钛合金在硅酸盐溶液中微弧氧化陶瓷膜的组织结构

利用微弧氧化方法在硅酸盐溶液中在Ｔｉ－６Ａｌ－４Ｖ合金表面生长出一层厚度达５０μｍ的陶瓷氧化膜,并用Ｘ射线衍射（ＸＲＤ）、扫描电镜（ＳＥＭ）初步研究了氧化膜的组织结构。该氧化膜由大量金红石型ＴｉＯ２、ＳｉＯ２非晶相及少量锐钛矿型ＴｉＯ２相组成,且膜内层金工石含量比膜外层结相都是由微弧区熔融快速冷却形成的。硅元素已扩散到膜内层,Ｔｉ、Ｓｉ元素在膜内部分布是不均匀的。     

电解液组成对纯钛微弧氧化膜结构及光催化活性的影响

分别在钨酸钠和磷酸二氢钾电解液中制备了纯钛的微弧氧化(MAO)膜,利用SEM、EDX、XRD分析了膜层的形貌、元素分布及相组成,并测试了2种膜层的光催化活性.结果表明,纯钛在2种电解液中均形成粗糙多孔的微弧氧化膜层,但钨酸钠溶液中形成的膜层表面的孔洞尺寸较小、分布较均匀.膜层的元素组成和相组成与电解液成分有关,钨酸钠溶液中的膜层由W、Ti、O元素组成,W在膜层中近似均匀分布,锐钛矿与金红石的含量比(质量比)为27:73,而磷酸二氢钾电解液中的膜层由P、Ti、O元素组成,P从表面向内层逐渐增加,锐钛矿与金红石的含量之比则为84:16.吸光度测试结果表明,钨酸钠溶液中制备的膜层光催化活性高于磷酸二氢钾溶液中制备的膜层的光催化活性.     

铝酸盐溶液对TiAl合金微弧氧化膜生长和膜层特性的影响

目的 改善TiAl合金表面结构,提高其力学性能。方法 利用微弧氧化（MAO）方法,在NaAlO2电解液中制备了TiAl合金表面的陶瓷膜,分析微弧氧化过程中不同阶段的膜层生长特点,并研究铝酸盐溶液对微弧氧化膜生长速率的影响。通过硬度测试和显微划痕测试方法,评价膜层对基体硬度的影响和膜/基结合力的变化。利用扫描电子显微镜（SEM）分析不同厚度膜层的结构,结合能谱仪（EDS）分析膜层中元素的分布变化。使用X射线衍射仪（XRD）分析膜层相结构的变化。结果 铝酸盐溶液中微弧氧化膜的厚度随着微弧氧化时间增加,可以达到57 μm。微弧氧化过程分为明火花和暗火花生长两个阶段：前30 min是明火花生长阶段,生长速率可达1 μm/min;后续时间为暗火花生长阶段,生长速率约为0.23 μm/min。膜层包括致密内层和疏松外层。致密层中孔隙较少,Al、Ti含量较低;外层有较大的孔隙,Al含量较高,Ti含量较低。扫描电子显微镜结果显示,膜的内层与基体结合良好。显微划痕实验测得膜/基结合力达到45 N。陶瓷膜的相成分是Rutile-TiO2和Al2TiO5,且随着膜层变厚,Al2TiO5的相对含量上升。陶瓷膜的显微硬度随着膜厚度的增加而增加,120 min膜的显微硬度值可达1450 HV,是基体硬度的3倍多。结论 在NaAlO2中对TiAl合金进行微弧氧化处理,可以制备55 μm的陶瓷层。该膜层与基体间有优异的结合力,可以有效改善基体的表面结构,提高材料的硬度,改善其耐磨性能。     

多弧离子镀铝对TiAl合金高温抗氧化性能的影响

利用多弧离子镀技术在TiAl合金表面制备镀铝层.采用SEM、EDS和XRD分析了膜层的显微组织、化学成分及其相组成,研究了镀铝层对TiAl合金的高温抗氧化性能的影响.结果表明:TiAl合金表面离子镀铝后,形成致密的纯铝层,经850℃×100 h高温氧化后,氧化膜外层为连续致密的A12O3,内层为扩散层TiAl3相,有效地提高了TiAl合金高温抗氧化性能; 经950℃×100h高温氧化后,表面氧化膜由A12O3及少量的TiO2组成,膜层中TiAl2为主要成膜相.对TiAl合金的抗高温氧化性能起到一定的提高作用.     

医用钛合金的微弧氧化膜层组织及其磨损性能

采用微弧氧化方法对医用钛合金表面进行改性,利用X射线衍射分析(XRD)、扫描电镜(SEM)对微弧氧化膜层的表面形貌和化学成分进行分析,通过小振幅往复摩擦磨损试验测量膜层的耐磨损性能.结果表明:钛合金经过微弧氧化表面处理后,所得膜层存在不同尺寸的放电微孔,氧化膜内层相对外层较为致密;膜层主要由大量金红石型TiO2相、非晶相SiO2及少量锐钛矿型TiO2相组成;与基体相比,微弧氧化膜层的初期摩擦因数从0.7降低至0.1,耐磨性提高.     

