纳米SiO_2对低碳钢表面常温磷化处理的影响

在常温磷化的条件下,通过向磷化液中加入纳米SiO2,在低碳钢表面制备磷化膜。通过硫酸铜点滴试验以及腐蚀电化学测试等手段,研究磷化液中加入纳米SiO2对磷化膜结构和性能的影响。结果表明,在本试验条件下,磷化膜的膜厚随着纳米SiO2浓度的增加而增加。当纳米SiO2的加入量为1 g/L时,膜厚为7.81μm,磷化膜耐蚀性能最好,耐硫酸铜点滴腐蚀时间大于115 s,3.5%NaCl溶液中的腐蚀电流密度为0.931μA/cm2,缓蚀效率为97.9%。     

采用预浸铜提高焦磷酸盐镀铜结合力试验情况

焦硫酸盐无氰镀铜工艺具有溶液成份稳定,操作简便,结晶细致,镀层光亮之特点。不足之处由于钢铁另件与该溶液中的铜离子电位相差较大,往往在另件表面形成一层疏松的置换铜层,而影响镀铜层与钢铁表面的结合力。疏松的置换铜层是影响镀铜层结合力的主要矛盾。如果在硫酸铜溶液中加入适量的丙烯基硫脲或其它硫脲     

锌锰系磷化膜硅酸钠封闭工艺研究

通过单因素对比实验,研究了硅酸钠浓度、添加剂以及封闭时间、封闭温度等对磷化膜封闭效果的影响,获得了最佳封闭工艺。采用加速腐蚀实验方法和电化学测试技术,将硅酸盐封闭的效果与铬酸盐封闭进行了对比,并探讨了封闭机理。结果表明:硅酸钠封闭后,磷化膜中性盐雾试验(NSS)24h未见腐蚀,自腐蚀电位正移,自腐蚀电流明显降低;硅酸钠封闭是通过形成硅酸盐沉淀封闭磷化膜的微小凹陷处,从而提高磷化膜耐蚀性的。     

硅酸钠封闭后处理对磷化热镀锌钢耐蚀性的影响

将热镀锌钢板磷化后再用硅酸钠（水玻璃）溶液封闭后处理,以进一步提高磷化膜的耐蚀性.用SEM、EDS、NSS试验和电化学极化测量研究了硅酸钠封闭后处理对磷化膜组成和耐蚀性的影响.结果表明,经硅酸钠封闭处理后,磷化镀锌钢板表面磷酸锌晶体间的孔隙被含Si、P、Zn的新膜填补,形成了连续完整的复合膜;复合膜的耐蚀性能明显提高,且与硅酸钠溶液的浓度及封闭时间有关;硅酸钠浓度为5 g/L、封闭10 min时形成的复合膜的耐蚀性最佳,NSS试验6个周期（天）后仍不出现腐蚀;试样的阳极极化和阴极极化阻力均显著增强,腐蚀电流密度明显减小,极化电阻增大了一个多数量级.     

环保型中温磷化工艺

采用正交试验法优选了一种环保型中温磷化工艺配方。通过硫酸铜点滴,3%NaCl溶液浸泡等方法,测定了磷化膜的外观、耐蚀性、防锈性、膜重以及漆膜附着力等性能。结果表明,本研究得到的磷化膜呈彩色,均匀、致密,平均膜重约3.40 g/m2;耐蚀性、防锈性均较好,磷化后漆膜附着力大幅度提高。     

乙二胺在电刷镀铜溶液中的作用

主要就乙二胺在电刷镀铜溶液中的作用及其对镀铜层性能的影响进行了试验研究。研究结果表明：在电刷镀铜溶液中，乙二胺与铜离子的最佳摩尔浓度比为(2～3)／L。以甲基磺酸铜为主盐的电刷镀铜溶液比以硫酸铜为主盐的电刷镀铜溶液具有更快的沉积速度。     

清洁型免水洗常温锰钙钡系磷化液的研究

以磷酸二氢锰、硝酸钙、硝酸钡、钼酸钠等为原料配制锰钙钡系磷化液,对Q235钢铁试片进行常温磷化,磷化后免水洗,自然干燥3 h以上,获得了彩色锰钙钡系磷化膜。分析了磷化膜的形貌和组成,考察了磷化液pH值、磷化温度、磷化时间、磷化量等工艺条件对磷化膜性能的影响。结果表明,在磷化液pH值2.3～2.8、磷化温度5～40℃下浸渍磷化8～10 min,可生成连续、致密且颗粒细小的免水洗锰钙钡系磷化膜;磷化膜由Fe,Mn,Ca,Ba的磷酸盐及少量钼酸盐等组成,耐硫酸铜溶液腐蚀时间>85 s,膜质量0.9 g/m2左右,喷涂铁红环氧底漆后的涂层附着力达1级。     

汽车齿轮锰系磷化质量优化浅析

本文讨论了磷化前表面调整液浓度、磷化液游离度、总酸度等过程控制参数对汽车齿轮高温锰系磷化膜质量的影响。结果表明:磷化前表面调整液浓度影响磷化膜生长,在一定范围内,浓度越高,磷化膜结晶越均匀;蚀坑尺寸随着游离酸度增加而变大,总酸度影响甚微;磷化膜厚和结晶晶粒尺寸受游离酸度影响较小,但在一定范围内随总酸度增加而增大,总酸太高晶粒疏松且分布不均匀;酸比控制在7左右为宜。     

超薄低铜镀层CO2气体保护焊焊丝

为降低气保焊丝的镀铜层厚度,减少含铜量.选用一种葡萄糖类环状有机络合物,在镀铜置换反应中首先与铜离子反应生成亚稳态络合物,然后再与铁原子发生置换反应,从而控制置换反应速度、改变铜离子在置换反应中的各向异性,提高铜离子的反应功能,使镀铜层致密,舍铜量降低,提高了产品质量.具体效果:缩短了镀铜时间,减少了硫酸铜的使用量,降低了生产成本,减少了对生产环境及焊接环境的污染.     

碳钢的电解磷化工艺探究

以碳钢为研究对象,采用正交试验方法探究了一种基于普通磷化液的电解磷化工艺参数。并采用磷化膜外观、厚度、硫酸铜点滴时间等手段对磷化膜的成膜性能和耐腐蚀性能进行表征和评价。结果表明,在电解时间60s,总酸110点,温度20℃,电流密度0.4A/dm2的条件下,形成具有厚度一致、耐腐蚀性能优越的膜层。通过SEM与XRD对磷化膜进行微观表征,得出此磷化膜是颗粒状分布均匀且由Zn3(PO4)2·4H2O单相构成。这种磷化方法可制备出成膜速度快、抗腐蚀性能优良的磷化膜,且磷化液无沉渣、无有毒离子,是一种高效环保磷化处理方法。     

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。