Addition Of Metal Powder Research Articles

ニッケルシースＰＩＴ法ＭｇＢ２テープの応力／ひずみ特性

The stress/strain dependence of critical current and the mechanical properties of nickel sheathed PIT MgB2 mono-core tapes with various kinds of metal powders addition to the core were evaluated at 4.2 K in the magnetic field of 2 T. No marked change in the stress-strain curve was found by the powder addition. The critical current was markedly enhanced by In and Sn powder addition. The critical current was almost constant irrespective of strain up to the irreversible strain where a steep degradation of critical current begins. The irreversible strain for the tape increased from 0.25 to 0.50% by the addition of In and Sn powder. The In addition also suppressed a slight increase in the critical current with strain. The effects of Ag and Cu addition are less as compared with those of the low melting point metal powder such as In and Sn. SEM observations on the longitudinal section of In added tape after the tensile test clarified that the cracks were few and rather large as compared with those in the tapes with no addition or high melting point metal powder addition. The strain characteristics were compared with those of MgB2 with other sheath materials and those of a conventional Nb3Sn wire.

Laser Beam Welding of 2205 Duplex Stainless Steel with Metal Powder Additions

Laser beam welding with the aid of metal powder additions to the weld pool was carried out to modify the ferrite/austenite (α/γ) ratio of the weld metal of 2205 duplex stainless steel (DSS). The α content in the weld metal of DSS welds could be controlled by the proper flow rate of nickel powder through a coaxial nozzle. This process had the advantage of using only a small amount of filler metal, i.e. a few grams per minute of nickel powder, in the welding process. Imapct and notched tensile tests were utilized to evaluate mechanical properties of laser welds. The notched tensile test was also carried out in hydrogen under a slow displacement rate. The susceptibility to hydrogen embrittlement (HE) was estimated from the loss in notched tensile strength and correlated with the microstructure of a given laser weld. On the whole, the susceptibility to HE decreased with increasing the γ content of DSS welds. Autogeneous laser welds containing the highest α content of all welds tested were most susceptible to HE. The base material with banded α+γ structures was susceptible to HE and exhibited severe secondary cracks mainly along α/γ phase boundaries. Although laser welds produced at a flow rate of 3 g/min nickel powder had similar α content to the base material, they were more resistant to HE owing to randomly distributed α and γ phases in the weld metal. The impact energy of laser welds at low temperatures (−75 to −100°C) along with the hardness test could also be used to check if the proper amount of nickel powder was added in laser welding of DSSs.

金属粉末添加MgB_2超伝導テープ線材の特性(S08-3 超電導材料システム,S08 極低温・超電導材料システムの強度・機能特性)

Effect of metal powder addition on the transport current and strain performance of ex-situ processed MgB_2 tapes with Ni sheath has been studied. The addition of low melting point metal powder, e.g. In and Sn, produces an appreciable increase in the Jc of MgB_2 core. The 10vol% In addition enhances Jc by a factor of 6-7 after the combination of the rolling and the annealing at 200℃. The 10vol% Sn addition enhances Jc by a factor of 〜3. Both of In and Sn metal impregnate into gaps among MgB_2 grains improving the linkage of the grains. The current may transfer through the impregnated metal by the proximity effect. Furthermore, the In and Sn addition improves appreciably the strain tolerance of the MgB_2 tapes.

Structure and critical current of Ni-sheathed PIT MgB 2 tapes with In metal powder addition

PIT MgB 2 tapes have been prepared through an ex situ process using a Ni sheath. Different kinds of metal powder were added to the MgB 2 core. Soft metals like Ag and Cu show an elongated morphology in the core after the fabrication. Low melting point metal powder like In impregnates into gaps among MgB 2 grains due to the heat generated during the fabrication. The addition of In and Sn produces an appreciable increase in the J c of MgB 2 tapes. The annealing at 200 °C yields further increase in the tape with In and Sn addition. The enhancement of J c by the In addition and the 200 °C annealing reaches a factor of ∼7. The In addition also improves the n value and the strain tolerance of the tape. The improvement in the linkage of MgB 2 grains seems to be the major origin for the enhancement in J c by the In addition.

