Low cobalt Fe-Co-W semihard magnetic alloys for remanent reed switch applications

Semihard magnetic alloys of Fe-Co-W have been developed for application in remanent reed switches. These alloys are very ductile and can be processed into fine wires. The 78%Fe-12%Co- 10%W alloy shows the magnetic properties: Br= 19.2 kG, Br/B200= 0.95, and Hc= 25 Oe. These magnetic properties are superior to those of the commercially used Remendur (49%Co-48%Fe-3%V) or Nibcolloy (85%Co-12%Fe-3%Nb), and the alloy itself consists of a much less expensive cobalt content than those alloys. This 78%Fe-12%Co-10%W alloy is flattenable into reeds, plateable with contact materials, and sealable in glass vials without losing its magnetic properties. Fe-Co-W alloys are adequate for use in remanent reed switches and present distinct advantages from the aspects of their inexpensiveness and superior characteristics.     

Interfacial reactions between lithium silicate glass-ceramics and Ni-based superalloys and the effect of heat treatment at elevated temperatures

Two lithium silicate glasses (S- and BPS-glass) were sealed to four different Ni-based superalloys (Inconel 600, Inconel 718, Haynes 230, and Hastelloy C-276) and the effects of long-term heating at 700–900°C on the chemical, microstructural, and mechanical properties of sealed interfaces were studied. The presence of a small amount of ZnO in the BPS-glass leads to the formation of a thin interfacial second phase layer and a less rough alloy interface compared to the ZnO-free S-glass. Inconel 718 was found to be the most reactive of the alloys, with Cr and Nb diffusing into the glass and forming a coarse glass-ceramic microstructure at the interface. Heat treatment of all the reaction assemblies at 900°C for 100 h in air resulted in degradation of the seals and their spontaneous failure. Heat treatments at 700 or 800°C did not cause any interfacial coarsening in BPS sealed to Inconel 600, Haynes 230, and Hastelloy C-276 alloys and did not alter the bond strength of Haynes 230 bars, sealed with a thin layer of BPS-glass, demonstrating the potential of these material combinations for applications up to 800°C.     

偶联剂处理镀镍碳纤维/环氧树脂界面特性

采用硅烷偶联剂KH560对镀镍碳纤维进行偶联处理。通过扫描电镜、 红外光谱、 接触角测量和单丝复合体系多次断裂法测试研究对比偶联处理前后碳纤维的表面形貌、 结构、 润湿性能以及纤维/树脂体系的界面状态和粘结性能。结果显示: 偶联处理后, 镍镀层表面平整, 羟基等表面极性基团增加, 表面涂覆的KH560膜层完整; 镀镍碳纤维/树脂界面的浸润性得到改善; 镀镍碳纤维/环氧树脂的界面处没有气泡产生, 断点两侧的脱粘现象减轻; 单丝饱和断点数由46增加到65; 镀镍碳纤维/环氧树脂的界面剪切强度由(34.87±2.23)MPa提高到(72.51±3.77)MPa。     

Strength evaluation and effect of graphite on strength of electroless nickel plating on cast iron

The effect of graphite on the strength of electroless nickel plating on cast iron was studied. Specimens of cast irons with four types of graphite and of 0.4% carbon steel were prepared and machined into plates with dimensions of 10 mm × 3 mm × 80 mm. Electroless nickel plating, about 40 m thick, was deposited on the test pieces. The plated test pieces were tested by three-point bending tests using both acoustic emission (AE) and microscopic observation to evaluate the strength of the plating film. It was found that the first AE signal was generated when the cracks initiated and the final AE signal was generated when the film was fractured by crack penetration into the film. In addition it was found that film cracks on cast iron were initiated by the graphite existing at the interface between the plating film and the substrate, and propagated to the surface of the film, unlike carbon steel. The strength of the plating film on cast iron measured by this method, decreased more sharply with increasing amount of graphite than with graphite shape. Observations of cast iron surfaces at early stages of plating showed that the nickel was deposited only on the matrix and not on the graphite. It is believed that the non-deposited areas of the cast iron acted as types of defects. It is concluded that the strength of electroless nickel plating film on cast iron is strongly influenced by graphite on the surface.     

