西方国家涂层技术一瞥(下)

二、铬合金公司铬合金公司是美国最大的二百五十家公司之一,我们考察的金属分公司又是铬合金公司所属六个分公司之一。分公司总共约有五千人,以修理涡轮喷气发动机冷端和热端气流通道重要零件为其主要业务,但不从事整台发动机的修理装配,是目前美国空、海军(航空兵)     

含有钒铬中间合金的钛合金

含有钒铬中间合金的钛合金美国Ｔｅｌｅｄｙｎｅ工业公司获得一项关于含钒和铬的高强度钛合金专利（美专利Ｎ。５１２４１２２）。钒和铬在加人钛之前，要进行合金化，得到的高强度钛合金基本ｂ不含未合金化的钒和铬，同时也基本上不含低熔点的钛铬合金。（冬）含有钒铬中...     

稀土金属涂层

在热障涂层中加入稀土金属成分可以延长发动机高压涡轮叶片在高温环境中的使用寿命。日前,铬合金公司开发了一种含有稀土金属的新型热障涂层,被称为RT-135涂层,主要用于空气等离子喷涂。与RT-35或Lowk涂层一样,     

定向结晶时陶瓷与熔融合金的相互作用

本文研究了定向结晶时电熔刚玉陶瓷壳型与熔融镍基高温合金的相互作用。发现壳型内层的松散和着色,以及铸件表层损坏是由于合金中含碳会使熔融金属与刚玉陶瓷强烈作用,使陶瓷中含铬量由0.2％增至～1.2％,同时使铸件表面层贫铬。预先使电熔刚五吸收一定量的铬,可以减少和防止熔融合金中的铬转入陶瓷中。     

西方国家涂层技术一瞥(上)

一九八二年十月发动机涂层技术小组赴美国、法国,考察了塞密特涂层公司(SermeTel Inc),铬合金公司金属分公司(Chromalloy Metal Tectonics Company)及其所属的涡轮及压气机服务分部和曼特科公司(METCOINC)以及法国赫尔科隆姆(Heurchrome)涂层公司。现将此行见闻结合国内同行们关心的一些问题介绍如下。在考察中我们有意识地请各公司对其竞争对手的涂层技术进行评价,以求尽可能得到较全面的认识,但     

钼合金电鍍試驗小結

前言钼合金是一种耐高温材料,但在空气中于650℃以上即强烈氧化,生成易升华的氧化物。为解决高温防氧化问题,国内外曾对钼合金的表面防护作过许多研究。钼合金的工作温度在1100～1200℃时,一般采用铬、镍等多层电镀层。在1300～1400℃时采用陶瓷涂层和硅化物涂层。因钼与铬具有相似的热膨胀系数,因而在镀(涂)多层镀(涂)层时,常以铬层作底层。根据设计部门提出     

表面涂层-高温合金之间的高温过程研究

采用刷涂和烧结的方法制备了高温合金表面的无机涂层，并对基体进行了预氧化处理。应用俄歇能谱仪（AES）、扫描电镜（SEM）研究了预氧化处理和高温长时间退火条件下，涂层和高温合金之间元素的相互作用。结果表明：氧在合金中的分布曲线服从抛物线法则，高温下基体中铬优先氧化，对高温合金基体进行预氧化处理能有效地阻滞高温条件下基体元素铬的贫化。     

电镀工艺中的一个新领域——复合镀

一、什么叫做复合镀复合镀是将一种金属或合金和某种不溶性非导体或导体的细微颗粒在电流作用下,在一定的电解质溶液中实现共沉积的一种工艺过程。原则上讲,所有能在阴极上镀得的单金属和合金都能与一些不溶性的非导体或导体颗粒在一定条件下实现共沉积而形成复合镀层,但实际上问题并不这么简单。到目前为止,报导较多的金属有镍、铜、铬、钻等,还有银、金、锌、镉、铂、铑等;合金中有铁-铬、镍-铬、铅-锡、镍-钼、钴-钨等二元合金。至于不溶性颗粒,则种类很多,其中非导体材料有氧化物、     

一种铸造低偏析高温合金的凝固偏析

用金相探针法研究了一种低偏析高温合金的凝固。经研究发现，合金中除了钛有轻微的正树枝状偏析外，铬、钴、钼、铝等几乎不发生树枝状偏析；但在共晶内部和前沿，合金元素的偏析与普通合金几乎相同     

K25铬基铸造高温合金的研制和应用

本文通过合理强化和工艺途径,解决了铬基合金室温塑性低的技术关键,研制成功高塑性铬基铸造合金K25和某发动机合金加力点火分流器精铸件。K25合金加力点火分流器在发动机上经422小时长期试车考核,零件无变化,可继续使用,并已投入批量生产。该合金的研制成功填补了国内高熔点铬基铸造高温合金空白。     

