材料期刊网

Structure Investigation of Poly(vinyl alcohol)-Collagen Composite

Qiqing ZHANG , Lei REN and Lingrong LIU(Institute of Biomedical Engineering , Chinese Academy of Medical Sciences , Tianjin 300192 , China)Chun WANG(CCCD , University of Utah , Salt Lake City , UT84112 , USA)

材料科学技术（英文）

Naturally derived collagen protein was mixed thoroughly with medical grade poly (vinyl alcohol)(PVA) at the ratio of 90:10 (w/w) and was crosslinked by formaldehyde to form a homogeneous composite membrane. The buIk structure of the membrane was characterized ly means of Xray diffraction (XRD) and transmission electron microscoor (TEM). The membrane surface Structure was investigated using Fourier transform-infrared spectroscopy (attenuated totalrefraction) (FTIR-ATR), electron spectroscopy for chemical analysis (ESCA) and contact angle measurement. lt was found that collagen and PVA can remain Stable. This was supported by the fact that no sign of phase separation had been observed. The use of crosslinking agent can Substantially influence the Structure of the composite. It is suggested that this new compositedeserves further investigation and is potentially usable as a biomedical material.

关键词:

Service Performance of Engineering Materials

Andrej Atrens

材料科学技术（英文）

Corrosion research by Atrens and co-workers has made significant contributions to the understanding of the service performance of engineering materials. This includes: (1) elucidated corrosion mechanisms of Mg alloys, stainless steels and Cu alloys, (2) developed an improved understanding of passivity in stainless steels and binary alloys such as Fe-Cr, Ni-Cr, Co-Cr, Fe-Ti, and Fe-Si, (3) developed an improved understanding of the melt spinning of Cu alloys, and (4) elucidated mechanisms of environment assisted fracture (EAF) of steels and Zr alloys. This paper summarises contributions in the following: (1) intergranular stress corrosion cracking of pipeline steels, (2) atmospheric corrosion and patination of Cu, (3) corrosion of Mg alloys, and (4) transgranular stress corrosion cracking of rock bolts.

关键词: Stress corrosion cracking , null , null

两种组织的Ren80高温合金的蠕变裂纹扩展行为

孙坚 , 张源虎 , 胡赓祥

金属学报

研究了定向凝固和普通铸造的Ren80合金在1123K静载荷下的蠕变裂纹扩展行为结果表明,Ren80合金蠕变裂纹扩展速率,可用应力强度因子较好地关联定向凝固合金蠕变裂纹与扩展速率较低,其应力强度因子指数约为普通铸造合金的1/2

关键词: 高温合金 , directional solidification , stress intensity factor , creep crack propagation , null

Cold Plasma Surface Modification of NiTi for Biomedical Applications

Jun YANG , Jianhua WANG

材料科学技术（英文）

Surface-grafted poly(ethylene glycol) (PEG) molecules are known to prevent protein adsorption to the surface. Nitinol samples were coated under tetraglyme ECR cold plasma conditions to enhance its biocompatibility. The modified Nitinol surfaces were characterized by high resolution ESCA and contact angle, it was demonstrated that the deposited PEG-like coatings were built up mainly of –CH¬2-CH¬2-O- linkages in surfaces. The surface wettability of the modified Nitinol was increased compared with the control surface. Human plasma protein was adsorbed on Nitinol evaluated by SEM, the protein adsorption on modified surfaces decreased rapidly. Thus, the potential benefits of cold plasma technique will be of use to the biomedical industries improving the biocompatibility of metals.

关键词: Cold plasma , null , null , null

Biomimicry of bamboo bast fiber with engineering composite materials

Materials Science & Engineering C-Biomimetic Materials Sensors and Systems

Bamboo, one of the strongest natural structural composite materials, has many distinguishing features. It has been found that its reinforcement unit, hollow, multilayered and spirally-wound bast fiber, plays an extremely important role in its mechanical behavior. In the present work, on the basis of the study on bamboo bast fiber and wood tracheid, a biomimetic model of the reinforcing element, composed of two layers of helically wound fiber, was suggested. To detect the structural characteristics of such a microstructure, four types of macro fiber specimens made of engineering composites were employed: axially aligned solid and hollow cylinders, and single- and double-helical hollow cylinders. These specimens were subjected to several possible loadings, and the experimental results reveal that only the double-helical structural unit possesses the optimum comprehensive mechanical properties. An interlaminar transition zone model imitating bamboo bast fiber was proposed and was verified by engineering composite materials. In our work, the transition zone can increase the interlaminar shear strength of the composite materials by about 15%. These biomimetic structural models can be applied in the design and manufacture of engineering composite materials.

