高温合金脉冲电化学复合抛光实验研究

电化学机械复合抛光是近年来发展起来的一种抛光新技术。针对粗糙表面的高效抛光问题,提出一种两阶段的电化学机械复合抛光和纯机械抛光相结合的方法。论述了脉冲电化学机械复合抛光加工的实验设备,进行了系统的工艺参数实验研究;用方差分析的方法分析了各参数对加工试件表面粗糙度影响的显著性,得出最佳的工艺参数;详细分析了不同磨头加工时各参数对表面粗糙度的影响规律。实验研究表明,利用脉冲电化学机械复合抛光的加工方法,采用各种类型的阴极工具头,可实现镜面加工。     

铝合金高频窄脉冲电化学抛光的研究

为了研究铝合金高频窄脉冲电流电化学抛光中各抛光工艺参数与表面粗糙度之间的关系,采用正交试验法安排脉宽、抛光电压和抛光间隙等抛光工艺参数,用极差分析法初步定性地分析了各参数对表面质量影响的大小,然后运用逐步回归分析的方法建立教学模型,最终确定四次函数的回归方程(最优回归方程)为数学模型,并通过单因素试验验证了数学模型的可靠性,从而可对各工艺参数与表面粗糙度的关系作定量分析,为铝合金脉冲电流电化学抛光的研究和推广应用打下了一定的理论基础.     

钛合金材料OIM试样的电解抛光及制备工艺

由于钛合金材料强度硬度较高，机械抛光通常不能去除试样表面的残余应变层，因而采用电解抛光是制备电子背散射衍射试样的理想方法。本研究通过正交试验进行优选，并对优选的电解抛光工艺参数进行调整，制定出了钛合金电子背散射衍射试样的快速制备工艺。     

铜合金化学抛光技术的研究

为了提高铜合金表面的整平性及抗变色能力,研究了铜合金化学抛光液的组分、含量, 并对各成分的作用及影响进行了讨论,通过试验分析了工艺条件对抛光质量的影响,确定了铜合金化学抛光的工艺流程及最佳工艺参数.结果表明:该工艺配方简单,操作方便,抛光作用时间短,表面整平性好,耐蚀性和抗污染能力强.     

生物医用TLM钛合金的水热法表面改性

对Ti-25Nb-3Zr-2Sn-3Mo合金（TLM钛合金）进行水热处理，温度为100-200℃。X射线衍射、拉曼光谱、扫描电镜和X射线光电子能谱分析表明，TLM钛合金经140-200℃水热处理后，表面形成了由氧化钛和氧化铌纳米颗粒（尺寸80-100nm）组成的、含有较多羟基的薄膜。140℃以上水热处理TLM试样的亲水性和表面能升高，表面能以极化分量为主。在无钙Hank’s平衡盐液中的动电位极化实验表明，水热处理TLM试样的耐蚀性高于抛光试样。水热处理有利于改善TLM钛合金的生物相容性。     

超声波作用下医用钛合金(Ti-6Al-4V)植入物的电解抛光

在电解抛光钛合金(Ti-6Al-4V)植入物的过程中引入功率超声波.分析了功率超声波对电解抛光过程的作用及对抛光效果的影响.通过合理利用功率超声波的能量特性,发挥其对传质过程的强化作用、空化效应,并与电化学抛光的特点相结合,对钛合金植入物进行抛光处理.结果表明,引入功率超声波,不但可以大幅度改善钛合金植入物的表面粗糙度,而且还可以增加其表面氧化膜中Ti的氧化物含量,进一步提高钛合金植入物的生物相容性和耐腐蚀性.     