Effects of metal powder addition on the structure and critical current of Ni-sheathed PIT MgB/sub 2/ tapes

MgB/sub 2/ commercial powder was encased in a Ni tube and rolled into a monocore tape of about 5 mm in width and 0.3 mm in thickness. Different kinds of metal powder, i.e., In, Sn, Ag, Cu and Ni, were added to the MgB/sub 2/ core. Addition of the low melting point metal powder, e.g., In and Sn, has been found to enhance significantly the J/sub c/ value in MgB/sub 2/ tapes. Annealing at a low temperature yields further increase in the J/sub c/ of tapes with In and Sn addition. The enhancement in J/sub c/ by the In addition and the low temperature annealing reaches a factor of 6-7. The J/sub c/ of the tapes with 10vol% In addition, annealed at 200/spl deg/C for 10 h is on the order of 10/sup 5/ A/cm/sup 2/ at 4.2 K and 0.5 T. The TEM observation shows that In fills up the gaps among MgB/sub 2/ grains. The additional annealing produces better impregnation of In in the core. The improvement in grain linkage seems to be the probable origin for the enhancement in J/sub c/ by the In addition. The optimum amount of In addition to the MgB/sub 2/ core is likely 10-15vol%. Ag, Cu and Ni powder addition yields no apparent effect on J/sub c/ of PIT MgB/sub 2/ tapes.

Some Physical Properties of Pure and Doped Polyvinyl Alcohol under Applied Stress

Thick films of polyvinyl alcohol (PVA) containing very finemetallic powder, copper (Cu), iron (Fe) and aluminum (Al) 2.5% by weight,were prepared by the casting method. The temperature dependence of Young'smodulus at constant stress, the stress dependence of Young's modulus(Y), the stress dependence of dielectric constant (e) and stressdependence of phonon velocity, were studied. It was found that Young'smodulus (Y) of the pure sample has the lowest value and that of PVA + Alhas the highest value. This can be explained on the basis that Ydepends on the ratio between the energy of molecular interactions andthe energy of thermal motion of the sample units. We also found that thedielectric constant increases with the addition of metallic powder, andwith an increasing applied stress. The phonon velocity increased withincreasing stress. The increase of stress decreases imperfectionsleading to the increased phonon velocity. The electronic absorptionspectra of PVA is not affected by doping Al and Fe, whereas the PVA dopedwith Cu shows a shift of the absorption maxima toward a longer wavelength.The instantaneous elastic behavior may be observed only at lowtemperatures and very short creep times.

Ｅｘ−ｓｉｔｕ法ＭｇＢ２テープ線材の電流及び歪特性に及ぼす低融点金属粉末の添加効果

Ｅｘ−ｓｉｔｕ法ＭｇＢ２テープ線材の電流及び歪特性に及ぼす低融点金属粉末の添加効果

High-productivity multiple-wire submerged-arc welding and cladding with metal-powder addition

The paper deals with multiple-wire submerged-arc welding and cladding with metal-powder addition. Three different ways of supplying the metal powder to the welding area are described and shown schematically. It was found that the use of metal powder will increase the deposition rate, and the welding-arc efficiency and reduce the shielding-flux consumption. A suitable device permits submerged-arc welding and cladding with metal-powder addition. The process is primarily meant for the cladding of worn surfaces or the production of surfaces with certain characteristics (corrosion or wear resistance). By using the metal-powder addition it is possible to alloy a weld or a cladding with optional chemical elements.

Effects of metal powder addition on the critical current in MgB 2 tapes

MgB 2 commercial powder was encased in a Ni sheath and fabricated into a monocore tape. Different kinds of metal powder, i.e., Ag, Ni, Cu, In and Sn, were mixed with the MgB 2 powder. The addition of low melting point metal powder, especially In, has been found to enhance appreciably the J c in MgB 2 tapes. The annealing at a low temperature yields further increase in the J c of tapes with In addition. The enhancement in J c by the In addition and the low temperature annealing reaches a factor of five. The In addition may improve the linkage among MgB 2 grains, which provides the improvement in J c and avoids a sintering treatment at high temperatures. The optimum amount of In addition to the MgB 2 core seems to be about 10 vol%. The effect of other metal powder addition is also described.