真空玻璃边缘封接强度及可靠性分析

用于真空玻璃边部封接的玻璃焊料不仅要满足真空密封性能,同时应满足封接强度要求。采用十字交叉法试验,获得了真空玻璃边缘封接部位界面拉伸与剪切强度,分析了真空玻璃服役过程中因玻璃自重、风载荷和温差作用而导致的真空玻璃边缘封接部位应力。通过试验验证和理论分析比较,结果表明:真空玻璃边缘封接部位强度能够承受因玻璃自重,温差,风压作用而产生的应力;在真空度失效的情况下,真空玻璃边缘封接强度足够高,依然可以承受3600Pa的风压作用,在应用过程中安全可靠。     

Effects of Liquid Contaminants on Heat Seal Strength of low‐density polyethylene Film

Heat sealing is commonly applied for making form‐fill‐seal packages fabricated from thermoplastic films. One of the challenges frequently faced by the industry is inadvertent contamination of film–film interface by the product during filling, which can compromise package seal strength. In this study, the effects of dwell time (0.5–1.5 s), jaw pressure (28–1860 kPa), jaw configuration (narrow versus wide contact area) and jaw temperature (150°C–180°C) on the interface temperature and seal strength of a linear low‐density polyethylene (LLDPE) film were investigated. Three different film–film interface conditions were studied: (1) no contaminant; (2) with water contaminant; and (3) with vegetable oil contaminant. In the presence of liquid contaminant, jaw pressure played an important role in displacing the liquid from the seal area to form intact seals. Short dwell time (0.3 s) and low jaw temperature (150°C) was not favourable for forming intact seals in both water‐contaminated and vegetable oil‐contaminated films. The optimum jaw temperature and dwell time required to produce intact seals for oil contaminated films was 180°C and 0.3 s, respectively, whereas a combination of 165°C jaw temperature and 1 s dwell time was required to form intact seals for water‐contaminated films. Within the experimental conditions investigated, interface temperatures of 130°C–140°C resulted in the most optimum seal strength for both water‐contaminated and clean film specimens. Above 140°C, a weakening of seal strength was observed, presumably because of the change in melt flow characteristics and possible initiation of thermal degradation of the polymer. Copyright © 2011 John Wiley & Sons, Ltd.     

Numerical and experimental evaluation of performance of centrifugal seals

‘Centrifugal seals’ or ‘Slinger seals’ offer an attractive choice as non-contact-type sealing in fluid machinery. These seals utilize the radial pressure gradient caused by centrifugal forces in a rotating fluid ring, to create a sealing of the working fluid. Basic construction of a typical seal consists of a rotating disc inside a stationary casing; one side of the disc (sealing side) is provided with a set of slots (Type-1) or vanes (Type-2) to enhance the tangential velocity of the fluid. The other side of the disk (back side) in both the configurations is exposed to high pressure liquid being sealed. Both numerical and experimental investigations of the performance of Type-1 seal (with slots) have been carried out so as to optimize the seal configuration to achieve maximum sealing capacity, with minimum power consumption. A comparison of the performance of Type-1 seal has been made with that of conventional one (Type-2) in view of economy of construction and better sealing with minimal expense of power consumption. A test rig that allows for varying the major geometrical and operating parameters was designed and tests were conducted with water as the medium. Influence of major geometric parameters like dimensions and number of slots, axial/radial clearances and major operating parameters like rotational speed, inlet pressure and sealing fluid bypass flow rate has been investigated. Apart from various pressure, temperature, flow and torque measurements, the interface between the sealing and working fluid for the experiments was captured and recorded using a high speed camera at ~26,000 frames per second. Geometrical configuration for the slots that maximizes the sealing capacity is arrived through 3D numerical simulations using commercial CFD solver ANSYS Fluent^®. A good agreement is obtained with respect to experimental results. In view of economy of construction and better sealing with minimal expense of operating power, a modified version of Type-1 seal termed as Type-3 seal is investigated. A simple 1D model for prediction of the interface radius during the seal operation, which could be used as a quick design guide, is also presented.     

