微纳超疏水钛合金表面的制备及其性能研究

目的 制备超疏水自清洁的Ti6Al4V合金表面。方法 首先使用飞秒激光在Ti6Al4V合金表面预制备微米级结构,然后将预制备的样品置于1.0 mol/L的氢氧化钠溶液中,在超声水浴状态下进行电化学去合金,获得微纳米复合结构。经表面改性后,得到微纳超疏水钛合金表面。结果 经复合制备的微纳超疏水表面结构由微米级的梯形凸柱阵列,以及通过电化学去合金形成的三维纳米孔洞骨架和沉积的微米或亚微米金属氧化物组成。经过表面改性后,该微纳复合结构表面呈现优异的超疏水性,其接触角可达162.5°,滚动角低至3.4°。自清洁性能测试结果表明,该微纳超疏水钛合金表面展现出优异的低黏附性和自清洁性,1滴水对表面的清洁效率达到99.8%。激光加工参数与静态水接触角之间的关系表明,接触角与扫描间距呈负相关,与能量密度、重复次数呈正相关。结论 飞秒激光结合电化学去合金方法制备的具有微纳结构的钛合金表面呈现出优异的超疏水自清洁性能,通过改变激光加工参数能够有效增大表面的静态水接触角,为后续研究提供了一定参考。     

超疏水结构对AZ91D镁合金微摩擦磨损性能的影响

目的 研究微/纳米复合超疏水结构的摩擦磨损机制,提高镁合金微摩擦磨损性能。方法 首先采用激光刻蚀获得微米结构,然后表面涂覆SiO2纳米颗粒,获得微/纳米复合结构,最后涂覆低表面能物质获得超疏水表面。用接触角测量仪测量超疏水表面的静态接触角,使用微摩擦磨损实验机分析超疏水表面的摩擦磨损性能,使用扫描电子显微镜观察表面磨痕形貌。结果 当载荷为1 N时,超疏水表面的摩擦系数约为0.04,基体表面约为0.06。随着载荷的增加,超疏水表面的摩擦系数逐渐与基体相近,并逐渐超过基体。随着时间的增加,超疏水表面的摩擦系数呈增加趋势,由0.04逐渐增加到0.08,基体试样没有明显的上升趋势。相同条件下,超疏水表面的磨痕宽度大于基体表面,但磨痕宽度的增大趋势小于基体表面。结论 微/纳米复合结构超疏水表面的摩擦磨损过程不同于光滑基体。超疏水表面的磨损首先发生于微/纳米凸起结构,之后发生于被微/纳米凸起填平的微米凹坑区,然后发生于激光加工热影响区表面,最后发生于镁合金基体。在所受载荷低于1~3 N时,超疏水表面微凸起结构能延缓超疏水表面摩擦磨损的发生,改善耐磨性能。     

气凝胶微球表面改性及对隔热涂料的影响

制备并表征了完全疏水及表面亲水改性两种二氧化硅气凝胶微球,研究了疏水型,表面亲水型及润湿剂处理气凝胶微球后隔热涂料的热导率。结果表明,表面亲水改性后,硅羟基及氨基被嫁接到气凝胶微球表面,气凝胶微球压片与水滴的接触角减小,表明二氧化硅气凝胶微球的亲水性增强;表面亲水改性及润湿剂处理有助于增加气凝胶微球与聚合物之间的相容性,同时减小疏水气凝胶微球在聚合物中的团聚,热导率检测显示润湿剂处理后的气凝胶隔热涂料热导率比内疏外亲气凝胶微球隔热涂料热导率更低,而三者中疏水二氧化硅气凝胶微球隔热涂料的热导率最高。     

仿生微织构与氟硅烷修饰对6061铝合金浸润性的影响

利用激光辐射效应在铝合金表面构建仿生微织构,通过自组装工艺在微织构表面实现氟硅烷改性处理,制备得到特殊浸润性表面。 利用扫描电镜、三维形貌仪、接触角测量仪对试样微观形貌和浸润性进行表征。 测试与分析结果表明,仿生微织构和氟硅烷修饰对构建特殊浸润性表面起到重要作用;微织构的形貌差异、加工矩阵间距的变化均会影响试样表面对水接触角。 通过数学模型的计算进一步证实,仿生微织构表面具有的超疏水浸润状态符合 Cassie 模型预测。     

飞秒激光与电沉积复合工艺制备不锈钢超疏水表面及减阻性能EI北大核心CSCD

在远程管道运输过程中,固液间摩擦阻力是一个不容忽视的问题,类鲨鱼结构减阻效率低且制备困难。基于荷叶表面仿生思想,构筑微结构制备超疏水表面,减小摩擦阻力。采用飞秒激光刻蚀与电沉积复合工艺,在不锈钢表面构筑框-锥多级结构,经自组装氟硅烷制备超疏水表面,讨论复合工艺参数对微结构形貌及润湿性能的影响,探究框-锥多级结构超疏水表面减阻。结果表明,利用飞秒激光可获得周期性分布的框结构,随着激光功率的增加,微米框结构内部形成不规则沟壑金属堆积物,且关光延时的增长会产生单侧分布微孔结构,损伤基体整体强度;通过电沉积工艺制备亚微米尖锥结构镍镀层,随着电流密度的增加,镀层微结构形态发生变化,形成亚微米尖锥石结构,表面由疏水转变为超疏水。与激光刻蚀10次自组装氟硅烷涂层试样相比,激光刻蚀与电沉积复合工艺自组装氟硅烷涂层的试样表面接触角由138.6°提高到156.7°,对水和30wt.%甘油的减阻率分别由8.17%、14.38%提高到27.74%、23.69%。将激光刻蚀与电沉积相结合,构筑微纳结构经自组装制备超疏水表面,可为降低管道输运中固液间摩擦阻力提供新的技术途径。     

