钛及钛合金粉末的制备现状

钛及钛合金具有优良的综合力学性能,在航空航天、航海、化工等领域得到日益广泛的应用.用粉末冶金法制造零部件,材料的利用率几乎可以达到100%,是降低钛及钛合金零部件生产成本的重要途径.本文评述了钛及钛合金粉末的制备技术及其现状,指出HDH钛粉和雾化钛粉是当今工业中主要应用的钛粉.伴随着钛粉末制备技术的成熟与发展,还原法直接生产钛粉和新兴的TiO2熔盐电解法生产钛粉,将成为制备低成本、高性能钛粉新的工业生产方法,是降低钛粉末冶金零部件成本的新的发展方向.元素混合法制备钛合金粉,因其较预合金化法成本低廉,工艺成熟,且性能优越,必将成为钛合金粉的主要生产方法.     

钛及钛合金箔带材加工成型的影响因素

钛及钛合金是一种性能优异的新型功能结构材料,被誉为第三金属,因而在许多工业领域获得了广泛的应用。本文较详细的介绍了影响钛及钛合金箔带材加工成型的几种因素,包括金属本身的性能、轧制工艺、热处理等。     

我国钛及钛合金牌号的发展和标准化

回顾了我国钛及钛合金牌号发展和标准化历程,阐述了本世纪钛牌号和成分国标的重要变化,包括牌号的发展、化学成分与国际接轨,并与国际牌号进行了对比,提出了进一步完善我国钛及钛合金牌号的发展思路和建议.     

世界钛及钛合金产业现状及发展趋势

总结和阐述了近年来世界各国钛及钛合金的发展现状和未来发展趋势.重点描述了近年来钛及钛合金最新制备及加工技术的发展和应用,主要包括钛及钛合金的冶炼提取、熔炼铸造、最新加工方法、热处理规范以及在航空航天、舰船、化工、生物及医用材料、汽车、体育等领域的发展和应用.通过对钛及钛合金近年来发展现状的了解,结合钛研制开发过程中出现的一些问题,简要分析了钛及钛合金的几个主要的发展方向及趋势.     

中国航发北京航空材料研究院铸造钛合金技术中心EI北大核心CSCD

中国航发北京航空材料研究院是我国较早开展钛合金及其制造精确成型技术研究的单位,是航空航天系统的专业化钛合金材料研究单位,其中铸造钛合金及其精确成型技术专业至今已有50余年的历史。铸造钛合金技术中心(以下简称中心)主要从事航空航天、汽车船舶等行业用常规钛合金、高温钛合金、高强钛合金、钛铝系金属间化合物等轻质高温高强材料研制及其精确成型技术研究和产品研制,是北京市先进钛合金精密成型工程技术研究中心。     

氢化钛粉制备钛及钛合金材料研究进展

综述了采用氢化钛粉制备钛及钛合金材料的历史及现状,报道了以氢化钛粉为原料制备医用钛材料的研究进展,并将其性能与锻造钛合金做了对比。指出采用该粉末冶金技术制备钛及钛合金性能满足应用要求,并具有工艺短、能耗低、成材率高、设备投入小的特点,能使生产成本得到控制,适用于制造批量小、品种规格多的医用钛产品。最后,分析了氢化钛粉制备钛及钛合金中存在的问题,并展望了其未来发展方向。     

钛及钛合金搅拌摩擦焊研究进展

搅拌摩擦焊技术已经成功应用于铝合金等低熔点材料的焊接,但针对钛及钛合金等高熔点材料的研究仍在进行之中。从焊具设计、接头显微组织与力学性能和焊接过程仿真等方面综述了钛及钛合金搅拌摩擦焊国内外研究进展,为搅拌摩擦焊技术应用于钛及钛合金提供参考。     

航空发动机用先进高温钛合金材料技术研究与发展

新一代高推重比航空发动机压气机和涡轮系统高温环境使用的叶片、盘、机匣、整体叶盘和整体叶环等构件设计通常选用先进高温钛合金材料。本文综述近年来我国600℃高温钛合金、阻燃钛合金、TiAl合金、连续SiC纤维增强钛基复合材料及其应用技术取得的最新研究进展,并提出材料及构件设计、加工和使用亟待突破的关键技术,包括工业铸锭成分高纯化和均匀化控制技术、大规格棒材及特殊锻件制备技术、整体叶盘和整体叶环零件机械加工技术、材料性能评价及应用设计技术等。先进高温钛合金材料的不断应用将有力推动我国航空发动机技术发展。     

我国航空用变形钛合金材料

钛合金材料作为一种20世纪中叶出现并发展起来的新兴结构材料,因其具有优异的耐腐蚀性、高的比强度以及无磁性等一系列独特的优点,在航空航天等高端工业部门获得了广泛应用,目前飞机机体结构中的隔框、大梁、起落架以及航空发动机压气机匣、轮盘、叶片等承力部件大量使用钛合金材料制造。在上世纪60年代,美国、英国、前苏联等工业发达国家就已经在飞机及航空发动机制造中大量使用钛合金材料。我国钛合金材料在航空工业中的应用起步较晚,上世纪80年代开始才陆续在飞机及航空发动机制造中少量使用钛合金材料,但是进入21世纪之后,我国航空工业钛合金材料的应用水平大幅度提升。对我国目前已经进入工业化生产并在航空工业中获得工程化应用的变形钛合金材料进行了系统阐述。     

低能耗节约型钛及钛合金熔炼技术的发展趋势

钛合金具有密度低、比强度高和耐腐蚀性能好等优点,是一种优异的航空航天材料,其应用领域也正在向民用领域扩展.但是,熔融态的钛和钛合金具有极高的化学活性,几乎能与目前已知的所有耐火材料发生反应,因此,钛及钦合金熔炼技术及相关的耐火材料研究一直是钛合金研究极具挑战性的领域.综述了钛及钛合金的熔炼技术及相应的耐火材料的研究发展现状,并对高效节能钛合金感应熔炼技术所需的耐火材料的研究做了展望.     

