可降解生物医用Zn-1Al合金的制备及性能研究

以商业铸态纯锌和纯铝为原料,制备得到Zn-1Al铸态合金。利用光学显微镜和扫描电子显微镜观察Zn-1Al铸态合金的显微组织,利用万能试验机测定Zn-1Al铸态合金的压缩力学性能,利用模拟体液浸泡实验表征Zn-1Al铸态合金的生物降解性能和诱导Ca-P沉积能力。结果表明,向Zn中加入1%(质量分数)的合金元素Al后,铸态纯锌的显微组织明显细化,且Zn-1Al合金的压缩力学性能也较铸态纯锌明显提高。模拟体液浸泡实验结果表明铸态Zn-1Al合金在浸泡过程中降解速率与铸态纯锌相比未出现明显差别,但Zn-1Al合金能更有效地诱导Ca-P沉积。     

Modification of Iron with Degradable Silver Phases Processed via Laser Beam Melting for Implants with Adapted Degradation Rate

In medical technology, implants are used to improve the quality of patients’ lives. The development of materials with adapted properties can further increase the benefit of implants. If implants are only needed temporarily, biodegradable materials are beneficial. In this context, iron-based materials are promising due to their biocompatibility and mechanical properties, but the degradation rate needs to be accelerated. Apart from alloying, the creation of noble phases to cause anodic dissolution of the iron-based matrix is promising. Due to its high electrochemical potential, immiscibility with iron, biocompatibility, and antibacterial properties, silver is suited for the creation of such phases. A suitable technology for processing immiscible material combinations is powder-bed-based procedure like laser beam melting. This procedure offers short exposure times to high temperatures and therefore a limited time for diffusion of alloying elements. As the silver phases remain after the dissolution of the iron matrix, a modification is needed to ensure their degradability. Following this strategy, pure iron with 5 wt% of a degradable silver–calcium–lanthanum alloy is processed via laser beam melting. Investigation of the microstructure yields achievement of the intended microstructure and long-term degradation tests indicates an impact on the degradation, but no increased degradation rate.     

生物医用镁合金研究进展

由于具有优异的力学相容性、生物相容性和可降解性,镁及其合金成为新一代生物医用可降解金属植入材料的研究焦点。但镁及其合金由于较快的降解速率,严重制约了其在临床上的应用步伐。开发高强度、高韧性、高耐蚀,且降解行为可控的高性能镁合金迫在眉睫。综述了生物医用可降解镁合金的最新研究进展,详细介绍了镁及其合金作为生物医用材料的优势与不足、产品研发现状、降解机理及腐蚀行为和耐蚀性研究,并指出了研究中存在的问题和未来发展方向。     

生物可降解镁合金的发展现状与展望

镁合金作为新型可降解医用金属材料,近年来成为生物材料领域的研究热点,并越来越受到生物、材料和医学界的关注和重视.从工程用镁合金、新型医用镁合金、表面改性镁合金和新颖结构镁合金4个方面综述了国际和国内生物可降解镁合金方面的研究现状,系统地介绍和总结了目前生物可降解镁合金材料的合金设计、力学性能、体液腐蚀特性、细胞毒性和动物体内植入实验的相关结果,展望了未来生物可降解镁合金亟待解决的科学问题和应用前景.     

Bulk and porous metastable beta Ti-Nb-Zr(Ta) alloys for biomedical applications

In this work, metastable beta Ti-Nb-Zr(Ta) ingots were manufactured by vacuum arc melting. The ingots thus obtained were divided into two batches: the first subjected to cold rolling (CR) from 30 to 85% of thickness reduction and subsequent annealing in the 450 to 900 °C temperature region, and the second atomized to produce 100 μm size powders. This powder was used to manufacture open-cell porous material. Regardless of the CR intensity, Ti-(18…20)Nb-(5…6)Zr (at.%) samples subjected to 600 °C (1 h) annealing showed a significant material softening due to the stress-induced martensitic transformation. The Young's modulus of these alloys varied between 45 and 55 GPa, and the yield stress, between 300 and 500 MPa. The obtained Young's moduli, which are comparable to 55-66 GPa of concurrent beta-titanium alloys and 45-50 GPa of superelastic Ti-Ni alloys, come close to those of cortical bones. Compression testing of the porous material as a function of porosity (from ~ 45 to 66%) and interconnected cell size (d₅₀ from 300 to 760 μm) showed the following properties: Young's modulus from 7.5 to 3.7 GPa, which comes close to that of trabecular bones, and ultimate compression strength, of from 225 to 70 MPa.     

