Ar O2 Atmosphere Research Articles

アーク溶接過程における酸素吸収におよぼす合金元素の影響 ＩＩＩ Ｆｅ‐Ａｌ溶接金属の酸素吸収について

Pure iron plates were welded using Fe-Mn and Fe-Si-Mn alloy electrode wires in a controlled arc atmosphere. The effects of manganese and silicon-manganese on the oxygen contents and non-metallic inclusions in the weld metals were investigated under various welding conditions in Ar-O2 and Ar-CO2 welding atmospheres. The oxygen contents of the Fe-Mn and Fe-Si-Mn weld metals increase with an increasing the partial pressure of oxidizing gases and decrease with an increasing manganese and silicon-manganese contents in the weld metals. The oxygen contents of the weld metals welded in Ar-CO2 are lower than those in Ar-O2. The oxygen contents of the Fe-Si-Mn weld metals significantly decrease comparing with those of the Fe-Si and Fe-Mn weld metals. The nonmetallic inclusions in the Fe-Mn and Fe-Si-Mn weld metals increase with an increasing oxygen contents of the weld metals. The nonmetallic inclusions in the Fe-Mn weld metals are oxide of manganese-oxide accompanying with iron-oxide. The nonmetallic inclusions in the Fe-Si-Mn weld metals are oxide composed of silica, manganese-oxide and iron-oxide. Behavior of the oxygen absorption into the Fe-Mn and Fe-Si-Mn weld metals is discussed using thermodynamic data.

アーク溶接過程における鋼溶接金属の酸素吸収におよぼす合金元素の影響 ＩＩ Ｆｅ‐ＭｎおよびＦｅ‐Ｓｉ‐Ｍｎ溶接金属の酸素吸収について

Pure iron plates were welded using Fe-Mn and Fe-Si-Mn alloy electrode wires in a controlled arc atmosphere. The effects of manganese and silicon-manganese on the oxygen contents and non-metallic inclusions in the weld metals were investigated under various welding conditions in Ar-O2 and Ar-CO2 welding atmospheres. The oxygen contents of the Fe-Mn and Fe-Si-Mn weld metals increase with an increasing the partial pressure of oxidizing gases and decrease with an increasing manganese and silicon-manganese contents in the weld metals. The oxygen contents of the weld metals welded in Ar-CO2 are lower than those in Ar-O2. The oxygen contents of the Fe-Si-Mn weld metals significantly decrease comparing with those of the Fe-Si and Fe-Mn weld metals. The nonmetallic inclusions in the Fe-Mn and Fe-Si-Mn weld metals increase with an increasing oxygen contents of the weld metals. The nonmetallic inclusions in the Fe-Mn weld metals are oxide of manganese-oxide accompanying with iron-oxide. The nonmetallic inclusions in the Fe-Si-Mn weld metals are oxide composed of silica, manganese-oxide and iron-oxide. Behavior of the oxygen absorption into the Fe-Mn and Fe-Si-Mn weld metals is discussed using thermodynamic data.

Proximity-Effect and Tunneling in YBa2Cu3O7/Metal Layered Structures

AbstractSuperconducting thin films of YBa2Cu3O7 are prepared in-situ by on-axis, sputter deposition from a single, composite target. Our planar magnetron target composition of Y:Ba:Cu = 1.08:1.76:4.5 sputtered onto MgO at T~750°C in a 600mTorr Ar-O2 atmosphere yields reproducible superconducting films having Tc(R = 0)>80K and stoichiometry 1:2:3, that are shiny and of near epitaxial, crystalline quality. In order to ensure clean interfaces, YBa2Cu3O7/normal metal bilayers (to form SNS' Josephson junctions) and YBa2Cu3O7/normal metal/insulating barrier trilayers (to form SNIS' proximity tunnel junctions) are grown completely in-situ. (The S' = Pb counter electrode is evaporated ex-situ.) A supercurrent and Shapiro steps are observed in microwave irradiated SNS' (N = Ag) small area (5x10-5cm2) junctions. In SNIS' tunnel junctions, high-quality Pb tunneling is observed.

