在Q235钢表面原位生长的氧化铁膜对其在含Cl-溶液中腐蚀行为的影响Ⅰ-原位生长的γ-FeOOH膜的防护性能

    利用动电位极化曲线和交流阻抗谱等电化学测量技术,研究了Q235钢表面原位生长的γ- FeOOH膜在0.25 mol/L Na₂SO₄+10^-4mol/L NaCl、0.25 mol/L Na₂SO₄+10-3mol/L NaCl、0.25 mol/L Na₂SO₄+10^-2 mol/L NaCl水溶液中的电化学行为及在不同浓度的Cl^-水溶液中γ-FeOOH膜对Q235钢的保护作用.结果表明,Cl^-含量较低时,γ-FeOOH膜的存在明显地促进了Q235钢的阴极反应,该膜对基材无保护作用;随Cl-浓度的增加,阴极电流密度大幅减小,当Cl^-浓度达到10^-2 mol/L时,γ-FeOOH 膜能在一定程度上抑制基材的腐蚀,此时γ-FeOOH膜表现出对基材有保护作用.     

稀土元素添加对铁基非晶复合材料腐蚀行为影响

采用工业原料经包覆剂(CaO-Fe₂O₃-SiO₂)处理制备Fe-15Mn-5Si-14Cr-0.2C非晶复合材料棒状试样,添加稀土元素Ce、Dy及Ce+Dy,通过XRD研究稀土元素对微观组织的影响;采用电化学工作站三电极体系测试试样在1mol/L的HCl及1mol/L的NaOH中的腐蚀行为。结果表明：合金在添加稀土元素的组织依然为非晶复合材料(过冷奥氏体相CFe_15.1+ 铁素体相Fe-Cr),加入1%Ce的试样在HCl及NaOH的耐蚀性均为最佳,在HCl中自腐蚀电位为-0.16205V,自腐蚀电流密度为7.6999×10^₈A.cm^_-2,极化阻值达到9.5774×10^₈Ω.cm^₂,在NaOH自腐蚀电位和自腐蚀电流密度为-0.1839V,1.7453×10^_-8A.cm^_-2,极化阻值为7.1574×10^₈Ω.cm^₂,耐蚀性远优于AISI304,是潜力巨大的耐蚀材料。     

NH4F浓度对镁合金表面微弧氧化制备氟化物膜层结构和性能的影响

目的 考察乙二醇-氟化铵电解液中氟化铵浓度对镁合金表面微弧氧化制备氟化物膜层结构和性能的影响,提高镁合金氟化物膜层的耐腐蚀性能。方法 在含不同浓度NH4F的EG-NH4F电解液中,采用微弧氧化的方法制备氟化物膜层,NH4F质量浓度分别为40、60、80、100、120 g/L。通过扫描电子显微镜(SEM)、X射线能量色散谱仪(EDS)和X射线衍射仪(XRD),对膜层表面微观形貌和成分组成进行分析,并通过电化学测试表征了膜层的腐蚀防护性能,通过盐雾试验评估了膜层长效防腐蚀行为,通过SEM和EDS表征了腐蚀形貌和腐蚀产物。结果 在EG-NH4F中制备膜层的物相组成主要是MgF2。随着NH4F浓度的提高,微弧氧化的起弧电压与工作电压均逐渐减小,膜层中氟含量逐渐增加,膜层的孔径减小,孔数量分布更加均匀,膜层表面粗糙度降低。质量浓度为100 g/L NH4F的膜层自腐蚀电流密度(Jcorr)为2.226×10^‒7 A/cm²,较镁合金基材降低了1个数量级,极化电阻Rp增大到90.156 kΩ.cm²,其阻抗模量|Z|f=0.01 Hz=8.55×10⁵ Ω.cm²,与镁合金基材的阻抗模量|Z|f=0.01 Hz=8.86×10² Ω.cm²相比,提高了3个数量级。结论 微弧氧化处理能够显著改善AZ31镁合金的腐蚀防护性能。NH4F浓度的增加有利于提高膜层的耐腐蚀性能,质量浓度为100 g/L NH4F的膜层耐腐蚀性能最优。     

电流密度对ZK60镁合金表面超疏水涂层的制备及耐腐蚀性的影响

为了提高镁合金的耐腐蚀性能,基于层状双氢氧化物（LDHs）膜在ZK60镁合金表面制备了超疏水（SH）涂层。涂层制备过程中引入电场辅助,研究了工作电流密度对涂层性能的影响。结果表明,工作电流密度显著影响LDHs膜的微观结构,这对SH涂层的疏水性具有重要影响。当工作电流密度为25 mA/cm²时,SH涂层表面呈现均匀的微纳米结构,并表现出超疏水性。超疏水涂层的腐蚀电流密度（I_corr=9×10^-7 A·cm^-2）比ZK60基体的腐蚀电流密度（I_corr=3×10^-5 A·cm^-2）低了2个数量级,表现出优异的耐腐蚀性。     