Designation and development of biomedical Ti alloys with finer biomechanical compatibility in long-term surgical implants

Developing the new titanium alloys with excellent biomechanical compatibility has been an important research direction of surgical implants materials. Present paper summarizes the international researches and developments of biomedical titanium alloys. Aiming at increasing the biomechanical compatibility, it also introduces the exploration and improvement of alloy designing, mechanical processing, microstructure and phase transformation, and finally outlines the directions for scientific research on the biomedical titanium alloys in the future.     

化学镀法制备镍系非晶态合金的研究及应用进展

化学镀法制备的镍系非晶态合金材料以其高催化活性、超强的耐腐蚀性和耐磨性而得到广泛应用.本文概述了化学镀法制备非晶态合金材料的特性,综述了近年来化学镀法制备非晶态合金的研究进展及其在催化、防腐及耐磨材料等领域的应用.阐述了现阶段化学镀废液造成的环境问题及其净化和再利用方面取得的进展,对化学镀法制备非晶态合金的发展进行了展望。     

高强韧锆合金的发展与应用

锆及其合金具有较好的尺寸稳定性、抗辐照和耐腐蚀等性能,因此在航空航天、航海、核反应堆和生物医用等领域具有重要的应用前景.而纯锆及应用较为广泛的锆合金的抗拉强度较低,提升锆及其合金的力学性能成为其能成功应用于结构件的关键环节.本文简要概述了锆及其合金在核工业、化工、医疗及航空航海等领域的发展现状.此外,本文还着重介绍了新型高强韧锆合金的设计与制备,获取了可在空间探测、深海探测以及高速铁路等特殊领域中使用的锆系合金的最佳成分,并详细阐述了新型高强韧锆合金的强化机理及其在核电、化工及航空领域中的应用.     

Surface film characteristics of Al-Li-Cu-Mg alloys in 0·1 N NaOH

The nature of surface films that form under free corrosion conditions, and their effect on the subsequent polarization behaviour of an Al-1·90Li-1·80Cu-1·00Mg-0·09Zr alloy in 0·1 mol/l NaOH solution at 35°C have been studied. The variation of open circuit potential (OCP) as a function of time is characteristic for the alloy in the electrolyte. It initially changes in the noble direction with the surface of the specimen being enveloped by a black coating, and, later, when the black coating is punctured at some localized regions, the OCP shifts and stabilizes at an active value of −1450 mV vs saturated calomel electrode (SCE). X-ray diffraction analysis of the surface film layer indicates that it consists of essentially lithium aluminum hydroxide at shorter immersion time, and lithium aluminum hydroxide and copper hydroxide after longer immersion time in the electrolyte. The scale morphology as a function of immersion time has also been studied by scanning electron microscopy. Polarization experiments conducted after 2 and 15 h of immersion revealed that the alloy exhibited active-passive type polarization behaviour in both the cases. The polarization behaviour of the specimen immersed for longer times has been explained by considering Cu ennoblement on the surface. It was also observed that the hydride LiAlH₄ forms on the surface regions of the alloy under free corrosion conditions.     