检定和校准证书的异同与应用

本文介绍了检定和校准以及证书的两点相同、五点不同之处,说明了对检定证书和校准证书的正确应用。     

Synthesis and luminescent properties of alkali-metal and ammonium fluorosulfatozirconates and fluorosulfatohafnates

We have synthesized a variety of alkali-metal and ammonium fluorosulfatometallates (titanates, zirconates, and hafnates). The alkali fluorosulfatozirconates and fluorosulfatohafnates have been shown to exhibit efficient roentgenoluminescence (RL) in the UV through visible spectral region, with a maximum at 390–440 nm. Their RL spectra depend significantly on their composition (cation, anion, and water content), coordination of KF and K₂SO₄, and relative amounts of fluorine and SO₄ groups. We have examined the effect of heat treatment on the RL of these compounds. The rubidium and cesium fluorosulfatozirconates Rb₃Zr₂F₉SO₄ · 2H₂O, Cs₂ZrF₂(SO₄)₂ · 2H₂O, Cs₈Zr₄F₂(SO₄)₁₁ · 16H₂O, and Cs₂ZrF₄SO₄ offer the most efficient RL.     

Heat and Mass Transfer and Modeling and Prediction of Environmental Catastrophes

Basic definitions and concepts of the physicomathematical theory of natural catastrophes are given. Possibilities of mathematical modeling of natural and technogenic catastrophes are discussed in the context of the theory of heat and mass transfer and the mechanics of reacting media. The importance of taking into account conjugate heat and mass exchange in modeling catastrophes is emphasized. A formula for evaluating the probability of a collisional catastrophe is given.     

Multi-ferroic and magnetoelectric materials and interfaces

The existence of multiple ferroic orders in the same material and the coupling between them have been known for decades. However, these phenomena have mostly remained the theoretical domain owing to the fact that in single-phase materials such couplings are rare and weak. This situation has changed dramatically recently for at least two reasons: first, advances in materials fabrication have made it possible to manufacture these materials in structures of lower dimensionality, such as thin films or wires, or in compound structures such as laminates and epitaxial-layered heterostructures. In these designed materials, new degrees of freedom are accessible in which the coupling between ferroic orders can be greatly enhanced. Second, the miniaturization trend in conventional electronics is approaching the limits beyond which the reduction of the electronic element is becoming more and more difficult. One way to continue the current trends in computer power and storage increase, without further size reduction, is to use multi-functional materials that would enable new device capabilities. Here, we review the field of multi-ferroic (MF) and magnetoelectric (ME) materials, putting the emphasis on electronic effects at ME interfaces and MF tunnel junctions.     

CellML and associated tools and techniques

We have, in the last few years, witnessed the development and availability of an ever increasing number of computer models that describe complex biological structures and processes. The multi-scale and multi-physics nature of these models makes their development particularly challenging, not only from a biological or biophysical viewpoint but also from a mathematical and computational perspective. In addition, the issue of sharing and reusing such models has proved to be particularly problematic, with the published models often lacking information that is required to accurately reproduce the published results. The International Union of Physiological Sciences Physiome Project was launched in 1997 with the aim of tackling the aforementioned issues by providing a framework for the modelling of the human body. As part of this initiative, the specifications of the CellML mark-up language were released in 2001. Now, more than 7 years later, the time has come to assess the situation, in particular with regard to the tools and techniques that are now available to the modelling community. Thus, after introducing CellML, we review and discuss existing editors, validators, online repository, code generators and simulation environments, as well as the CellML Application Program Interface. We also address possible future directions including the need for additional mark-up languages.     

热交换器的分类及优缺点分析

热交换器是将不同温度介质之间的热量通过热传导的形式,由高温介质传递给低温介质,使介质达到生产所需温度的工艺设备,也可作为一种节能设备使用.通过对不同热交换器的结构分析,总结不同热交换器的优缺点、适用环境,为生产工艺设计人员及设备制造单位在选择可降低能耗、提高效率的设备上提供参考.     

The shape and stability of wall-bound and wall-edge-bound drops and bubbles

The behavior of wall-bound drops and bubbles is fundamental to many natural and industrial processes. Key characteristics of such capillary systems include interface shape and stability for a variety of gravity levels and orientations. Significant solutions are in hand for axisymmetric pendent drops for a variety of uniform boundary conditions along the contact line with gravity acting normal to a planar wall. The special case of a wall-bound drop or bubble that is also pinned at an edge (i.e. a ‘wall-edge-bound’ drop) is considered here where numerical solutions are obtained for interface shape and stability as functions of drop volume, contact angle, fluid properties, and uniform gravity vector. For a semi-infinite zero-thickness planar wall (plate), a critical contact angle is identified below which wall-edge-bound drops are always stable. The critical contact angle is computed as a function of the gravity vector. The numerical procedure, which makes no account for contact angle hysteresis, predicts that such wall-edge-bound drops are unconditionally unstable for any gravity field with a component that is tangent to the wall while inwardly normal to the edge. Select experiments are conducted that support the conclusions drawn from the numerical results.