Characteristics of Nb-based tunnel junctions fabricated by selective trilayer ion-beam etching process

Characteristics of Nb/Nb oxide/Pb‐alloy junctions fabricated by selective trilayer ion‐beam etching process have been studied with respect to junction quality, reproducibility, uniformity, and thermal stability. The key steps in the process comprise in situ junction trilayer formation involving thermal oxidation, junction area definition by deep ultraviolet photolithography, and highly selective Pb‐alloy layer patterning by ion‐beam etching in an Ar–O2 atmosphere. Especially, the junctions fabricated in this process have exhibited excellent uniformity and reproducibility with PbAuIn and PbIn counterelectrodes. Standard deviations in critical current for 100 series‐connected junctions with 4×4 and 2×2 μm areas are 0.8% and 2.4%, respectively. The junctions with critical currents of about 80% of Bardeen–Cooper–Schrieffer values and without any knee structure in I–V curves are obtained reproducibly over a wide critical current range from 102 to 104 A/cm2. Annealing tests have indicated that these junctions h...

Stoichiometry control mechanisms for bias-sputtered zinc-oxide thin films

We have deposited transparent, conducting ZnO thin films of resistivity 3 × 10−3 Ω∙cm by the technique of DC planar-magnetron sputtering in a reactive Ar–O2 atmosphere, incorporating a reactive gas baffle and substrate RF discharge. The substrate discharge was found to increase the oxygen content of the growing film. Films at low values of the RF-induced substrate self-bias voltage were characterized by a brown colour, resistivities of about 4 × 10−2 Ω∙cm, and composition ZnO0.8. Films at higher bias voltages of −80 V were clear with resistivities of 3 × 10−3 Ω∙cm and a composition approaching stoichiometric ZnO. The oxidation of the films by the RF discharge was shown to occur through preferential resputtering and re-evaporation of excess zinc and by activation and ion-plating of oxygen species. Resputtering and re-evaporation rates were found to be enhanced above that expected for bulk Zn, owing to the loosely bound nature of surface adatoms during film growth.

反応スパッタＦｅ３Ｏ４膜の熱処理に伴う特性変化

The magnetic properties of sputtered iron oxide films have been studied. Fe3O4 films were directly formed by reactive sputtering of an Fe target in Ar-O2 atmosphere, and were annealed in a temperature range from 265 to 345°C.Coercive force Hc of the films at low temperatures increased with increasing annealing temperature, though the decrease in coercivity was reported for powder specimens. The values of Hc and Mr/Ms, were also affected by crystallite orientation of the films. The relation between Hc and structure of the films was discussed.

Cadmium–tin-oxide films deposited by dc reactive sputtering from a Cd-Sn alloy target

Cadmium–tin-oxide films with high conductivity and high visible transmission were prepared by dc reactive sputtering from a Cd-Sn alloy target in an Ar-O2 atmosphere. The electrical and optical properties of these films were found to depend strongly uponthe oxygen concentration in an Ar-O2 atmosphere during deposition. Films with a lowest resistivity of 2.0×10−4 Ω cm and a highest transmission of 90% over the visible region have been obtained for a 6% oxygen concentration in an Ar-O2 atmosphere.

Cadmium-tin oxide films deposited by rf sputtering from a CdO-SnO2 target

Cadmium-tin oxide (CTO) films with high conductivity and high transparency were prepared by rf sputtering from a CdO-SnO2 target in an Ar or Ar-O2 atmosphere. The resistivity of CTO films was 6.5×10−4 Ω in the film thickness range of 2500–15000 Å, and the average transmission was 90% over the visible region.

