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Inclusions in melting process of titanium and titanium alloys
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作者 Meng-jiang Cen Yuan Liu +2 位作者 Xiang Chen Hua-wei Zhang Yan-xiang Li 《中国铸造:英文版》 SCIE 2019年第4期223-231,共9页
This paper summarizes melting methods of titanium and titanium alloy, such as vacuum arc melting(VAR) and electron beam cold hearth melting(EBCHM), and the related inclusions formed when using these melting methods. L... This paper summarizes melting methods of titanium and titanium alloy, such as vacuum arc melting(VAR) and electron beam cold hearth melting(EBCHM), and the related inclusions formed when using these melting methods. Low-density inclusions are resulted from contamination of air, and high-density inclusions are caused by refractory elements. The formation process of inclusions was analysed. The removal mechanism of different kinds of inclusions was specified. Low-density inclusions are removed mainly by resolving. This is a comprehensive process containing reaction diffusion. The resolving rate of high-density inclusions is so low that these inclusions are mainly removed by sedimentation. The experiments and physical models of inclusions are detailed. In various melting methods, vacuum arc melting is prominent. However, this method cannot remove inclusions effectively, which usually results in repeat melting. Electron beam cold hearth melting has the best ability of removing inclusions. These results can provide instructions to researchers of titanium and titanium alloys. 展开更多
关键词 TITANIUM INCLUSIONS VACUUM arc MELTING electron BEAM cold HEARTH MELTING
高锌压铸ADC12ZS合金性能的研究
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作者 杨兴国 《特种铸造及有色合金》 CAS 北大核心 2019年第1期38-41,共4页
针对目前的再生铝行业需求,旨在研究一种Zn含量不高于2.5%的ADC12ZS铝合金。通过分析,相比于ADC12合金,ADC12ZS高温热脆性趋势增加,热裂倾向更大;熔炼过程中烧损严重,铝液耗损率大。铝锭制备时通过控制Zn元素的组织形式可以避免压铸的... 针对目前的再生铝行业需求,旨在研究一种Zn含量不高于2.5%的ADC12ZS铝合金。通过分析,相比于ADC12合金,ADC12ZS高温热脆性趋势增加,热裂倾向更大;熔炼过程中烧损严重,铝液耗损率大。铝锭制备时通过控制Zn元素的组织形式可以避免压铸的高温热脆性。严格控制炉料清洁度、比面积和除渣剂用量,适当提高加热速度,缩短熔炼时间,控制好炉内O2浓度,有利于降低铝液烧损率以及含渣量。 展开更多
关键词 铝合金 热脆性 烧损 含渣量 熔炼
Anisotropic corrosion resistance of TiC reinforced Ni-based composites fabricated by selective laser melting
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作者 Hongmei Zhang Dongdong Gu +3 位作者 Lixia Xi Han Zhang Mujian Xia Chenglong Ma 《材料科学技术学报:英文版》 SCIE EI CAS CSCD 2019年第6期1128-1136,共9页
Electrochemical measurements on three planes of TiC/Inconel 718 composites fabricated by selective laser melting(SLM) were performed to study the corrosion property. The results showed that the YZplane with dense and ... Electrochemical measurements on three planes of TiC/Inconel 718 composites fabricated by selective laser melting(SLM) were performed to study the corrosion property. The results showed that the YZplane with dense and fine columnar structures possessed high microhardness and superior corrosion resistance in 3.5 wt% NaCl solution. For the XZ-plane, a decreased anti-corrosion property was observed owing to its inhomogeneous microstructures. While the XY-plane with large irregular pores and clustered ring-like structures was more susceptible to corrosion compared with the other two planes. Comparative analysis suggested that the anisotropic corrosion behaviors were significantly dependent on the surface defects, microstructure characteristics and added reinforcements. 展开更多
关键词 SELECTIVE laser MELTING Corrosion resistance NICKEL based composite Microstructure
镁合金压铸生产过程中的质量控制 预览
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作者 张艺钟 《世界有色金属》 2019年第9期168-169,共2页
镁合金的应用范围非常广,为了提升镁合金的质量,需要在对压铸质量进行严格控制。本文首先介绍了镁合金锭融化前的准备,随后阐述了镁合金压铸生产过程中的质量控制,以期对提升镁合金压铸质量有一定参考作用。
关键词 镁合金压铸 融化 质量控制
