spark Plasma Sintering for Fabrication of Bulk Nanocomposite (WC/7(10Co/4Cr))-Based ZrO<Subscript>2</Subscript> Systems

Mechanically induced solid-state mixing, using high-energy ball milling technique, was employed for preparing WC/7 wt.% (10Cr/4Cr) solid-solution powders. The solid-solution powders obtained after 50 h of milling were mechanically mixed for 50 h together with small weight fractions (0-7 wt.%) of (ZrO₂ + 1.5 wt.% Y₂O₃) powders. The powders were then consolidated in vacuum under a uniaxial pressure of 30 MPa at 1250 °C, using spark plasma sintering. The consolidated bulk samples were nearly full dense and maintained their nanocrystalline structure after this consolidation step. The results showed that the consolidated samples over the entire range of ZrO₂ concentrations (0–7 wt.%) had low values for Young’s modulus (297–318 GPa) due to their nanocrystalline structures. Moreover, the WC/7 wt.% (10Cr/4Cr)/7(ZrO₂-1.5 mol.% Y₂O₃) showed excellent wear resistance, indexed by its low-value friction coefficient (~0.29).     

A relation between the hyperfine magnetic and electronic structure and the passivability of the heat treated Fe-23% Cr alloy

The effect of heat treatment conditions (quenching and tempering at 475°C for 200 h or at 650°C for 10 h) on the hyperfine magnetic structure, electron density distribution at ⁵⁷Fe nuclei, and passivability of Fe-23% Cr alloys in either a highly pure state or with a heightened content of impurity elements is studied with the use of M?ssbauer γ-resonance spectroscopy combined with voltammetric measurements in a 1 mol/l HClO₄ + 0.25 mol/l NaCl solution at room temperature. M?ssbauer spectra are processed (decomposed in three subspectra) with the help of Normos computer program, and the following parameters are estimated: the effective magnetic field intensity H _eff (kOe); the half-width of the first subspectrum peak Γ (mm/s); the first-to-third (W ₁₃) and second-to-third (W ₂₃) ratios of the subspectrum peaks; the isomeric (chemical) shift δ (mm/s) with respect to α-Fe; the quadrupole electric splitting Δ_eq (mm/s); and the area part S (%) of the hyperfine structure subspectrum in the summary spectrum. Hyperfine magnetic structure and electron density distribution at iron nuclei are found to change depending on the alloy purity and heat-treatment conditions. The γ-spectroscopy data are considered in relation to the passivating characteristics of the alloy. Original Russian Text O.V. Kasparova, Yu. V. Baldokhin, A.S. Solmatin, 2006, published in Zashchita Metallov, 2006, Vol. 42, No. 1, pp 25–31.     

Activation behaviors of isotropic pitch-based carbon fibers from electrospinning and meltspinning

Pitch fibers were prepared from identical petroleum-derived isotropic pitch precursors (IPPs) by both meltspinning and electrospinning. The fibers obtained were stabilized, carbonized, and then finally activated by steam at various conditions. The specific surface area of the noble electrospun (E-spun) fibers was calculated to be 6.4 times larger than that of meltspun (M-spun) fibers due to their finer diameter. The activation was considered as first-order reaction with frequency factor 6.55 × 10⁻⁴ s⁻¹ and the activation energy of 162.3 kJ/mol for E-spun fibers, and for the M-spun fibers with respective values of 4.45 × 10⁻⁴ s⁻¹ and 183.5 kJ/mol. The activation rates of the E-spun fibers were calculated to be 13–20 times faster than those of M-spun fibers in the activation temperatures. The higher activation rates for the E-spun fibers were rationalized on the basis of the higher frequency factors and the lower activation energy due to their finer diameters and less ordered structure than those of M-spun fibers.     

Electrochemical characterisation of the porosity and corrosion resistance of electrochemically deposited metal coatings

Electrochemical techniques for the assessment of porosity in electrodeposited metal coatings are reviewed. The determination of porosity and corrosion, resistance is illustrated by electrochemical data from three coating/substrate systems namely: electroless nickel on aluminium and steel and immersed gold coatings on an electroless copper-plated ABS polymer. Nickel coatings were up to 24 μm thick while gold deposits had thickness between 75 and 190 nm. Tafel extrapolation and linear polarisation resistance methods were used to determine the corrosion rate of the coated substrates. The aluminium samples were tested in 5% w/v (0.85 mol dm^− 3) NaCl, while coated steel and ABS samples were immersed in 0.125 mol dm^− 3 H₂SO₄ and 0.1 mol dm^− 3 NaBH₄, respectively, at 295 K. Current vs. time curves and anodic polarisation behaviour have also been considered.     

Hydrogen storage properties of Mg(Al) solid solution alloy doped with LaF3 by ball milling

LaF₃ was doped to the Mg(Al) solid solution alloy for enhancing the hydrogen absorption and desorption by ball milling. XRD was used to analyze the phases of the samples and the phase transition induced by hydrogenation and dehydrogenation. The microstructure and phase distribution were investigated by SEM and STEM. The hydrogen storage properties were measured by Sieverts method. For Mg_0.93Al_0.07-5wt.%LaF₃ nanocomposite, the hydrogen storage kinetic properties were significantly improved by reducing the hydriding and dehydriding activation energies to 65 and 78 kJ/mol, respectively, and the dehydriding enthalpy was calculated to be 69.7 kJ/mol. The improved hydrogen storage properties were mainly attributed to the catalytic effects of the in situ formed nanostructure Al₁₁La₃ and MgF₂ together with the dissolving of Al in Mg lattice.     