微等离子体氧化制备TiO2薄膜的结构特性

利用微等离子体氧化方法在纯Ti金属表面生长出一层厚度达20μm的陶瓷氧化膜，并用X射线衍射、扫描电镜初步研究了氧化膜的组织结构和表面形貌。在不同电解质溶液条件下，得到3种不同类型结构组成的氧化膜：单一TiO2的锐钛型结构、TiO2锐钛型 金红石型的混合相结构、单一TiO2金红石结构。TiO2单一的锐钛型结构的氧化膜薄膜比较粗糙，TiO2金红石结构的氧化膜表面比较平滑，而混合相结构陶瓷膜的表面层为疏松的锐钛型结构TiO2，亚表层为金红石结构的TiO2。     

TiAl合金微弧氧化膜的制备及抗氧化性能研究

利用微弧氧化的方法在γ-TiAl合金上制备陶瓷膜，探讨了氧化过程中电流密度与成膜速度的关系。利用扫描电镜研究了氧化膜的表面形态和截面结构，结果表明，氧化膜由三层组成，且氧化膜与基体间有良好的冶金结合；物相分析发现氧化膜中含有金红石、Al2TiO5和SiO2非晶成分，并且物相组成和分布与成膜时间及膜的深度无关；氧化膜的硬度随着氧化时间的增加而增加，极大值出现在距离膜基交界面约10μm附近的氧化膜中。1100℃下的高温氧化实验发现微弧氧化处理后样品的氧化速度只有原始基体材料的1／3，微弧氧化处理后提高了TiAl合金的抗氧化性。     

Al涂层对γ-TiAl合金高温抗氧化能力的影响

研究了多弧离子镀铝对γ-TiAl合金850℃、950℃恒温氧化性能的影响,同时分析讨论了镀铝层的氧化机制.结果表明:多弧离子镀铝后,形成的纯铝涂层均匀致密,无裂纹、孔洞,与基体结合良好.静态空气中,850℃氧化100 h后,形成了连续致密的Al2O3膜层及扩散层TiAl3相;950℃氧化100 h后,表面氧化膜由Al2O3及少量的TiO2组成,膜层中TiAl2为主要成膜相.多弧离子镀铝有效地提高了γ-TiAl合金高温抗氧化性能.     

锆表面微弧氧化膜1000~1200 ℃高温蒸汽氧化行为研究

目的 研究微弧氧化表面处理对纯锆高温蒸汽氧化行为影响.方法 采用微弧氧化技术(MAO)在磷酸盐电解液中纯锆表面制备厚约2.5μm的陶瓷膜,再利用热重分析仪(TGA)测量它们在1000～1200℃蒸汽环境中的氧化性能,并分析蒸汽氧化前后氧化膜的微观结构、物相组成.用辉光放电谱仪(GDOES)分析蒸汽氧化前后锆基体及微弧氧化样品Zr、O、P、Na、C、H元素的成分深度分布.结果 锆基体及微弧氧化膜加速氧化动力学转变温度约为600℃.在1000℃蒸汽中,微弧氧化处理的纯锆样品氧化增重低于锆基体.蒸汽温度达到1100℃以上时,锆基体和微弧氧化膜的氧化增重曲线几乎重合.蒸汽氧化初期氧原子快速扩散至β-Zr中,当较厚α-Zr(O)层和ZrO2层形成后,氧化速率主要取决于氧在α-Zr(O)层中的扩散速率,而且氧化锆层阻挡了氢扩散进入锆基体.高温蒸汽氧化后,纯锆表面氧化层主要由单斜氧化锆(M-ZrO2)相和少量的四方氧化锆(T-ZrO2)相组成.结论 在1000℃以下,微弧氧化膜增强了锆基体的抗蒸汽氧化能力,但1100℃以上没有保护作用.     

纯钛表面微弧氧化多孔陶瓷膜的结构特性

采用微弧氧化处理技术和电解液成分的优化设计,在纯钛表面制备了含钙磷的多孔复合陶瓷膜,并考察了陶瓷膜的表面形貌、截面形貌、化学成分、物相构成、生物活性及其与基体的结合强度等特性。研究结果表明:纯钛表面微弧氧化后形成了凹凸不平的多孔陶瓷膜,整个膜层分为表层疏松层、中间过渡层和内部致密层三个区域,总厚度为25～40μm,膜层与基体的界面呈"锯齿状"紧密结合。膜层主要由金红石相TiO2和锐钛矿相TiO2构成;膜层中含有Ca,P,O,Ti四种元素,其钙磷比ω(Ca)∶ω(P)为1.528;膜层中的Ti,Ca,P元素呈梯度分布,由表及里Ti含量逐渐增多,Ca和P含量逐渐减少,O元素分布比较均匀。含钙磷多孔复合陶瓷膜具有良好的生物活性,样品经碱液处理后再在快速钙化溶液(FCS)中浸泡4d即有羟基磷灰石(HA)形成;膜层与基体具有高的结合强度,在450V和600Hz时膜层的临界载荷值高达29.5N。     

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.     

