Ni—P镀层磷含量对Ni—P／TiO2复合膜耐蚀性能的影响

采用化学镀／溶胶一凝胶技术在碳钢表面制备了低磷（Ni—LP／TiO2）、中磷（Ni-MP／TiO2）和高磷（Ni-HP／TiO2）Ni—P／TiO2复合膜．采用X衍射分析仪和环境扫描电镜表征了Ni—P／TiO2复合膜的结构与形态．应用动电位极化和极化阻力（Rp）测量研究了复合膜在0．5mol／l,H2SO4溶液中的耐蚀性能。实验结果表明Ni—P／TiO2复合膜耐蚀性能优于Ni-P镀层,随NiP镀层磷含量的增加,Ni—P／TiO2复合膜的耐蚀性增强。Ni—HP／TiO2复合膜在0．5mol/L H2SO4溶液的自腐蚀电流密度（icorr）为3．15μA·cm^-2,分别为Ni—LP／TiO2和NiMP／TiO2复合膜的40％和62％;其Rp为11．72kΩ·cm^2．分别为Ni—LP／TiO2和Ni—MP／TiO2复合膜的1．5倍和1．3倍,Ni—HP／TiO2复合膜较NiLP／TiO2和Ni—MP／TiO2复合膜有更佳的耐蚀性能。     

GW93镁合金磁控溅射类石墨镀层的耐蚀性

通过对铸造GW93镁合金表面非平衡磁控溅射沉积的类石墨镀层的交流阻抗谱和塔菲尔曲线的电化学研究,定量分析了类石墨镀层的耐蚀性,并用失重法对电化学测试结果进行了进一步验证.利用扫描电镜(SEM)研究了类石墨镀层表面微观结构对其耐蚀性的影响.结果表明,非平衡磁控溅射类石墨镀层由Cr层,过渡层和C层组成,薄膜生长方式为岛状生长.类石墨镀层在本底真空度为8.8×10-3 Pa时,可将GW93镁合金的电化学阻抗提高到5.0×1019Ω,自腐蚀电位提高到-0.940 V,从而改善镁合金的耐蚀性.本底真空度是影响GW93镁合金磁控溅射镀类石墨镀层耐蚀性一个重要因素,真空度越大,其耐蚀性越好.     

Nb表面合金化对Ti6Al4V腐蚀行为的影响

采用失重法和电化学扫描法研究了等离子表面合金化技术在Ti6Al4V（TC4）合金表面形成的Ti-Nb合金层及基体材料的腐蚀行为,分析了Nb的渗入对Ti 6Al4V耐蚀性的影响.失重法研究表明：在10%H2SO4和10%HCl溶液中Ti-Nb合金层较基体耐蚀性提高,在10%NaCl溶液中无明显变化;电化学腐蚀研究表明,在5%H2SO4、5%HCl、3.5%NaCl溶液中,Ti-Nb合金层耐蚀性较基体均有不同程度的提高.     

添加纳米TiO2的Ni-P化学复合镀层显微结构与性能

采用化学复合镀法制备了Ni-P-纳米TiO2复合镀层,研究了纳米TiO2添加对Ni-P复合镀层的显微结构、硬度、耐磨性、孔隙率及耐蚀性的影响,并讨论了其影响机理。结果表明:纳米TiO2粒子较为均匀地分布在Ni基镀层,未发生明显团聚;纳米TiO2粒子的弥散强化作用,使复合镀层具有较高的表面硬度和良好的耐摩擦性能,晶化热处理后的复合镀层表面硬度达到了10 925 MPa,耐摩擦性能也显著提高。添加纳米TiO2粒子后,镀层的孔隙率增加,耐碱和耐盐腐蚀的能力稍有降低,耐HCl溶液腐蚀的能力较差。     

Ni-Fe-P镀层在H2S/CO2腐蚀环境中的腐蚀电化学研究

在油管常用钢N80钢表面制备了Ni-Fe-P化学镀层,采用SEM、EDS、XRD等分析手段,对所制备镀层的成分、微观形貌、结构等性能进行了分析研究;采用电化学方法评价了Ni-Fe-P镀层在H2S/CO2溶液中的耐蚀性。结果表明,N80钢表面经过化学镀Ni-Fe-P处理后,其耐蚀性得到很大的提高,镀层结构为非晶态;电化学测试结果表明该镀层在H2S/CO2溶液中具有极强的钝化倾向和很好的耐酸性,结果均证明Ni-Fe-P镀层具有良好的抗H2S/CO2腐蚀性能。     

