Zenzo Henmi

Palladium with a Thin Gold Layer as a Sliding Contact Material

A study has been carried out to evaluate two types of palladium contacts as a substitute for gold contacts presently used in connectors. Both types are electroplated palladium, one with a thin gold layer over it and the other without, Platings in this experiment were pure palladium from an alkaline bath (pH = 8.8) and pure gold from an acid bath (pH = 5.0). Although the gold was rather soft, its sliding properties, even with the thicker deposit, were as good as the acid hard gold deposits. Friction coefficients of the electroplated palladium investigated were 0.4-0.7. These values were quite large compared with the 0.15-0.3 of electroplated gold, and resistance to wear of the electroplated palladium was very poor. The proposed multilayer contact, which consists of electroplated palladium with a thin gold layer over it, exhibited friction properties similar to conventionally available gold contacts. The thin gold layer over the palladium acts as a lubricant between the harder palladium electroplates. Palladium itself showed good results in corrosion test performed in an 80%N2-20%O2 atmosphere containing 10 ppm H 2 S with a relative humidity of 90 percent at room temperature for 1000 h, and the palladium with the thin gold layer over it showed even better results.

New Semi‐Hard Magnetic Alloys of Co–Fe–Be System

New semi‐hard magnetic alloys, which have a square hysteresis loop and a low value of magnetostriction, are presented here. These alloys consist of about 90% Co, about 1% Be, and the balance Fe. We can attain a coercive force between 10 and 30 Oe by controlling the Be content. The Co content affects the stress sensitivity of the hysteresis‐loop shape. One example is a tape 0.126 mm wide and 0.011 mm thick containing 88.5% Co, 1.3% Be, and 10.2% Fe, finally annealed at 800°C for 10 sec. This tape exhibits a coercive force of about 30 Oe, a squareness ratio of about 0.9, and very small change in the hysteresis‐loop shape with 20‐kg/mm2 tensile stress. In a sample containing more than 0.7% Be, CoBe precipitates and the grain size is much smaller than in a sample without Be. This fact contributes to the increase of coercive force with Be content. Moreover, the drawn wire has a 〈111〉 fiber texture, and the rolled‐flat tape has a {110} 〈111〉 texture. These textures do not change until at least 900°C annealing t...

Semihard Magnetic Alloys of Co–Fe–Nb System

Ductile alloys of the Co–Fe–Nb system in the vicinity of 90% Co were studied for reed switch applications. Wires have been investigated which have high values of coercive force, squareness ratio and remanence as well as high stability of these magnetic properties against heating. As a result of this research, an 85 Co–12Fe–3Nb wire, 0.5 mm in diam., subjected to a sequence of a 1100°C intermediate anneal, 90% cold reduction and 750°C aging is deemed best for this application. This wire shows a coercive force of 20 Oe, a squareness ratio of 0.95 and a remanence of 15 000 G. Intermetallic Co–Nb compounds precipitate during aging treatment. This phenomenon causes the coercive force to increase. The cold drawing facilitates the precipitation. The intermediate anneal temperature should be sufficiently high to realize a complete solid solution in the wire. The drawn wire has 〈111〉 fiber texture. Since 〈111〉 is an easy magnetization direction, the wire shows a good rectangular hysteresis loop along the axis. Thi...

A New Laser Hermetic Sealing Technique for Aluminum Package

A new laser hermetic sealing technique which combines nickel plating with laser welding has been developed for aluminum packages. Laser welding has proved to be the most promising hermetic sealing technique for the aluminum packages. However, laser welding of the package has been difficult because of aluminums tendency to suffer centerline cracks in the weld zone. Nickel was added in the weld zone by laser welding nickel-plated aluminum to strengthen the weld metal and prevent centerline cracks. With this aim, the optimum plating method and plating thickness were investigated. Consequently, electroless Ni-1wt%B, 5 µm in thickness was found to be best suited to the new technique, because the laser weld zone of the package exhibits a high joint strength almost equal to the tensile strength of the parent metal, and a package leakage of less than 10-9atm · cm3/s. The reliability of the hermetically sealed package was tested in accordance with MIL-STD-202F. It was confirmed that the new technique is suitable for the aluminum package for use in space, in the stratosphere and in salt-laden air.

Temperature‐sensitive Nd‐Co compounds produced by powder metallurgy

A powder metallurgical process has been developed to prepare Nd‐Co compounds which show the spin reorientation (SR) phenomenon. In this process, single crystals of the compounds in fine powder form are aligned in a magnetic field at a temperature more than 50 °C above the SR temperature. Complete uniformity is especially important in the chemical composition of the powders. As a result of studying many elements as substituents in NdCo5, an Nd (Co1−x−yAlxFey)5 system has been developed. The SR temperature of this compound system can be extended beyond 150 °C by controlling composition of the compound as may be required for different applications.