Surface plasmonic effect of nanoparticle-like silver nanostructure on the high responsivity of visible/infrared silver-based heterojunction photodetector

The fabrication of a silver (Ag) based photodetector on a silicon dioxide/p-silicon (SiO₂/p-Si) substrate using direct current (DC) magnetron sputtering is demonstrated. The proposed method deposits a nanoparticle-like Ag thin film that favours the photoconduction mechanism under light illumination at 468?nm and laser illumination at 660 and 980?nm. The thin film is characterized using scanning electron microscope (SEM), energy dispersive x-ray (EDX), x-ray diffraction (XRD), Raman scattering, photoluminescence (PL) and ultraviolet–visible (UV–VIS) analysis. Current–voltage (I–V) analysis and the calculated rectifying ratio (RR) suggests the establishment of good Schottky contacts for incident light/laser at 468, 660 and 980?nm, with good responsivity towards light and laser illumination in the forward and reverse DC bias regions. The responsivity increases as the wavelength decreases from 980?nm → 660?nm → 468?nm, with the highest responsivity of 213.7?mAW^?1 at 468?nm indicating better photoconduction at low light powers.     

镁基合金应用于生物医用材料的研究进展

镁基合金具有较高的强韧性和加工性能以及较好的生物相容性,可应用于骨组织工程、整形外科以及血管支架中。而镁基合金在人体体液环境下的腐蚀性又反过来影响其使用寿命。采用适宜的改性方法不仅可以提高镁基合金的耐腐蚀性能,降低其生物降解速率,而且可以进一步提高其力学性能和表面生物活性。综述了镁基合金的力学相容性、生物相容性、可降解性以及针对以上性能的各种改性方法,并评述了国内外对镁基合金医用生物材料的应用研究概况。     

从可降解金属的角度审视医用镁合金的元素选择

进入21世纪以来,可降解金属成为医用金属材料研究的热点。镁及镁合金是过去10余年被广泛研究的代表性可降解金属材料。Web of Science检索显示,过去10余年有关医用镁合金的基础研究工作在全球范围内已经发表了3000余篇文章,人们对可降解镁合金与机体的力学、化学和生物学相互作用机制有了较深入的认识,初步开展了"医用镁合金的成分设计与性能优化"、"镁合金在体内的降解机制及其调控方法"、"镁合金降解产物的生物安全性与代谢途径"、"镁合金降解过程中的力学强度退化"等基础科学研究。尽管已有大量的新配方镁合金被设计与研究用于生物医学,但多为工程材料专家们的炒菜式思维,企业对投入费时费钱的生物医学验证坐等,医学转化成效低。在成百上千的已有材料配方中,迄今在全球上市的医用镁合金植入式医疗器械只有德国WE43系镁合金和韩国Mg-Ca-Zn合金,国内进入创新医疗器械的两个产品是以纯镁为材料。因此,拟从生物材料专家的视角出发,摒弃对力学性能的追求,从可降解金属的生物降解性和生物安全性两个最基本的判据出发,对元素周期表中适合可降解金属的元素进行初步筛选,在此基础上选出用于医用镁合金的合金化元素,换一个角度,从更佳的生物学性能和生物功能性出发,对未来医用镁合金材料设计指明可以尝试的新方向。     

Zirconium alloys in nuclear technology

This paper describes the historical development of zirconium and its alloys as structural materials for nuclear reactors. The various problems encountered in the early stages of the development of zircaloys and their performance in reactors operating presently are described in detail. The development of Zr-2.5 % Nb alloys for pressure tube applications is discussed. The paper concludes with a detailed discussion on the development potential of zirconium alloys for high temperature applications and a brief account of the work carried out at Trombay in this field.     

Deposition of amorphous Fe-Zr alloys by magnetron co-sputtering

In the last decades, amorphous metal alloys were under intensive research because of their specific properties. Furthermore, amorphous magnetic metallic alloys, also known as metallic glasses, are important because of their application in electronic industry, information technology, recording media, etc. [Shen J, Kirschner J. Surf. Sci. 2002;500:300-322; Bass J, Pratt Jr WP. Physica 2002;B321:1-8; Dugaev VK, Vygranenko Yu, Vieira M, et. al. Physica 2003;E16:558-562]. Fe_1−xZr_x amorphous films co-condensed by magnetron sputtering were studied. X-ray diffraction methods were applied for studying a glass forming range vs. the composition of the elements. Electrical properties of the samples were measured by so-called four-probe and Van der Pauw methods. The surface morphology was investigated by SEM. The results show that amorphous Fe_1−xZr_x alloys with 1.5 nm crystallites could be synthesized by magnetron co-sputtering on the substrates at room temperature when the alloy's composition was Fe_0.91Zr_0.09 with a very smooth surface. The grain size of alloys decreased increasing the Zr concentration. The resistivity of the thin films of these alloys depends on the crystalline size and structure.     