Effect of Short-Time Aging on the Pitting Corrosion Behavior of a Novel Lean Duplex Stainless Steel 2002

The effect of short-time aging in the temperature range between 400 and 1000 °C on the pitting corrosion behavior and mechanical property of a novel lean duplex stainless steel(LDSS) 2002 was investigated through the potentiostatic critical pitting temperature(CPT) tests and the Charpy impact tests. Both the pitting corrosion resistance and the toughness of aged specimens degraded due to the precipitation of detrimental secondary phases and the most significant reduction of CPT and impact energy emerged at 650 °C concurrently. The CPT of LDSS 2002 specimen aged at 650 °C decreased by 28 °C, and the impact energy dropped from 69 to 29 J/cm~2 compared with the solution-annealed sample. Transmission electron microscopy characterization showed that the main precipitates in LDSS 2002 were Cr_2N and M_(23)C_6 along the ferrite–austenite grain boundaries.     

INTRODUCTION TO PATENTS

The invention provides a method of making a mold which can reduce SOx generation rate while preventing decrease in hardening rate in the case of using sulfuric acid for a hardener composition. The method has a mixture step in which fire-resistant particles, a hardener composition and a binder composition are mixed to obtain a composition for a mold. The hardener composition contains sulfuric acid. In the mixture step, sodium carbonate is added. A molar ratio of the sulfuric acid to the sodium carbonate is 0.5 or more and 4.0 or less.     

China Foundry Week 2014

China Foundry Week, hosted by the Foundry Institution of Chinese Mechanical Engineering Society （FICMES） each year, is a large academic event in China. It is one of the ten high-impact activities sponsored by the Chinese Mechanical Engineering Society.     

17th Conference of Hydrodynamic and Electromechanical Control Engineering Call for papers

正1.Contents In order to promote the academic exchanges and technical communication of the research in the field of fluid power transmission and control,fluid control engineering specialized committee of the Chinese Society of Theoretical and Applied Mechanics will hold the 17th Conference of Hydrodynamic and Electromechanical Control Engineering on July 27-29,2014 in Tibet,Lhasa city.     

Information for Contributors

正The Transactions of Nonferrous Metals Society of China,founded in 1991 and sponsored by The Nonferrous Metals Society of China,is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology,including mineral processing,extraction metallurgy,metallic materials and heat treatments,metal working,physical metallurgy,powder metallurgy,with the emphasis     

Preface

<正>We are pleased to present this Special Issue of Transactions of Nonferrous Metals Society of China containing selected papers from the First Asian Conference on Aluminum Alloys(ACAA-2013),held in Beijing,China,13–17 October 2013.This conference has been initiated,with approval of     

Information for Contributors

The Transactions of Nonferrous Metals Society of China, founded in 1991 and sponsored by The Nonferrous Metals Society of China, is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology, including mineral processing, extraction metallurgy, metallic materials and heat treatments, metal working, physical metallurgy, powder metallurgy, with the emphasis on fundamental science. It is the unique preeminent publication in English for scientists, engineers, under/post-graduates on the field of nonferrous metals industry. This journal is covered by many famous abstract/index systems and databases such as SCI Expanded, Ei Compendex Plus, 1NSPEC, CA, METADEX, AJ and JICST.     

FORMULAS OF TENSION OF CONTINUOUS ROLLING PROCESS

The development of computer controlled continuous rolling process calls for a mathematical expression that can express the inequality condition of "constant flow". Tension is the link of the continuous rolling process. From the condition of dynamic equilibrium, a differential equation of tension is given out. On the basis of the physical rules established from the industrial practice and experimental studies, the law of volume constancy, the linear relation of forward slip and tension, the state equation of continuous rolling, the formula of dynamic tension, and the formula of static tension have been obtained. These formulae reflect the functional relations between tensions, thickness, roll velocity, and time in the continuous rolling process. It is implied that the continuous rolling process is a gradually steady, controllable, and measurable dynamic system. An assumption of predicting the thickness of a steel plate using these tension formulae is also put forward.     

Bulletin of the Awards in 2013

<正>Five reviewers and 9 published articles are selected as the Excellent Rewewerand Excellent Article in 2013 respectively.Excellent Reviewers:Prof.Z ongyi Ma(Institute of Metal Research,CAS,C hina);Prof.Y ongbo Xu(Institute of Metal Research,CAS,C hina);Prof.Guangping Zhang(Institute of Metal Research,C AS,C hina);Prof.Z hendui Cui(Tianjin University,China);