直接喷墨打印喷头直径对铁磁软磁材料成形性能的影响

以羰基铁粉为原料,DISPER-Y220为分散剂,制备出粘度为0.55 Pa·s,流动性良好的料浆,以此料浆作为打印"墨水",利用直接喷墨打印成形技术制备出纯铁软磁材料制件。喷头直径分别0.5、0.8和1.0 mm,打印成形后通过脱脂和烧结制备出制件。结果表明:分散剂添加量为1%时(质量分数),料浆粘度最低,随着固含量的增大,料浆粘度变大,随着剪切速率的增大,料浆表现为剪切变稀特征;喷头直径为0.8 mm所打印的烧结体,表面粗糙度(R_a)最低,其R_a为0.8μm;在1300℃保温2 h烧结后,喷头直径为0.5 mm打印的烧结体致密度最高,为96.3%,其磁饱和感应强度Bs达到1.53 T,最大磁导率μmax达到2630。     

熔融沉积(FDM)工艺参数对SiC陶瓷微观结构和力学性能影响

为提高熔融沉积成型(FDM)碳化硅(SiC)陶瓷的质量,本文主要研究工艺参数(料筒温度、喷嘴直径和打印层厚)对SiC陶瓷表面形貌、微观结构和力学性能的影响。结果表明:在料筒温度180℃、喷嘴直径0.8 mm和打印层厚0.2 mm时可获得稳定可控的挤出流量,SiC生坯和烧结体微观结构致密,层间结合效果好。SiC烧结体密度为3.18 g/cm~3,达到理论密度的99%,抗弯强度为302 MPa左右。成功制备了具有复杂几何形状和可控尺寸精度的SiC生坯,研究结果为3D打印SiC陶瓷工艺参数的制定提供了参考依据。     

Si元素对Ti-Cu-Zr-Ni基非晶钎料微观组织和性能的影响

采用电弧熔炼和快冷甩带工艺制备了(Ti_0.46Cu_0.14Zr_0.27Ni_0.13)_1-xSi_x非晶钎料,研究了添加一定量的Si对钎料非晶形成能力的影响。结果表明,当Si的含量达到0.5%时钎料的非晶形成能力最强,钎料的润湿面积为3.06 cm₂,过冷液相区宽度(?T_x)?T_x=56 ℃,约化玻璃转变温度(T_rg)T_rg=0.5387,液相线温度为949 ℃。以此非晶合金作为钎料对SiC和TC4进行真空钎焊,所得钎焊接头剪切强度为80 MPa。Si元素的加入显著提高了钎料的非晶形成能力。     

球形烧结态Cr3C2–25%NiCr复合粉末制备研究

试验通过添加高分子分散剂配制Cr₃C₂–25%NiCr料浆，采用喷雾干燥技术制备球形粉末，在保护气氛下进行液相烧结，气流粉碎分级后形成合适粒度粉末。实验研究了不同分散剂含量对喷雾干燥制备Cr₃C₂–25%NiCr复合粉末性能的影响，液相烧结工艺对Cr₃C₂与NiCr合金相之间冶金化结合状态的影响。研究结果表明：高分子分散剂能够很好的调解料浆性能，使喷雾干燥粉末具有良好的物性。采用SEM、XRD及化学成分分析表明粉末物理性能与国外粉末相当，超音速火焰喷涂涂层性能较好。     

钼包铁粉对Fe-2Cu-1Mo-0.8C合金显微组织、工艺性能和力学性能影响

分别采用元素混合粉和钼包铁粉将钼元素引入到Fe-2Cu-1Mo-0.8C成形混合料中,经压制烧结后得到烧结体,考察了两种钼元素引入方式对粉末工艺性能及烧结体显微组织和力学性能的影响.结果表明,由钼包铁粉所制备的Fe-2Cu-1Mo-0.8C成形混合料松装密度和流动性都优于元素混合粉末,分别提高了0.22 g/cm3和2.14 s/50 g.经800 MPa压力压制后,由钼包铁粉制备的压坯密度为7.29 g/cm3,于1150℃烧结90 min后得到烧结体的密度为7.26 g/cm3.烧结体的显微组织以珠光体和铁素体为主,由钼包铁粉制备的烧结体组织更为致密,钼元素在烧结体中分布更均匀,其抗拉强度和硬度分别为533 MPa和98.2 HRB,由元素混合粉制备的烧结体的抗拉强度和硬度分别为501 MPa和93.5 HRB.     