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Characteristics of urea under high pressure and high temperature
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作者 房帅 马红安 +6 位作者 郭龙锁 陈良超 王遥 丁路遥 蔡正浩 王健 贾晓鹏 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第9期348-352,共5页
The properties of urea under high pressure and high temperature(HPHT) are studied using a China-type large volume cubic high-presentation apparatus(CHPA)(SPD-6 × 600).The samples are characterized by scanning ele... The properties of urea under high pressure and high temperature(HPHT) are studied using a China-type large volume cubic high-presentation apparatus(CHPA)(SPD-6 × 600).The samples are characterized by scanning electron microscopy(SEM), x-ray diffraction(XRD), and Raman spectroscopy.By directly observing the macroscopic morphology of urea with SEM, it is confirmed that the melting point of urea rises with the increase of pressure.The XRD patterns of urea residues derived under different pressures show that the thermal stability of urea also increases with the increase of pressure.The XRD pattern of the urea residue confirms the presence of C3H5N5O(ammeline) in the residue.A new peak emerges at 21.80°, which is different from any peak of all urea pyrolysis products under normal pressure.A more pronounced peak appears at 708 cm^-1 in the Raman spectrum, which is produced by C-H off-plane bending.It is determined that the urea will produce a new substance with a C-H bond under HPHT, and the assessment of this substance requires further experiments. 展开更多
关键词 HIGH pressure and HIGH temperature(HPHT) UREA THERMAL stability MELTING POINT
Zircon U-Pb-Hf constraints from Gongga Shan granites on young crustal melting in eastern Tibet 预览
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作者 Nick M.W. Roberts Michael P. Searle 《地学前缘:英文版》 CAS CSCD 2019年第3期885-894,共10页
The Gongga Shan batholith is a complex granitoid batholith on the eastern margin of the Tibetan Plateau with a long history of magmatism spanning from the Triassic to the Pliocene. Late MioceneePliocene units are the ... The Gongga Shan batholith is a complex granitoid batholith on the eastern margin of the Tibetan Plateau with a long history of magmatism spanning from the Triassic to the Pliocene. Late MioceneePliocene units are the youngest exposed crustal melts within the entire Asian plate of the Tibetan Plateau. Here, we present in-situ zircon Hf isotope constraints on their magmatic source, to aid the understanding of how these young melts were formed and how they were exhumed to the surface. Hf isotope signatures of Eocene to Pliocene zircon rims ( 3 Hf(t)=-4 to t4), interpreted to have grown during localised crustal melting, are indicative of melting of a Neoproterozoic source region, equivalent to the nearby exposed Kangding Complex. Therefore, we suggest that Neoproterozoic crust underlies this region of the Songpan eGanze terrane, and sourced the intrusive granites that form the Gongga Shan batholith. Localised young melting of Neoproterozoic lower or middle crust requires localised melt-fertile lithologies. We suggest that such melts may be equivalent to seismic and magnetotelluric low-velocity and high-conductivity zones or “bright spots” imaged across much of the Tibetan Plateau. The lack of widespread exposed melts this age is due either to the lack of melt-fertile rocks in the middle crust, the very low erosion level of the Tibetan plateau, or to a lack of mechanism for exhuming such melts. For Gongga Shan, where some melting is younger than nearby thermochronological ages of low temperature cooling, the exact process and timing of exhumation remains enigmatic, but their location away from the Xianshuihe fault precludes the fault acting as a conduit for the young melts. We suggest that underthrusting of dry granulites of the lower Indian crust (Archaean shield) this far northeast is a plausible mechanism to explain the uplift and exhumation of the eastern Tibetan Plateau. 展开更多
