电沉积制备镁合金HA涂层的组织及其可降解性能

采用碱热处理＋电沉积＋碱热处理相结合的工艺,在Mg-4.0Zn-1.0Ca-0.6Zr合金板材表面制备羟基磷灰石（HA）涂层。利用X射线衍射和SEM对涂层的组织和形貌进行了分析,对合金板材及HA涂层板材在SBF溶液中的可降解性能进行了研究,结果表明：通过前碱热处理＋电沉积＋后碱热处理的方法在电沉积温度50℃,电压10 V条件下,在Mg-4.0Zn-1.0Ca-0.6Zr合金板材表面制备出了平整、致密的HA涂层,其Ca/P的比值（1.72）与人骨的（1.67）相近;HA涂层Mg-4.0Zn-1.0Ca-0.6Zr合金板材在SBF溶液腐蚀过程中,发现3 d时腐蚀液穿过HA涂层开始浸蚀基体。随着腐蚀时间的延长,部分点蚀的直径扩大,构成局部腐蚀;HA涂层Mg-4.0Zn-1.0Ca-0.6Zr合金板材在SBF溶液中的初始腐蚀速率低于未涂层的合金板材,其在SBF溶液中的初始pH值的变化低于未涂层的,随降解时间延长,pH变化幅度开始增大,10 d后pH值平均值约为9.2,随后逐步趋于稳定;HA涂层Mg-4.0Zn-1.0Ca-0.6Zr合金板材在SBF溶液中的初始自腐蚀电位与未涂层的相比正移200 mV以上,亦说明了其在SBF溶液中的初始腐蚀速率低于未涂层的,但是随着涂层的脱落将促使腐蚀速率增大。     

Mg-4.0Zn-2.5Sr合金HA涂层体外降解及生物相容性

通过电沉积工艺在生物材料Mg-4.0Zn-2.5Sr合金表面制备HA涂层,对比研究了HA涂层与无涂层Mg-4.0Zn-2.5Sr合金在Hank’s溶液中的降解性能及生物相容性。结果表明:通过电沉积工艺电压5 V,温度50℃,时间2 h后,再经过后碱热处理2 h可制备出组织细小、致密、均匀并与基体有良好结合的HA涂层。Mg-4.0Zn-2.5Sr合金在Hank’s溶液中的最终腐蚀速率为0.264 g/(cm~2·h)。HA涂层Mg-4.0Zn-2.5Sr合金在Hank’s溶液中最终腐蚀速率为0.163 g/(cm~2·h)。电化学分析发现HA涂层Mg-4.0Zn-2.5Sr合金的腐蚀电位是-0.801 V,明显高于无涂层Mg-4.0Zn-2.5Sr合金的腐蚀电位-1.33 V,说明经过HA涂层后镁合金的抗腐蚀性能获得提高。HA涂层与无涂层Mg-4.0Zn-2.5Sr合金的细胞溶血率均在生物材料5%的允许范围之内,作为生物材料使用时均不会发生溶血现象。HA涂层与无涂层Mg-4.0Zn-2.5Sr合金的细胞增殖率均超过96%,为1级细胞毒性,通过细胞形貌特性分析也证明了二者的细胞毒性作用非常小,满足生物材料细胞毒性的要求。     

水热处理对电化学沉积HA涂层物相的影响

采用电化学沉积在碱处理Ti6Al4V钛合金基体上生成羟基磷灰石（HA）涂层,研究了水热处理对该涂层物相的影响。结果表明,电化学沉积HA涂层结晶度低、晶粒尺寸较小,经120 ℃和160 ℃水热处理后,HA结晶度和晶粒尺寸显著增大,且随水热处理温度的增加,结晶度和晶粒尺寸增加。     

钛合金表面声电沉积／碱热处理法制备HA涂层研究

为了使钛合金（Ti-6Al-4V）具有生物活性，可在其表面施加生物活性羟基磷灰石（HA）涂层。对比了声电沉积法和碱热处理法实验结果，采用扫描电镜（SEM）、X射线衍射仪（XRD）、电子能谱（EDS）、傅立叶红外透射光谱（FTIR）以及划痕测试等进行了分析。结果表明，直接采用声电沉积法在钛合金表面制备的羟基磷灰石涂层，经热处理后存在龟裂剥落现象；通过碱热处理法，对钛合金基体表面进行预处理，然后，借助声电沉积法，在钛金属表面沉积了透钙磷石涂层，经热碱液处理转变成的羟基磷灰石涂层，涂层完整，未出现剥落。经进一步高温烧结处理，所制涂层仍呈片状形貌，其由部分含钠的羟基磷灰石组成，而且HA涂层破坏的临界载荷未烧结前的4．365N提高至烧结后的8．175N。     

电泳沉积法制备羟基磷灰石涂层

羟基磷灰石是一种最有发展前途的生物材料之一.采用电泳沉积方法分别在Ti6Al4V基体和电泳沉积的HA/TiO2复合涂层上制备了HA生物陶瓷涂层.将HA粉体分散到正丁醇溶液中,通过测量zeta电位确定了悬浮体系中三乙醇胺和HA的含量.研究发现:HA沉积量随沉积温度和沉积电压的增加而增加,随沉积时间延长呈线性增长.对沉积量与电泳沉积工艺参数的关系进行了理论探讨.SEM结果表明,采用二次电泳沉积在HA/TiO2涂层表面制备的HA涂层更加致密、平整.     

