碱性介质中304不锈钢交流调制电位着色工艺研究

为了改善不锈钢着色过程中高温和重离子的环保和耗能问题,室温下,在无Cr的NaOH溶液中304不锈钢交流调制电位法着色处理工艺,该工艺具有经济环保的特点.获得了稳定的金黄色、黄紫色、紫色、蓝紫色和蓝色膜,着色膜具有良好的耐蚀性,耐磨性、机械加工性和抗污性.探讨了工艺参数对着色膜耐蚀性和稳定性的影响.结果表明:着色电压幅值为7.0～8.0V、着色时间为4～7min时,着色膜稳定性和耐蚀性能最好.     

口腔医用不锈钢托槽表面着色及膜层成分研究

为了获得重现良好﹑色彩鲜艳的不锈钢表面色彩和了解不锈钢表面着色膜的成分,采用了电位控制不锈钢表面着色方法;并利用俄歇能谱分析表面膜层成分.研究表明通过利用电位变化曲线能够控制不锈钢表面氧化膜的厚度,使着色工艺易于控制,同时分析了化学着色溶液的温度和浓度﹑着色时间对不锈钢托槽表面颜色的影响,测定了着色过程中的电位变化曲线.俄歇能谱成分分析表明不锈钢表面膜层含有Cr、Fe、S、O等元素.     

前处理及添加剂对不锈钢化学着色的影响

在H2SO4-CrO3化学着色法基础上，探讨了前处理工艺对着色过程的影响，探讨了不同前处理对着色膜的形态、微观组织、均匀性、光亮度和重现性等的影响，研究了在化学着色液中加入添加剂对着色过程和色膜的影响。在这些研究的基础上探讨了最为可行的着色工艺。还对色膜的耐蚀性及耐磨性进行了检测。     

不锈钢着色的光干涉效应

采用化学氧化法,测定不锈钢在着色溶液中,着色电位与颜色的对应关系,并采用俄歇能谱测定了着色膜的化学元素组成和膜厚与着色电位的关系.根据薄膜光干涉原理,提出了颜色与膜层的关系式,对着色膜层的折射率进行了估算.     

工艺参数及前后处理对 Cu-Se 系铜合金化学着色的影响

以Cu-Se系铜合金化学着色液为对象,通过检测着色膜层的颜色,观察着色膜的均匀性和表面形貌,研究了着色液pH值、着色温度、着色时间等工艺参数及抛光、除油、擦拭等着色前后处理方法对最终着色质量的影响。研究结果表明:pH值和着色温度对着色膜的颜色和均匀性影响显著,最佳pH值为1.5～2,最佳着色温度为20～30℃;着色时间对着色膜层的颜色影响显著,对均匀性没有影响,时间越长,膜层越趋于黑色。     

不锈钢化学着色工艺的研究

对不锈钢的化学着色工艺进行了研究，并讨论了预处理和后处理对着色工艺的影响，同时还测试了着色件的耐蚀性，耐磨性及加工成形性。     

不锈钢着色的"绿色"工艺研究

通过实验研究，提出一种新型的不锈钢着色工艺——载波钝化着色。运用色差计、电化学阻抗谱和其它电化学测量方法对载波钝化着色中的影响因素、着色膜色彩的控制和着色样品的耐蚀性作了研究，并与化学着色样品作了比较。结果表明，载波钝化着色工艺是一种可以替代化学着色法(如INC0法)的新型“绿色”工艺，该工艺可避免“INCO法”中Cr^6 对环境的污染。在膜层色彩的控制方面较化学着色有着更准确的控制方法，同时具有较好的耐蚀性，是一种有广阔应用前景的表面处理工艺。     

镍离子对不锈钢化学着色的影响

试验研究了着色液中镍离子(Ni~(2 ))浓度变化对不锈钢化学着色的影响。用扫描电子显微镜(SEM)和自制镜面反射装置分别对着色膜成分和光泽度进行微区分析与表征,结果表明,随着着色液中Ni~(2 )浓度的增大,不锈钢的着色起色电位下降;着色速度减慢,着色时间延长;着色膜光泽度降低,色调变暗。着色膜中主要成分Fe含量呈现振荡式略微下降趋势,O、Ni含量基本无变化,Cr含量呈缓慢上升趋势;当C_(Ni)~(2 )>8.0 g/L时,着色膜表面发雾,此时着色液不再适合着色。     

不锈钢环保型彩色工艺及其耐腐蚀性能

通过对传统着色工艺的改进,摸索出了一种以硫酸亚铁铵为主盐的低温、无铬、环保的配方,添加适量的添加剂,利用微机控制着色时间,得到了蓝色、黄色、紫红色、绿色和褐色五种色彩。采用扫描探针和X射线光电子能谱等表面分析手段,研究了着色膜的表面形貌和元素组成,并采用动电位扫描的电化学方法考察了着色膜的耐腐蚀性能。结果表明,着色膜主要由铁、氧等元素组成,着色膜色泽鲜艳、光亮。着色后的不锈钢耐蚀性优于未着色的试样,随着色膜厚度的增加耐蚀性增强,此工艺操作温度低(50~60℃),具有较高的应用推广价值。     

不锈钢化学着色的低温工艺研究

为了降低不锈钢化学着色的高温条件,在CrO3-H1SO4着色体系中加入过渡金属无机盐添加剂,对不锈钢进行化学着色,使用正交设计方法优化工艺条件为铬酐浓度250g/L,着色温度60℃,添加剂用量5g/L,得到不同颜色的不锈钢,并对不锈钢的性能进行测定,结果表明:添加剂的使用可明显降低着色温度,减少铬酸挥发带来的环境污染,同时彩色钝化膜保持良好的性能.     

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。