关键词 Tibet HIMALAYA HF ISOTOPES ZIRCON CRUSTAL melting
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Influence of Al/Cu content on grain boundary diffusion in Nd-Fe-B magnet via in-situ observation
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作者 Xinghua Cheng Jian Li +3 位作者 Lei Zhou Tao Liu Xiaojun Yu Bo Li 《中国稀土学报:英文版》 SCIE EI CAS CSCD 2019年第4期398-403,共6页
The influence of aluminum and copper content in the starting Nd-Fe-B magnet on grain boundary diffusion process(GBDP) was studied by observing the phase transformation behaviors of the magnets in-situ at high temperat... The influence of aluminum and copper content in the starting Nd-Fe-B magnet on grain boundary diffusion process(GBDP) was studied by observing the phase transformation behaviors of the magnets in-situ at high temperature. A higher coercivity increment is discovered in the sample with higher AI/Cu despite the fact that its Dy diffusion amount is the same as the other. DSC analysis shows an evident melting behavior in the higher Al/Cu sample. Laser scanning confocal microscopy(LSCM) in-situ characterization shows a large amount of melted intergranular phase spills out to the surface simultaneously at around 600 ℃ in the high Al/Cu sample, while the phase spills out gradually one after another in the range between 623 and680 ℃ in the other sample, which indicates that the intergranular phase can be more easily melted in the sample containing more AI/Cu. The area fraction of matrix phase remarkably shrinks while that of intergranular phase enlarges after LSCM heating, which demonstrates the outer region of the Nd2 Fe14B grains melt at the temperature of 900 ℃. Electron probe microanalyzer result(EPMA) shows that the Nd and Dy concentrate in edge regions and subsequently mix into the intergranular phase with the melting of the grain edge, while a large amount of AI and Cu in the intergranular phase spill out. Nevertheless, the sample with higher starting AI/Cu still remains higher residual contents after LSCM experiments, and that could probably be the main reason why the high AI/Cu magnet shows smaller coercivity decrement after LSCM experiment. Overall, the increase of AI/Cu in the starting magnet optimizes the Dy distribution and the wettability of intergranular phase, enhancing coercivity increment effect further. 展开更多
关键词 ND-FE-B sintered MAGNET Grain boundary diffusion process IN-SITU LSCM MELTING behavior Copper Aluminum
Phosphorus migration mechanism between iron and high phosphorus gangue phase at high temperatures
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作者 Lei Guo Jin-tao Gao +1 位作者 Sheng-ping Zhong Zhan-cheng Guo 《钢铁研究学报:英文版》 SCIE EI CAS CSCD 2019年第2期113-122,共10页
The phosphorus migration mechanism during melting separation of non-carbon-reduced high phosphorus iron ore was investigated.Firstly,the equilibrium compositions of hydrogen-reduced high phosphorus iron ore at differe... The phosphorus migration mechanism during melting separation of non-carbon-reduced high phosphorus iron ore was investigated.Firstly,the equilibrium compositions of hydrogen-reduced high phosphorus iron ore at different temperatures were simulated by the use of equilibrium composition module of HSC Chemistry software.Then,thermodynamic calculation was verified by the real heat treatment of simulated hydrogen-reduced high phosphorus iron ore with several pure reagents including self-made pure fluorapatite.The iron particles in the simulated samples gathered and grew up during heat treatment.Meanwhile,the hypoeutectic structure of Fe-P with grid shape of high phosphorus phase and circular shape of low phosphorus phase emerged within those iron particles.With the penetration of phosphorus from the periphery into the iron particles,the grid structure became denser and denser.It proves that the elemenlal phosphorus can be reduced from the gangue phase by metallic iron without solid carbon at high temperatures. 展开更多