Supercapacitor characteristic of La-doped Ni(OH)<Subscript>2</Subscript> prepared by electrode-position

Samples of lanthanum-doped nickel hydroxide were prepared by electrodeposition method. The structure and electrochemical properties of the samples were studied by X-ray diffraction and a home-made open three-electrode cell system, respectively. The results show that the deposition process of Ni(OH)₂ and La(OH)₃ is mainly controlled by electrochemical polarization, which makes it easy to form uniform fine crystals. In addition, La(OH)₃ is not a separate phase and lanthanum ions are doped into Ni(OH)₂ crystal lattices. When V(0.5 mol/L Ni(NO₃)₂)/V(0.25 mol/L La(NO₃)₃) was 9:1, the lanthanum-doped nickel hydroxide reached the highest discharge capability of 840 F/g with a good cyclic reversibility. The capability still retains 670 F/g when the discharge current reaches 1000 mA/g.     

液相对ZnO陶瓷放电等离子体烧结过程的影响

本文采用放电等离子体烧结技术制备了ZnO陶瓷,主要研究了液相(醋酸溶液)的添加对烧结过程的影响。结果表明,通过对初始粉料添加微量的2 mol/L的醋酸溶液,在等离子体烧结过程中,ZnO陶瓷试样在52 _^oC开始收缩,115 _^oC开始致密化,160 _^oC致密度可达95%以上,200 _^oC度即可完成致密化。在250 ℃烧结5 min后,晶粒尺寸从初始粉体的200 nm增长到600 nm。X衍射结果表明,在液相辅助等离子烧结过程中,ZnO陶瓷中未出现明显杂相,并且晶粒生长表现出沿外施压力垂直的方向取向生长。通过计算发现液相辅助等离子体烧结ZnO陶瓷,其晶粒生长活化能仅为78.8 kJ/mol,约为传统高温烧结的三分之一。ZnO陶瓷试样的室温阻抗结果表明,晶界阻抗随烧结温度的升高而下降,从120 _^oC烧结试样的9.82×10_⁶ W下降到250 _^oC烧结试样的2.75×10_³ W。     

Development of hydrometallurgical process for indium recovery from waste liquid crystal display using Cyphos IL 101

The main goal of this study was to recover indium from the waste liquid crystal display (LCD) panel. In this context, an ionic liquid Cyphos IL 101 was explored. The extraction parameters such as equilibration period, acid concentration, chloride ion concentration, hydrogen ion concentration were examined on the extraction efficiency of Cyphos IL 101 towards In(III). Quantitative extraction of indium was found at 2.0 mol/L HCl using 0.005 mol/L Cyphos IL 101 and quantitative stripping with 1.0 mol/L H₂SO₄. Job's method was used to determine the extracted species and R₃R‘PInCl₄ (R=C₆H₁₃; R′=C₁₄H₂₉) was proposed. Based on the observations on multi-metal studies, Cyphos IL 101 was further employed for the removal of indium, tin and copper from the leach liquors of waste LCDs. Optimized conditions were generated for the recovery of indium from waste LCDs. McCabe−Thiele diagram analysis, counter-current extraction and selective stripping were carried out to separate the metal ions, i.e., indium, tin and copper. Two stages at O/A ratio of 1:3 were required for complete removal of tin from the feed and selective stripping of In and Sn was achieved using 0.1 mol/L H₂SO₄. A scheme for separating indium from the waste LCDs was proposed.     

Electrochemical behavior of sintered oxide dispersion strengthened stainless steels

The electrochemical behavior of powder metallurgy (P/M) oxide dispersion strengthened stainless steels (SS) (316L and 434L) have been compared with standard 430 and 316 wrought samples in 0.05 mol/l sulfuric acid. The effects of sintering temperature and yttria addition on the electrochemical behavior have been studied. The behaviour of the dispersion strengthened SS was comparable to that of the straight P/M samples. The straight P/M samples sintered at 1400 °C exhibited better corrosion resistance compared to the samples sintered at 1250 °C and this has been correlated to sintered densities. The P/M austenitic SS were superior to the P/M ferritic SS. Pitting resistance, studied by cyclic polarization experiments in 3.56 wt.% NaCl, of the P/M samples were comparable to the wrought samples. The addition of Y₂O₃ did not affect the pitting resistance.     

Role of titanium valence states in optical and electronic features of PbO–Sb2O3–B2O3:TiO2 glass alloys

PbO–Sb₂O₃–B₂O₃ glasses mixed with different concentrations of TiO₂ (ranging from 0 to 1.5 mol.%) were synthesized. The samples are characterized by X-ray diffraction, scanning electron microscopy and DSC techniques. A variety of properties, i.e. optical absorption, photoluminescence, infrared, ESR spectra, magnetic susceptibility, photo-induced birefringence (PIB) and dielectric properties (constant ′, loss tan δ, a.c. conductivity σ_ac over a wide range of frequency and temperature) of these glass–ceramics have been explored. The analysis of these results indicated that Ti ion surrounding ligands play principal role in the observed PIB and the sample crystallized with 0.8 mol.% of TiO₂ is the most suitable for the applications in non-linear optical devices.