汽车车门密封结构的传声实验研究

汽车高速行驶时气流导致的车身内外压差和密封件局部压力变化,会使车门密封传声加剧,目前针对车门密封传声的相关研究较少.通过小型气动-声学风洞实验测试手段,参考汽车实车门结构密封和气动力作用特点,建立门单道密封和门板四周密封结构实验研究环境和试验件,研究其密封结构的传声特性.研究表明:竖向和横向密封对门板中高频传声影响较大...     

Aspects of phase equilibria in Fe/Co/2.5 to 3.0% V alloys

Remendur alloys, one of which is used as the base material in remanent reed sealed contacts for the communications industry, are ternary alloys containing approximately equal iron and cobalt with 2 to 4 wt % vanadium. The available equilibrium diagram for this system does not provide precise positioning of the phase boundaries in the regions of commercial interest and, consequently, does not permit accurate determination of the amounts of the phases present or their compositions. This paper reports on the precise determination of five tie lines in theα ₁+γ two-phase field in the region of interest, by metallographic and microprobe techniques. In the 900 to 950° C range, this field was found to be narrower than expected from published data. Submicron fcc (γ) particles form during annealing at 600° C by decomposition of a non-equilibrium bcc (α₂) phase into a secondary ordered bcc phase (α′₁) and stabilizedγ. Deformation, by drawing and by stamping, enhances coercivity in these alloys by promoting a more uniform, more finely divided dispersion ofγ particles. Annealed microstructures are especially sensitive to vanadium content, annealing temperature, and annealing time.     

基于Ansys的铝箔密封受热温度场研究

目的研究铝箔不同的密封情况对电磁加热过程中铝箔表面温度分布的影响,建立非接触式密封性检测方法的理论依据。方法首先创建感应加热理论的有限元数学模型,计算感应电流产生的焦耳热量,以此为内部热源求解温度场。然后通过有限单元法创建6种不同密封情况的铝箔封口稳态热传导模型,对不同铝箔密封情况在恒定温度条件下进行温度分布的三维分析求解,并采用Ansys软件模拟分析加热温度场下铝箔密封的传热特性。结果得到了各种密封情况对应的温度场图像及温度曲线,其中铝箔密封完好的热图像呈高温闭合且均匀的环状区域,在其温度曲线中,温度集中分布在70～80℃,并具有对称性特点,且有2个高温峰值;另外5种为不成环或成环不均的热图像,表明铝箔密封失败。结论通过研究热温度场分布特性可以判断铝箔封口密封程度,能够为进一步优化非接触式密封性检测的自动化程度提供理论支持。     

Oxide/metal interface on 20Cr–25Ni–Nb stainless steel

Abstract

20Cr–25Ni–Nb stabilised stainless steel is used to contain the fuel in the advanced gas cooled reactor. During operation, this steel must withstand temperatures from 600 to 1073 K in CO₂ gas at 40 atm pressure. It is important that the oxide which forms on this steel is thoroughly characterised and the adherence of the oxide to the metal is understood. A technique of sputter ion plating has been used to remove the oxide from the metal without destroying either metal or oxide. This involves plating the oxide with nickel or molybdenum at a temperature of 600 K, while sputtering the surface with argon ions. On cooling, stresses set up between the oxide and the metal cause the oxide plus sputtered layer to peel off allowing both the metal and oxide sides of the interface to be examined. Results are presented from studies of the metal/oxide interface using scanning Auger microscopy. Analysis of grain centres and grain boundaries indicates that silicon and chromium play an important role in oxide/metal adhesion and, together with conventional analysis of the bulk oxide, assist in determining the oxidation mechanism.