Fragment distribution as an aid to forensic failure investigations at the scene of explosions

Twelve pipe bombs were exploded, and the fragments were collected and weighed. The distribution of fragment masses was shown to follow a Weibull-type form M (n)=M0 [1 − exp (−Bnλ)] when RDX-based military explosives were used and a bimodal distribution when commercial explosives were used. The constant, B, was a function of the mass of fragments recovered, making its use inappropriate in a forensic context where complete collection of the fragments would not be possible. For RDX-based explosives with added Mg or Al powder, the value of the constant, λ, was reduced compared to that of the RDX-based explosive without metal powder additions. An alternative fragment distribution formula, log [(100 M (N))/M0]=FWDM [m(N)/ M0], can also be used to distinguish between explosives, although the correlation coefficient is inevitably somewhat lower and the scatter between the results of nominally identical tests can be greater. The coefficient, FWDM, has a dependence on the mass of fragments collected, restricting its utility in forensic contexts.

Study of the performance of secondary alkaline pasted zinc electrodes

Calcium zincate was prepared by a chemical coprecipitation method and characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The electrochemical performance of pasted zinc electrodes with bismuth and calcium additives was investigated by the charge–discharge method. The addition of metallic bismuth powder improves the discharge performance of zinc electrodes due to the formation of an electronic conduction matrix. The calcium-containing zinc electrodes showed higher discharge capacity, less shape change and longer cycle lifetime. Moreover, zinc electrodes using calcium zincate as active material show better electrochemical performance than those with the physical mixture of zinc oxide and calcium hydroxide.

High performance water atomized alnico powders : H.Koyama et al. Denki Seiko (Electric Furnace Steel), vol 69, no 2, 1998, 131–136. (In Japanese.)

Results of polymer matrix hard magnetic composite materials with particles of powdered rapid quenched Nd-Fe-B strip are presented in this paper. Influence of additional materials on magnetic, mechanical and electrical properties of composite materials was studied. The composite without additions revealed good magnetic properties. With addition of soft magnetic materials—iron, the coercive force decreased while remanence of composite was almost not influenced. The addition of steel reduces both coercive force and remanence. However addition of metallic powders improves mechanical properties of the composite materials.

Effect of zinc metal addition on microstructural evolution of Zn 0.22 Cd 0.78 S$ phosphors studied by transmission electron microscopy

The effect of zinc powder addition on the microstructural evolution of fine Zn0.22Cd0.78S:Ag$, Cl phosphor particles was investigated in relation to the luminescent property of phosphors. The phosphor microstructures were analyzed by high-resolution transmission electron microscopy (HRTEM) using the ultramicrotome technique for specimen preparation. The phosphor baking process at 480 °C for 30 min in air results in significant damage to the surface structure of the phosphors due to the decomposition and oxidation of the phosphor itself. The addition of zinc metal powders into the Zn0.22Cd0.78S$ phosphors suppresses the oxidization and decomposition of phosphors by oxidizing zinc metal during the baking process in air. The oxidation of the zinc powders during baking provides the baking furnace with less oxidizing atmosphere for phosphor particles. The structure of phosphors, especially at the surface region, is much less degraded compared to the phosphors baked with no zinc metal addition. © 2000 Kluwer Academic Publishers

Effect of Metal Powder Addition on Mechanical Properties of Submerged Arc Welds

Effect of Metal Powder Addition on Mechanical Properties of Submerged Arc Welds

Metal powder addition effect on the photocatalytic reactions and the photo-generated electric charge collected at an inert electrode in aqueous TiO 2 suspensions

The photocatalytic reaction in an aqueous TiO 2 suspension has been found to be enhanced by the additiona of some metal powders such as copper, silver, nickel and cobalt into the suspension. Just mixing a metal powder into the suspension gave nearly the same efficiency as metal-loading on the semiconductor particles. The effect is attributed to the rapid transfer of the photogenerated electrons from the TiO 2 to the metal particles, resulting in the effective separation of the electrons and holes. The photo-current measurements were performed using inert collecting electrodes in the suspensions of TiO 2, where formate was added as a hole scavenger, with and without a metal powder. Higher anodic photocurrent was obtained in the presence of a metal than in its absence, indicating that the metal-mediated electron transfer reaction occurs more effectively from the electron-rich TiO 2 particles to the collecting electrode than the direct discharge of the electron-rich TiO 2 on the collecting electrode.