The characteristics of TiAl-based alloys melted in graphite crucibles

ABSTRACT

In the paper, the phase composition, microstructure, and selected mechanical and operational properties at room and elevated temperature of a TiAl intermetallic alloy from the TNB group – Ti–45Al–8Nb–0.5(B, C), induction melted in special graphite crucibles, are characterised. Selected properties of this alloy were compared to those of the reference TNB-V2 alloy with similar chemical composition, prepared with technologies currently used in the world. The result of this comparison was a positive recommendation for the proposed melting technology as an alternative to this and other groups of TiAl-based alloys.

This paper is part of a thematic issue on Titanium.     

Simulation of constrained dendrite growth of multicomponent alloys using a Calphad method

Abstract

The conventional theory of constrained dendrite growth for binary alloys has been extended to multicomponent alloys based on the Calphad method by consideration of solute interactions in each phase. The variable solute partition coefficients and liquidus slopes under different tip undercooling were calculated in detail for a series of Al-Si-Mg alloys. Their influence on the kinetics of dendrite growth was demonstrated quantitatively. The most important microstructure scale, the primary dendrite spacing, was predicted in several Al-Si-Mg alloys. By comparing with the experimental results of former researchers, it is found that the present method coupled with Calphad is a satisfactory way for the prediction of primary dendrite arm spacing.     

Dynamic fracture of tungsten heavy alloys

Dynamic fracture of tungsten heavy alloys was induced by two different test techniques. The first was spall (e.g., 1-D strain fracture). The second was transverse impact, as occurs in a yawed penetrator. Spall failure is stress driven, and spall stress corresponds to the threshold for void formation, which is 2.6 GPa for a 91% WNiCo alloy and 2.1–2.5 GPa for a 95% WNiFe alloy. Yaw-induced fracture, on the other hand, is strain driven. Surface flaws can provide fracture sites. At the meso scale, grain cleavage is mainly responsible for transverse fracture. Grain fracture also appears to play a critical role in the initiation of spall fracture.     

Effects of thermal treatment on the electrical and optical properties of silver-based indium tin oxide/metal/indium tin oxide structures

In this article, we report the results of the study of thermal treatment effects on the electrical and optical properties of silver-based indium tin oxide/metal/indium tin oxide (IMI) multilayer films. Heat treatment conditions such as temperature and gaseous atmosphere was varied to obtain better electrical and optical properties. We obtained improved electrical properties and observed considerable shift in the transmittance curves after heat treatment. Several analytical tools such as X-ray diffraction, spectroscopic ellipsometer and spectrophotometer were used to explore the causes of the changes in electrical and optical properties. The sheet resistance of the structure was severely influenced by deposition conditions of the indium tin oxide (ITO) layer at the top. Moreover, the shift of optical transmittance could be explained on the basis of the change in refractive indices of ITO layers during heat treatment. The properties of Ag-alloy-based IMI films were compared with those of pure Ag-based ones. Some defects originating from Ag layer corrosion were observed on the surface of ITO-pure Ag–ITO structures, however, their number decreased significantly in the cases of Ag-alloys containing Pd, Au and Cu, though the resistivity values of Ag-alloys were slightly higher than those of silver. Atomic force microscopy measurement results revealed that the surface of the IMI multilayer was so smooth that it meets the required qualifications as the bottom electrode of organic light emitting diodes.     

不锈软磁合金研究

探讨了不锈软磁合金的产生、发展和应用。提出了开发不锈软磁合金、提高磁性能和耐蚀性的设计理念和方法。推荐了磁感应强度B25,电阻率ρ与合金成分关系的经验方程式。