从竞争到合作

维修企业在售后市场既可以是OEM的竞争对手，也可以成为OEM的合作伙伴。     

Magnetic Fields in Massive Stars, Their Winds, and Their Nebulae

Massive stars are crucial building blocks of galaxies and the universe, as production sites of heavy elements and as stirring agents and energy providers through stellar winds and supernovae. The field of magnetic massive stars has seen tremendous progress in recent years. Different perspectives—ranging from direct field measurements over dynamo theory and stellar evolution to colliding winds and the stellar environment—fruitfully combine into a most interesting and still evolving overall picture, which we attempt to review here. Zeeman signatures leave no doubt that at least some O- and early B-type stars have a surface magnetic field. Indirect evidence, especially non-thermal radio emission from colliding winds, suggests many more. The emerging picture for massive stars shows similarities with results from intermediate mass stars, for which much more data are available. Observations are often compatible with a dipole or low order multi-pole field of about 1 kG (O-stars) or 300 G to 30?kG (Ap/Bp stars). Weak and unordered fields have been detected in the O-star ζ Ori A and in Vega, the first normal A-type star with a magnetic field. Theory offers essentially two explanations for the origin of the observed surface fields: fossil fields, particularly for strong and ordered fields, or different dynamo mechanisms, preferentially for less ordered fields. Numerical simulations yield the first concrete stable (fossil) field configuration, but give contradictory results as to whether dynamo action in the radiative envelope of massive main sequence stars is possible. Internal magnetic fields, which may not even show up at the stellar surface, affect stellar evolution as they lead to a more uniform rotation, with more slowly rotating cores and faster surface rotation. Surface metallicities may become enhanced, thus affecting the mass-loss rates.     

新发动机的维修策略

近期将会有9种新型发动机投入市场。这些发动机中即有推力4.0千牛的PW610,也有推力为362.5千牛的GP7200。其中有两种发动机已于2004年秋季取证,其他的会在2007年年底前取证。这9种发动机均采用了最新的技术,但侧重点有所不同,有的是以减少零部件的数量为特长,有的则是以采用新型材料作为卖点,但其中有一点是共同的,这些发动机自设计的第一天起就考虑了维修性。     

新发动机的维修策略

近期将会有9种新型发动机投入市场。这些发动机中即有推力4.0千牛的pW6乍O,也有推力为362 .5千牛的Gp7200。其中有两种发动机已于2004年秋季取证,其他的会在2007年年底前取证·这9种发动机均采用了最新的技术,但侧重点有所不同,有的是以减少零部件的数量为特长甲有的则是以采用新型材料作为卖点,但其中有一点是共同的,这些发动机自设计的第一天起就考虑了维修性。     

电压跌落及其抑制

电能质量的电压跌落问题正日益被关注,为此对动态电能质量中电压跌落问题进行研究,分析电压跌落的原因、传播过程及对电力系统的危害,并在此基础上对电压跌落进行了分类,提出了评估指标及应对电压跌落问题的措施。     

部分气动执行机构及其应用

介绍了气动舵机和射流执行机构的分类和工作原理,分析了不同气动舵机和射流执行机构的特点和应用情况,根据射流执行机构的工作特性,认为其将在防空反导导弹中得到广泛应用。     

美国空军高层峰会一席谈

在今年2月的美国空军峰会空中作战研讨会上，美国空军高层领导人就他们目前面临的经费紧张、F-35项目拖期、机队老龄化以及维修和部队培训等问题发表讲话。其中有造势的成分，也有真实的看法和计划。     

微叠层材料及其制备工艺研究进展

着重论述了各种微叠层材料及其制备方法，认为电子束物理气相沉积是制备微叠层材料的有效方法：同时对微叠层材料性能方面的研究也作了相应的论述，并展望了我国今后在这方面的研究方向。     

Substorms and Their Solar Wind Causes

Consequences of the solar wind input observed as large scale magnetotail dynamics during substorms are reviewed, highlighting results from statistical studies as well as global magnetosphere/ionosphere observations. Among the different solar wind input parameters, the most essential one to initiate reconnection relatively close to the Earth is a southward IMF or a solar wind dawn-to-dusk electric field. Larger substorms are associated with such reconnection events closer to the Earth and the magnetotail can accumulate larger amounts of energy before its onset. Yet, how and to what extent the magnetotail configuration before substorm onset differs for different solar wind driver is still to be understood. A strong solar wind dawn-to-dusk electric field is, however, only a necessary condition for a strong substorm, but not a sufficient one. That is, there are intervals when the solar wind input is processed in the magnetotail without the usual substorm cycle, suggesting different modes of flux transport. Furthermore, recent global observations suggest that the magnetotail response during the substorm expansion phase can be also controlled by plasma sheet density, which is coupled to the solar wind on larger time-scales than the substorm cycle. To explain the substorm dynamics it is therefore important to understand the different modes of energy, momentum, and mass transport within the magnetosphere as a consequence of different types of solar wind-magnetosphere interaction with different time-scales that control the overall magnetotail configuration, in addition to the internal current sheet instabilities leading to large scale tail current sheet dissipation.     

Dynamical Origin of Comets and Their Reservoirs

It is widely believed that cometary orbits contain important clues to both the outer solar system’s current structure and its past dynamical evolution. The first part of this paper summarizes the results of numerical simulations designed to study the dynamical origins of observed comets and to link the observed populations to the reservoirs from which they are currently leaking. The second part reviews simulations which are designed to study the dynamical origin of the reservoirs themselves. The paper concludes with a brief discussion of the currently unresolved issue of where in the primordial solar nebula the different dynamical classes of observed comets originated.