Effect of metals on the liquid chromatographic determination of paralytic shellfish poisons

The effects of metal contamination on the liquid chromatographic (LC) determination of paralytic shellfish poisons have been investigated. There is an indication that the presence of ferric ions can cause conversion of at least one toxin to another. The mechanism of this reaction is at present unknown. In order to discover the effects of metal on the toxins, several approaches were adopted, including addition of metal ions or metal powders to paralytic shellfish poisons containing solutions. The authors show that the operation of a metal component LC system is generally vindicated.

Effect of adding metal powder and inorganic salt to a pyrolysis foil on selective pyrolysis of phenyl alkylamines by Curie-point pyrolysis-gas chromatography

The purpose of this study was to determine the effects on pyrolysis of metal powder and inorganic salt additives. Aniline, benzylamine, 2-phenyl-1-ethylamine and 3-phenyl-1-propylamine were used as samples for pyrolysis, because they have a benzene ring and an amino group as common structural units, and alkyl side chains of varying length. It can be concluded that the choice of metal and inorganic salt additives is one of the most important factors in the design of procedures allowing a high degree of control over the products of pyrolysis. It is suggested that the choice of metal should be made on the basis of bond dissociation energy, and the choice of salt on the basis of cation complexation ability with amine.

Curie-point pyrolysis-gas chromatography of aliphatic amines in the presence of metal powder and inorganic salt

A fundamental investigation has been undertaken to determine the optimum conditions for the addition of metal powder and metal chloride to a pyrolysis foil for the analysis of aliphatic amines by means of Curie-point pyrolysis-gas chromatography. It is suggested that the effectiveness of the addition of a suitable inorganic salt to the pyrolysis foil is associated with the ability of the metal ion to complex with amines. Nickel powder was useful when the pyrolysis was carried out at lower temperatures and chromium was preferred at higher temperatures. The suitable pyrolysis temperature was related to the molecular weight of the amine samples. The optimum conditions for the pyrolysis of three butylamines resembled one another. The recommended conditions for dibutylamine hydrochloride are that the pyrolysis be carried out at 333°C in the presence of a mixture of nickel powder and cobaltous chloride hexahydrate (10:3 w/w). The calibration curves for dibutylamine hydrochloride, constructed by using the peak area method, were linear over the sample size range of 2.1–41.2 μg. The relative standard deviation ( n = 4) was 2.56% for 20.6 μg.

Influence of rare earth metals on the nucleation and solidification behavior of iron and 1045 steel

Two series of experiments have been conducted to determine the influence of rare earth additions on the nucleation and crystallization behavior of pure iron and 1045 steel. In the first series, additions of rare earth suicide or cerium dioxide powder to two-Kg 1045 steel ingots indicated that rare earth suicide can refine the as-cast structure of such ingots. However, if the holding time after rare earth silicide addition is over two minutes, the grain refinement decreases. With cerium dioxide additions, a relatively large columnar zone was obtained. In the second series, the effects of cerium metal or cerium dioxide powder additions on the degree of undercooling obtainable in pure iron and 1045 steel were examined by the levitation melting method. Surface tension measurements of the levitated droplets were carried out at the same time to investigate the possible effects of surface tension variations on the nucleation and crystallization behavior of the metals. The experimental data show that rare earth inclusions can greatly reduce the degree of undercooling of iron and steel, and that a small amount of dissolved cerium can further reduce the degree of undercooling of levitated droplets. The structure and reaction products obtained with Fe-Ce levitated droplets were examined with both optical and scanning electron microscopy as well as X-ray diffraction analysis. The experimental results clearly indicated that cerium solute redistribution during solidification is the dominant factor in refining the as-cast structure. A nucleation and solidification model for the Fe-Ce levitated droplets has been developed, which can successfully explain the experimental results.

Automatic Submerged Arc Welding with Metal Powder Addition to Increase Productivity and Maintain Quality

This paper presents the results of a SNAME SP-7 Welding Panel research and development project recently completed by Newport New Shipbuilding. It was directed toward the evaluation, testing, and qualification of automatic submerged arc welding (SAW-AU) with metal powder additions for shipyard use. It is concluded that using controlled metal powder additions with SAW-AU is indeed a production concept that can reduce shipbuilding costs. This is possible through increased deposition rates and (possibly) reduced consumables costs while, at the same time, maintaining or improving quality.