飞秒激光不锈钢表面陷光微结构的制备与性能研究

利用飞秒激光高真空环境下,在316L不锈钢表面两次交叉扫描制备了周期性微纳结构,并研究了微纳结构对波长范围200~900nm的光波的吸收增强能力。样品表面的微结构的形貌与成分采用扫描电子显微镜(SEM)和X射线衍射仪测试。第1次扫描采用高能流激光,获得了微米级锥状钉结构,表面覆盖了典型的激光诱导周期性表面结构(LIPSS)。然后将样品旋转90°,采用能流为0.02J/cm2的激光进行第二次扫描,路径与第1次扫描相交。第1次扫描的结构中的LIPSS被第2次低能流激光打断纳米颗粒,从而与锥状钉结构结合形成双尺度微结构。反射率测试结果表明,这 种 双 尺 度 微 结 构 表 面 的 平 均 反 射 率 约为2.28%,为光滑表面平均反射率的3.42%。结合XRD分析结果,不锈钢表面获得强陷光性能主要归因于飞秒激光制备的微结构。     

医用316L不锈钢表面微结构的飞秒激光制备及血液相容性研究

利用飞秒激光在316L不锈钢表面诱导制备血液相容性微结构,并从微结构的润湿性角度分析血液相容性改善的机理。随着激光能量密度的增加,在样品表面分别制备了单一的亚微米级典型激光诱导周期性波纹(LIPSS),以及两种双尺度结构,即覆盖了LIPSS的微米级波纹结构和锥状钉结构。硅烷化后的微结构样品表观接触角都超过150°,达到了超疏水性能要求,并且随着所采用激光能量密度的增强而增大,尤其是锥状钉双尺度结构的接触角达到了163.8°。采用了3种常规评价方法对微结构表面的血液相容性进行了评价,结果表明微结构表面的血液相容性显著优于光滑表面,且随着表面的表观接触角的增大而改善。     

飞秒激光直写诱导PMN-PT晶体表面LIPSS结构相变特性

本文提出一种由飞秒激光直写技术诱导的基于弛豫铁电体PMN-PT晶体的表面周期结构(LIPSS)，通过不同激光参数的改变，实现了LIPSS结构周期从750 nm到3μm的变化。最后，通过升高温度探究了LIPSS结构的相变特性。对比基底的相变特性，飞秒激光诱导的LIPSS结构的居里温度有明显的降低，这一特性将会为基于PMN-PT晶体的温控调制器的制备提供新思路。     

秒激光双光子微纳加工技术及其在光子学微器件制备中的应用

飞秒激光可以与包括玻璃、陶瓷、半导体、金属、塑料、树脂等各类物质产生相互作用,其相互作用原理不同,加工方法也不同。利用非线性光学效应——双光子吸收的飞秒微纳加工技术是最独特也是最具有应用前景的微纳加工技术。利用显微物镜将飞秒激光聚焦到加工介质时激光光强在焦点处呈三维空间分布,双光子吸收过程仅产生在具有足够激光强度的微小区域,通过控制激光光强可以调节双光子吸收的产生范围,在适当的激光强度时,可以突破光学衍射极限的限制,将双光子吸收过程控制到远小于激光波长甚至纳米尺度范围,从而达到进行纳米加工的目的。飞秒激光双光子微纳加工技术具有真三维、一次成型及高加工分辨率的特点,是三维微纳结构制备的理想工具之一。通过“理论计算-计算机辅助图形设计-微纳激光制造“这样一个简单的流程可以实现制备可设计的复杂三维微细结构,因此在光子学微器件、微机电系统等领域具有巨大的应用前景。最近几年双光子微细加工技术也已成功地应用到功能性光子学器件中。在制备基于光子晶体带隙原理的三维光子元器件及其立体集成方面,飞秒激光双光子方法具有无可比拟的优势。我们研究小组利用碳硅烷树状大分子修饰的激光染料与光聚合制备的光固化树脂,采用双光子聚合微加工技术制...     

