激光加工超疏水表面抗结冰性能研究进展

在低温环境中，表面结冰会严重影响户外装备的运行效率和安全，基于疏水材料的新型被动式防除冰方法引起了广泛关注。超疏水表面凭借其优越的拒水、抑制冰核形成和降低冰黏附强度等能力，在防除冰技术领域表现出广阔的应用前景。激光加工技术具有高效率和灵活性，成为制备超疏水表面的有效方法，并被进一步用来研究表面的抗结冰性能。首先，概述了固体表面润湿理论和结冰机理。其次，综合评估了激光加工超疏水表面的抗结冰性能，包括静态水滴延迟结冰时间、动态水滴累积、冰黏附强度、延迟结霜与抗冻能力、表面积冰与除冰等方面。静态水滴延迟结冰时间受到水滴与表面接触界面的成核速率和传热速率的影响，动态水滴累积与表面润湿性密切相关，冰黏附强度反映了表面对冰的附着性和除冰的难易程度。超疏水表面具有显著的延迟结冰能力，但在低温高湿条件下，表面的超疏水性可能会减弱，甚至失效。除冰过程也可能破坏超疏水表面的微观结构，进而影响其持续的抗结冰性能。最后，对超疏水表面激光加工与抗结冰性能的未来研究方向进行了展望。     

光热超疏水材料防除冰机理及应用研究进展

液滴的冻结、积聚往往会对生产、生活造成不利影响,降低设备的运行功效,甚至严重危害生命安全。相较于需要借助外力的主动式防除冰技术,超疏水表面优异的拒水性使其能够实现被动式防除冰,且无需消耗外部能量,从而受到广泛关注。在此基础上,光热超疏水表面结合了主动防除冰和被动防除冰两方面的优势,能在结冰过程的各个时期发挥作用。比如,在结冰前促进液滴的自清除,在结冰时升温表面、延缓成核,在结冰后加速融冰、快速除冰,从而实现节能且高效的固体表面防除冰。概述了超疏水表面的润湿特性和防除冰机理,重点介绍了不同种类光热材料的光热转化机理,包括基于分子热振动的碳纳米光热材料,基于纳米粒子等离激元效应的光热材料,以及基于电子?空穴对非辐射弛豫的半导体光热材料。总结了常用的提高光热转化效率的思路方法,并对比了各类光热超疏水表面在结冰、防冰、除冰及光热响应等方面的性能。最后,针对光热超疏水材料在制备和实际应用中可能存在的问题,分析了未来的发展方向与面临的挑战,为光热超疏水材料的进一步发展与应用提供思路。     

耐用铝基超疏水涂层的机械稳定性及抗结冰性能

通过简单的一步喷涂法,以成膜树脂和疏水纳米粒子为材料,构建具有优异机械稳定性和抗结冰性的无氟耐用超疏水涂层（RSHC）。方法 以有机硅树脂（SI）和环氧树脂（EP）为成膜物质,掺入具有疏水性的SiO2复合尺度纳米粒子,采用一步喷涂法制备涂层。采用接触角测量仪等测量涂层的表面浸润性,通过线性摩擦实验、胶带剥离实验、射流冲击实验等测定涂层的机械稳定性,通过静态结冰实验、低温弹跳和冻雨实验等测定涂层的抗结冰性能。结果 制备的涂层表现出优异的超疏水性,其接触角为158°4°,滚动角为8°0.6°。当有机硅树脂、环氧树脂和SiO2纳米粒子的质量比为2.8∶1.2∶1时,涂层表面在具有良好疏水性的同时仍具有极佳的力学性能。线性摩擦实验结果表明,涂层具有良好的耐磨损性能,经过100次摩擦循环后,其表面水滴接触角仍可达到157°;胶带剥离实验结果表明,涂层与基底间具有坚实的附着力,在测试20次后其表面的水滴接触角仍保持大于150°;射流冲击实验结果表明,涂层具有一定的抗冲击性,在射流冲击30 min后涂层的表面接触角未明显减小。此外,覆盖涂层的基底具有优异的静态结冰延迟性能和动态防覆冰性能。在静态结冰实验中,涂层表面液滴的结冰时间延迟了约7倍;在低温弹跳和冻雨实验中,滴落的水滴能从表面完全弹起滚落,并且在低温冻雨环境中其表面可以保持无覆冰。结论 制备的耐用超疏水涂层具有良好的疏水性、机械稳定性和抗结冰性能,对耐用超疏水涂层的研究及实际应用具有一定的参考价值。     