AP2铝硅合金超疏水表面的制备和耐腐蚀性研究

目的 针对AP2铝硅合金中相组织结构种类较为丰富的特点,通过化学刻蚀的方法,构建出层次丰富、耐腐蚀性强的超疏水表面结构。方法 由于在不同刻蚀溶液中,所构建出的表面润湿性存在较大差距。因此采用正交设计的方法设计试验,找到最适宜的刻蚀浓度和反应时间。由于AP2铝硅合金中含量最多的Al与Si元素之间的固溶度低,NaOH溶液可以对主体α-Al相进行刻蚀,HCl溶液可以腐蚀Al、Cu、Mg、Si等元素形成的金属间相(IMPs)和共晶硅相,采用先碱后酸的刻蚀方法相比使用单一的刻蚀溶液推测能形成更丰富的触突结构。结果 在0.25 mol/L NaOH溶液和9 mol/L HCl溶液中分别刻蚀60 s,在2%(质量分数)十七氟癸基三甲氧基硅烷(FAS-17)溶液表面改性的条件下,成功构建出了表面接触角为157°,滚动角为5.64°的超疏水表面。表面腐蚀电位由抛光后的−1.282 V提高到了超疏水表面制备完成后的–1.228 V,腐蚀速率由抛光后的1.07×10^–4 A/cm²降低到7.44×10^–5 A/cm²,耐腐蚀性显著提高。结论 制备的超疏水表面的耐腐蚀性有显著提高,为亚共晶铝硅合金材料在超疏水方向的应用提供了一定的参考。     

KS-B高吸收高发射率无机热控涂层低轨环境效应

目的 研究低轨环境对KS-B高吸收高发射无机热控涂层(简称KS-B涂层)性能的影响。方法 对KS-B涂层分别进行总剂量为3.9×10²² atoms/cm²的原子氧辐照、剂量为5000 ESH的真空-紫外辐照、总注量为9.30×10¹¹ p/cm²的真空-质子及总注量为1.108×10¹⁴ e/cm²的真空-电子综合辐照试验,分析空间模拟辐照环境中KS-B涂层太阳吸收比(αS)、半球发射率(εH)、表面形貌、表面组分含量、质量损失率等性能的变化规律,研究KS-B涂层的耐空间环境稳定性。结果 原子氧暴露后,KS-B涂层太阳吸收比增加0.003,半球发射率增加0.004;原子氧辐照后,KS-B涂层表面形貌出现了一定程度的糙化,表面Si、O元素含量下降。初始暴露时,KS-B涂层质量损失率逐渐提高,最终质量损失率为0.96%。真空-紫外辐照后,KS-B涂层太阳吸收比增加0.003,半球发射率无变化。真空-质子及真空-电子辐照前后,KS-B涂层太阳吸收比增加0.001,半球发射率无变化。结论 经历原子氧、真空-紫外、真空-质子及真空-电子模拟辐照后,KS-B涂层的太阳吸收比及半球发射率变化较小,具有较好的耐空间辐照性能,可以满足空间站等低轨航天器的长寿命服役需求。     

超高频脉冲电流作用下纳米Al2O3颗粒对Mg-Gd-Y-Zr合金微弧氧化涂层的影响

目的 进一步提高Mg-Gd-Y-Zr合金微弧氧化涂层的耐腐蚀性能。方法 采用超高频微弧氧化技术在含有Al2O3纳米颗粒的溶液中制备了微弧氧化涂层。利用扫描电子显微镜(FESEM)、能谱仪(EDS)和X射线衍射仪(XRD)对微弧氧化涂层的表面形貌、截面形貌、成分和晶体结构进行分析。利用极化曲线和电化学阻抗谱(EIS)测试了涂层的耐腐蚀性能。结果 频率由0.5 kHz提升至20 kHz后,涂层表面放电孔洞面积由0.07~24.4 μm²降低至0.08~6.3 μm²,涂层的孔隙率由6.47%减小至3.35%。Al2O3纳米颗粒的添加使超高频涂层表面形成大量自封闭孔洞结构,进而进一步降低了涂层表面的孔径面积(0.1~ 4.63 μm²)和孔隙率(0.97%)。极化试验表明,提高频率至20 kHz,涂层的自腐蚀电流密度由4.7×10^‒6 A/cm²降低至4.7×10^‒7 A/cm² ,添加 Al2O3纳米颗粒,涂层的自腐蚀电流密度进一步降低至1.7×10^‒7 A/cm²,表明其耐蚀性能显著提高。阻抗谱显示,20 kHz-Al涂层具有最大的阻抗,说明该工艺可有效提高微弧氧化涂层的耐蚀性能。 结论 超高频可有效降低放电孔洞尺寸,提高微弧氧化涂层的致密性,改善涂层的耐腐蚀性能。超高频与Al2O3纳米粒子的协同作用使涂层表面形成自封闭孔洞结构,进一步提高微弧氧化涂层的致密性和耐腐蚀性能。     

