北工大成功开发新素材刀具与磨具

近年来，陶瓷(SiC)晶须(细纤维)和类金刚石(DLC)薄膜因其引人注目的机械与物理化学特性如高硬度(与金刚石接近)、高耐磨性等以及晶须的高强度(韧性好)及与基质材料良好的相容性，因而晶须、DLC薄膜分别被广泛地用作于金属、陶瓷及塑料等复合材料的强化材料及机械零部件和工具的涂附材料。北京工业大学留日留韩归国学者魏源迁博士成功开发了定向排列晶须增韧A12O3陶瓷刀片和定向排列晶须磨具与类金刚石(DLC)纤维磨具新素材刀具与磨具。     

一种金刚石柔性磨轮胶粘剂的改性实验研究

本文研究了不同晶须材料、不同粒径颗粒状材料作为填料对金刚石柔性磨轮用树脂胶粘剂的改性,通过对比改性前后复合材料的抗拉强度、抗冲击强度和耐磨系数,分析研究了不同填料对树脂胶粘剂的改性效果及原因。实验结果表明:采用晶须材料改性需要实现晶须定向分布;3%的纳米氧化铝添加量能提高复合材料31%的耐磨性,相同量的W 3氧化铝微粉能使复合材料的耐磨性提高51%,而微粉级氧化铝添加后制作的金刚石柔性磨轮刚度太大,不能充分发挥金刚石柔性磨轮的柔性特质。     

莫来石纤维对氧化铝陶瓷性能的影响

选用莫来石纤维为增强体,通过添加适量的烧结助剂,制备莫来石纤维增强氧化铝陶瓷基复合材料,探讨了不同烧结温度和不同纤维含量对复合材料性能的影响规律.结果表明:莫来石纤维增强氧化铝陶瓷基复合材料的相对密度、弯曲强度和断裂韧性随烧结温度和纤维含量的增加先增大后减小,当烧结温度为1450 ℃、纤维含量为15%时,复合材料的弯曲强度、断裂韧性最高,复合材料弯曲强度和断裂韧性分别达到502.36 MPa和3.48 MPa·m~(1/2),比基体材料分别提高63.8%和54.7%;相对密度达到98.41%.纤维的拔出和脱粘消耗了大量的能量,是莫来石纤维增强氧化铝陶瓷复合材料力学性能提高的主要原因.     

氧化铝-氧化铈陶瓷复合刀具的开发

陶瓷的迅速发展为许多工程应用引进了各种陶瓷复合材料。陶瓷复合材料的发展在很大程度上是由于基本陶瓷显微组织的改进，这就引起了显微组织增强陶瓷的开发。添加颗粒和晶须／纤维能够改善脆性陶瓷的断裂韧性，可能引起断裂韧性改善的机理是相变及伴生应力诱导相变增韧和微裂纹增韧、韧性增强、孪生和纤维／晶须增强。氧化铝（Al2O3）是一种特别重要的陶瓷材料，在技术上有很多用途。     

具有梯度特性的齿科修复复合材料制备及表征

本工作的目的是研究原生牙齿的梯度力学性能,制备聚合物渗透陶瓷网络(PICN)复合材料,模拟天然牙的力学行为。采用纳米压痕法测定了牙釉质和牙本质的弹性模量和维氏硬度。结果表明,原生牙齿的力学性能具有梯度特性。树脂填充部分烧结硅铝酸钠、氧化铝和氧化锆的力学性能有很大差异。通过逐步改变陶瓷组分,实现了力学性能的梯度变化。一种是纳米玻璃相硅铝酸钠/微米α氧化铝层合复合材料。陶瓷坯体的烧结温度为700℃,保温时间分别为2、4和6 h。对复合材料的抗弯强度、断裂韧性、弹性模量和硬度进行了测试,结果表明:硅铝酸钠/微米α氧化铝复合材料的弹性模量和硬度呈现梯度特性。另一种是3Y-TZP/微米α氧化铝层合复合材料。坯体烧结温度分别为1150和1200℃,保温时间为2h。其弹性模量和硬度均呈现梯度特性。SEM观察表明,过渡区形成了相互咬合的网络结构。与普通均质材料不同,本研究制备的复合材料具有各向异性。因此,复合材料的力学性能更接近于原生牙齿。     

Si3N4基层状复合陶瓷材料的室温与高温性能

采用凝胶注模成型-浸涂-热压烧结工艺制备出了SiC晶须增韧Si3N4基层状陶瓷复合材料,并对这一材料的室温及高温力学性能、微观结构及增韧机理进行了研究.结果表明,采用层状结构可使陶瓷材料的断裂韧性大幅度提高,但抗弯强度有所下降.层状陶瓷复合材料的增韧机理主要是由于弱的界面层对裂纹扩展产生偏折,形成界面裂纹而使断裂路径大大增加.高温性能试验条件下,由于界面层中玻璃相的融化,界面对裂纹的偏折作用消失,造成材料性能的显著下降.     