关键词 MELTING separation FLUORAPATITE THERMODYNAMICS PHOSPHORUS migration High PHOSPHORUS IRON ore
配合料制粒技术在玻璃生产熔化工艺中的应用 预览
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作者 李涛 《玻璃》 2019年第7期43-49,共7页
主要介绍配合料制粒技术在浮法玻璃生产中的试验应用,通过在试验中发现问题并探索解决方案,逐步将配合料制粒技术加以完善,以实现产业化推广,达到节能降耗、提升产品品质的目的,同时为玻璃生产中原料制备技术的创新提供一种思路。
关键词 配合料 制粒 试验 熔化 节能
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飞秒激光制瓣LASIK增效术后上皮植入伴有角膜融解一例
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作者 张媛 韩浩 +2 位作者 贾冰冰 张岩 庞玉珍 《中华眼外伤职业眼病杂志》 2019年第3期237-238,共2页
飞秒激光制瓣LASIK术因具有较高的安全性,较好的预测性和较少的并发症,已经成为主流手术方式之一。飞秒激光制瓣LASIK术减少了角膜板层刀所带来的弥漫性层间角膜炎、角膜上皮植入和角膜融解等并发症。我院自2010年7月至2018年7月,共手术... 飞秒激光制瓣LASIK术因具有较高的安全性,较好的预测性和较少的并发症,已经成为主流手术方式之一。飞秒激光制瓣LASIK术减少了角膜板层刀所带来的弥漫性层间角膜炎、角膜上皮植入和角膜融解等并发症。我院自2010年7月至2018年7月,共手术近2万例,增效手术43例,只有1例发生上皮植入伴有角膜融解,经治疗,患者病情稳定,报告如下。 展开更多
关键词 LASIK 增效 上皮植入 角膜融解
抗冲共聚聚丙烯的结构与性能 预览 被引量:1
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作者 王帆 刘小燕 +2 位作者 周玲 朱博超 王晶晶 《合成树脂及塑料》 CAS 北大核心 2019年第1期58-62,68共6页
研究了5种熔体流动速率为28 g/10 min,乙烯质量分数为10%左右的车用抗冲共聚聚丙烯(IPC)的力学性能、相态结构、熔融结晶行为、橡胶相尺寸及分布、加工性能。结果表明:IPC-4整体力学性能最优,拉伸强度为24.60 MPa,弯曲模量为1 401.71 M... 研究了5种熔体流动速率为28 g/10 min,乙烯质量分数为10%左右的车用抗冲共聚聚丙烯(IPC)的力学性能、相态结构、熔融结晶行为、橡胶相尺寸及分布、加工性能。结果表明:IPC-4整体力学性能最优,拉伸强度为24.60 MPa,弯曲模量为1 401.71 MPa,冲击强度为10.02 kJ/m2;IPC是由无规共聚物、嵌段共聚物和均聚聚丙烯三部分组成;IPC-4具有最高的熔融焓和结晶焓,即材料有高的结晶度和刚性;IPC-4的孔洞分布更均匀、孔洞直径相差不大,平均值为1μm;5种试样的加工性能较为接近,最适宜的注塑温度为200℃。 展开更多
关键词 抗冲共聚聚丙烯 无规共聚物 熔融 结晶 流变性能 非等温动力学
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相对分子质量对聚丙烯结晶和熔融行为的影响 预览
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作者 邹发生 宋文波 +1 位作者 张晓萌 刘振杰 《石油化工》 CAS CSCD 北大核心 2019年第4期357-361,共5页
在中试装置上合成了一系列相对分子质量不同但相对分子质量分布相似的均聚聚丙烯。利用 GPC,MFR,SAXS,DSC 等方法考察了相对分子质量对聚丙烯晶体结构、结晶和熔融行为的影响。表征结果显示,相对分子质量越大,聚丙烯注塑样条的片晶越容... 在中试装置上合成了一系列相对分子质量不同但相对分子质量分布相似的均聚聚丙烯。利用 GPC,MFR,SAXS,DSC 等方法考察了相对分子质量对聚丙烯晶体结构、结晶和熔融行为的影响。表征结果显示,相对分子质量越大,聚丙烯注塑样条的片晶越容易沿剪切方向取向,且其片晶厚度和非晶层厚度也越大。随着相对分子质量下降,聚丙烯的结晶温度和熔融温度降低,而结晶度增大。等规聚丙烯的平衡熔点为 188.2 ℃。 展开更多
关键词 相对分子质量 聚丙烯 结晶 熔融
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高掺率废玻璃熔化及成分补偿技术在浮法玻璃生产中的应用 预览
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作者 唐菊芳 冯朝辉 《玻璃》 2019年第8期50-54,共5页
高掺率废玻璃熔化及成分补偿技术针对浮法玻璃中高比例掺入外购废玻璃,通过燃烧技术、成分补偿及马蹄焰窑炉结构的创新等技术措施,解决由此引起的成分波动、澄清困难、结石增多等技术质量问题,并有效节约原矿资源和化工材料,实现清洁生... 高掺率废玻璃熔化及成分补偿技术针对浮法玻璃中高比例掺入外购废玻璃,通过燃烧技术、成分补偿及马蹄焰窑炉结构的创新等技术措施,解决由此引起的成分波动、澄清困难、结石增多等技术质量问题,并有效节约原矿资源和化工材料,实现清洁生产,降低污染物的排放,减少土地和人畜危害。 展开更多
关键词 高掺率 废玻璃 熔化 成分补偿 熔窑结构 节能降耗
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Strategies for creating living, add lively manufactured, open-cellular metal and alloy implants by promoting osseointegration, osteoinduction and vascularization;An overview
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作者 Lawrence E. Murr 《材料科学技术学报:英文版》 SCIE EI CAS CSCD 2019年第2期231-241,共11页
Additive manufacturing of porous, open-cellular metal or alloy implants, fabricated by laser or electron beam melting of a powder bed, is briefly reviewed in relation to optimizing biomechanical compatibility by assur... Additive manufacturing of porous, open-cellular metal or alloy implants, fabricated by laser or electron beam melting of a powder bed, is briefly reviewed in relation to optimizing biomechanical compatibility by assuring elastic (Young's) modulus matching of proximate bone, along with corresponding pore sizes assuring osseointegration and vasculature development and migration.In addition, associated, requisite compressive and fatigue strengths for such implants are