植酸修饰改性对TC4钛合金微弧氧化膜层性能的影响

通过向电解液中添加有机酸植酸,提升了TC4钛合金微弧氧化涂层的耐腐蚀性能和热稳定性。通过扫描电子显微镜、X射线衍射仪、X射线光电子能谱仪和热冲击实验等技术手段,分析了植酸对涂层形成、形貌和性能的影响。结果显示,植酸的添加使放电微孔更加细小,提高了涂层的形成效率并优化了相结构。通过动电位极化测试,发现添加植酸显著提高了微弧氧化涂层的耐腐蚀性能。将电解液中的植酸浓度调整为12 mL/L（最佳植酸浓度）后,腐蚀电流密度由8.406×10^-5 A·cm^-2降低至2.580×10^-6 A·cm^-2。循环高温氧化试验结果表明,TC4钛合金的耐热冲击性能和高温抗氧化性能得到了改善。     

30CrMnSiA钢表面镉镀层化学转化膜的电化学特性

目的 通过研究镉镀层绿色化学转化膜的电化学性能,获得镉镀层最佳绿色化学钝化工艺。方法 采用无氰镀镉工艺,在30CrMnSiA钢表面电镀镉。采用植酸和钼酸钠在镉镀层表面进行绿色钝化处理,构建复合化学转化膜。通过研究钼酸钠浓度、处理时间和植酸浓度对绿色钝化处理镀镉层在质量分数为3.5%的NaCl溶液中电化学性能的影响,获得最佳的镀镉层绿色钝化工艺。结果 在处理时间为10 min、植酸的质量分数为1.0%的条件下,当钼酸钠的质量分数增至3%时,开路电压先从−0.741 9 V增至−0.739 7 V后,再降至−0.761 1 V,电荷转移电阻Rct从2.34 kΩ.cm²增至8.79 kΩ.cm²,腐蚀抑制率从72.9%增至92.8%,自腐蚀电流密度Jcorr从81.47 μA/cm²降至最低值(6.887 2 μA/cm²)。当钼酸钠和植酸的质量分数分别为2.0%和1.0%时,随着处理时间的延长,开路电压从−0.755 9 V增至−0.729 5 V,Rct先增至6.68 kΩ.cm²,然后降至5.28 kΩ.cm²,自腐蚀电流密度从16.26 μA/cm²降至4.527 μA/cm²。当钼酸钠的质量分数为2.0%、处理时间为10 min时,随着植酸浓度的增加,试样的开路电压从−0.739 3 V降至−0.756 1 V,Rct先增至6.68 kΩ.cm²,然后降低,自腐蚀电流密度Jcorr呈现先降至最小值后再增大的趋势。结论 与镉镀层相比,经化学转化膜处理后试样表现为高的开路电压、大的电荷转移电阻和低的自腐蚀电流。得到了耐蚀性好且成本较低的镉镀层表面绿色钝化工艺,钼酸钠和植酸的质量分数分别为2.0%和1.0%,处理时间为10 min。     

含氟聚氨酯防护涂层体系在模拟海洋环境下的防护性能

目的 考核评价Q345低合金钢表面“热喷锌铝基底”和“磷化膜基底”的含氟聚氨酯防护涂层体系在模拟海洋环境下的防护性能。方法 分别制备2类含氟聚氨酯防护涂层体系划痕和非划痕试样,采用实验室多因素组合循环试验方式对涂层试样进行模拟加速试验,分析涂层的外观、光泽、色差的变化情况;对比分析划痕部位涂层的耐腐蚀扩展性能,并采用金相法分析热喷锌铝层试验前后的截面变化;分别采用傅里叶变换红外光谱和电化学阻抗谱表征涂层的老化特征和电化学性能。结果 2类含氟聚氨酯防护涂层体系试验后的变色等级为1级,失光等级为2级,保护性漆膜综合老化性能等级为0级。磷化膜基底层试样划痕部位的含氟聚氨酯防护涂层出现了鼓泡、锈蚀等现象,单边腐蚀宽度为9.18 mm;热喷锌铝基底层试样划痕部位的含氟聚氨酯防护涂层未出现鼓泡现象,单边腐蚀宽度仅为2.58 mm。含氟聚氨酯防护涂层红外光谱特征峰的形状、位置、强度均未发生明显变化;磷化膜基底层试样涂层体系0.01 Hz阻抗模值(|Z|0.01 Hz)为2.3×10⁹ Ω.m²,热喷锌铝基底层试样涂层体系0.01 Hz阻抗模值(|Z|0.01 Hz)为4.6×10⁹ Ω.cm²。结论 含氟聚氨酯防护涂层具有较好的抗光老化和耐蚀性能。热喷锌铝基底层相较于磷化膜基底层,不仅可以提高涂层体系的持久耐蚀性能,而且能够有效缓解涂层破损后发生的腐蚀扩展现象。     

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).     

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.     

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.