文摘辑要

高频脉冲复合电镀（Ni-Co）-SiC复合镀层的耐蚀性研究 用高频脉冲复合电镀方法制备了（Ni-Co）-SiC复合镀层。研究了脉冲频率对镀层硬度及耐蚀性的影响。结果表明：随着脉冲频率的增加,复合镀层表面更加致密、均匀,硬度提高。在3.5%NaCl溶液和15%H2SO4溶液中,（Ni—Co）-SiC复合镀层的自腐蚀电位均发生正移,腐蚀失重速率变慢。与Ni-Co合金镀层相比,复合镀层具有较高的硬度和耐蚀性。     

化学镀Ni-Fe-P和Ni-Fe-P-B合金的耐蚀性研究

利用失重法和电化学测试法,对比研究以铝合金为基体化学镀Ni-Fe-P和Ni-Fe-P-B合金的耐蚀性.结果表明:这两种镀层浸泡在3.5%NaCl和10%NaOH溶液中均比浸泡在0.1mol/L H2SO4和1mol/L HCl中有更好的耐蚀性.另外,在3.5%NaCl和10%NaOH溶液中,Ni-Fe-P-B镀层合金比Ni-Fe-P有更好的耐蚀性;但是在0.1mol/L H2SO4和1mol/L HCl溶液中,Ni-Fe-P镀层合金却比Ni-Fe-P-B有更好的耐蚀性;     

电沉积纳米晶Ni-Fe合金在碱性溶液中的腐蚀性能

通过脉冲电沉积的方法制备纳米晶Ni和Ni-Fe镀层,采用浸泡法和电化学的方法研究了镀层在10%NaOH溶液中的腐蚀行为.结果表明:在纳米Ni中加入适量的Fe可以提高其耐蚀性能.Ni-7.72?合金镀层的耐蚀性能高于纳米Ni,而Ni-12.65?合金镀层耐蚀性与纳米Ni的相当.在Ni-Fe合金镀层中,耐蚀性随着铁含量的增加而降低.在10%NaOH溶液中,所有镀层的Tafel曲线上均可观察到钝化区,表现了很好的耐蚀性.     

铝靶电流对磁控溅射AlSn20镀层耐蚀性的影响

采用非平衡磁控溅射镀膜设备通过改变铝靶电流在铝基轴承合金表面制备了AlSn20镀层.并对镀层的交流阻抗谱和塔菲尔曲线进行了电化学研究,定量分析了镀层的耐蚀性,并用失重法进行了进一步验证.利用SEM研究了镀层表面微观结构.结果表明,铝靶电流为1.5 A时,轴承合金磁控溅射AlSn20镀层使合金的电化学阻抗提高5～6个数量级,可将镀层的自腐蚀电位提高到-1.12 V,改善轴承合金的耐蚀性.铝靶电流是影响AlSn20镀层耐蚀性的一个重要因素,铝靶电流越小,其耐蚀性越好.     

高活性TiO_2薄膜电极的制备及其光电化学性能

以Ti(n-OC4H9)4和CH3COOK为原料,采用溶胶-凝胶法在导电玻璃基底上制备K2Ti2O5薄膜,进一步以K2Ti2O5薄膜为前躯体,用离子交换法获得TiO2纳米薄膜电极。利用X射线衍射(XRD)和扫描电子显微镜(SEM)分析薄膜的组成和表面特征;以草酸为有机污染物代表,通过光电化学技术考察薄膜的光电化学活性。结果表明:TiO2纳米薄膜具有锐钛矿晶型,其粒径随着K2Ti2O5薄膜制备温度的降低而减小,约为30～150nm;TiO2纳米薄膜在0.1mol/LNa2SO4溶液中具有典型的光电化学活性以及较高的稳定性,比在含少量草酸的溶液中采用溶胶-凝胶法制备的TiO2薄膜具有更强的光激发和更稳定的光电流响应性能,TiO2薄膜电极的平带电位发生负移,负移值为0.140V(vsSCE),饱和光电流密度为0.32mA/cm2。     

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.     

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.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

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.