described. Strategies for optimizing osteoblast (bone cell) development and osteoinduction as well as vascularization of tissue in 3D scaffolds and tissue engineering constructs for bone repair are reviewed in relation to the biology of osteogenesis and neovascularization in bone, and the role of associated growth factors, bone morphogenic proteins, signaling molecules and the like. Prospects for infusing hydrogel/collagen matrices containing these cellular and protein components or surgically extracted intramedullary (bone marrow) concentrate/aspirate containing these biological and cell components into porous implants are discussed, as strategies for creating living implants, which over the long term would act as metal or alloy scaffolds. 展开更多
关键词 Additive manufacturing Open cellular metal and alloy IMPLANTS Electron beam melting LIVING implant STRATEGIES VASCULARIZATION OSSEOINTEGRATION OSTEOINDUCTION
Progress in additive manufacturing on new materials;A review
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作者 Neng Li Shuai Huang +5 位作者 Guodong Zhang Renyao Qin Wei Liu Huaping Xiong Gongqi Shi Jon Blackburn 《材料科学技术学报:英文版》 SCIE EI CAS CSCD 2019年第2期242-269,共28页
Recent efforts and advances in additive manufacturing (AM) on different types of new materials are presented and reviewed. Special attention is paid to the material design of cladding layers, the choice of feedstock m... Recent efforts and advances in additive manufacturing (AM) on different types of new materials are presented and reviewed. Special attention is paid to the material design of cladding layers, the choice of feedstock materials, the metallurgical behavior and synthesis principle during the AM process, and the resulted microstructures and properties, as well as the relationship between these factors. Thereafter, the trend of development in the future is forecasted, including: Effects of the particles size and size distribution of powders;Approaches for producing fine microstructures;Opportunities for creating new materials by AM;Wide applications in reconditioning of damaged components;Challenges for deep understanding and applications of the AMed new materials. The idea of "Develop Materials" or "Create Materials" by AM is highlighted, but a series of scientific, technological and engineering problems remain to be solved in future. 展开更多
关键词 ADDITIVE MANUFACTURING FEEDSTOCK material Laser and electron BEAM MELTING Microstructure Property
A review of selective laser melting of aluminum alloys;Processing,microstructure, property and developing trends
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作者 Jinliang Zhang Bo Song +2 位作者 Qingsong Wei Dave Bourell Yusheng Shi 《材料科学技术学报:英文版》 SCIE EI CAS CSCD 2019年第2期270-284,共15页
Selective laser melting(SLM) is an attractive rapid prototyping technology for the fabrication of metallic components with complex structure and high performance. Aluminum alloy, one of the most pervasive structural m... Selective laser melting(SLM) is an attractive rapid prototyping technology for the fabrication of metallic components with complex structure and high performance. Aluminum alloy, one of the most pervasive structural materials, is well known for high specific strength and good corrosion resistance. But the poor laser formability of aluminum alloy restricts its application. There are problems such as limited processable materials, immature process conditions and metallurgical defects on SLM processing aluminum alloys. Some efforts have been made to solve the above problems. This paper discusses the current research status both related to the scientific understanding and technology applications. The paper begins with a brief introduction of basic concepts of aluminum alloys and technology characterization of laser selective melting. In addition, solidification theory of SLM process and formation mechanism of metallurgical defects are discussed. Then, the current research status of microstructure, properties and heat treatment of SLM processing aluminum alloys is systematically reviewed respectively. Lastly, a future outlook is given at the end of this review paper. 展开更多