Cr-Cu and Cr-Cu-Cr thin film metallization : J. J. O'Neill and J. L. Vossen. J. Vac. Sci. Technol. 10 (4), 533–538 (July-Aug. 1973)

Elemental chromium and Cr-Cu powder mixtures were milled in a vibrational ball mill under air-, nitrogen- and oxygen-containing argon atmospheres. Structural changes during milling and the thermal stabilities of the milled powders were examined by means of X-ray analysis, transmission electron microscopy and differential scanning calorimetry. The amounts of the gaseous elements absorbed by the powder particles during milling were also determined from the pressure reduction in the vial. It was found that large amounts of nitrogen were absorbed during milling in argon-air and argon-nitrogen atmospheres, resulting in significant grain refinement and subsequent amorphization of chromium and Cr70Cu30 powders. On annealing, crystallization of the amorphized powders occurred accompanied by the formation of a stable Cr2N phase. Amorphization did not occur in either the chromium or the Cr-Cu powders when milled in a pure argon or Ar-O2 atmosphere. A thermodynamic explanation for the grain refinement and the amorphization was proposed.

Thin-film thermoelectric transducer for measurements of low-level power between 0 and 11 GHz : R. Koike. Proc. IEE121, 28 (1974)

Elemental chromium and Cr-Cu powder mixtures were milled in a vibrational ball mill under air-, nitrogen- and oxygen-containing argon atmospheres. Structural changes during milling and the thermal stabilities of the milled powders were examined by means of X-ray analysis, transmission electron microscopy and differential scanning calorimetry. The amounts of the gaseous elements absorbed by the powder particles during milling were also determined from the pressure reduction in the vial. It was found that large amounts of nitrogen were absorbed during milling in argon-air and argon-nitrogen atmospheres, resulting in significant grain refinement and subsequent amorphization of chromium and Cr70Cu30 powders. On annealing, crystallization of the amorphized powders occurred accompanied by the formation of a stable Cr2N phase. Amorphization did not occur in either the chromium or the Cr-Cu powders when milled in a pure argon or Ar-O2 atmosphere. A thermodynamic explanation for the grain refinement and the amorphization was proposed.

Croissance de monocristaux d'orthoferrite d'yttrium par tirage czochralski

Single crystals of yttrium orthoferrites have been grown for the first time using the Czochralski technique. Starting from high purity oxides Y2O3 and Fe2O3 and using the congruent melting of YFeO3 near 1700 C in ArO2 atmosphere, it is possible, from particular and well-oriented seeds, to obtain perfectly oriented [001] crystals of YFeO3, 15 to 30 mm in diameter and several mm in length. The magnetostriction and magnetodynamic properties of such crystals, as well as the optical absorption spectra and the results of chemical analysis are presented and compared with those of flux grown crystals.

Pressure dependence of the absolute catalytic efficiency of surfaces for removal of atomic nitrogen: R.A. Young, J. Chem. Phys., 34 (4), April 1961, 1292–1294

Oxidation behaviors of three-dimensional woven C/PyC/SiC and SiC/PyC/SiC prepared by CVI processing were investigated in an O2-Ar atmosphere at 600 °C, 900 °C and 1200 °C, respectively, by using thermogravimetric analysis. After machining, both composites should be protected by CVD SiC coating, which was demonstrated effectively in improving the oxidation resistance of both composites. The oxidation behavior of SiC/PyC/SiC was different from that of C/PyC/SiC. The oxidation kinetics of C/PyC/SiC was controlled by the rate of the reaction between carbon and oxygen at 600 °C and by the oxygen diffusion through the coating microcracks at 900 °C. The oxidation kinetics of SiC/PyC/SiC at both 600 °C and 900 °C were assumed to be controlled by the oxygen diffusion through channels of coating and matrix defects and looped pipelines instead of PyC interphase. At 1200 °C, the oxidation was controlled by oxygen diffusion through the SiO2 scale, which took place mainly on the surfaces of both composites.