MST/862     

Peelable seam systems and their production

In packaging, heat-seal seams have been known as ‘peelable seals’ for a long time. In this system seal medium A is sealed with seal medium B. They are combined in such a way that the sealed seam can be reopened by a defined force without destroying the packaging. Typical applications for peelable seals are boxes or containers with sealed cover sheets, blisters and flexible packagings. The tendency towards peelable packagings has increased recently. This research project dealt with the relevant processes and parameters that influence peelable seals and aims to define reproducible, peelable sealed seams and to elaborate upon a method to develop and produce peelable seam systems. Compared with other research programmes or bibliographical data, this project dealt, in particular, with:

• i the definition of a ‘reproducible, peelable sealed seam’;
• ii an analysis of peelable seam production using the different sealing techniques (heat-contact, ultrasonic and inductive high-frequency);
• iii the influence of the type of sealer jaw on the production and characteristics of peelable seams.

     

陶瓷散热片用铜浆玻璃相的制备

厚膜陶瓷散热片的制备工艺一般为丝网印刷铜浆、烧结、化学镀镍3部分。目前印刷在散热片上的铜浆,经化学镀镍工艺后附着力下降,因此研究制备导电性好、导热性优和附着力高的铜浆是制备陶瓷散热片的关键。通过对铜浆玻璃相的制备、玻璃软化温度的测定和玻璃釉在化学镀镍液中的耐蚀性测试,得到了耐蚀性较好的玻璃釉,其玻璃相成分为40%SiO₂-31%Bi₂O₃-5%B₂O₃-3%Al₂O₃-5%TiO₂-3%CaO-4%SrO-5%Na₂O-5%K₂O（质量分数,下同）。     

玻璃纤维/环氧树脂复合材料与镀层界面的Ni颗粒强化工艺

针对玻璃纤维/环氧树脂复合材料与镀层结合界面强度低的问题,基于复合材料/镀层间的机械互锁原理及传统塑料基体化学镀工艺,提出通过增强颗粒的桥接作用,增加含有增强颗粒的过渡层来强化镀层界面的复合材料金属化方法。对金属化后的玻璃纤维/环氧树脂复合材料试件采用拉伸试验法测量镀层的结合强度,并通过截面和断面的显微观测,分析了增强颗粒对于镀层界面的强化机制;同时获得了玻璃纤维/环氧树脂复合材料表面粗糙度和增强颗粒质量分数对含有过渡层的镀层结合强度的影响规律。结果表明:采用上述金属化方法可以显著提高镀层的界面强度,与传统的金属化工艺制备试件相比,玻璃纤维/环氧树脂复合材料在不同表面粗糙度下,镀层结合强度平均提高161%;同时,镀层的结合强度随着增强颗粒质量分数的增加,呈现先增大后减小的趋势,当增强颗粒的质量分数为50%时,镀层的结合强度达到最大。      

控制电缆水下联接密封插座的研制

控制电缆水下联接密封插座是采用自密封原理,由普通航空插座改装而成的。通常只利用其内部芯针、芯孔及定位座,在其外部加抗压密封壳体、中间加具有自密封性能的密封件,通过有机组合,从而达到良好的密封效果;同时,对密封结构设计的方法和注意事项进行了分析和说明。     

Preparation of ultra-fine copper powder and its lead-free conductive thick film

In this paper, non-agglomerated monodispersed ultra-fine copper metallic powders have been synthesized with chemical reduction method. Fine lead-free glass powders were also prepared by solid synthesis process. Thick film paste prepared by above-mentioned copper metallic powders and lead-free glass powders was applied as conductive paste of MLCC. Mixture of glass and zinc oxide give the thick film a high adhesion strength which is attributed to the rough interface from interfacial reaction between glass and chip, and a good densification. Diffusion of metal between copper thick film and nickel thick film is clear. Ni-Cu solid solution appears under high temperature firing.     