关键词 SELECTIVE laser MELTING Aluminum alloy Metallurgical DEFECTS Mechanical properties Heat treatment DEVELOPING TREND
Effect of ultrasonic vibration-assisted laser surface melting and texturing of Ti-6Al-4V ELI alloy on surface properties
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作者 Sourabh Biswas S. Habib Alavi +2 位作者 Bhishma Sedai Frank D. Blum Sandip P. Harimkar 《材料科学技术学报:英文版》 SCIE EI CAS CSCD 2019年第2期295-302,共8页
Ultrasonic vibration-assisted laser surface processing that involves application of vertical ultrasonic vibrations to the Ti-6 Al-4 V alloy substrates while being irradiated with a CO2 laser was performed for the deve... Ultrasonic vibration-assisted laser surface processing that involves application of vertical ultrasonic vibrations to the Ti-6 Al-4 V alloy substrates while being irradiated with a CO2 laser was performed for the development of laser melted and textured surfaces with potential applications in biomedical implants.The laser processing resulted in very consistent repeating undulating grooved surfaces, and the undulations were significantly more pronounced in the samples processed with higher ultrasonic power outputs.The phase evolution, studied by x-ray diffraction, confirmed that the laser processing triggered transformation of globular α→ acicular α and martensitic α’ as well as increased amounts of retained α phases,which were also reflected in the microscopic analysis. The surface texture developed by laser processing resulted in increased surface wettability with increasing ultrasonic power output. The textured surfaces exhibited marked decrease in coefficients of friction during sliding wear testing performed under simulated body fluid due to lubricant entrainment within the textured grooves. The texturing also resulted in significant reduction in surface contact area during the wear process, which considerably reduced the overall wear rates due to abrasive wear. 展开更多
关键词 LASER TEXTURING LASER MELTING ULTRASONIC vibrations WEAR
路基冻胀-融化-沉降循环作用下板式无砟轨道受力与变形分析 预览
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作者 向俊 林士财 +3 位作者 余翠英 袁铖 陈林 杨海明 《中南大学学报:自然科学版》 EI CAS CSCD 北大核心 2019年第8期2043-2052,共10页
基于有限单元法及混凝土塑性损伤模型,建立路基上单元板式无砟轨道静力分析模型,研究路基冻胀—融化—沉降循环作用下,无砟轨道结构的受力和变形特性及伤损演化规律。研究结果表明:在路基冻胀—融化—沉降循环作用下,轨道板和底座板在... 基于有限单元法及混凝土塑性损伤模型,建立路基上单元板式无砟轨道静力分析模型,研究路基冻胀—融化—沉降循环作用下,无砟轨道结构的受力和变形特性及伤损演化规律。研究结果表明:在路基冻胀—融化—沉降循环作用下,轨道板和底座板在冻胀过程中逐渐形成塑性损伤,且轨道板的塑性损伤早于底座板的塑性损伤;在融化回落及沉降阶段,轨道板的损伤状态相对稳定,而底座板在距其端部1/3位置处逐渐形成第二塑性区;在路基冻胀—融化—沉降循环作用下,将不可避免地引起轨道不平顺,轨道不平顺幅值呈增加—减小—反向增加的变化趋势;当路基回落至初始状态时,轨道结构存在部分残余变形;底座板与基床表层间的离缝呈张开—闭合—张开的循环性变化规律。该研究可为高速铁路无砟轨道养护维修提供参考。 展开更多
关键词 铁道工程 无砟轨道 塑性损伤 冻胀 融化 沉降 受力 变形
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Hierarchical microstructures with high spatial frequency laser induced periodic surface structures possessing different orientations created by femtosecond laser ablation of silicon in liquids 预览
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作者 Dongshi Zhang Koji Sugioka 《光电进展(英文)》 2019年第3期1-18,共18页
