电弧喷涂铝基涂层耐腐蚀性能

采用铝带制作粉芯线材,电弧喷涂方法制备铝基涂层.试验对比研究了铝基涂层、Fe-Al涂层和45CT涂层的抗氧化和耐腐蚀性能,以及铝基涂层、Fe-Al涂层和A304不锈钢的耐硫化氢腐蚀性能.试验结果表明,电弧喷涂铝基粉芯线材制备的涂层在650℃高温下具有优良的抗高温氧化性能;在涂盐和硫化氢耐腐蚀环境下,由于铝基涂层的硫化腐蚀反应仅发生在涂层表面,腐蚀层很薄,涂层内部几乎没有受到影响,因此铝基涂层具有优良的耐腐蚀性能.     

抗氧化耐氯腐蚀电弧喷涂铁基粉芯线材

采用304L不锈钢带包覆铬、镍、钼、铝、稀土等金属粉末制备粉芯丝材,使用电弧喷涂方法制备涂层,研究了合金元素成分对涂层抗高温氧化性能和抗氯腐蚀性能的影响,并与传统的Ni-Cr-Ti涂层(PS45)的性能进行了对比。结果表明,Cr元素的抗氧化性能要好于Ni元素,在氯腐蚀环境下,Ni元素的耐腐蚀性能比Cr元素更为优异,添加适当数量的Al元素、Mo元素对耐氯腐蚀性能有一定的促进作用。所研制的LJ-1铁基涂层在650℃温度下具有良好的抗高温氧化性能和耐氯腐蚀的性能,其抗氧化性能和耐氯腐蚀性能分别是Ni-Cr-Ti涂层(PS45)的0.74倍和0.67倍,但涂层成本大幅度降低,性价比提高。     

高速电弧喷涂Fe-Al复合涂层高温腐蚀研究

研究了高速电弧喷涂（HVAS）的几种Fe-Al复合涂层的耐高温腐蚀行为,用SEM观察分析了腐蚀表面的形貌和成分、涂层截面的组织结构.结果表明：随温度升高,4种Fe-Al涂层的腐蚀增重都增加,添加Cr3C2比添加WC或不添加任何增强的Fe-Al涂层有更高的耐腐蚀性. Fe-Al/Cr3C2涂层外表面形成了铝和铬的氧化物,阻止了氧化的进一步进行. 关键词：高速电弧喷涂;高温腐蚀;Fe-Al涂层     

电站锅炉防护用Fe-Al/Cr3C2涂层性能研究及应用

使用高速电弧喷涂技术结合Fe-Al/Cr3C2粉芯丝材制备了铁铝金属间化合物涂层,对涂层的常温与高温性能进行了研究,并进行了应用的探索.结果表明,Fe-Al/Cr3C2复合涂层具有典型的层状结构、较高的结合强度和硬度;涂层的耐高温冲蚀性能良好,温度升高、角度增大,冲蚀性能提高;由于Cr2O3的存在以及涂层结合能的提高,Fe-Al/Cr3C2涂层的高温抗腐蚀性能较高;其常温和高温耐磨损性能也较高;应用研究表明,该涂层适合用于电站锅炉＂四管＂的防护.     

高速电弧喷涂Fe-Al/Cr3C2复合涂层摩擦学特性

使用THT07—135高温磨损实验机对高速电弧喷涂Fe-Al／Cr3C2复合涂层进行了滑动摩擦特性的研究．并在扫描电镜上观察分析了磨斑的形貌和成分、涂层截面的组织结构。结果表明，在常温下涂层具有良好的耐摩擦性能．随着滑动距离的增加，摩擦系数基本无波动；随着温度的增加．涂层耐磨损性能降低较快，并在250℃开始趋于平稳，在550℃后，涂层的耐磨损性能重新增强，剥层磨损是Fe-Al/Cr3C2涂层磨损的主要机理；由于硬质相的阻碍作用以及铁铝金属间化合物本身高的硬度，Fe-Al／CrC3涂层具有优于20钢的耐磨损性能。     

高速火焰喷涂Fe-Al/Cr3C2复合涂层抗高温腐蚀性能研究

利用高速火焰喷涂方法,选用自主研发的Fe-Al/Cr3C2喷涂粉材,在20钢基体上制备Fe-Al/Cr3C2复合涂层。研究了复合涂层在650℃的抗高温腐蚀性能。采用SEM,XRD,EDS等先进测试手段分析了复合涂层的抗高温腐蚀机理。结果表明：Fe-Al/Cr3C2复合涂层在650℃的抗高温腐蚀性能明显优于基体20钢,并且优于Fe-Al涂层,其腐蚀动力学曲线呈抛物线变化;复合涂层经腐蚀后,内层生成的致密Al2O3及Cr2O3阻止了高温腐蚀的进一步深入。现场应用表明,Fe-Al/Cr3C2复合涂层具有广泛的应用前景。     