Vakuum‐Lineardurchführungen mit Magnetflüssigkeitsdichtungen

Vacuum linear feedthroughs with magnetic fluid seal A magnetic fluid sealed feedthrough is a device that transmits linear motion into a vacuum chamber with minimal frictional resistances and minimal contamination level.They are widely employed in high and ultra‐high vacuum equipment among others in semiconductor fabrication industry and robotics applications. The operating conditions of magnetic fluid seals during reciprocating motion are so different from those with rotating motion that the use of their conventional structures for reciprocating motion seals yield no good results. Analysis of sealing mechanism of magnetic fluid seal in reciprocating motion shows that the operation of these seals is affected by the carry‐over and the magnetic fluid deformation in the sealing gap, which depends on the velocity of reciprocating motion. The reduction of magnetic fluid quantity in the sealing gap,caused by the reciprocating motion of the shaft is reason of the seal failure. In the paper a short characteristic of magnetic fluid sealing technology , principle of sealing, behaviour of the ferrofluid and seal failure mechanism in the linear motion of the shaft are given. Moreover some new structure designs of vacuum linear feedthroughs with magnetic fluid seals, which have practical application value are presented.     

The adhesion and interface chemistry of ion-plated selenium

A combination of fracture measurements and photoelectron spectroscopy has been used to investigate the bond strength of selenium evaporated onto α-brass substrates. Failure of thermally evaporated deposits occurs at an SeCuO interface layer even though selenium is chemically bonded to the oxide. It is shown that the interface oxide complex is removed during an ion plating process and that as a consequence the Se-brass bond strength increases significantly. However, the bulk adhesion properties of thermally deposited and ion-plated specimens are found not to be significantly different. This anomaly is discussed in terms of crack propagation, dispersion of the interface oxide during ion plating and failure at a new highly bonded CuSe interface layer.     

Design of elastomer O-ring vacuum seals

Elastomer O-rings were developed in hydraulics, but design criteria from this field are not suitable in high vacuum technique. In the literature, information on O-ring vacuum seals is normally given in the form of tabulated recipes for groove dimensions. Measurements of the mechanical properties (shown in figures) of O-ring enable us to extend these recipes to a general criterion for high vacuum sealing: a contact pressure at the rubber-metal interface of 13 kg/cm². Design of seals using free rings between flat flanges and seals using rings confined in grooves of rectangular and triangular section is treated. Figures and tables of design parameters are given. Correct design in the case of stretched rings is discussed. Important secondary results include the required compression force and the maximum allowed gap (if required) between mating flanges. Figures deal with these parameters. The influence of tolerances is treated too in the given examples.     

Haftung und Grenzflächenreaktionen im Verbundsystem α-Al2O3/Ni

Adhesion and Interfacial Reactions in the αAl ₂ O ₃/ Ni Composite System. Composite models consisting of a zylindrical sapphire rod surrounded by a sintered nickel ring are used to determine the influence of small amounts of titanium or zirconium (as alloying additions in the nickel) on the adhesion and compatibility between the composite components. Poor nickel gives temporally and thermally stable-shear strength values between 50 and 70 N/mm². With nickel containing 0,05 at.-% Ti or Zr the shear strength increases to 250–280 N/mm² by using favourable sintering conditions (i. e. 1300°C, 1 h). This increase is caused by an improvement of adhesion which can be explained by the formation of strong chemical bonds. These bonds are produced by chemical reactions between the sapphire surface and the alloyed active metals Ti or Zr in the nickel. With longer sintering times, higher sintering temperatures, and/or higher active metal concentrations, these reactions cause roughening of the sapphire surface and precipitation of active metal oxide phases at the interface or in the adjacent nickel zone. Those reactions-caused alterations of the interface region are changing the shear behaviour and can lead to a decrease of shear strength. The shear strength values of such specimens dont allow conclusions of the real adhesion between the components.