Magnetic Properties of Co–Fe–Nb Alloys for Remanent Reed Switches

Previous studies revealed that an 85Co–12Fe–3Nb wire for a remanent reed switch showed a coercive force of 20 Oe. The magnetic properties of Co–Fe–Nb alloys containing 6∼18 wt % Fe , O ∼7 wt % Nb , and the balance Co, were further investigated. Wires were made by a serial process of solution treatment at 1200°C, cold drawing and aging at 700°C for 1 hour. The value of coercive force increases linearly with Nb content, and reaches 48 Oe at 7 wt% Nb. The magnetic moment decreases linearly with Nb content from 172 to 132 emu/g. Changes in coercive force and magnetic moment with Fe content are not so large as those with Nb content. The magnetostriction constant, however, changes with Fe content and becomes nearly zero as Fe approaches 9 wt%. The squareness ratio (Br/B100) is higher than 0.90 for all the specimens except for the specimen with 7 wt% Nb. It was clarified by X‐ray diffractometer and electron microscope that the increase in coercive force with Nb is due to fine precipitates of Co 3 Nb in the grain.

Magnetic hysteresis behavior and microstructure of severely cold‐worked and aged Co‐Fe‐Nb alloy

The magnetic hysteresis behavior of severely cold‐worked and aged 85Co‐12Fe‐3Nb alloy was studied in relation to the microstructure. Magnetic hardening of the alloy can be attributed to the pinning of the domain wall by quasispherical Co3Nb precipitates. Alloys cold worked to 97.8% reduction in area and aged at 700, 800, and 900 °C showed the hysteresis behavior characteristic of inhomogeneous domain wall pinning, whereas alloys cold worked to 99.7% and aged at 700, 800, and 900 °C exhibited extremely rectangular loops indicative of homogeneous wall pinning. The differences in hysteresis behavior can be explained by differences in their microstructures. It was ascertained by high‐voltage electron microscopy that the spatial distribution of precipitates in the 99.7% cold‐worked sample was more homogeneous than that in the 97.8% cold‐worked one. Domain structures observed by Lorentz microscopy indicate that the domain walls are not rigid but they have sufficient flexibility. From these results, the magnetiz...

Semihard Magnetic Alloys of Co[Single Bond]Fe[Single Bond]Ni[Single Bond]Nb System

Ductile alloys which have approximately equal amounts of Co and Fe, plus Ni and a small amount of Nb were investigated for remanent reed switch applications. As a result, 39Fe–38Co–20N–3Nb wire 0.6mm in diameter, made by intermediate annealing at 700°C, cold drawing to 92% reduction in area, and final annealing at 6007deg;C for 1 hour, showed a coercive force of 30 Oe, remanence of 16000 G, squareness ratio higher than 0.95, and thermal expansion coefficient of 98×10−7/°C between 30 and 400°C. This alloy could be cold‐worked easily after annealing. The phase was f.c.c. after annealing at a temperature over 800°C. However, cold working caused partial phase transformation of f.c.c. into b.c.c. This intermixing of f.c.c. and b.c.c. phases in a high coercive force state survived up to 700°C annealing. On the other hand, remanence was low in the cold drawn state, but increased by annealing over 600°C. The coercive force grew larger as the Nb content increased.

Rare earth–cobalt permanent magnets with improved mechanical properties

A rare earth–cobalt permanent magnet with improved mechanical strength has been developed. Sm1−uCeu(Co1−x−yCuxTmy)z with Tm=Fe or a combination of Fe with other transition metals were prepared by powder‐metallurgical means. Mechanical strength was evaluated by flexural strength testing for sintered permanent magnet rods. The compositional dependence on flexural strength σf as well as the influence of the different parameters, as for instance particle size and sintering temperature, were investigated. For z ≳ 5, σf increases with increasing z and other substitution parameters u, x and y. For instance, fine grained magnet of Sm0.8Ce0.2(Co0.785Cu0.15Fe0.05 Cr0.015)7.6 shows σf of 290 MPa, iHc of 360 kA/m and Br of 0.85 T.

Cobalt - Iron Alloy for Nonself-Latching Dry Reed Contacts

A Co-Fe alloy having a low electrical resistivity and a high Curie temperature suitable for use in high current-load reed contacts is described. The Co-12-14-wt% Fe alloy was selected as the optimum composition, considering its thermal-expansion matching with sealing glass. The Co-12-14-wt% Fe alloy shows sufficient electrical, magnetic, and mechanical properties for use in nonself-latching dry-reed contacts. These material properties are discussed in relation to their microstructure. Results of trial production of reed contacts made of the alloy are also discussed.