镀锡板无铬钝化工艺研究

基于钛锆-磷硅无铬钝化体系,采用正交试验方法,改变钝化液浓度、干燥温度和时间,成功获得了高性能无铬钝化膜,并确定了无铬钝化最佳工艺.通过测定试验样板的抗酸抗硫性能、涂漆附着力性能和电化学耐蚀性能,发现其综合性能接近铬酸盐钝化产品.     

双一[γ一（三乙氧基硅）丙基]四硫化物处理热镀铝锌层的耐蚀性研究

采用双-[γ-(三乙氧基硅)丙基]四硫化物(BTESPT)硅烷钝化液对热镀铝锌钢板进行了钝化处理.研究了在5%NaCl溶液中未钝化、硅烷钝化及铬酸盐钝化热镀铝锌钢板的极化曲线和电化学交流阻抗谱.通过中性盐雾试验比较了硅烷钝化膜与铬酸盐钝化膜的耐蚀性能.结果表明:经硅烷钝化液钝化后的热镀铝锌钢板,其腐蚀电位和电流密度下降,极化电阻增大,硅烷钝化膜抑制了热镀铝锌钢板的腐蚀过程,使得耐蚀性能远远高于铬酸盐钝化后的热镀铝锌钢板.     

一种新型镀锌层无铬钝化工艺

为了提高锌镀层的耐蚀性能,必须对其进行钝化处理。采用钼酸铵和磷酸钠组合,加入适量的添加剂XZ-03B,确定了一种新的镀锌层无铬钝化工艺,探讨了其主要成分和工艺条件对钝化膜性能的影响。结果表明:所形成的钝化膜为彩虹色,色泽鲜艳、均匀,钝化膜性能接近铬酸盐钝化膜的性能,耐腐蚀性较好,且钝化液不含铬酸盐,对环境污染极小,因此具有一定的应用价值。     

热镀锌钢板钝化工艺对耐蚀性的影响

为提高热镀锌钢板的耐蚀性,对热镀锌钢板铬酸盐钝化工艺进行了研究.采用盐雾试验、钝化膜的微观形貌等手段分析了钝化液浓度及钝化工艺参数(钝化液温度、烘干时间、烘干温度等)对热镀锌钢板铬酸盐钝化膜耐蚀性的影响.结果表明,采用试验确定的钝化工艺处理得到的钝化膜耐蚀性明显提高,对实际生产具有较好的指导意义.     

镀锌板硅烷-硝酸锆复合转化膜的性能与表征

目的获得一种防腐性能优越的转化膜。方法将KH560和KH791两种硅烷复合后水解,添加硝酸锆,得到KH560-KH791-硝酸锆复合钝化液,采用该钝化液对镀锌钢板进行钝化处理,通过盐水浸泡实验、中性盐雾试验和附着力测试,与添加硝酸锆前的转化膜进行性能对比。结果盐水浸泡和中性盐雾腐蚀72 h的实验中,添加硝酸锆后的转化膜性能都明显优于添加前,二者的附着力测试均能达到一级。结论加入的硝酸锆填充了膜层空隙,更加有效地阻挡了腐蚀介质的渗透,使得钝化膜的防腐性能提高。     

环保型镀锌层蓝色钝化膜耐腐蚀性能的研究

采用钛盐溶液替代铬酸盐溶液对镀锌层进行表面钝化处理,获得了色泽光亮、耐腐蚀性能优良的蓝色钝化膜层。探讨了钛盐钝化溶液成分及工艺参数对镀锌层表面钝化膜的耐腐蚀性影响;中性盐雾、电化学测试等腐蚀性能试验结果表明,钛盐钝化溶液所获得的蓝色钝化膜,其耐腐蚀性能更优于铬酸盐钝化膜。     

热镀锌层钛盐钝化膜耐蚀性能的研究

以钛盐为主盐,加入双氧水、硝酸(磷酸)、络合剂等配制无铬钝化液,经钝化后在镀锌层表面获得一层均匀的无铬钝化膜.通过电化学试验、盐雾腐蚀试验、大气暴露试验等测试手段对比研究了铬酸盐钝化膜、钛盐钝化膜、镀锌层的耐蚀性能以及影响钝化膜耐蚀性的因素.结果表明:镀锌层经钛盐钝化后耐蚀性能明显改善,在中性盐雾箱内可以通过48 h连续喷雾而不产生白锈.     

铈基钝化法在金属防护中的应用研究进展

铈盐由于其自身无污染、成本低、性能好、用途广等优点,已成为代替铬酸盐钝化的重要方法之一.简要总结了国内外研究人员的发现,得出铈盐可以自行成膜,且铈盐有着良好的自愈能力.同时,也发现纯铈膜的防腐效果不是很理想,易出现裂纹、附着力差等问题.为解决此问题,可以将铈盐与其他金属盐结合,得到混合钝化液,所得到的复合膜效果较好,能减少裂纹的形成;也可以在铈盐钝化液中加入有机化合物,形成的有机和无机复合钝化膜效果更佳,防腐效果甚至高于铬酸盐技术.铈盐以及铈盐复合钝化膜能广泛地应用在各类金属及金属合金表面,极大程度地扩展了铈盐钝化液的应用范围,提高了在工业上的使用率.对铈盐钝化液的机理、钝化方法、应用领域等方面的最新进展进行简单地总结与探讨.为解决铈盐钝化液在钝化机理以及钝化方法方面存在的不足,对最新的工艺方法或配方改善方法进行了提炼,并对未来铈盐钝化液能有效解决原铬基钝化液的污染问题和提高涂层的防腐能力进行了展望.     

取代铬酸盐钝化处理工艺的动向

六价铬对人体、特别是对皮肤会造成伤害而成为环境问题,现在铬酸钝化膜,特别是镀锌层的铬酸盐钝化膜在欧洲已经受到限制。本文对铬酸盐钝化膜的性能以及所进行的以三价铬盐或无铬盐取代铬盐钝化的开发状况加以解说。     

热镀Zn层钼酸盐钝化工艺

研究了用低毒性钼酸盐取代剧毒的重铬酸盐对热镀 Zn层进行钝化的工艺,探讨了钝化液组成、pH值、钝化处理温度及时间对钝化成膜及膜层耐 蚀性的影响.中性盐雾腐蚀(NSS)试验表明,采用该工艺可获得耐蚀性与低Cr钝化相当的具有 较为均匀的淡黄或浅蓝色钝化膜.     

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.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.