高固含量碳化硅/炭黑料浆制备工艺研究

研究了碳化硅粉料种类以及颗粒级配和炭黑种类对碳化硅/炭黑料浆流变性能的影响,通过优化工艺参数,当F240同F1200比例为6/4、碳黑为N990时,制备出的碳化硅/炭黑料浆固相体积分数达到70vol%,在50 s~(-1)剪切速率下,料浆的粘度值为1.6 Pa·s.     

烧结压力对自钎剂钎料性能的影响

采用热压烧结法制备了Al-12Si自钎剂钎料环,对不同烧结压力下钎料的润湿性、显微硬度和显微组织进行了研究. 结果表明,自钎剂钎料润湿性环随着烧结压力升高呈现上升趋势,在烧结压力为222 MPa时铺展面积达到152 mm2;随着烧结压力的增大,自钎剂钎料密度、显微硬度逐渐增大,但上升趋势变缓;钎料显微组织主要是灰色基体上均匀分布着黑色大块状相和白色小颗粒;XRD结果显示自钎剂钎料只有α-Al固溶体,初晶硅和Nocolok钎剂三种物相,热压烧结法制备自钎剂钎料未发生氧化、水解等反应,加上硅的活化作用保证了钎料高活性.     

高锥形件的拉伸

<正> 零件如图1,材料为08冷轧钢板,料厚0.5mm。它的相对高度 h/d=40/40>0.8,属高锥形件,采用锥形法拉伸成形。即首先将毛坯拉成圆筒形,其直径等于锥形件大端直径,然后锥面从底部开始成形,在各道工序中锥面逐渐增大,直至最后锥面一次成形。     

不同锂源对高温固相法制备NCM811正极材料储锂性能的影响

采用4种不同的锂盐(LiOH.H₂O、Li₂CO₃、LiNO₃、CH₃COOLi),以高温固相法制备了LiNi_0.8Co_0.1Mn_0.1O₂正极材料。利用X射线粉末衍射(XRD)和场发射电子显微镜(FESEM)对所制LiNi_0.8Co_0.1Mn_0.1O₂材料的微观结构进行了表征,发现所有合成的LiNi_0.8Co_0.1Mn_0.1O₂样品尺寸均为微米级大小,具有层状结构(R-3m空间群)。电化学测试结果表明采用不同锂源制备的LiNi_0.8Co_0.1Mn_0.1O₂样品的电化学性能差别很大。其中采用LiOH?H₂O为锂源,经500 °C预烧结6 h后,在800 °C下烧结16 h获得的样品锂镍混排程度最低,电化学性能最佳。例如,在0.1 C(1 C=180 mA/g)倍率下其可逆比容量高达206.2 mA.h/g,在10 C大倍率下,其可逆比容量仍保持有80.9 mA.h/g;在0.5 C倍率下100次充放电循环过程中,最高放电比容量为176.2 mA.h/g,平均放电比容量为140.1 mA.h/g。动力学及电极稳定性分析发现,LiOH?H₂O制备的样品的电化学可逆性最好,Li^₊扩散系数最大,充放电循环过程中结构稳定性最好。     

微孔网状多孔钼制备方法及其烧结状况

本文制备了一种微孔多孔钼块体.制备方法是以通孔有机泡沫为载体,采用浸浆法获取毛坯,然后采用高温真空烧结而成.其中料浆由钼粉和无毒性有机粘结剂组成,浆料粘度用去离子水调节.测定了烧结后钼块体的孔隙率,其孔隙率约为65%.对制备出的多孔钼块体进行了扫描电镜分析,测定了其孔隙的直径,测得其孔隙主要由7-9μm的微孔所组成,孔...     

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。     

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.