钛合金阳极氧化法制备自组装纳米多孔结构薄膜的研究

以TLM钛合金为阳极氧化的基片,通过改变阳极氧化电压、钛合金相结构,找到制备纳米多孔阵列的参数,通过条件试验发现,在恒电压小于30 V时,通过时效处理的TLM钛合金表面可以制备得到TiO2纳米多孔结构薄膜     

钛合金结构件磁流变电解复合抛光试验研究

目的 针对钛合金结构件高质高效抛光需求，提出了磁流变电解复合抛光新方法，探究不同抛光参数对钛合金表面质量的影响，以实现钛合金构件的高质高效抛光。方法 深入探究了加工电压、加工间隙、电解质质量分数和抛光转速等参数对钛合金抛光表面粗糙度以及粗糙度变化率的影响，分析了不同抛光参数下的钛合金表面形貌变化，验证了磁流变电解复合抛光钛合金的可行性。结果 随着电解液中Na NO3质量分数的提高，钛合金表面粗糙度先减小后增大，质量分数为1.0%～2.5%时，得到了优于单磁流变抛光加工的抛光效果。不同加工电压下的表面粗糙度对比结果表明，在加工电压为0.1 V时，钛合金加工后表面粗糙度达到最小，而后随着加工电压的增大，加工区域表面粗糙度呈现增大趋势；随着加工间隙的增大，钛合金抛光表面粗糙度呈现先减小后增大的趋势；随着抛光工具转速增大，钛合金加工后表面粗糙度先减小后增大。相比于单一的磁流变抛光，磁流变电解复合抛光钛合金90 min，可使表面粗糙度从初始323 nm降低至15nm，加工效率提高了62.5%。结论 磁流变电解复合抛光工艺能够用于钛合金人工关节假体高效高质量的抛光。     

钛合金抛光表面粗糙度与表面形貌研究

为了优化钛合金抛光工艺参数,采用中心复合响应曲面法,建立了抛光表面粗糙度的预测模型;采用方差分析方法,检验了预测模型以及各抛光参数的显著性,分析了各抛光参数对表面粗糙度及表面形貌的影响规律。结果表明:该预测模型可对抛光表面粗糙度进行有效的预测;页轮粒度、页轮线速度和进给速度对表面粗糙度影响极显著;表面粗糙度随页轮粒度、页轮线速度和进给速度的增大而减小;表面形貌整体均匀,存在一定的隆起和沟壑。     

–50 ℃冷风条件下抛光硬质合金刀片加工TC4钛合金的表面粗糙度分析

目的提高硬质合金刀片加工TC4钛合金的表面质量。方法利用化学机械抛光技术对传统磨削的硬质合金刀片分别进行粗抛、半精抛和精抛处理,运用正交试验法,在常温干切和–50℃冷风条件下,分别采用传统磨削的硬质合金刀片(磨削刀片)与化学机械抛光的硬质合金刀片(抛光刀片)进行切削TC4钛合金正交试验,利用方差分析法分析切削参数对已加工表面粗糙度Ra的影响。运用多元线性回归方法建立磨削刀片、抛光刀片在常温干切和–50℃冷风条件下切削TC4钛合金已加工表面粗糙度Ra的经验预测模型。结果硬质合金刀片前刀面通过粗抛、半精抛和精抛后,刀片前刀面的表面粗糙度Ra为19 nm。当切削参数相同时,磨削刀片在–50℃冷风条件下切削TC4钛合金的已加工表面粗糙度,比常温干切条件下平均降低了35.9%;抛光刀片在–50℃冷风条件下切削TC4钛合金的已加工表面粗糙度,比常温干切条件下平均降低了43.5%。在常温干切条件下,抛光刀片比磨削刀片切削TC4钛合金的已加工表面粗糙度平均降低了19.2%;在–50℃冷风条件下,抛光刀片比磨削刀片切削TC4钛合金的已加工表面粗糙度平均降低了28.7%。抛光刀片在–50℃冷风条件下切削TC4钛合金的已加工表面粗糙度Ra,比磨削刀片在常温干切条件下切削TC4钛合金的已加工表面粗糙度Ra平均降低了54.4%。结论采用对硬质合金刀片表面进行化学机械抛光技术和以–50℃冷风为切削介质的组合工艺,可有效降低TC4钛合金已加工表面粗糙度。     

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。