低冰粘附力涂层的设计与制备技术研究进展

基于飞机快速、高效除冰的目的,设计与制备低冰粘附力的涂层,以期实现较低(甚至超低)的冰层粘附强度,减轻对现有高能耗主动防/除冰技术的依赖程度.总结了现有疏冰涂层的发展历程,基于不同涂层的防覆冰机理,以冰粘附性能或除冰外力作为主要技术指标来评估涂层的防/除冰性能,依次阐明了超疏水涂层、超润滑涂层和低界面韧性涂层的除冰机理,具体介绍了三者的疏水/冰效果,对比分析了各自的优劣性.其中重点阐述了低界面韧性涂层大面积除冰的优势,即在大面积结冰条件下,以冰层剪切粘附强度定义的(超)疏冰涂层材料,其除冰外力都受限于结冰面积,随着结冰面积的增加而成比例增加.但新型的低界面韧性涂层通过诱导材料表面萌生固-冰界面微裂纹,降低其界面断裂韧性,使得微裂纹在较低的除冰外力(甚至冰层自身重力)作用下快速扩展,从而实现冰层脱离.以此总结了设计、制备新型(超)疏冰涂层的方法,展望了低冰粘附力涂层在防/除冰领域的发展方向.     

环氧树脂/SiO2涂层混凝土表面主动抗凝冰性及除冰性能研究

目的 了解超疏水涂层混凝土路面的抗凝冰性能,克服混凝土路面除冰困难问题。方法 将环氧树脂与无水乙醇混合得到涂料底层,纳米二氧化硅与无水乙醇混合得到涂料面层,分别将涂料底层和面层喷涂于混凝土表面,制备了一种由环氧树脂及二氧化硅纳米颗粒组成超疏水涂层。利用水滴在超疏水表面易滚落的特性来减少低温下混凝土表面的结冰量。同时由于混凝土表面存在超疏水涂层,混凝土表面与结冰接触面之间存在一层空气膜,可大幅减小路面冰层与混凝土接触面间的粘附力,达到易除冰的目的。结果 制备的超疏水涂层有良好的超疏水性,静态水接触角达到152°±1.9°,滚动角约为4°±1.2°;在–20 ℃下,冷冻2 h仍能保持超疏水性;同时,还能大幅度降低混凝土的渗水率。与普通混凝土相比,超疏水涂层混凝土表面的结冰量明显减少,并且冰层与混凝土表面的粘附力仅为普通混凝土的14%,结冰更易清除。结论 超疏水涂层能很好地改善混凝土表面的抗结冰性能,减少混凝土表面结冰量,降低冰层与混凝土表面的粘附力。     

防冰涂层材料及电力材料防覆冰应用的研究进展

防冰涂层材料可有效减轻自然界结冰现象的影响,其通过防冰材料低表面能或高润滑性的特点,降低在低温严寒天气条件下物体表面冰的粘附强度,延迟材料覆冰时间,减少表面覆冰量,在保护电力材料免受冰冻灾害影响方面有着重要应用价值.基于热喷涂法制备的复合型表面防冰涂层材料,以及主被动相结合的防覆冰方法,是未来电力材料防覆冰应用发展的重要方向.然而截止目前,有关复合型表面防冰涂层材料的热喷涂制备,以及涂层在电力材料防冰中应用的研究进展综述鲜见报道.从超疏水材料与光热、电热除冰相结合的除冰方式,及超疏水-超润滑复合材料实现防冰除冰的角度出发,对近年来国内外复合防冰涂层的制备及性能的研究进展进行了综述,并重点讨论了适合于热喷涂制备的复合型涂层的防冰除冰效果.最后,讨论了超疏水防冰涂层、复合型防冰涂层在电力材料表面防覆冰方面应用的研究进展,并对热喷涂法制备防冰涂层在的局限性问题进行了总结,对其应用前景进行了展望,希望在复合型防冰方面进一步开展研究,为电力材料表面防冰涂层的未来发展提供指导.     