High spatial frequency laser induced periodic surface structures(HSFLs)on silicon substrates are often developed on flat surfaces at low fluences near ablation threshold of 0.1 J/cm2,seldom on microstructures or micro... High spatial frequency laser induced periodic surface structures(HSFLs)on silicon substrates are often developed on flat surfaces at low fluences near ablation threshold of 0.1 J/cm2,seldom on microstructures or microgrooves at relatively higher fluences above 1 J/cm^2.This work aims to enrich the variety of HSFLs-containing hierarchical microstructures,by femtosecond laser(pulse duration:457 fs,wavelength:1045 nm,and repetition rate:100 kHz)in liquids(water and acetone)at laser fluence of 1.7 J/cm^2.The period of Si-HSFLs in the range of 110–200 nm is independent of the scanning speeds(0.1,0.5,1 and 2 mm/s),line intervals(5,15 and 20μm)of scanning lines and scanning directions(perpendicular or parallel to light polarization direction).It is interestingly found that besides normal HSFLs whose orientations are perpendicular to the direction of light polarization,both clockwise or anticlockwise randomly tilted HSFLs with a maximal deviation angle of 50°as compared to those of normal HSFLSs are found on the microstructures with height gradients.Raman spectra and SEM characterization jointly clarify that surface melting and nanocapillary waves play important roles in the formation of Si-HSFLs.The fact that no HSFLs are produced by laser ablation in air indicates that moderate melting facilitated with ultrafast liquid cooling is beneficial for the formation of HSFLs by LALs.On the basis of our findings and previous reports,a synergistic formation mechanism for HSFLs at high fluence was proposed and discussed,including thermal melting with the concomitance of ultrafast cooling in liquids,transformation of the molten layers into ripples and nanotips by surface plasmon polaritons(SPP)and second-harmonic generation(SHG),and modulation of Si-HSFLs direction by both nanocapillary waves and the localized electric field coming from the excited large Si particles. 展开更多
关键词 HIGH spatial frequency LASER induced periodic SURFACE structures SILICON LASER ablation in liquids HIERARCHICAL MICROSTRUCTURES femtosecond LASER HIGH fluence formation mechanism SURFACE melting nanocapillary wave SURFACE plasmon polaritons second-harmonic generation
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A continuous net-like eutectic structure enhances the corrosion resistance of Mg alloys 预览
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作者 Cijun Shuai Wenjing Yang +3 位作者 Youwen Yang Chengde Gao Chongxian He Hao Pan 《国际生物打印期刊》 2019年第2期49-60,共12页
Mg alloys degrade rather rapidly in a physiological environment,although they have good biocompatibility and favorable mechanical properties.In this study,Ti was introduced into AZ61 alloy fabricated by selective lase... Mg alloys degrade rather rapidly in a physiological environment,although they have good biocompatibility and favorable mechanical properties.In this study,Ti was introduced into AZ61 alloy fabricated by selective laser melting,aiming to improve the corrosion resistance.Results indicated that Ti promoted the formation of Al-enriched eutecticαphase and reduced the formation ofβ-Mg17Al12 phase.With Ti content reaching to 0.5 wt.%,the Al-enriched eutecticαphase constructed a continuous net-like structure along the grain boundaries,which could act as a barrier to prevent the Mg matrix from corrosion progression.On the other hand,the Al-enriched eutecticαphase was less cathodic thanβ-Mg17Al12 phase in AZ61,thus alleviating the corrosion progress due to the decreased potential difference.As a consequence,the degradation rate dramatically decreased from 0.74 to 0.24 mg·cm-2·d-1.Meanwhile,the compressive strength and microhardness were increased by 59.4%and 15.6%,respectively.Moreover,the Ti-contained AZ61 alloy exhibited improved cytocompatibility.It was suggested that Ti-contained AZ61 alloy was a promising material for bone implants application. 展开更多
关键词 eutecticαphase net-like structure selective laser melting mg alloys corrosion resistance
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