关键词: bamboo;bast fiber;biomimetics;engineering composites

PM René 95合金涡轮盘等温锻造工艺的模拟式设计

张麦仓 , 董建新 , 曾燕屏 , 谢锡善 , 罗子健

金属学报

利用热力耦合有限元程序FORMT,对PM René 95合金中等尺寸(外径尺寸约为630 mm)涡轮盘的等温锻造工艺进行了模拟式设计.结果表明,采用TZM钼基合金模具,在1050℃以接近10-3s.的应变速率进行闭式模锻和开式模锻,模具材料均能满足使用要求,且开式模锻设备最大载荷不超过31×103kN;采用K21合金模具,在1000℃以相同条件等温成形,模具材料因变形热效应及边界摩擦引起温升而失效且所需设备吨位相对较大.

关键词: PM , null , null , null

PM René 95合金涡轮盘等温锻造工艺的模拟式设计

张麦仓 , 董建新 , 曾燕屏 , 谢锡善 , 罗子健

金属学报 doi:10.3321/j.issn:0412-1961.2002.10.022

利用热力耦合有限元程序FORMT,对PM René 95合金中等尺寸(外径尺寸约为630 mm)涡轮盘的等温锻造工艺进行了模拟式设计.结果表明,采用TZM钼基合金模具,在1050℃以接近10-3s.的应变速率进行闭式模锻和开式模锻,模具材料均能满足使用要求,且开式模锻设备最大载荷不超过31×103kN;采用K21合金模具,在1000℃以相同条件等温成形,模具材料因变形热效应及边界摩擦引起温升而失效且所需设备吨位相对较大.

关键词: PM René 95合金,等温锻造,热力耦合有限元,模拟式工艺设计

电渣重熔连续定向凝固René88DT合金的组织与热变形行为

付锐 , 陈希春 , 任昊 , 冯涤

航空材料学报 doi:10.3969/j.issn.1005-5053.2011.3.002

自行设计开发了适合工业化生产高纯净,低偏析,无宏观缺陷铸锭的电渣重熔连续定向凝固技术(ESR-CDS)的设备和工艺,利用该技术成功制备了直径为φ150mm的René88DT合金定向凝周铸锭.采用XRD测试了定向凝固柱状晶的生长取向,结果表明,ESR-CDS René88DT铸锭柱状晶择优生长方向为<100>系晶向;ERS-CDS铸锭与传统ESR铸锭相比,枝晶组织生长方向保持一致,二次枝晶臂均匀细小,元素偏析程度低,且晶间一次析出相呈颗粒状,尺寸细小;等温热压缩实验结果表明,ESR-CDS René88DT合金热压缩试样在1100℃,0.0-50.1s-1应变速率下可达到70%以上压缩变形量并获得均匀细小的动态再结晶组织;ESR-CDS René88DT合金铸锭经等温锻造制备出了φ170mm×73mm的饼坯件,锻压变形量超过70%,饼坯件除上下两端的变形死区外均发生了动态再结晶,晶粒尺寸约50μm.

关键词: 电渣重熔连续定向凝固 , 热变形 , 动态再结晶

Strengthening Materials by Engineering Coherent Internal Boundaries at the Nanoscale

Science

Strengthening materials traditionally involves the controlled creation of internal defects and boundaries so as to obstruct dislocation motion. Such strategies invariably compromise ductility, the ability of the material to deform, stretch, or change shape permanently without breaking. Here, we outline an approach to optimize strength and ductility by identifying three essential structural characteristics for boundaries: coherency with surrounding matrix, thermal and mechanical stability, and smallest feature size finer than 100 nanometers. We assess current understanding of strengthening and propose a methodology for engineering coherent, nanoscale internal boundaries, specifically those involving nanoscale twin boundaries. Additionally, we discuss perspectives on strengthening and preserving ductility, along with potential applications for improving failure tolerance, electrical conductivity, and resistance to electromigration.

关键词: strain-rate sensitivity;stacking-fault energy;nano-scale twins;cu-al;alloys;nanocrystalline metals;mechanical-properties;activation;volume;copper;deformation;behavior

Crystal facet engineering of semiconductor photocatalysts: motivations, advances and unique properties

Chemical Communications

Crystal facet engineering of semiconductors has become an important strategy for fine-tuning the physicochemical properties and thus optimizing the reactivity and selectivity of photocatalysts. In this review, we present the basic strategies for crystal facet engineering of photocatalysts and describe the recent advances in synthesizing faceted photocatalysts, in particular TiO(2) crystals. The unique properties of faceted photocatalysts are discussed in relation to anisotropic corrosion, interaction dependence of adsorbates, photocatalytic selectivity, photo-reduction and oxidation sites, and photocatalytic reaction order. Ideas for future research on crystal facet engineering for improving the performance of photocatalysts are also proposed.

关键词: shape-controlled synthesis;exposed 001 facets;rutile tio2 nanorods;visible-light photocatalysis;solvent-solute interactions;anatase;titanium(iv) oxide;low-temperature synthesis;ordered solid-phases;platinum nanocrystals;hydrogen-production