MB8镁合金表面超疏水复合膜层的制备与表征

利用微弧氧化技术在镁合金表面制备微米级粗糙结构,采用环氧树脂溶液和纳米二氧化硅分散液对该表面进行涂覆处理,得到二氧化硅纳米颗粒均匀分布的粗糙表面,再利用全氟硅烷改性,制备得到具有超疏水性的复合膜层。采用扫描电镜、X射线衍射仪、接触角测量仪、高速摄影系统评价膜层的形貌结构和润湿性。结果表明,微弧氧化层所具有的微米级结构和纳米二氧化硅颗粒组成的微/纳二元粗糙结构对疏水性的提高具有重要作用;复合膜层表面的接触角随二氧化硅分散液浓度的提高呈现先增加后减小趋势,并最终逐渐稳定在150o左右;在二氧化硅分散液浓度为10.0g/L时,复合表面的接触角最大,可达161o,在此条件下获取的复合表面对不同pH值的液滴均具有超疏水性。同时该表面对水滴呈现低黏附特性。     

加工参数对AZ91D镁合金表面超疏水性能的影响

通过优化加工参数,在镁合金表面获得优良的超疏水性能。用激光刻蚀法获得微米结构,结合纳米涂覆技术制备微/纳米复合结构,再结合低表面能物质,制得超疏水表面。系统研究了加工参数对超疏水性能的影响。通过接触角和滚动角测试,评价镁合金表面的超疏水性,并通过扫描电子显微镜对复合结构表面形貌进行分析。采用涂覆法在激光加工后的基体上成功获得了超疏水改性层。加工参数对AZ91D镁合金超疏水性具有重要的影响。当采用点阵形貌,点阵间距50μm,加工电流为15 A,纳米分散液浓度15 g/L时,AZ91D超疏水表面的静态接触角达到最大值161.1°,滑动角为2.109°,超疏水性能达到最佳。     

铝基彩色超疏水表面制备

先用电化学刻蚀在铝表面加工出超疏水性所需的微纳米粗糙结构,再通过直流阳极氧化在微纳米结构表面形成氧化层,并在高锰酸钾和硫酸的混合溶液中进行电解着色,最后通过氟硅烷修饰降低表面能后即可获得彩色的铝基超疏水表面。对样品表面的微观形貌、化学成分及润湿性进行了表征,结果表明:当电解加工时间为4 min时,铝表面颜色较暗,其超疏水性一般,水滴与表面的接触角达到153.1°,滚动角为1°;当电解加工时间为3 min时,铝表面为黄褐色,有较好的疏水性能,水滴与表面的接触角达到157.2°,滚动角为1°。     

超疏水镁合金表面制备及耐生物腐蚀性

采用激光加工结合构筑纳米结构,并涂覆低表面能物质的方法制备了镁合金超疏水表面。使用光学显微镜和扫描电镜观察表面形貌,接触角测量仪测量超疏水表面的静态接触角,电化学分析方法测试试样在模拟生物体液中的腐蚀性能。结果表明:激光加工参数对超疏水表面形貌和性能具有重要的影响。当加工电流为13 A,点阵间距为50μm时,表面微/纳米结构均匀,静态接触角达到最大值161.7°。超疏水试样的腐蚀电位增加,极化电阻增大,腐蚀电流降低,腐蚀速率降低31%,有效提高了WE43镁合金的耐生物体液腐蚀性能。     

超疏水钛合金表面的制备及其摩擦学性能

为研究表面形貌和润湿性对表面摩擦学性能的影响,采用激光加工技术在Ti6Al4V表面加工间距为100μm的网格和点阵微结构,将Si O2纳米粒子涂覆在微结构上构建微纳结构。采用接触角测量仪测量试样的表面接触角和滚动角,采用摩擦磨损实验机(UMT)测试摩擦学性能,采用LEXT OLS4000型3D激光共聚焦显微镜进行表面形貌和磨痕表征。结果表明:在具有微结构的表面涂覆Si O2可制备出具有微纳结构的超疏水Ti6Al4V表面,且网格表面比点阵表面更难以润湿。表面越难以润湿,试样的比磨损率越低,点阵和网格超疏水表面分别将比磨损率降低32.3%和53.8%,且摩擦因数曲线的波动幅度和数值均减小。且具有微纳结构的超疏水表面可显著提高Ti6Al4V的摩擦学性能。     

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.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

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).     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

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.