镍-金刚石复合刷镀的工艺

河南信阳空军第一航空学院研究了镍-金刚石复合电刷镀工艺中施镀电压、施镀温度和镀笔与工件之间相对速度对复合镀层中金刚石含量和耐磨性能的影响，得到了制备高耐磨性镀层的最佳工艺参数，     

复合电刷镀Ni—金刚石的工艺研究

复合电刷镀是一种新的电刷镀工艺方法,Ni-金刚石复合镀层的硬度及耐磨性能非常好,具有很好的经济、使用价值、本文研究,分析了复合电刷镀Ni-金刚石镀液配方、工作电压、溶液温度、镀笔运动速度等工艺条件对镀层中金刚石含量、沉积速度的影响,总结出复合电刷镀Ni-金刚石的工艺条件。     

金刚石复合镀层的工艺研究

研究了Ni-P-金刚石化学镀液主要成分、pH值、温度以及时问等工艺参数，通过正交实验对金刚石复合镀施镀工艺参数进行了优化，探讨了镀液成分及工艺参数对镀层沉积厚度、镀层中金刚石微粒含量及分布的影响。结果表明，采用合适的工艺条件，可得到金刚石含量较高、均匀分布的复合镀层，Ni-P-金刚石复合化学镀层硬度可达1850HV0．1左右，耐磨性比化学镀Ni-P大大提高。     

电镀镍-纳米金刚石复合镀层研究

本文采用电镀的方法获得了镍-纳米金刚石复合镀层，用间接法分析了镀层中纳米金刚石的含量，用TEM对纳米金刚石在镀层中的形态、分布情况及镀层结构进行了分析，并通过优化施镀温度、时间、电流密度及金刚石悬浮量等工艺参数，使镀层的性能获得改变。试验结果表明：镀液温度为60℃，电流密度为2A／dm^2的共沉积条件下，镀层的硬度、耐磨性高，镀层中纳米金刚石的沉积量也较高，纳米金刚石能够均匀分布在镀层中，特别是复合镀层耐磨性的改变具有重要的实际意义。     

金刚石复合镀层的工艺研究

研究了Ni-P-金刚石化学镀液主要成分、pH值、温度以及时间等工艺参数,通过正交实验对金刚石复合镀施镀工艺参数进行了优化,探讨了镀液成分及工艺参数对镀层沉积厚度、镀层中金刚石微粒含量及分布的影响。结果表明,采用合适的工艺条件,可得到金剐石含量较高、均匀分布的复合镀层,Ni-P-金刚石复合化学镀层硬度可达1850 HV0．1左右,耐磨性比化学镀Ni-P大大提高。     

Ni-P-纳米金刚石粉复合电刷镀层的耐磨性研究

研究了纳米金刚石粉对复合电刷镀镀层形成速率、显微硬度和耐磨性的影响;测试了在不同的热处理温度、载荷及金刚石粉含量下复合刷镀层的耐磨性能;分析了复合镀层的磨损机理.结果表明:镀层的磨损体积损失均随热处理温度的升高而下降,并在400℃时达到最小值;载荷增大,磨损体积损失增大;当纳米金刚石加入量为20～30g/L时,镀层的耐磨性最好.复合镀层提高耐磨性的原因在于复合粒子在基体金属表面形成突起,起到了支撑载荷、避免粘着磨损及减小摩擦系数的作用.     

Ni-P-金刚石化学复合镀层耐磨性能研究

在镍磷化学镀的基础上,研究了微米、纳米金刚石化学复合镀工艺。采用正交试验方法,研究化学镀液、金刚石种类与浓度、表面活性剂种类与含量以及热处理温度对镀层耐磨性能的影响。通过超声搅拌,实验成功制备出具有优异耐磨性能的Ni-P-金刚石复合镀层。结果表明：对镀层耐磨性影响明显的因素依次为表面活性剂的种类和含量,金刚石颗粒的含量和种类,而镀液的种类和热处理温度对镀层耐磨性的影响较小。并且,最佳工艺为：添加阴离子表面活性剂,含量为1：15,复合颗粒为金刚石微粉,浓度为10g/L,镀层热处理温度为400℃。     

Ni/P金刚石化学复合镀层性能与组织研究

本文研究了金刚石含量、热处理温度、表面活性剂种类等因素对Ni-P-金刚石复合镀层的显微硬度与耐磨性能的影响;采用扫描电子显微镜、X射线衍射仪对复合镀层的表面形貌及组织结构进行了分析。结果表明:在化学镀层中共沉积金刚石微粉能显著提高镀层的耐磨性;各工艺因素对复合镀层显微硬度与耐磨性的影响程度各不相同,热处理温度对复合镀层耐磨性能的影响最大;当镀液中金刚石微粉含量为2 g/L、热处理温度400℃、表面活性剂为SHP其含量为1∶15时,复合镀层的耐磨性能最好。与Ni-P化学镀层相比,金刚石复合镀层的耐磨性提高50%。     

电刷镀多层复合镀层的应用研究

用电刷镀研制具有层状结构的Ni-Cr2O3复合电刷镀层，采用碱铜层作为中间过渡层；研究了多层复合镀层的组织，显微硬度以及耐磨性等性能，对电刷镀多层复合镀层工艺进行了实际应用研究，结果表明，多层Ni-Cr2O3复合电刷镀层与Ni镀层相比具有较高的显微硬度，细小的结晶晶粒和较耐磨性，层状的复合镀层结构会导致磨损机理的变化，该工艺可用于大型机械设备现场不解体修复。     

18Cr2Ni4WA钢磨损表面修复工艺研究

通过分析飞机襟翼作动筒活塞失效的原因,提出了修复该零件的新工艺——刷镀Ni-金刚石复合镀层。研究结果表明,最佳刷镀工艺参数为：工作电压12 V,镀液温度45～60℃,镀笔与工件相对运动速度10～15 m/min。采用该工艺对作动筒活塞进行修复,镀层的厚度为30μm时,硬度可达HV770,附着力良好,杯突高度为5.1 mm,耐磨性与基体相当,能满足修复磨损活塞的要求。     

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。