Ni-P-SiO2(纳米)化学复合镀研究

通过Ni-P化学镀及Ni-P-SiO2(微米)、Ni-P-SiO2(纳米)化学复合镀探讨纳米SiO2颗粒对镀速及镀层性能的影响。结果表明：添加适量的SiO2纳米粒子于镀液中，使镀速上升，所得镀层硬度、耐磨性等性能相对于Ni-P镀层及微米颗粒复合镀层都有显著地提高。     

Ni-P-纳米ZrC化学复合镀的结构与性能

采用化学镀技术,在AZ31镁合金表面制备出Ni-P-纳米Zr C复合镀层。使用扫描电镜、显微硬度计和磨损试验机研究了不同纳米Zr C浓度对复合镀层微观形貌、镀速、硬度和磨损性能的影响。结果表明,复合镀层为胞状结构,镀液中添加适量的纳米Zr C颗粒能细化镀层胞状结构的尺度,提高镀速,增加镀层厚度;而且显著提高镀层的硬度和耐磨性。镀液中的纳米Zr C颗粒添加量为1.5g/L时,所得Ni-P-纳米Zr C复合镀层的胞状结构较细小,镀速最快,硬度达到最高值892 HV,耐磨性比Ni-P镀层更高。     

镍基纳米(SiC)P化学复合镀层的研究

为了进一步提高化学复合镀层的性能,采用纳米级（SiC）,制备出了Ni—P-纳米（SiC）,化学复合镀层,研究了各工艺条件对镀层性能的影响,同时观察了镀层形貌,测试了镀层的成分、性能,并与常见的Ni—P镀层、Ni—P-（SiC）P镀层进行了比较。实验结果表明：当pH4．5,T=（85±1）℃时,镀液的镀速最快,镍磷沉积量最大,所获得的镀层均匀、致密、硬度高,耐磨性能好,500℃热处理后硬度可达到HV1337。     

纳米SiC颗粒对微米Ni-SiC复合镀层性能的影响

采用双脉冲复合电镀技术,在瓦特型镀液中,制备了含微/纳米SiC颗粒的Ni基复合镀层,研究镀液中纳米SiC添加量对复合镀层微观形貌、摩擦性能和抗氧化性能的影响。结果表明:在SiC颗粒(5μm)浓度为10 g/L的镀液中,添加纳米SiC和Ni-SiC复合镀层镍择优取向由晶面(200)转变为晶面(111);当SiC(40μm)浓度为4.0 g/L时,复合镀层显微硬度最大,为456 HV;复合镀层摩擦因数最小,平均值为0.28,为微米复合镀层的1/2;经900℃氧化100 h后,氧化质量增加为6.025 mg/cm2,为微米复合镀层的1/3。     

铝合金表面化学镀 Ni-Co-P / SiC 复合镀层的组织与性能研究

通过化学镀的方法,在铝合金表面成功地制备了Ni-Co-P/SiC复合镀层。对复合镀层的表面形貌、化学成分、晶态结构、硬度进行了表征分析,通过电化学测试对其耐腐蚀性进行了研究。结果表明:SiC纳米微粒起到了提高Ni-Co-P合金镀层硬度的作用,向镀液中加入12 g/L SiC纳米微粒时,复合镀层的硬度达到最大值524HV;Ni-Co-P/SiC复合镀层能增强铝合金材料的耐蚀性能,镀液中SiC微粒的质量浓度为9 g/L时,复合镀层的耐腐蚀性相对最好。     

Ni-P-SiC(纳米)复合镀层的滑动磨损特性

利用化学镀方法制备了Ni-P-SiC(纳米)复合镀层,研究了镀液中纳米SiC微粒含量对复合镀层硬度的影响,在MPX-2000型摩擦磨损试验机上进行了复合镀层与45钢配对的滑动磨损试验,用扫描电镜观察了磨损面的形貌.结果表明,镀层中纳米SiC微粒的存在使复合镀层的硬度显著提高,为1000～1100 HV0.025,退火处理后硬度可达到1650 HV0.025.200～400 N负荷下的摩擦系数基本保持稳定,而磨损质量损失随载荷的增加而小幅增加.与微米SiC复合镀层相比,纳米复合镀层的耐磨性也有明显改善,其磨损机理主要为轻微擦伤.     

Ni-P-α-Al2O3纳米复合电镀工艺研究

采用复合电镀技术,在黄铜表面制备高硬度的Ni-P-α-Al2O3纳米复合镀层,研究了阴极电流密度、纳米α-Al2O3添加量、镀液pH值、镀液温度和电镀时间对镀层硬度的影响。结果表明:当镀液温度为45℃,阴极电流密度为4A/dm2,镀液pH值为4.0,电镀时间为40min,镀液中纳米α-Al2O3的质量浓度为10g/L时,所得镀层均匀、细致、平滑,经适当热处理后,显微硬度可达到1 332HV。     

SiC粒子增强化学复合镀层性能的工艺研究

本文主要进行了Ni-P-SiC化学复合镀工艺研究。为了得到一个复合粒子(纳米SiC)添加量合适、沉积速度快、外观光亮、与基体结合牢固等良好性能的化学复合镀层,在参考有关化学复合镀镀液组成研究的基础上,选择了不同的复合粒子添加量和相应的施镀工艺条件进行试验,并对所得到的复合镀层,采用金相显微镜进行了金相组织、外观、厚度等方面的性能测试。着重分析了复合粒子添加量对镀层的影响。     

SiC含量对铝合金表面电镀Ni-SiC的影响

试验研究了SiC浓度对铝合金表面电镀Ni-SiC的影响,着重探讨不同SiC浓度对镀速和镀层形貌、成分及耐腐蚀性的影响,并得出SiC的最佳浓度。研究结果表明,当SiC的浓度为80g/L时镀速最大,而且镀层均匀、紧凑、细密、耐腐蚀性良好。     

复合镀用纳米金刚石悬浮液制备和复合镀铬研究

通过对市售纳米金刚石进行适当的机械化学改性、分散及分级,制得了复合镀用纳米金刚石悬浮液,悬浮液粒度分布在150nm以内,浓度可调,长期保持稳定,不含污染镀液成分;研究了标准镀铬液和添加表面活性剂镀铬液中的复合镀情况,测试了镀层的显微硬度和表面形貌,结果表明,标准镀液中加入纳米金刚石镀层,显微硬度反而降低,添加表面活性剂,镀液中的复合镀层显微硬度有较大提高,晶粒明显细化.     

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。