飞秒激光双光子聚合三维微纳结构加工技术

飞秒激光双光子聚合微纳加工技术作为重要的三维微纳结构制备手段，已成为国际前沿研究热点。该技术利用激光与物质相互作用的双光子非线性吸收效应和阈值效应，可以突破经典光学理论衍射极限，实现纳米尺度的激光加工分辨力，在三维功能性微纳器件制备领域正在发挥着十分重要的作用。本文在介绍飞秒激光双光子聚合三维微纳加工技术的光物理和光化学过程基本原理的基础上，重点回顾人们在改善加工线宽及分辨力、提高加工效率等方面的研究进展与发展概况。该技术所制备的各种微光学器件、集成光学器件、微机电系统以及生物医学器件，不仅充分展示了飞秒激光双光子聚合三维微纳加工技术的高空间分辨力和真三维加工特点，也为其在相关前沿领域的应用提供具有启发性的思路。最后，对该技术实现高精度、高效率、低成本、大面积、多功能的三维微纳结构加工所存在的挑战和未来发展方向，进行了讨论和展望。     

激光纹理化调控材料表面疏水性能研究进展

超疏水表面由于具有减阻、抗污、防水等独特性能,广泛应用于日常生活、军事、工业等场景,材料表面的微纳结构及化学成分对其超疏水性能有着重要影响。激光纹理化技术由于具有加工分辨率高、加工方式灵活、可加工材料多等优势,可用于制备疏水性能精确可控的表面微纳结构,在制造超疏水表面方面有着广阔的应用前景。首先,介绍了激光纹理化的作用机理,综述了常用的激光纹理化方式,如激光直接写入法、激光干涉图案化法及激光诱导周期性结构法等,并介绍了激光参数对微纳结构的影响。根据表面微纳结构的形貌、周期及尺寸特点对激光纹理化制备的表面分层微纳结构进行了总结归纳,包括覆盖随机纳米结构或激光诱导周期性结构的微沟槽、微网格、微柱及微峰,重点介绍了分层微纳结构的制备方式及微纳结构对疏水性的影响。总结了提高分层微纳结构表面疏水性的后处理方式,包括环境老化、表面化学改性及热处理等,并介绍了后处理方式调控疏水性的作用机理。最后,对采用激光纹理化技术制备超疏水表面的应用前景进行了展望。     

多光子纳米加工中激光扫描条件对金属微纳结构的影响

研究了飞秒激光多光子还原制备银微纳结构技术中激光扫描条件对金属微纳结构与形貌的影响。结果表明:增加激光扫描点间距d可获得较小线宽,延长曝光时间t使线条变宽,增加扫描次数N可使金属微纳结构表面银纳米粒子熔融凝固成较大尺寸颗粒及块状物。     

单晶黑硅微结构对其反射率影响的研究

采用Ag辅助化学腐蚀法在不同H2O2浓度、腐蚀温度和腐蚀时间条件下制备了单晶黑硅微结构,并系统地研究了这种微结构对表面反射率的影响规律。采用场发射扫描电子显微镜对样品形貌进行了观察,并利用分光光度计对样品的表面反射率进行了测试,最终采用陷光模型对黑硅微结构与其反射率的关系进行了深入分析。发现当腐蚀液为7.8mol/L HF和0.6mol/L H2O2混合液、腐蚀温度为20℃以及腐蚀时间为90s时,所制备黑硅的腐蚀深度为900nm,其表面平均反射率为0.98%(400~900nm)。     

飞秒激光冲击强化技术的研究现状及展望

作为一种微尺度范围内的表面强化技术，飞秒激光冲击强化具有热影响小、冲击深度浅、能量利用率高、工艺灵活等特点，在实现复杂形状微结构表面改性、宏观尺度零件表面微造型、微冲击成形等方面应用优势显著。概述了飞秒激光冲击强化技术的发展历程，总结了冲击模式、激光参数、附加能场等因素对强化效果的影响规律和机理，并对飞秒激光冲击强化技术的潜在应用及发展趋势进行了展望，以为突破飞秒激光冲击强化的关键问题、推动技术的产业化应用提供必要的指导与支持。     

仿生超滑表面的飞秒激光微纳制造及应用

仿猪笼草的超滑表面由于可以抵抗多种液体的粘附,具有优异的稳定性与自修复性,受到越来越广泛的关注.而飞秒激光由于其对加工材料的普适性、高精度,以及高可控性,成为仿生超滑表面制备的有力手段.本文以仿猪笼草的超滑表面为背景,以飞秒激光微加工技术为手段.从超滑表面的飞秒激光微纳制备和应用两个方面,概述了超滑表面的微纳制造和应用...     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.