Al-Ti-Si-RE高速电弧喷涂层热震与电化学腐蚀行为

通过对Al-Ti-Si-RE涂层抗热震性能以及热震前后电化学腐蚀行为分析研究,发现Al-Ti-Si-RE涂层在500℃时能够保持良好的抗热震性能,且在热震前后耐电化学腐蚀性能没有明显下降,主要原因是Ti在高速电弧喷涂过程中,与Al结合反应放热,使涂层与基体"冶金结合"部位增多,提高了涂层结合强度。同时经透射电镜(TEM)观察,喷涂层中晶粒尺寸较小,且Al与钛铝金属间化合物具有良好共格关系,降低了Al-Ti-Si-RE涂层开裂敏感度。另外Al-Ti-Si-RE涂层具有发达的"骨架"结构,电化学腐蚀过程中形成的Al氧化物能够有效填充到"骨架"孔隙和热震引起的微裂纹当中,对涂层同时起到"自封闭"与"自修复"作用,使其更加致密并兼具良好抗热震性能与耐电化学腐蚀性能。     

低碳钢表面电弧喷涂层FeNiCr/Cr_3C_2与NiCrTi的热腐蚀性能

采用高速电弧喷涂工艺在低碳钢基体表面制备了FeNiCr/Cr3C2和NiCrTi两种电弧喷涂涂层。通过光学显微镜对涂层的显微组织进行了观察研究。试验选用摩尔比为7：3的Na2SO4＋K2SO4饱和水溶液涂刷在涂层表面,在700℃的条件下进行了156 h的热腐蚀试验。通过腐蚀动力学测试对电弧喷涂涂层的抗热腐蚀性能进行了评估。采用了X射线衍射,扫描电镜和能谱分析技术对热腐蚀机理进行了探讨。结果表明,两种电弧喷涂涂层具有致密的层状结构,涂层中含有少量空隙。在涂层表面生成的连续致密的氧化膜使得NiCrTi涂层具有良好的抗热腐蚀性能。FeNiCr/Cr3C2涂层则遭受了较严重的氧化腐蚀和硫化腐蚀,并且有内硫化物析出,抗热腐蚀性能较差。     

304不锈钢表面单层/多层TiN基涂层制备及耐磨蚀性能研究

目的探究钢基表面TiN基涂层在海洋环境中的耐磨蚀性能。方法采用电弧离子镀技术,在304不锈钢和单晶硅表面分别沉积TiN、TiBN、TiBN/TiN涂层,并对3种涂层样品的表面–截面形貌、摩擦系数、在人工海水中的电化学性能和摩擦腐蚀行为进行测试。结果形貌表征和干摩擦测试结果显示,TiBN和TiBN/TiN涂层有着比TiN柱状晶更加致密的微观结构,3种涂层的摩擦系数相差不大,比304SS的摩擦系数低。在人工海水环境中的电化学测试结果表明,TiBN/TiN涂层的耐腐蚀性能最佳,TiBN涂层次之,TiN涂层则表现出比304不锈钢基底更差的耐腐蚀特性。在发生摩擦腐蚀的过程中,3种涂层的电位（OCP）均发生了下降。结论利用电弧离子镀技术在304不锈钢表面沉积的单层/多层TiN基涂层,在人工海水环境下,发生的摩擦会增加涂层发生腐蚀的趋势,结构致密,表面易形成钝化膜的涂层,其耐磨蚀性较好。     

Fe/Cr涂层抗热腐蚀性能研究

设计制造出Fe/Cr粉芯丝材,利用电弧喷涂技术制备出耐高温腐蚀的工作涂层。运用光学显微镜、扫描电子显微镜(SEM)、X射线衍射仪(XRD)等研究了电弧喷涂Fe/Cr合金涂层的微观结构、腐蚀动力学和高温下的腐蚀性能。结果表明,该涂层组织致密,涂层中形成Cr2O3或尖晶石型氧化物是其具有优异的抗高温腐蚀性能的主要原因,涂层抗高温腐蚀性能较好。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

电化学噪声数据处理方法概述

综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。