基于氧化铝模板直接电沉积法镍纳米线的制备与表征

在未氧化铝和氧化铝之间经过降压剪薄阻挡层直接进行电沉积,采用不同电压进行电沉积制备了镍纳米线,并采用SEM,TEM和X射线衍射对所制备的镍纳米线进行了表征,研究了电沉积电压对纳米线结构的影响。结果表明：镍纳米线的外形决定于氧化铝模板的形貌,其直径和最大长度分别依赖于模板孔洞的直径和长度,当电沉积电压为1,1.5和2V时制备的镍纳米线为多晶结构,随着电沉积电压的升高,镍纳米线为沿[220]择优取向的单晶结构（电沉积电压分别为3V和4V）,当电沉积电压进一步升高时,择优取向由[220]转为[111]方向（电沉积电压5V）。     

AZ91镁合金表面电化学沉积羟基磷灰石涂层的制备及其耐蚀性

采用电化学沉积方法在AZ91镁合金表面制备了羟基磷灰石(HA)涂层,研究了电沉积工艺参数对羟基磷灰石涂层形貌和相组成的影响,并通过腐蚀浸泡试验、极化曲线测试等方法对该涂层的耐蚀性进行了研究。结果表明:当溶液pH为4.5,温度为60℃时,涂层的致密性最好,呈放射状的结构,主要成分为HA相,涂层的厚度约为60~70μm,与基体结合较好;HA涂层对镁合金基体具有较好的保护作用,显著提高了基体合金在生理溶液中的耐蚀性。     

钛合金表面声电沉积/碱热处理法制备HA涂层研究

为了使钛合金(Ti-6Al-4V)具有生物活性,可在其表面施加生物活性羟基磷灰石(HA)涂层.对比了声电沉积法和碱热处理法实验结果,采用扫描电镜(SEM)、X射线衍射仪(XRD)、电子能谱(EDS)、傅立叶红外透射光谱(FTIR)以及划痕测试等进行了分析.结果表明,直接采用声电沉积法在钛合金表面制备的羟基磷灰石涂层,经热处理后存在龟裂剥落现象;通过碱热处理法,对钛合金基体表面进行预处理,然后,借助声电沉积法,在钛金属表面沉积了透钙磷石涂层,经热碱液处理转变成的羟基磷灰石涂层,涂层完整,未出现剥落.经进一步高温烧结处理,所制涂层仍呈片状形貌,其由部分含钠的羟基磷灰石组成,而且HA涂层破坏的临界载荷未烧结前的4.365 N提高至烧结后的8.175N.     

表面喷涂对体育器械耐磨性能的影响

以涂层结合力和磨损失重为考核指标,研究了电弧喷涂电流、喷涂电压、喷涂距离和空气压力对体育器械表面涂层的组织与性能的影响,并优化了喷涂工艺参数,在此技术上研究了涂层厚度和热处理对涂层结合强度和磨损失重的影响。结果表明,器械表面最佳电弧喷涂工艺参数为:喷涂电压为31 V、喷涂电流为250 A、喷涂距离为210 mm和雾化空气压力为0.5 MPa;随着器械表面涂层厚度的增加,涂层结合强度呈现逐渐降低的趋势;随着热处理温度的升高,涂层的结合强度表现为先增加而后降低,而涂层的磨损失重表现为逐渐降低的趋势。     

电压及电流对等离子喷涂Mo涂层微观组织和性能的影响

采用等离子喷涂技术在45钢表面制备纯Mo涂层,研究了喷涂高电压、低电流参数下涂层表面与截面的微观组织与性能。结果表明:等离子喷涂过程中电压参数变化对该涂层组织和性能的影响较之电流参数变化更为明显;等离子喷涂电压降低同时H_2流量减少,粉末颗粒熔化时间得以延长,但运动速度和动能下降,导致涂层沉积率和孔隙率降低,涂层变薄;喷涂电流降低使粉末熔化质量下降,同时受到未熔粉末反弹因素影响,涂层厚度和沉积率也相应减少;当等离子喷涂电压为165 V、电流为360 A时,制备出的纯Mo涂层沉积率较高且具有较好的组织和综合性能,其中涂层表面硬度为757 HV0.5、粗糙度Ra为2.26μm。     

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.     

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。