NIR驱动MWCNT修饰的超滑PI光热响应膜表面液滴定向输运

目的 制备多壁碳纳米管(MWCNT)修饰的超滑聚酰亚胺(PI)光热响应膜表面,实现近红外光(NIR)驱动液滴定向输运.方法 基于静电纺丝结合喷涂法制备MWCNT修饰的超滑PI光热响应膜表面,分别通过扫描电子显微镜、接触角测量仪、红外热成像仪表征样品的微观形貌、润湿特性及光热特性,分析液滴大小与润滑油黏度对液滴定向输运的影响规律,研究NIR驱动液滴在MWCNT修饰的超滑PI光热响应膜表面定向输运的作用机理.结果 MWCNT修饰PI膜表面的疏水性提高,液滴静态接触角从115°增大至160°.NIR连续照射MWCNT修饰的超滑PI光热响应膜表面90 s,表面温度的最大上升速率为42.6℃/s,表面最大温度达到123.6℃.通过NIR照射超滑PI纳米纤维膜表面,表面局部温度上升,产生润湿梯度力,驱动液滴在表面定向输运.液滴定向输运与润湿梯度力及粘滞阻力有关.超滑PI光热响应膜表面的润滑油黏度相同时,液滴体积越小,粘滞阻力越小,液滴定向输运的速度越快.5μL液滴在润滑油黏度为0.65 mm2/s的超滑PI光热响应膜表面的运动速度最大,运动速度为1.64 mm/s.液滴体积相同时,超滑PI光热响应膜表面的润滑油黏度越大,液滴受到的润湿梯度力越小.5μL液滴在润滑油黏度为100 mm2/s的超滑PI光热响应膜表面的润湿梯度力Fwet-grad最小,润湿梯度力为6.39×10?6 N.结论 MWCNT修饰的超滑PI光热响应膜表面具有良好的光热效应,NIR可精准驱动单液滴及多液滴在表面的定向输运.     

微纳结构表面防冰研究进展

首先从冰的2种形成机理—均相成核和非均相成核进行了阐述,并介绍了液体在固体表面上的润湿现象。在此基础上,根据微纳结构防冰机理,分别综述了在固体表面结冰的前、中、后不同时期的最新防冰除冰策略。结冰前,借助液滴的脱落和自除预防固体表面结冰;结冰时,可通过延长冰的冻结时间,延缓冰在固体表面上的覆盖;结冰后,降低冰在固体表面的附着力,使之更易脱离固体表面,达到防冰除冰的需求。最后,对于如何提高微纳结构表面的耐久性进行了总结,对有关这些问题的最新研究成果进行了归纳和讨论,并对今后微纳结构表面防冰除冰的研究进行了展望。     

TC4钛合金超疏水表面/超润滑表面的制备及防冷凝性防冰性能研究

目的 为研究疏水表面与润滑表面的防冷凝及防冰机理，拓宽TC4钛合金在航空航天、医疗、化工石油、船舶制造等多个领域的应用。方法 采用阳极氧化法，在TC4表面构建了不同粗糙微结构，利用扫描电镜和原子力显微镜分别对表面形貌和粗糙度进行表征，对表面进行氟化和注油后，应用接触角测量仪测试表面的接触角、滚动角和滑动角，并在恒温恒湿箱内对氟化超疏水TC4表面和注油超润滑TC4表面的冷凝行为和结冰行为进行观测。结果 以HF溶液为电解液，10 V恒定电压下，在TC4表面制备得到了突触状微结构，20 V恒定电压下制备得到了排列有序的纳米管状结构。氟化改性后，纳米管状结构TC4表面接触角可达156.1°，滚动角为8°，表现为超疏水性。注油后的纳米管状超润滑TC4表面接触角为109.1°，滑动角为2°，表现为超润滑性。在冷凝测试中，超疏水表面出现了液滴自发滑移和自发跳跃行为。在结冰测试中，注油后的纳米管状超润滑TC4表面比其他测试样品表面具有最长的结冰延迟时间45s和最低冰黏附强度8.8 kPa。结论 超疏水TC4表面比其他测试样品表面具有更加优异的防冷凝性，进行注油润滑后，超润滑表面的防结冰性优于超疏水表面...     

受猪笼草启发的多孔微腔低冰黏附防除冰表面

目的 提高光滑液体注入表面(SLIPS)的防/除冰耐用性。方法 将镍箔完全浸没在无水乙醇中,使用飞秒激光照射无水乙醇环境中的镍箔表面诱导出立体多孔纳米微腔阵列结构,并使用氟硅烷改性增加表面对硅油的亲和力,最后用50 cSt的硅油旋涂在改性后的表面上。通过扫描电镜和光学显微镜对立体多孔纳米微腔结构进行形貌分析,并通过延缓结冰试验、冰黏附强度测试和高温蒸发试验,分别评价该SLIPS的延缓结冰性能、冰黏附强度和防除冰耐用性。结果 在立体多孔纳米微腔结构的毛细作用下,具有亲油憎水性的立体多孔纳米微腔表面上的蒸馏水滴也会被钉扎。相比非结构化表面,该SLIPS将延缓结冰时间提升了2.8倍,同时,在低温高湿度环境中,实现了冷凝水的自去除。在80 ℃高温环境下的蒸发10 min后进行结冰/除冰操作,10个周期后,该SLIPS的接触角(θCA)为110°,滑动角(θSA)为8.5°,以及冰黏附强度参数(τice)为3.6 kPa。结论 利用飞秒激光加工无水乙醇环境中的镍箔表面生成的立体纳米多孔微腔阵列结构能够减少SLIPS表面的润滑剂损失,可有效提高防除冰SLIPS的耐用性。     

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。