使用高温烧结氧化铝陶瓷温度梯度法合成宝石级金刚石

在高温高压下采用温度梯度法合成宝石级金刚石，采用高纯氧化铝粉烧结制备氧化铝陶瓷腔体保温材料，研究不同烧结温度下的氧化铝陶瓷性能以及用作腔体保温材料时对应的晶体生长情况。研究表明:随着氧化铝烧结温度的提升，氧化铝陶瓷的密度增大，显气孔率降低，所对应的晶体生长速度增大，晶体内夹杂物减少。1 650 ℃烧结4 h时，氧化铝陶瓷相对密度为97%，显气孔率为0.05%；用于保温腔体材料时，可制得质量为0.4 g(2 ct)、生长速度达4.0 mg/h的基本不含任何夹杂物的高品级金刚石。      

单向碳化硅短纤维增强玻璃陶瓷材料弯曲断裂行为的研究

制备了单向短碳化硅纤维增强玻璃陶瓷的复合材料。研究了复合材料的弯曲断裂行为，以及相关的增强机制。结果表明．短碳化硅纤维可以有效提高玻璃陶瓷的断裂强度，纤维体积分数为30％时，沿纤维方向的平均弯曲断裂强度是基体材料的3倍：短碳化硅纤维增强玻璃陶瓷基复合材料的弯曲应力-挠度曲线、以及断裂行为具有与长纤维复合材料类似的特征．其断裂方式为非灾难性断裂。单向短碳化硅纤维增强玻璃陶瓷基复合材料的主要增强机制为纤维脱粘、纤维滑移、纤维桥接、纤维断裂与纤维拔出。     

氧化铝纤维的优良性能

氧化铝纤维是一种新型无机材料。该产品具有优异的高温力学性能、好的抗化学侵蚀能力、低的导热率等特点。利用其上述优点 ,可应用于铝基复合材料增强剂、隔热隔音材料等领域。氧化铝纤维与碳纤维、碳化硅纤维等非氧化物纤维相比 ,氧化铝纤维不仅具有高强度、高模量、耐高温等优良性能 ,而且还有很好的高温抗氧化性、耐腐蚀性和电绝缘性。氧化铝纤维是当今国内外最新型的超轻质高温耐火纤维 ,是整个Al2 O3 -SiO2 系陶瓷纤维中的一种 ,使用温度在 15 0 0～16 0 0度 ,高出玻璃态纤维 2 0 0～ 30 0度。利用氧化铝纤维增强的铝基复合材料活塞…     

氧化铝纤维的优良性能

氧化铝纤维是一种新型无机材料。该产品具有优异的高温力学性能、好的抗化学侵蚀能力、低的导热率等特点。利用其上述优点 ,可应用于铝基复合材料增强剂、隔热隔音材料等领域。氧化铝纤维与碳纤维、碳化硅纤维等非氧化物纤维相比 ,氧化铝纤维不仅具有高强度、高模量、耐高温等优良性能 ,而且还有很好的高温抗氧化性、耐腐蚀性和电绝缘性。氧化铝纤维是当今国内外最新型的超轻质高温耐火纤维 ,是整个Al2 O3 -SiO2 系陶瓷纤维中的一种 ,使用温度在 15 0 0～16 0 0度 ,高出玻璃态纤维 2 0 0～ 30 0度。利用氧化铝纤维增强的铝基复合材料活塞…     

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.     

Rheology Feature of Simple Metal Melt

The rheology feature of Sb, Bi melt and alloys was studied using coaxial cylinder high-temperature viscometer. The results showed that the curve of torsion-rotational speed for Sb melt presents a linear relation in all measured temperature ranges, whereas for the Bi melt, the curve presents obvious non-Newtonian feature within the low temperature range and at relative high shear stress. The rheology feature of Sb80Bi20 and Sb20Bi80 alloy melts was well correlated with that of Sb and Bi, respectively. It is considered that the rheology behavior of Sb melt plays a crucial role in Sb80Bi20 alloy and that of Bi melt plays a crucial role in Sb20Bi80 alloy.